BACKGROUND ART With the increasing recognition that carbohydrates play fundamental roles in many critical biochemical processes, including cell-to-cell recognition, cell-adhesion, neural cell development and tumour metastasis, more and more attention has been paid to such compounds (and their analogues) as potential therapeutic agents. Since carbohydrates themselves incorporate chemically and metabolically vulnerable acetal and/or hemi-acetal linkages at the anomeric carbon (C1), methods for replacing these linkages with more robust functionalities that do not alter the fundamental biological properties of the would-be therapeutic agent have been pursued. One class of highly stable carbohydrate derivatives that often retains the shape and function of the original compound are the C-glycosides in which the anomeric carbon to oxygen bond has been replaced by a Cl to carbon bond. Because of the proven metabolic stability of members of the C-glycoside class, such compounds are receiving much attention as a potential source of therapeutic agents. There is an attendant need to develop efficient (in terms of chemical yield, stereoselectivity and flexibility) syntheses of C-gylcosides and there are numerous reports in the literature of such syntheses.

(i) The previously reported syntheses are variations of the following fundamental inter-or intra-molecular addition of a carbon-centred electrophile to a carbohydrate processes: (ii) inter-or intra-molecular addition of a carbon-centred nucleophile to a carbohydrate- based electrophile bearing positive character at Cl ; -based nucleophile bearing negative character at Cl ; (iii) inter-or intra-molecular addition of a Cl-centred radical to radical acceptor; (iv) de raovo syntheses involving, inter alia, cycloaddition and cyclisation processes to create the tetrahydro-pyranyl or-furanyl ring system (s) associated with the target C- glycoside.

There is a need for processes for synthesising C-glycosides which have at least one of the following characteristics: (i) they proceed in a satisfactory chemical yield (generally greater than 20%);

(ii) there is control over the isomerism at the anomeric carbon; (iii) they employ simple and readily available starting materials; and (iv) they are flexibile in that a variety of related C-glycosides can be obtained and which are capable of elaboration, by simple methods, to other useful C-glycosides with different chemical (including stereochemical) properties.

Whilst anomeric nucleophiles and radicals have been exploited in the generation of C- glycosides, the addition of a C-centred nucleophile to an activated and electrophilic C- glycosyl donor represents by far the most common approach to the title compounds. In this context, pyrroles seem to have been overlooked despite the fact that (i) they are very effective carbon-centred nucleophiles, (ii) that electrophilic attack at C2 or C3 of this heterocycle can be controlled by appropriate substitution at the ring nitrogen and, (iii), the pyrroles are capable of manipulation in remarkably diverse ways. This oversight may be attributed to the reputation of pyrroles as somewhat intractable compounds especially when exposed to other organic compounds in the presence of acidic reagents.

SUMMARY OF THE INVENTION The object of the invention is to provide a process for the synthesis of C-glycosides utilising readily available precursors and in synthesis there is at least some control of stereochemistry at the anomeric carbon.

In a broad format, the invention provides a process for the synthesis of C-glycosides, the process comprising the steps of : (i) reacting an O-glycosyl trichloroimidate with a pyrrole in the presence of a Lewis acid; and (ii) isolating said C-glycoside from the reaction mixture formed in step (i).

In other embodiments, the invention provides C-glycosides produced by the process of the invention and certain C-glycosides per se.

Additional embodiments of the invention will become apparent from a reading of the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION The present inventors have, surprisingly, found that O-glycosyl trichloroacetimidates react with pyrroles in the presence of a suitable Lewis acid to give, in satisfactory chemical yields, pyrrole C-glycosides. An advantage of such C-glycosides is that the pyrrole moiety within such products can be manipulated in various simple ways so as to generate other potentially useful C-glycosides.

Scheme 1 below illustrates a synthesis according to the invention where the precursors of the C-glycoside are peracetylated O-maltosyl trichlaroacetimide and pyrrole. Details of this synthesis are given below. Ac0 HN CC13 AcOA qz I AcO,,,,. O 0 11- + OAc OAc OAc OAc y catalyst see Table 1 Ace 41 OAc 3' Au31' AcO,,,,, 6 1 a N i ,, 5 \v H fC II 0,, 4 3 2, DAC OAc OAc OAc OAc OAc OAc

2 The glycosyl moiety of the O-glycosyl trichloroacetimidate can be any moiety falling within the definition in the art of a glycosyl fragment or radical. However, it will be appreciated that reactive groups on the moiety must be protected. Any of the protective groups known to those of skill in the art can be employed including benzyl and silyl ether- based protecting groups as well as various acetals.

The pyrrole component can be pyrrole per se as shown in Scheme 1 or derivatives thereof. Such derivatives include N-silylated pyrroles.

The Lewis acid used in the reaction is typically trimethylsilyl triflate (TMSOTf) or BF3-Et2O. A preferred Lewis acid is BF3 Et20.

Reactions are carried out in any suitable organic solvent and typically at a reduced temperature. Temperatures as low as-100°C can be used for the process with the preferred temperature generally being ca.-50°C. The reaction time will depend on the reactants and temperature but generally falls within the range of 1 minute to of the order of a day.

The C-glycoside product of a reaction can be isolated from a reaction mixture by any of the processes known to those of skill in the art. Similarly, in instances where a synthesis yields a mixture of a-and 0-isomers, the isomers can be separated using known techniques.

In general terms, the present invention falls within the category (i) process listed in the "Background Art"section. Furthermore, the precursors to the required carbohydrate-based electrophile (or glycosyl donor) are the readily available and easily handled glycosyl trichloroacetimidates. The novel aspect of the present invention is the use of pyrrole and its derivatives as the carbon-centred nucleophile for C-glycoside formation. Such nitrogen- containing heterocycles have not been used, at least in a non-C-metallated form, previously for the formation of C-glycosides.

The use of pyrroles in this manner is important for three fundamental reasons: (i) Pyrroles are readily available and potent carbon-centred nucleophiles.

(ii) In the parent, N-substituted and other C2-symmetric pyrroles, there are generally two non-equivalent carbon centres (C2 and C3) available which can react with the carbohydrate-based electrophile to give C-gylcosides in which the carbohydrate residue becomes attached at either C2 or C3 of the pyrrole ring. By controlling the nature of the substituent at N1 of the pyrrole, the selective formation of either one of the above- mentioned C-gylcosides can be achieved. With groups present at other positions on the pyrrole ring then alternate substitution patterns in the product C-glycoside can also be obtained. Consequently, a diverse range of C-gylcosides varying in the nature and pattern of substituents present on the pyrrole ring can be obtained.

(iii) In addition to functionalising the pyrrole ring prior to its attachment to the carbohydrate residue, this nitrogen heterocycle could be manipulated (for example, via hydrogenation, acylation, halogenation, or halogenation followed by cross-coupling) after its incorporation into the C-glycoside so as to give an entirely new collection of C- glycosides.

Furthermore, the regochemical outcomes of reactions can be controlled by varying the nature of the substituents on the pyrrole ring. This is illustrated below. The pyrrole C- glycosides formed by the process of the invention are also amenable to interconversion between a and (3-forms by sustained treatment with the appropriate catalyst.

