| US5124468A | 1992-06-23 | |||
| US4383120A | 1983-05-10 | |||
| US4448980A | 1984-05-15 | |||
| US4783543A | 1988-11-08 | |||
| US4785126A | 1988-11-15 | |||
| US2803637A | 1957-08-20 | |||
| US4424392A | 1984-01-03 |
| 1. | A process for the preparation of an αsilyloxyalde¬ hyde of the formula: wherein Ph is phenyl, and R is a substituted or unsubstituted alkyl, aryl, aralkyl, or heterocycle, or R is wherein R1 and R2 are independently selected from the group alkyl, aryl, aralkyl, alkoxy, dialkylamino, or heterocycle radical, said process comprising: reacting a compound of the formula: RCHO with dimethylphenylsilane in the presence of carbon mon¬ oxide and a rhodium catalyst to form said αsilyloxyalde hyde. |
| 2. | The process of claim 1 wherein R is selected from the group of substituted or unsubstituted phenyl, lower (C, to C4) alkyl, furanyl, pyrrolyl, and thiophenyl. |
| 3. | The process of claim 1 wherein the reaction takes place at a temperature of between about 0° and about 25° centigrade. |
| 4. | The process of claim 1 wherein the rhodium catalyst is bis(rhodium cycloόctadiene chloride). |
| 5. | The process of claim 1 wherein the rhodium catalyst is a compound of the formula: [L*RhCl]2 wherein L* is 2,2,bipyridine, phenanthroline and chiral bidendate nitrogen ligand of the formula: . |
| 6. | The process of claim 1 wherein said rhodium catalyst is a compound of the formula:. |
| 7. | The process of claim 1 wherein R is: and the thus synthesized compound has a specific relative stereochemistry. |
| 8. | An αsilyloxyaldehyde of the formula: O Ar II I HC COSi(CH3)2Ph H wherein Ph is phenyl, and Ar is a substituted or unsubstituted aryl, aralkyl, or heterocycle, or Ar is I' CH R2 wherein R, and R2 are independently selected from the group alkyl, aryl, aralkyl, alkoxy, dialkylamino or heterocycle. |
| 9. | The compound of claim 8 wherein Ar is selected from the group of substituted or unsubstituted phenyl, furanyl, pyrrolyl, and thiophenyl. |
| 10. | The compound of claim 8 wherein Ar is: R1 and said compound is optically pure. |
Technical Field. The invention relates to a method for preparing chiral and achiral α-silyloxyaldehydes.
More specifically the invention relates to a process for silaformylating aldehydes with a silicon hydride and carbon monoxide in the presence of a rhodium catalyst.
State of the Art. A method for the silaformylation of aldehydes is shown in Murai et al., Anσew. Chem. Int. Ed. Enσl.. 18: 393 and 837 (1979). Three aldehydes, R- CHO; (where R was cyclohexyl, pentyl, and heptyl) , were reacted with carbon monoxide (50 Kg/cm 2 ) and dimethyl- phenylsilane in the presence of a Co 2 (CO) 8 /PPh 3 catalyst. A benzene solution was used at a temperature of 100°C and a three-fold excess of aldehyde had to be employed. Although this method could produce α-silyloxyaldehydes, the limited substrate scope, high reaction temperatures and pressures, and excess aldehyde limit this method's scope and utility.
It is known that at elevated temperature in the presence of a cobalt catalyst, a silane reagent exten¬ sively reacts and thus consumes the desired α-sily¬ loxyaldehyde product. This consumption drastically low- ers the yield of the desired α-silyloxyaldehyde based on the starting aldehyde. Although highly desirable, a catalytic synthesis of diastereomerically pure α-sily¬ loxyaldehydes has not been developed.
It would be an improvement in the art to have a catalytic synthesis of α-silyloxyaldehydes useful with a broad range of aldehydes which would operate under reaction conditions wherein the desired product is stable. Such a catalytic process would provide α-sily¬ loxyaldehydes, enhancing these compounds' utility as intermediates in chemical synthesis.
DISCLOSURE OF THE INVENTION
The invention includes a process wherein aldehydes of the formula: R-CHO, (I)
are reacted with a silane of the formula:
Me 2 PhSiH, (II) in the presence of carbon monoxide and a rhodium cata¬ lyst, to produce an α-silyloxyaldehyde (III) :
(IV)
In these formulae, R is a substituted or unsubstituted alkyl, aryl, aralkyl, or heterocyclic hydrocarbon.