Beyond providing an operationally simple and useful new platform for the preparation of novel C-gylcosides, the invention can be utilised in the ways to be summarised hereafter.

A first use of the process of the invention is for the synthesis of C-nucleoside analogues that might display anti-bacterial, anti-viral and/or anti-tumour properties.

Secondly, in general C-glycosides can yield enzyme inhibitors (e. g. of glycosidases) with structures that may be difficult or impossible to construct utilising standard carbohydrate chemistry and the pyrrole-based subset of such compounds available through the present invention should be no exception to this rule. Potential targets, beyond those implied in the preceding paragraph, include enzymes on the shikimic acid pathway (that if inhibited could lead to new herbicides) and leukotriene-based enzymes (inhibition of which could lead to anti- inflammatory agents as well as treatments for asthma, rheumatism, psoriasis and arthritis).

Thirdly, the use of pyrrole-centred nucleophiles for the formation of C-glycosides lends itself to the application of solid-phase synthesis techniques such that the construction of combinatorial libraries of such C-glycosides can be undertaken and then subject to high- throughput screening techniques in order to identify, for example, new enzyme inhibitors.

Fourthly, the process can be used for the construction of dendritic and similar pyrrole- based C-glycosides that can be used to mimic the polyvalent nature of many pathogen-host cell interactions and thereby provide inhibitors of such processes.

Fifthly, the tetramerisation of certain pyrrole-based C-glycosides can provide porphyrins derivatised with robust C-glycoside residues that can be used in cell-targeted photodynamic therapy regimes for the treatment of solid tumours.

Non-limiting examples of the invention follow. The examples include possibilities for the hydrogenation, acylation and halogenation of a pyrrole ring incorporated into a C- glycoside.

Example 1 Testing of Lewis Acid Catalysts and Reaction Conditions A variety of Lewis acids and reaction conditions were used in connection with the reaction shown in Scheme 1 above. Dichloromethane was used as the solvent in each case with powdered 4 A molecular sieves present in reaction mixtures. In all experiments, approximately 2.5 mole equivalent of the relevant Lewis acid was employed. The experimental results are presented in Table 1 below.

Table 1 Reaction of Trichloroacetimidate 1 and Pyrrole in the Presence of Various Lewis Acids <BR> <BR> <BR> <BR> <BR> Entry Lewis acid Equiv. Temp.(°C)/Time Yield of 2<BR> pyrrole <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> 1 TMSOTf 5 0°/45 min 20% 2 TMSOTf 5 -40°/20 min 53% 3 TMSOTf 5-50 20 min 54% 4 TMSOTf 5-78°/2 min 15% 5 BF3Et2O 5-50 20 min 84% 6 BF3Et20 2-50 20 min 56% The above results indicate that use of BF3'Et20 as promoter and a reaction temperature of-50°C (Entry 5) represent close to the best conditions for this glycosylation process.

Interestingly, reaction of the a-maltosyl bromide analogue of 1 with pyrrole in the presence of silver carbonate/iodine under various conditions failed to deliver any significant quantities of compound 2. Further, although TMSOTf reputedly activates lactose octaacetate, no reaction was observed, at-78 °C, between 0-maltose octaacetate and pyrrole in the presence of this promoter.

The optimum conditions defined above lead exclusively to the C-glycoside 2 with the stereochemistry of this material being readily established by'H NMR spectroscopic analysis.

In particular, the resonance due to H1 in compound 2 appears as a doublet at 6 4.55 with J 10.0 Hz, thus implying a trans-diaxial relationship for H1/H2 and, thence, the illustrated fl- configuration of the pyrrole ring at the anomeric centre. The location of the glycosyl moiety at C2'on the heterocyclic ring follows from the 13C NMR spectrum which shows that both the higher field resonances (at 8 108.5 and 107.6), due to the C3'and C4', derive from protonated carbons. Not surprisingly, substituents at nitrogen on the pyrrole ring can redirect attack of the glycosyl donor to C3'. Thus, reaction of compound 1 with N-methylpyrrole under the above- mentioned conditions afforded a ca. 2: 1 mixture of the C2'and C3'glycosylated products, albeit in an unoptimised yield of 20%. In contrast, and in keeping with outcome of the reaction of non-carbohydrate based electrophiles with N-(tri-isopropylsilyl) pyrrole, 8 treatment of this compound with trichloroacetimidate 1 in the presence of BF3Et2O afforded the C3'-product 3 (31%) exclusively, although now as a ca. 1: 2.5 mixture of a and (3-anomers. Details of the compound 3 are given below.

Example 2 Synthesis of Specific C-glycosides <BR> <BR> 2-(2, 2'3, 3'4'6, 6'-Hepta-O-acetyl-l-deoxy-, ßmaltosyl) py7role (2).

1 2 A magnetically stirred mixture of trichloroacetimidate 1 (160 mg, 0.20 mmol) and powdered 4A molecular sieves (1.00 g) in anhydrous CH2C12 (15 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to-50 °C. Pyrrole (0.07 mL, 1.00 mmol) and BF3Et2O (0.07 mL, 0.50 mmol) were then added, the resulting mixture stirred at-50 °C for 0.33 h and then filtered through a pad of CeliteTM which was washed with CH2CI2 (20 mL). The combined filtrates were washed with NaHCO3 (1 x 20 mL of a saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2SO4), filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subject to flash chromatography (silica gel, 3: 17 v/v acetone/toluene elution) and concentration of the appropriate fractions (Rf 0. 2) afforded C-glycoside 2 (115 mg, 84%) as slightly light-sensitive and white, microcrystalline masses, mp 75-77 °C, [a] D +51 (c 0.5, CHC13) (Found: C, 51. 95 ; H, 5.77 ; N, 1.90%. C3oH39NO17 requires C, 52.55 ; H, 5.73 ; N, 2.04%) ; Vmax (NaCl)/cm-l 3409,1748, 1650,1370, 1233,1039, 899,736, 602; #H (CDC13, 300 MHz) 8.42 (1H, broad s, NH), 6.74 (1H, ddd, J2. 6,2. 6 and 1.7, H5"), 6.09 (2H, m, H3"and H4"), 5.45 (1H, d, J4. 0, H1'), 5.37 (2H, m), 5.06 (1H, t, J 10.2), 5.02 (1H, t, J9. 9), 4.87 (1H, dd, J 10.6 and 4.0), 4.55 (1H, d, J 10.0, Hl), 4.46 (1H, dd, J 12.1 and 2.5), 4.27 (1H, t, J3. 4), 4.23 (1H, t, J4. 1), 4.05 (2H, m), 3.97 (1H, m), 3.79 (1H, ddd, J 9. 6,4. 4 and 2. 5), 2.12 (3H, s), 2.10 (3H, s), 2.05 (3H, s), 2.02 (3H, s), 2.00 (3H, s), 1.99 (3H, s), 1.88 (3H, s); dc (CDC13, 75 MHz) 170.6, 170.5, 170.2, 169.9, 169.6, 169.4, 167.7, 125.7, 118.6, 108.5, 107.6, 95.6, 76.1, 73.7, 72.8, 71.8, 69.9, 69.3, 68.5, 68. 1,67. 9,63. 2,61. 4,20. 9 (4), 20.8 (6), 20.7, 20.6, 20.5 ; m/z (ESI) 707.7 [ (M +

Na) +, 9%], 685.9 [ (M + H) +, 11], 589.0 (19), 457.0 (8), 414.0 (15), 396.1 (8), 380.1 (7), 330.8 (9), 283.9 (14), 191.9 (24), 173.9 (37), 84.1 (100), 71.1 (76), 60.0 (60).

3-(2,2',3,3',4',6,6'-Hepta-O-acetyl-1-deoxy-ß-maltosyl)- 1-(triisopropylsilyl)pyrrole (3).

3 A magnetically stirred mixture of trichloroacetimidate 1 (160 mg, 0.20 mmol) and powdered 4A molecular sieves (1.00 g) in anhydrous CH2C12 (15 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to-50 °C. N-(triisopropylsilyl) pyrrole (0.25 mL, 1.00 mmol) and BF3Et2O (0.07 mL, 0.50 mmol) were then added, the resulting mixture stirred at-50 °C for 0.33 h and then filtered through a pad of CeliteTM which was washed with CH2C12 (20 mL). The combined filtrates were washed with NaHCO3 (1 x 20 mL of a saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2S04), filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subject to flash chromatography (silica gel, 3: 17 v/v acetone/toluene elution) and concentration of the appropriate fractions (Rf 0.2) afforded C-glycoside 3 (52 mg, 31%) as slightly light-sensitive and white microcrystalline masses, mp 43-45 °C, D- +42 (c 0.5, CHC13) [HRMS Found: 842.3649. C39H59NO17Si requires (M + H) + 842. 3631]. iH-NMR analysis revealed this to be a 1: 2.5 mixture of a-and p-anomers ; vmax (NaCl)/cm-1 1748, 1369,1227, 1147,1038, 883,659 ; 9H (CDC13, 300 MHz) α-anomer: 6.72 (1H, t, J2.0, H2"or H5"), 6.69 (1H, t, J2. 4, H2"or H5"), 6.26 (1H, dd, J 1.5 and 2.4, H4"), 5.60 (1H, obscured d, H1), 5.47 (1H, d, J3. 9, H1'), 5.39 (1H, t, J9.8), 5.33 (1H, t, J9. 3), 5.07 (1H, m), 4.89 (1H, dd, J3. 9 and 10. 7), 4.47 (1H, d, J10. 3), 4.43 (1H, dd, J2. 4 and 11.4), 4.26 (2H, m), 4.06 (3H, m), 3.78 (1H, ddd, I2. 9,3. 9 and 9. 8), 2.10 (3H, s), 2.06 (3H, s), 2.02 (3H, s), 2.00 (3H, s), 1.99 (3H, s), 1.78 (3H, s), 1.41 (3H, sept, J 7. 3), 1.06 (18H, d, J 7. 3) ; anomer: 6. 70 (1H, t, J2. 4, H2"or H5"), 6.67 (1H, t, J 2. 9, H2"or H5"), 6.15 (1H, dd, J 1.5 and 2.4, H4"), 5.60 (1H, obscured d, H1'), 5.45 (1H, t, J9. 3), 5.07 (2H, m), 4.87 (1H, dd, J3. 9 and 10.3), 4.31 (1H, dd,

J2. 0 and 8.2), 4.26 (3H, m), 4.06 (4H, m), 3.62 (1H, d, J8. 8), 2.14 (3H, s), 2.13 (3H, s), 2.09 (3H, s), 2.04 (3H, s), 2.03 (3H, s), 1.83 (3H, s), 1.41 (3H, sept, J 7. 3), 1.07 (18H, d, J7. 3); dc (CDC13, 75 MHz) 170.8, 170.6, 170.5, 170.2, 169.6, 169.4, 127.8, 124.9, 124.7, 121.3, 108.8, 108.3, 97.0, 94.6, 74.7, 74.0, 72.2, 70.4, 70.1, 68.9, 68.3, 68.1, 67.1, 64.1, 61.8, 27.4, 20. 8, 20.72, 20.66, 20.6, 17.8, 11.6 ; m/z (ESI) 880. 3 [(M + K) +, 10%], 864.3 [ (M + Na) +, 100], 457.2 (6), 384.2 (5), 284.2 (9), 266.1 (56), 239.1 (20), 192.1 (41), 156.0 (10), 130.2 (13), 101.7 (49).

2- (2, 3, 4, 6-Tetra-O-acetyl-l-deoxy-ß-glucopyranosyl) pyrrole (6).

4 6 A magnetically stirred mixture of trichloroacetimidate 4 (110 mg, 0.22 mmol) and powdered 4A molecular sieves (1.00 g) in anhydrous CH2C12 (15 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to-78 °C. Pyrrole (0.08 mL, 1.10 mmol) and BF3-Et2O (0.07 mL, 0.55 mmol) were then added, the resulting mixture stirred at-78 °C for 0.33 h and then filtered through a pad of CeliteTM whice was washed with CH2C12 (20 mL). The combined filtrates were washed with NaHC03 (1 x 20 mL of a saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2S04), filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subject to flash chromatography (silica gel, 3: 17 v/v acetone/toluene elution) and concentration of the appropriate fractions (Rf 0.2) afforded C-glycoside 6 (63 mg, 72%) as slightly light-sensitive and white microcrystalline masses, mp 158-160 °C*, [a] D +2 (c 1.5, CHC13) [HRMS Found: 398. 1440. C1gH23N09 requires (M + H) + 398.1451] ; vmaX (NaCl)/cm-l 3352,1749, 1599, 1432,1369, 1231,1100, 1035,914, 826,732, 599; 9H (CDC13, 300 MHz) 8.52 (1H, br s, NH), 6.77 (1H, m, H5'), 6.12 (2H, m, H3'and H4'), 5.24 (3H, m), 4.52 (1H, d, J 10.0, HI), 4.28 (1H,

dd, J 4. 8 and 12.4), 4.12 (1H, dd, J3. 2 and 12.3), 3.83 (1H, ddd, J2. 2,4. 8 and 10.0), 2.08 (3H, s), 2.05 (3H, s), 2.01 (3H, s), 1.90 (3H, s); dic (CDC13, 75 MHz) 170.6, 170.2, 169.4, 169.2, 125.3, 118.9, 108.4, 108. 2,75. 9,74. 2,74. 0,71. 0,68. 4,62. 3,20. 9,20. 74,20. 71,20. 6; m/z (ESI) 435.7 [ (M + K) +, 23%], 419.8 [ (M + Na) +, 56], 397.8 [ (M + H) +, 68], 380.0 (39), 337.8 (19), 295.7 (19), 285.9 (29), 277.7 (53), 235.8 (31), 217.9 (50), 191.7 (100), 173.9 (74), 85.0 (34), 83.9 (39).

* NB: partially melts at approx 75 °C, remainder melts at 158-160 °C.

2-(2, 3, 4, 6-Tetra-O-acetyl-l-deoxy-or-mannopyranosyl) pyrrole (7).