The invention also includes a process for synthesizing compounds of specific relative stereochemis¬ try by reacting aldehydes of the formula:
wherein R, is aryl and R J can be alkyl, aryl, aralkyl, dialkylamino, or alkoxy radicals, with silane reagent of formula (II) and carbon monoxide in the presence of catalyst. Relatively pure syn-isomer:
was isolated. The rhodium(I) catalyzed silaformylation of alde¬ hydes has broad application, affords high yields of the α-silyloxyaldehydes, and does not require the use of excess aldehyde.
Once made, the α-silyloxyaldehydes are useful, for among other things, as intermediates, and can be convert¬ ed to α-silyloximine derivatives which are useful syn¬ thetic intermediates in the diastereoselective synthesis of 3-aminoalcohols.
DETAILED DESCRIPTION OF THE INVENTION
The aldehyde used in the process will generally be chosen for its constituent R group. Preferably the R group will be selected from the group of substituted or unsubstituted phenyl, lower (Cl to C4) alkyl, furanyl, pyrrolyl, and thiophenyl.
As used herein, alkyl is preferably a saturated or unsaturated, branched or unbranched hydrocarbon having one to twenty carbon atoms, e.g. methyl, ethyl, isopentyl, and allyl. Alkoxy groups will typically have one to four carbon atoms and include groups such as methoxy and ethoxy.
Aryl, as used herein, is an aromatic hydrocarbon group, preferably having six to ten carbon atoms, such as phenyl or naphthyl.
Aralkyl, as used herein, is an arene group (having both aliphatic and aromatic portions) , preferably having seven to thirteen carbon atoms, such as benzyl, ethyl- benzyl, n-propylbenzyl, or isobutylbenzyl.
A "substitution" with regard to the various R moi¬ eties generally relates to substituting a group such as alkoxy, halogen, hydroxy, nitro, or lower alkyl onto an aromatic ring for a hydrogen that would normally be pres- ent. Substitutions can also be made on an alkyl or alkoxy chain.
Halogen, as used herein, generally refers to fluo¬ rine, chlorine, bromine or iodine.
A variety of rhodium complexes can be used as a catalyst. Preferred rhodium catalysts for the silaformylation of aldehydes are rhodium cycloόctadiene chloride ([ (COD)RhCl] 2 ) or a compound of the formula:
Utilization of monohydric dimethylphenylsilane is found to work superbly in the rhodium(I) catalyzed sila- formylation of aldehydes. Since no evidence exists for the production of "diol" products, the relative rate of reaction for the starting aldehyde substrate must be much greater than that of the newly formed α-εilyloxyaldehyde. A simple bulb-to-bulb distillation affords analytically pure α-silyloxyaldehydes. (See Example I) Ketone sub¬ strates (e.g. acetophenone) yield silylenol ethers as the major product. This result suggests that 0-hydrogen elimination is much faster than migratory insertion of carbon monoxide.
A general process for synthesizing the compounds of the invention is given in Scheme 1.
Scheme I
β-hydtlde elimination reductive-elimination
Silylenol Hydrosllylliatlon ether Pro Ubt
Table I. Summary of Results for the Rhodium Cata¬ lyzed Silaformylation of Aldehydes.
/
a A THF solution (8_rtL) of the appropriate aldehyde (1.5 mmol) and Me 2 PhSiH (0.20 g, 1.5 mmol) was de¬ gassed (freeze-pump-thaw x 3) and then cannulated into a glass vessel containing the [ (COD)RhCl] 2 (1.8 mg, 0.5 mol-%) . The vessel was placed in the bomb and charged with carbon monoxide (1724 kilopascals above atmospheric) and allowed to react at -23°C for 24 hours b Yields reported were determined by NMR spectroscopy using an internal NMR standard (1,1,1-trichlor- ethane) . Isolated yields were slightly lower, but comparable, c 6895 kilopascals over atmospheric of carbon monoxide pressure used.