5 7 A magnetically stirred mixture of trichloroacetimidate 5 (130 mg, 0.26 mmol) and powdered 4A molecular sieves (1.00 g) in anhydrous CH2C12 (15 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to-50 °C. Pyrrole (0.09 mL, 1.30 mmol) and BF3Et2O (0.08 mL, 0.65 mmol) were then added, the resulting mixture stirred at-78 °C for 0.33 h and then filtered through a pad of CeliteTM which was washed with CH2C12 (20 mL). The combined filtrates were washed with NaHC03 (1 x 20 mL of a saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2S04), filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subject to flash chromatography (silica gel, 3: 17 v/v acetone/toluene elution) and concentration of the appropriate fractions (Rf 0.2) afforded C-glycoside 7 (86 mg, 83%) as slightly light-sensitive and white microcrystalline masses (mp not recorded). After solution in CDC13 the pure compound obtained from chromatography rapidly gave a 3: 5 mixture of the original product (presumed to be a) and its other anomeric form, which was recovered as a colourless syrup, [CCID +36 (mixture, c 1.2, CHC13) (HRMS data for ClgH23N09 to be collected); Vmax

(NaCl)/cm-l 3391,1745, 1369,1228, 1050,914, 734,601 ; 9 (CDC13, 300 MHz) a-anomer : 8.55 (1H, br s, NH), 6.85 (1H, in, H5'), 6.41 (1H, ddd, J 1.2, 2.6 and, H3'or H4'), 6.20 (1H, dd, J2. 6 and 6.0, H3'or H4'), 5. 87 (1H, dd, J2. 2 and 2.8), 5. 33 (2H, m), 5.13 (1H, br s, H1), 4. 30 0 (1H, dd, J5. 3 and 12.2), 4.09 (1H, dd, J2. 5 and 12.2), 3. 66 (1H, ddd, J2. 5,5. 3 and 8.4), 2.19 (3H, s), 2.12 (3H, s), 2.04 (3H, s), 2.01 (3H, s) ; anomer : 8.40 (1H, br s), 6.74 (1H, dt, J 1. 6 and 2. 8, H5'), 6.12 (dt, J, 2. 8 and 3. 4, H3'or H4'), 5.99 (1H, m, H3'or H4'), 5.61 (1H, dd, J 1.2 and 3.4), 5. 36 (2H, m), 5.16 (1H, dd, J 3, 4 and 10.1), 4. 85 (1H, br s, H1), 4. 32 (1H, dd, J 5.7 and 12.3), 4.18 (1H, dd, J2. 5 and 12.3), 3.81 (1H, ddd, J 2. 3,5. 7 and 9.8), 2.10 (3H, s), 2.08 (3H, s), 2.05 (3H, s), 2.00 (3H, s); ic (CDC13, 75 MHz) 170.62, 170.58, 170.09, 170.05, 170.0, 169.9, 169.6, 169.5, 125.7, 124.7, 119.1, 117.8, 108.9, 108.6, 108. 5,105. 5,73. 8,72. 7, 72.2, 71.1, 70.4, 70.2, 68.8, 66.3, 65.9, 62.9, 62.6 (+ 1 signal obscured by solvent); m/z (ESI) 420.0 [(M + Na) +, 9%], 380. 3 (16), 258. 1 (10), 214.4 (11), 192.1 (100), 173.9 (6), 104.6 (13), 63.3 (16).

S-O-tert-Butyldiphenylsilyl-2, 3-0-isopropylidene-ß-ribofuranosyl trichloroacetimidate (8).

8 A magnetically stirred mixture of 5-O-tert-butyldiphenylsilyl-2, 3-O-isopropylidene- ribofuranose (2.59 g, 6.03 mmol), trichloroacetonitrile (1.51 mL, 15.1 mmol) and Cs2CO3 (0.20 g, 0.60 mmol) in anhydrous CH2C12 (40 mL) was maintained at 18 °C for 5 h under a nitrogen atmosphere. The mixture was washed with water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2S04), filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subjected to flash chromatography (silica gel, 1: 9 v/v ethyl acetate/pentane elution) and concentration of the appropriate fractions (Rf 0.2) afforded trichloroacetimidate 8 (0.82 g, 43% based on recovered starting material) as a colourless

syrup, [a] D-38.3 (c 1.6, CHC13), (HRMS data for C26H32Cl3N05Si to be collected); #max (NaCl)/cm-l 3342,3072, 1670,1472, 1428, 1373,1317, 1264,1211, 1161,1113, 1071,969, 927,870, 824,797, 647,614, 569,504 ; #H (CDC13,300 MHz) 8. 43 (1H, s), 7.63 (4H, m), 7.39 (6H, m), 6.23 (1H, s), 4.84 (1H, d, J 5.9), 4.72 (1H, d, J 6.0), 4.50 (1H, dd, J 5.0 and 10.6), 3.74 (1H, dd, J 5. 0 and 10.4), 3.60 (1H, t, J 10.4), 1.53 (3H, s), 1.36 (3H, s), 1.08 (9H, s) ; dc (CDC13, 75 MHz) 160.3, 135.44, 135.39, 133.0, 132.7, 129.75, 129. 73, 127.6, 112.8, 106.2, 90.7, 87.8, 84.7, 81.7, 63.7, 26.9, 26.4, 25.0, 19.2 ; m/z (ESI) 609.7 [ (M + K) +, 14%], 593.6 [ (M + Na) +, 19], 457.0 (16), 380.1 (26), 352.9 (7), 283.9 (14), 235.9 (21), 191.8 (77), 173.7 (100), 156. 0 (24), 100.9 (18), 97.9 (26), 87.9 (16), 56.0 (41).

2-(5-0-tert-Butyldiphenylsilyl-l-deoxy-2, 3-0-isopropylidene-ribofuranosylppyrrole (9).

9 A magnetically stirred mixture of trichloroacetimidate 8 (130 mg, 0.22 mmol) and powdered 4A molecular sieves (1.00 g) in anhydrous CH2C12 (15 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to-78 °C. Pyrrole (0.08 mL, 1.10 mmol) and BF3Et2O (0.23 mL of a 0.16 M solution in anhydrous ether, 0.04 mmol) were then added, the resulting mixture stirred at-78 °C for 0.33 h and then filtered through a pad of CeliteTM which was washed with CH2C12 (20 mL). The combined filtrates were washed with NaHCO3 (1 x 20 mL of a saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2S04), filtered and concentrated under reduced pressure to give a light-yellow oil.

This material was subject to flash chromatography (silica gel, 1: 4 v/v ethyl acetate/hexane elution) and concentration of the appropriate fractions (Rf0. 2) afforded C-glycoside 9 (55 mg, 52%) as a colourless syrup, [a] D-14 (c 0.3, CHC13), [HRMS Found: 478.2409. C28H35NO4Si requires (M + H) + 478. 2414]. 1H-NMR analysis indicated that this was an approximately 4: 1

mixture of a and 3 anomers; vmax (NaCl)/cm-l 3452,3071, 3049,1589, 1472,1428, 1381, 1211,1160, 1113,1072, 901,823, 793,737, 702,613, 504, Q (CDC13, 300 MHz) major (a) isomer 9.03 (1H, br s, NH), 7.70 (4H, m), 7.43 (6H, m), 6.85 (1H, m, H5'), 6.23 (1H, m, H3'or H4'), 6.19 (1H, m, H3'or H4'), 5.33 (1H, d, J3. 4, H1), 5.03 (1H, dd, J 1.2 and 5.9), 4.86 (1H, dd, J3. 4 and 5.9), 4.15 (1H, t, J 3. 4), 3.90 (1H, dd, J3. 8 and 11.0), 3.79 (1H, dd, J3. 5 and 11.0), 1.64 (3H, s), 1.40 (3H, s), 1.10 (9H, s), minor (} S) isomer 8.65 (1H, br s, NH), 7.70 (4H, m), 7.43 (6H, m), 6.49 (1H, m, H5'), 6.11 (2H, m, H3'and H4'), 5.12 (1H, d, J3. 2, H1), 4. 79 (1H, dd, J3. 1 and 6. 3), 4.74 (1H, dd, J3. 2 and 6. 3), 4.22 (1H, dd, J4. 4 and 7. 8), 3.84 (1H, dd, J3. 8 and 11.1), 3.73 (1H, dd, J4. 7 and 11.3), 1.60 (3H, s), 1.37 (3H, s), 1.12 (9H, s) ; (5c (CDC13, 75 MHz) 135.6, 135.5, 133.1, 132.8, 130.2, 129.9, 129. 8, 127.8, 127.7, 126.3, 119.0, 117.7, 113.7, 112.3, 109.5, 108.4, 107.7, 105.0, 86.0, 84.8, 83.8, 83.3, 83.2, 81.5, 80.8, 77.1, 65.7, 64.1, 35.7, 27.3, 26.9, 26.8, 26.6, 25.4, 24.7, 19.3, 19. 1 ; m/z (ESI) 515.8 [ (M + K) +, 100%], 499.9 [ (M + Na) +, 68], 477.9 [ (M + H) +, 87], 456.9 (20), 399.8 (44), 380.1 (13), 341.8 (13), 235.9 (10), 221.8 (16), 191.9 (35), 173.9 (29), 163.9 (18), 102.0 (14), 89.9 (16), 73.9 (44), 71.0 (16).

2-(1-Deoxy-2, 3 : 5, 6-di-O-isopropylidene-mannfuranosyl)pyrrole (11).

10 11 A magnetically stirred mixture of trichloroacetimidate 10 (81 mg, 0.20 mmol) and powdered 4A molecular sieves (1.00 g) in anhydrous CH2C12 (15 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to-50 °C. Pyrrole (0.07 mL, 1.00 mmol) and BF3Et20 (0. 21 mL of a 0.16 M solution in anhydrous ether, 0.03 mmol) were then added, the resulting mixture stirred at-50 °C for 0.33 h and then filtered through a pad of CeliteTM

which was washed with CH2C12 (20 mL). The combined filtrates were washed with NaHC03 (1 x 20 mL of a saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2SO4), filtered and concentrated under reduced pressure to give a light-yellow oil.

This material was subject to flash chromatography (silica gel, 1: 4 v/v ethyl acetate/hexane elution) and concentration of the appropriate fractions afforded two separable isomers of C-glycoside 11 (66 mg total, 100%) as a slightly light-sensitive and colourless syrup, (Rf 0.2- 0.3). On dissolving in CDC13, each of the isomers rapidly equilibrated to give a mixture of both. Only the less mobile isomer (the major isomer of the two originally obtained) was recovered after recombination and flash chromatography, [a] D +22 (c 1.5, CHC13) (HRMS Found: 309.1588. C16H23NO5 requires M+ 309.1576) ; Vmax (NaCl)/cm-l 3436,3350, 3292, 3189,1725, 1599,1373, 1266,1209, 1162,1067, 838,825, 729,626, 515; #H (CDC13,300 MHz) 9.04 (1H, br s), 6.82 (1H, m), 6.26 (1H, m), 6.16 (1H, m), 4.86 (1H, dd, J3. 9 and 6.1), 4.81 (1H, dd, J 3.2 and 6.1), 4.55 (1H, d, J 2. 9), 4.44 (1H, dt, J 5.1 and 8.1), 4.08 (1H, d, J 5.1), 3.55 (1H, dd, J 3. 7 and 8.1), 1.62 (3H, s), 1.45 (3H, s), 1.38 (3H, s), 1.37 (3H, s); dc (CDC13,75 MHz) 125.2, 119.3, 112.2, 110.2, 109.2, 107.8, 82.4, 81.0, 80.7, 76.5, 72.9, 67.1, 27.0, 25.9, 25.2, 24.0 ; m/z (ESI) 347.8 [ (M + K) +, 53%], 331.8 [(M + Na) +, 100], 309.8 [ (M + H) +, 42], 251.8 (57), 233.8 (19), 193.8 (68), 173.9 (22), 149.9 (12), 79.9 (16), 73.9 (16).

(2, 2'3, 3'4'6, 6'-Hepta-O-acetyl-l-deoxy-B-maltosyl)-N-formyl-carboxamide (12).

12 A solution of 2 (98 mg, 0.14 mmol) in anhydrous CH2C12 (3 mL) was cooled to-78 °C.

Ozone was bubbled through the solution until the starting material was consumed by TLC, and the solution had turned blue. At this point oxygen was bubbled through the solution for 0.25 h (to discharge the blue colour) then a solution of thiourea (11 mg, 0.14 mmol) in anhydrous

MeOH (1 mL) was added. The resulting solution was stirred at-78 °C for 0.25 h, then at 0 °C for 1 h and then filtered through a pad of CeliteTM which was washed with CH2C12 (10 mL).

The combined filtrates were washed with NaHC03 (2 x 10 mL of a 1% w/v aqueous solution), water (1 x 10 mL) and brine (2 x 10 mL) then dried (Na2SO4), filtered and concentrated under reduced pressure to give a white solid. This material was subject to flash chromatography (silica gel, 2: 5 v/v acetone/toluene elution) and concentration of the appropriate fractions (Rf 0.2) affordedformimide 12 (33 mg, 34%) as white microcrystalline masses, mp 67-69 °C, [a] D +68 (c 0.9, CHC13) (HRMS data for C2gH37NO19 to be collected); Vmax (NaCl)/cm-l 1749,1704, 1465,1369, 1229,1138, 1037,901, 733,601 ; h (CDC13, 300 MHz) 9.09 (1H, d, J 10.1, CHO), 8.83 (1H, d, J 9. 5, NH), 5.36 (2H, m), 5.26 (1H, dd, J 6. 5 and 8.1), 5.08 (3H, m), 4.90 (1H, dd, J4.1 and 10.6), 4.56 (1H, d, J 12. 2), 4.27 (1H, dd, J4.3 and 12.8), 4.19 (1H, d, J7.8), 4.08 (1H, dd, J2. 2 and 12. 5), 4.00 (1H, m), 3.87 (2H, m), 2.17 (3H, s), 2.11 (3H, s), 2.10 (3H, s), 2.07 (3H, s), 2.04 (3H, s), 2.02 (3H, s), 2.01 (3H, s); dc (CDC13, 75 MHz) 170.4 (2), 170.2, 169.8, 169.6, 169.4, 169.2, 167.8, 161.0, 96.0, 75.6, 75.2, 73.6, 72.8, 69.8, 69.2, 69.0, 68.6, 67.9, 62.7, 61.5, 20.9, 20.8, 20.75, 20.66 ; m/z (ESI) 691.9 [ (M + H) +, 22%], 618.5 (5), 439.1 (6), 383.0 (5), 330.9 (62), 270.9 (21), 210.8 (8), 168.9 (100), 148.8 (11), 108.9 (38).