It can be seen from Table I that the reaction is quite general and works well for heterocyclic as well as aliphatic systems. The very mild reaction conditions permit discrimination of the starting aldehyde from the newly formed and more sterically demanding α-sily¬ loxyaldehyde. In the case of isobutyraldehyde small amounts of enol ether formed and at lower carbon monoxide pressures (1724 kilopascals over atmospheric) hydrosilylation product was observed. For aromatic aldehydes, carbon monoxide pressures of
862 kilopascals over atmospheric produce slightly lower yields of the α-silyloxyaldehydes with concomitant formation of the hydrosilylation byproduct (-10%) .
Preferably, strong electron-withdrawing substituents will be avoided in the silaformylation reaction. For example, jD-nitrobenzaldehyde shows only a 40% conversion with only some silaformylation product (20% yield) . Pyridine carboxaldehydes (both the 2- and 4-) were to be completely unreactive under the reaction conditions. Preferred temperature ranges for the reaction vary from 0°C to 25°C.
The rhodium catalyzed silaformylation is selective for the aldehyde functionality in the presence of an ester. Highly functionalized aromatic compounds have been isolated in 70% yield. Spectral data collected from the crude reaction mixture indicated complete chemo- selectivity for the aldehyde group.
The invention is further described by reference to the following illustrative EXAMPLES.
EXAMPLES
Methods. All manipulations of compounds and sol¬ vents were carried out by using standard Schlenk tech¬ niques. Solvents were degassed and purified by distilla¬ tion under nitrogen from standard drying agents. Spec- troscopic measurements utilized the following instrumen¬ tation: 1 H NMR, Varian XL 300; 13 C NMR, JOEL-270, Varian XL 300 (at 75.4 MHz); Infrared, Perkin Elmer 1750 FT-IR; UV-vis, HP-8452A diode array spectrometer. NMR chemical shifts are reported in δ versus Me 4 Si in H NMR and as- signing the CDCL j resonance at 77.00 ppm in 13 C spectra. The benzaldehyde, 4-bromobenzaldehyde, 4-dimethylamino- benzaldehyde, l-methyl-2-pyrrolecarboxaldehyde, 2- thiophenecarboxaldehyde, butyraldehyde, isobutyraldehyde, 2-furaldehyde, and ferrocenecarboxaldehyde were purchased from Aldrich Chemical Co. and used as received.
Dimethylphenylsilane, triethylsilane, triphenylsilane was purchased from Hύls America, Inc. and used as received. The [ (COS)RhCl] 2 , 4-acetoxybenzaldehyde, and 4-(trimethyl- silyloy) benzaldehyde were prepared from literature pro- cedures. Giordano, G. ; Crabtree, R.H. , Inorg. Synth.
1979, 19, 218; Highet, R.J. ; Highet, P.F. J. Org. Chem. 1965, 30, 902; and Cooper, G. J. Org. Chem. 1961, 26, 925. Elemental analyses were performed at Atlantic Microlab, Inc., Norcross, Georgia. Silaformylation Procedure. A round-bottom flask
(50mL) was charged with the appropriate aldehyde (1.5 mmol), dimethylphenylsilane (0.20 g, 1.5 mmol), and THF
(8 mL) . The mixture was degassed by three consecutive freeze-pump-thaw cycles and then cannulated into a nitro¬ gen purged glass vessel containing [(COD)RhCl] 2 (0.0018 g, 0.0038 mmol, 0.5 mol %) . The glass vessel was placed in a stainless steel bomb and purged three times with carbon monoxide {345 *→ 3448 kilopascals over atmospheric}. The bomb was brought to the desired reaction pressure and stirred at room temperature for 24 h. The glass vessel was removed from the bomb and the solvent removed under reduced pressure. The reaction mixture was analyzed by 1 H NMR using 1,1,1-trichloroethane as an internal standard to obtain the NMR yields. Purification of the α- silyloxyaldehyde was achieved through distillation at 0.1 mm Hg. EXAMPLE I
C B H ; .CH(OSiMe,Ph)CHO (3a). α-[ (phenyldimethylsilyl)- oxy]benzeneacetaldehyde (74 %, bp 130-140°C at 0.1 mm Hg) ; 1 H NMR (CDC1 3 ) <S 9.52 (s, 1 H, CHO), 7.55-7.28 (m, 10 H, Ar H) , 4.99 (s, 1 H, -CHCHO), 0.43, 0.37, 0.33 (s's, 6 H, SiCH 3 ) ; 13 C NMR (CDC1 3 ) δ 198.4 (CHO), 139.4 (Ar C) ,
136.3 (Ar C) , 135.9 (Ar C) , 133.3 (Ar CH) , 132.8 (Ar CH) , 132.7 (Ar CH) , 130.0 (Ar CH) , 129.7 (Ar CH) , 129.0 (Ar CH) , 128.5 (Ar CH) , 128.3 (Ar CH) , 128.2 (Ar CH) , 128.1 (Ar CH) , 128.0 (Ar CH) , 127.8 (Ar CH) , 127.5 (Ar CH) , 126.5 (Ar CH) , 126.2 (Ar CH) , 79.9 (-CHCHO) , 0.6, -1.4, - 1.6, (SiCH 3 ) ; IR (CH 2 C1 2 ) v c=0 1736 cm "1 . Anal. Calcd for C l6 H 18 0 2 Si: C, 71.06; H, 6.72%. Found: C, 71.12; H, 6.94%. It is noteworthy to mention that in each sila¬ formylation reaction studied to date at least two NMR signals for the pro-diastersotopic silicon methyl groups have been observed. Apparently, rotomers about the silicon-oxygen bond exist and have been indirectly supported by molecular mechanics analysis.