2-(2,2',3,3',4',6,6'-Hepta-O-acetyl-l-deoxy-ß-maltosyl)p yrrolidine (13).

13 A magnetically stirred mixture of 2 (38 mg, 0.06 mmol) and Pt02 (10 mg) in 1: 9 v/v AcOH/EtOH (5 mL) was maintained at 18 °C for 72 h under a hydrogen atmosphere (balloon). Additional portions of PtO2 (10 mg) were added after 24 h and 48 h. The mixture was then filtered through a pad of CeliteTM which was washed with EtOH (2 x 5 mL) and the combined filtrates were concentrated under reduced pressure to give a light-yellow oil. This material was subject to column chromatography (silica gel, 1: 14 v/v MeOH/CH2Cl2 elution) and

concentration of the appropriate fractions (Rf 0.2) afforded C-glycoside 13 (20 mg, 55%) as white microcrystalline masses, mp 83-85 °C, [a] D +38 (c 0.9, CHC13) [HRMS Found: 690.2622. C3oH43NO17 requires (M + H) + 690.2609] ; vmax (NaCl)/cm-l 3369,1747, 1619, 1431,1369, 1228, 1039,910, 732,602 ; #H (CDC13, 300 MHz) 5.51 (1H, d, J4. 1), 5.33 (1H, t, J9. 7), 5.15 (1H, t, J 9. 2), 4.86 (1H, dd, J4. 0 and 10.4), 4.50 (1H, dd, J 2. 6 and 11.9), 4.40 (1H, d, J 8. 4), 4.25 (1H, dd, J 3. 4 and 12.2), 4.16 (1H, dd, J4. 1 and 12.0), 4.07 (1H, dd, J2. 2 and 12.5), 3.92 (1H, m), 3.85 (1H, t, J 9. 4), 3.68 (1H, dd, J 3. 2 and 10.1), 3.60 (1H, m), 3.45 (2H, m), 3.30 (1H, t, J 9. 5), 2.12 (3H, s), 2.11 (3H, s), 2.09 (3H, s), 2.08 (3H, s), 2.07 (3H, s), 2.02 (3H, s), 2.01 (3H, s), 1.75-2. 18 (5H, m); ic (CDC13, 75 MHz) 171.5, 170.7 (2), 170.6, 170.3, 169.9, 169.4, 95.3, 79.2, 78.4, 76.1, 75.8, 72.3, 71.8, 69.9, 69.4, 68.3, 68.1, 62.8, 61.4, 58.1, 24.9, 24.2, 21.3, 20.8, 20.7, 20.6 ; m/z (ESI) 711.9 [ (M + Na) +, 39%], 689. 9 [ (M + H) +, 86], 589.0 (7), 458.0 (6), 380.0 (39), 359.8 (7), 330.8 (7), 285.9 (7), 284.0 (9), 236.0 (20), 191.9 (95), 173.9 (100), 155. 9 (23), 116.0 (13), 97.9 (36).

4-Acetyl-2-(2,2',3,3',4',6,-hepta-O-acetyl-1-deoxy-ß-mal tosyl)pyrrole (15).

15 A magnetically stirred mixture of trichloroacetimidate 1 (170 mg, 0.22 mmol) and powdered 4A molecular sieves (0.65 g) in anhydrous CH2Cl2 (5 mL) was maintained at 18 °C for 2 h then cooled to-50 °C. Glycosylpyrrole 2 (73 mg, 0.11 mmol) and BF3Et2O (0.03 mL, 0.27 mmol) were then added, the resulting mixture stirred at-50 °C for 0.33 h and then filtered through a pad of CeliteTM which was washed with CH2C12 (20 mL). The combined filtrates were washed with NaHCO3 (1 x 20 mL of a saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2SO4). filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subject to flash chromatography (silica

gel, 1: 4 v/v acetone/toluene elution) and concentration of the appropriate fractions (Rf 0.2) afforded C-glycoside 15 (46 mg, 57%) as white microcrystalline masses, mp 85-87. 5 °C, [α] D +41 (c 0.3, CHC13) (HRMS data for C32H41NO18 to be collected); #max (NaCl)/cm-2 3293, 1751,1648, 1496,1431, 1369,1230, 1041,914, 794,732, 602; (CDCl3, 300 MHz) 9.44 (1H, br s, NH), 6.77 (1H, dd, J2. 6 and 4.0, H5"), 6.10 (1H, dd, J2. 6 and 3.8, H3"), 5.44 (1H, d, J4. 0), 5. 37 (1H, t, J 10.6), 5. 34 (1H, t, J9. 2), 5.06 (1H, t, J 10.1), 4.97 (1H, t, J9. 7), 4. 88 (1H, dd, J4. 0 and 10.6), 4.59 (1H, d, J9. 7), 4.46 (1H, dd, J 2. 5 and 12.3), 4.25 (2H, m), 4.05 (2H, m), 3.99 (1H, ddd, J 1. 9,3. 4,10. 0), 3. 82 (1H, ddd, J2. 3,4. 5 and 9.7), 2.15 (3H, s), 2.11 (3H, s), 2.04 (3H, s), 2.03 (3H, s), 2.01 (3H, s), 1.92 (3H, s); (5c (CDCl3, 75 MHz) 187.7, 170.39, 170.37 (3), 169.8, 169.3, 169.2, 132.9, 132.2, 116.6, 108.9, 95.7, 76.4, 76.33, 76.31, 72.8, 72.0, 70.0, 69.3, 68.6, 67.9, 63.1, 61.5, 25.4, 21.03, 20.98, 20. 8, 20.7 (3), 20.6 ; m/z (ESI) 1477.3 [ (2M + Na) +, 19%], 766.2 [ (M + K) +, 6], 750.2 [ (M + Na) +, 89], 728.2 [ (M + H) +, 13], 618.9 (5), 476.2 (6), 458.2 (7), 380.3 (99), 331.1 (6), 302.1 (8), 280.1 (11), 263.2 (20), 258.2 (38), 236.2 (100).

2-(2,2',3,3',4',6,6'-Hepta-O-acetyl-1-deoxy-ß-maltosyl)- 4,5-dibromopyrrole (16).

16 A magnetically stirred solution of 2 (94 mg, 0.14 mmol) in anhydrous THF (1 mL) was cooled to-78 °C. N-Bromosuccinimide (25 mg, 0.14 mmol) was then added, the resulting solution stirred at-78 °C for 2 h and then allowed to warm to 18 °C over 1 h. Pyridine (1 drop) and hexane (1 mL) were added and the mixture was filtered through a short pad of CeliteTM which was washed with CH2C12 (10 mL). The combined filtrates were washed with Na2S2o3 (1 x 10 mL of a 10% w/v aqueous solution), NaHCO3 (1 x 10 mL of a saturated aqueous solution) and brine (1 x 10 mL) then dried (Na2SO4), filtered and concentrated under

reduced pressure to give a light-yellow oil. This material was subject to column chromatography (silica gel, 1: 4 v/v acetone/hexane elution) and concentration of the appropriate fractions (Rf 0. 2) afforded C-glycoside 16 (51 mg, 86% based on NBS required) as white microcrystalline masses (material decomposed before mp was recorded), [a] D +33 (c 1.7, CHCl3) [HRMS Found: 842.0479. C3oH37 7'Br2NO17 requires (M + H) + 842. 0507]; vmax (NaCl)/cm-l 3337,1751, 1455,1432, 1369,1232, 1137,1036, 912,775, 733,648, 602; #H (CDC13,300 MHz) 8.39 (1H, br s, NH), 6.02 (1H, m, H3"), 5.44 (1H, d, J4.1), 5.37 (1H, dd, J 9.5 and 10.6), 5.33 (1H, t, J9. 1), 5.07 (1H, t, J, 10.0), 4.99 (1H, t, J9. 8), 4.88 (1H, dd, J4. 0 and 10.4), 4.49 (1H, d, J 10.0), 4.46 (1H, dd, J2.3 and 12.3), 4.25 (2H, m), 4.02 (3H, m), 3.79 (1H, ddd, J2. 3,4. 3 and 9.5), 2.15 (3H, s), 2.11 (3H, s), 2.06 (3H, s), 2.03 (3H, s), 2.01 (3H, s), 1.91 (3H, s); dc (CDC13,75 MHz) 170.6, 170.5 (2), 170.2, 169.9, 169.6, 169.4, 127.3, 110.6, 109.5, 99.1, 95.7, 76.5, 76.1, 73.5, 72.9, 71.6, 70.0, 69.3, 68.5, 68.0, 63.2, 61.5, 20.92, 20.87, 20.7, 20.6 (3), 20.5 ; m/z (ESI) 867.7 (15%), 865. 6 (26), 863.7 [(M + Na) +, 13], 787.8 (100), 785.7 (94), 589.0 (13), 370.9 (16), 331.0 (47), 270.9 (29), 237. 8 (19), 235.9 (17).

2-(2, 2'3, 3'4'6, 6'-Hepta-O-acetyl-l-deoxy-ß-maltosyl)-l-methylpyrrole (17) and 3- (2, 2',3,3',4',6,6'-Hepta-O-acetyl-1-deoxy-ß-maltosyl)-1-methyl pyrrole (18).

17 18 A magnetically stirred mixture of trichloroacetimidate 1 (160 mg, 0.20 mmol) and powdered 4A molecular sieves (1.00 g) in anhydrous CH2C12 (15 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to-50 °C. N-Methylpyrrole (0.07 mL, 1.00 mmol) and BF3Et2O (0. 07 mL, 0.50 mmol) were then added, the resulting mixture stirred at-50 °C for 0.33 h and then filtered through a pad of CeliteTM which was washed with CH2C12 (20 mL). The combined filtrates were washed with NaHCO3 (1 x 20 mL of a

saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2S04), filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subject to flash chromatography (silica gel, 3: 17 v/v acetone/toluene elution) and concentration of the appropriate fractions (Rf 0. 2) afforded the C-glycoside 17 (18 mg, 13%) as slightly light-sensitive and white microcrystalline masses, mp 69-72 °C, [a] D +53 (c 0.6, CHC13) (HRMS for C3lH41NO17 data to be collected); vmax (NaCl)/cm-l 1749,1368, 1230, 1038,602 ; (CDCl3, 300 MHz) 6.61 (1H, dd, J2. 6 and 1.9, H5"), 6.05 (1H, dd, J3. 7,1. 8, H3"or H4"), 6.01 (1H, dd, J 3. 7 and 2.6, H3"or H4"), 5.45 (1H, d, J4. 0, H1'), 5.23 (3H, m), 5.05 (1H, t, J 10.0), 4.88 (1H, dd, J 10.6 and 4.1), 4.56 (1H, d, J 10.0, H1), 4.43 (1H, dd, J 12.0 and 2.8), 4.24 (1H, dd, J 12.6 and 4.1), 4.19 (1H, dd, J 12.0 and 5.0), 4.07 (2H, m), 3.98 (1H, ddd, J 10.1, 3.8 and 2.2), 3.81 (1H, ddd, J 9. 4,'4. 8 and 2.5), 3.65 (3H, s), 2.103 (3H, s), 2.095 (3H, s), 2.06 (3H, s), 2.03 (3H, s), 2.02 (3H, s), 2.01 (3H, s), 1.87 (3H, s); dc (CDCl3, 75 MHz) 170.7 (2), 170.62, 170.57, 170.1, 169.9, 169.6, 126.7, 124.6, 108.7, 107.3, 95.9, 75.9, 73.3, 72.9, 71.1, 70.3, 69.7, 68.8, 68.3, 61.9, 53.8, 34.3, 21.4, 21.2, 21.1 (2), 21.0 (3), 20.7, 20.6, 20.5 ; m/z (ESI) 738.2 [ (M + K) +, 14%], 722.2 [ (M + Na) +, 100], 640.2 (7), 617.1 (14), 380.3 (6), 331.1 (4), 239.0 (7), 236.2 (9), 192.1 (71), 108.8 (13). Further elution with 3: 17 v/v acetone/toluene afforded the C-glycoside 18 (10 mg, 7%) as slightly light sensitive and white microcrystalline masses, mp 63-65 °C, [oc] D +40 (c 0.2, CHC13) (HRMS data for C31H41NO17 to be collected); vmaX (NaCl)/cm-l 1748,1431, 1369,1229, 1142, 1038, 604; #H (CDCl3, 300 MHz) 6.59 (1H, t, J 1.9, H2"or H5"), 6.49 (1H, t, J2. 6, H2"or H5"), 6.06 (1H, dd, J2. 8 and 1.8, H4"), 5.46 (1H, d, J4. 1, H1'), 5.37 (3H, m), 5.00 (1H, dt, J 10.0 and 1.2), 4.88 (1H, dd, J 10.6 and 4.1), 4.43 (1H, d, J 10.0, H1), 4.41 (1H, dd, J 12.2 and 2.6), 4.25 (2H, m), 4.07 (2H, m), 3.98 (1H, m), 3.77 (1H, ddd, J 9.8, 4.3 and 2.9), 3.59 (3H, s), 2.12 (3H, s), 2.10 (3H, s), 2.07 (3H, s), 2.03 (3H, s), 2.01 (3H, s), 2.00 (3H, s), 1.86 (3H, s); k (CDCl3, 125 MHz) 170.7, 170.62, 170.57, 170.4, 170.0, 169.8, 169.5, 122.2, 120.5, 119.3, 107.3, 95.6, 77.4, 75.8, 74.6, 73.1, 72.9, 70.0, 69.4, 68.4, 68. 0,63. 6,61. 5,36. 2,21. 0,20. 9,20. 7 (2), 20.6 (3); m/z (ESI) 738. 2 [(M + K) +, 6%], 722.2 [(M + Na) +, 43], 640.0 (3), 380. 3 (23), 236. 2 (17), 192.1 (100), 174.1 (13).

2-(2,2',3,3',4',6,6'-Hepta-O-benzyl-1-deoxy-α,ß-maltosy l)pyrrole (20).

19 20 A magnetically stirred mixture of crude trichloroacetimidate 19 (ca. 0.53 mmol of a mixture of anomers) and powdered 4A molecular sieves (1.25 g) in anhydrous CH2C12 (20 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to-50 °C.

Pyrrole (0.18 mL, 2.62 mmol) and BF3Et2O (0.55 mL of a 0.16M solution in Et2O, 0.09 mmol) were then added, the resulting mixture stirred at-50 °C for 0.33 h and then filtered through a pad of CeliteTMwhich was washed with CHUCK (20 mL). The combined filtrates were washed with NaHC03 (1 x 30 mL of a saturated aqueous solution), water (1 x 25 mL) and brine (1 x 25 mL) then dried (Na2S04), filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subject to flash chromatography (silica gel, 1: 3 v/v EtOAc/hexane elution) and concentration of the appropriate fractions (Rf 0.2) afforded C-glycoside 20 (66 mg, 12% over 2 steps) as slightly light-sensitive and white microcrystalline masses, mp not recorded, [a] D not recorded, (HRMS data for C65H67NO10 to be collected).

1H-NMR revealed this to be a ca. 3: 1 mixture of anomers with undetermined bias; vmax (NaCl)/cm-l 3427,3351, 3063,3030, 1605,1496, 1453,1361, 1208,1155, 1091,1072, 1027, 912,734, 696,462 ; <t (CDC13, 300 MHz) major isomer : 8.61 (1H, br s, NH), 6.97-7. 33 (35H, m), 6. 80 (1H, m, H5"), 6.31 (1H, m, H3"or H4"), 6.23 (1H, m, H3"or H4"), 5.74 (1H, d, J 3. 7), 3.40-5. 05 (27H, m) ; minor isomer : 9.0 (1H, br s, NH), 6.97-7. 33 (35H, m), 6.77 (1H, m, H5"), 6.38 (1H, m, H3"or H4"), 6.23 (1H, m, H3"or H4"), 5.64 (1H, d, J3. 5), 5. 33 (1H, m), 3. 40-5.05 (26H, m) ; (CDCl3, 75 MHz) 139.0, 138.9, 138.6, 138.5, 138. 2,138. 1, 137.7, 129.0, 128.7, 128.6, 128.5, 128.3, 128.1, 128.03, 127.93, 127. 87, 127. 81, 127.76, 127.6, 127.5, 127.4, 127.0, 126.7, 118.2, 108.7, 108. 0,97. 2, 86. 5,83. 6,82. 4,79. 7,78. 8,78. 0,77. 8, 77.4, 76.9, 75.9, 75.3, 74. 8, 74.5, 73.8, 73.7, 73.5, 72.8, 71.4, 69.7, 68.6 plus minor peaks

which may belong to the minor isomer; m/z (ESI) 1060.4 [ (M + K) +, 6%], 1044.4 [ (M + Na) +, 63], 1009.4 (14), 457.2 (9), 380.3 (10), 236.2 (16), 192.1 (100), 174.0 (18), 104.7 (13).

2- (2, 3, 4, 6-Tetra-O-benzyl-1-deoxy-α,ß-glucosyl)pyrrole (22).

21 22 A magnetically stirred mixture of trichloroacetimidate 21 (160 mg, 0.24 mmol of a 1: 3 mixture of a-and (3-anomers) and powdered 4A molecular sieves (1.00 g) in anhydrous CH2Cl2 (15 mL) was maintained at 18 °C for 2 h under a nitrogen atmosphere then cooled to- 50 °C. Pyrrole (0.08 mL, 1.18 mmol) and BF3Et2O (0.31 mL of a 0. 16M solution in Et2O, 0.05 mmol) were then added, the resulting mixture stirred at-50 °C for 0.33 h and then filtered through a pad of CeliteTM which was washed with CH2C12 (20 mL). The combined filtrates were washed with NaHC03 (1 x 20 mL of a saturated aqueous solution), water (1 x 20 mL) and brine (1 x 20 mL) then dried (Na2SO4), filtered and concentrated under reduced pressure to give a light-yellow oil. This material was subject to flash chromatography (silica gel, 1: 3 v/v EtOAc/hexane elution) and concentration of the appropriate fractions (Rf 0.2) afforded C-glycoside 22 (83 mg, 58%) as slightly light-sensitive and white microcrystalline masses, mp 45-90 °C, [a] D +36 (c 0.8, CHCl3) (HRMS data for C3sH3gN05 to be collected).

1H-NMR showed that the initial product was a ca. 2: 1 mixture of anomers which equilibrates to a ca. 1: 4 mixture on standing in acidic CDC13 (presumably a to (3 is favoured); vmax (NaCl)/cm-l 3414,3063, 3030,1496, 1453,1359, 1209,1063, 1027,911, 736,697 ; #H (CDC13, 300 MHz) initial major isomer : 9.01 (1H, br s, NH), 7.11-7. 38 (20H, m), 6.74 (1H, m, H5"), 6.39 (1H, m, H3"or H4"), 6.22 (1H, m, H3"or H4"), 5.36 (1H, d, J5. 0), 4. 80-5. 04 (4H, m), 4.37-4. 69 (3H, m), 3.53-4. 05 (7H, m) ; initial minor isomer : 8. 63 (1H, br s, NH), 7.08-7. 38 (20H, m), 6.79 (1H, m, H5"), 6.30 (1H, m, H3"or H4"), 6.22 (1H, m, H3"or H4"),

4.79-5. 02 (4H, m), 4.35-4. 65 (3H, m), 3.95 (1H, d, J 10.1), 3.50-4. 00 (7H, m); gc (CDC13, 75 MHz) 138.5, 138.0, 137.9, 137.7, 137.6, 128.5, 128.4, 128.3, 128. 25,128. 20, 128. 17,127. 8, 127.69, 127.65, 127.60, 127.57, 127.53, 127.49, 117.9, 117.3, 108.24, 108.18, 107.7, 86.3, 82.9, 82.6, 80.9, 78.7, 78.1, 77.8, 75.62, 75.57, 75.1, 75.0, 74.6, 73.5, 73.4, 72.3, 70.1, 68.9, 68.8 ; m/z (ESI) 611.7 [(M + Na) +, 5%], 606.9 [(M + NH4) +, 20], 589.9 (88), 481.9 (9), 414.0 (7), 380. 0 (48), 294.7 (6), 283.8 (7), 262.9 (14), 233.9 (19), 191.9 (100), 111.9 (23).

It will be appreciated by one of skill in the art that many changes can be made to the processes exemplified above without departing from the broad ambit and scope of the invention.

The term"comprise"and variants of the term such as"comprises"or"comprising"are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required.