EXAMPLE II
(4«BrC < H lCH(OSiMe..Ph)CHO (3b). α-[ (phenyldimethyl¬ silyl)oxy]-4-bromobenzeneacetaldehyde (84%, bp 130-140°C
at 0.1 mm Hg) ; 1 H NMR (CDC1 3 ) δ 9.49 (s, 1 H, CHO) , 7.54- 7.20 (m, 9 H, Ar CH) , 4.92 (s, 1 H, -CHCHO) , 0.44, 0.38 (s , s, 6H, SiCH 3 ) ; 13 C NMR (CDC1 3 ) δ 198.7 (CHO), 136.1 (Ar C) , 135.2 (Ar C) , 133.4 (Ar CH) , 132.9 (Ar CH) , 131.8 (Ar CH) , 131.7 (Ar CH) , 130.1 (Ar CH) , 129.2 (Ar CH) , 128.2 (Ar CH) , 128.0 (Ar CH) , 127.8 (Ar CH) , 127.6 (Ar CH) , 122.5 (Ar C) , 79.4 (-CHCHO) , -1.3, -1.4 (SiCH 3 ) ; IR (CH 2 C1 2 ) v c=0 1731 cm "1 . Anal. Calcd for C l6 H 17 0 2 BrSi: C, 55.01; H, 4.91%. Found: C, 54.91; H 4.95%.
EXAMPLE III
M* (Me-N.C π H..CH.OBiMθ 3 Ph.CHO (3c.. α-[(phenyl- dimethylsilyl)oxy]-4-(dimethylamino)benzeneacetaldehyde (80%, bp 130-140°C at 0.1 mm Hg) ; 1 H NMR (CDC1 3 ) δ 9.48 (s, 1 H, CHO), 7.56-7.53 (m, 2 H, Ar CH) , 7.40-7.33 ( , 3
H, Ar CH) , 7.18-7.16 (m, 2 H, Ar CH) , 6.71-6.68 (m, 2 H, Ar CH) , 4.91 (s, 1 H, -CHCHO) , 2.92 (S, 6 H, N (CH 3 ) 2 ) , 0.40, 0.34, 0.33 (s's, 6 H, SiCH 3 ) ; 13 C NMR (CDC1 3 ) δ 198.3 (CHO) , 150.4 (Ar C) , 136.7 (Ar C) , 133.3 (Ar CH) , 132.8 (Ar CH) , 132.7 (Ar CH) , 129.6 (Ar CH) , 129.0 (Ar CH) ,
128.0 (Ar CH) , 127.8 (Ar CH) , 127.7 (Ar CH) , 127.5 (Ar CH) , 123.0 (Ar C) , 112.3 (Ar CH) , 79.8 (-CHCHO), 40.1 (N(CH 3 ) 2 ), 0.7, -1.2, -1.5 (SiCH 3 ) ; IR (CH 2 C1 2 ) v c=0 1733 cm "1 . Anal. Calcd for C 18 H 23 N0 2 Si: C, 68.96; H, 7.41%. Found: C, 68.96; H, 7.49%.
EXAMPLE IV
14« (Me- J SiO)C 0 H t lCH(OSiMe..Ph)CHO (3d) . α-[ (phenyl- dimethylsilyl)oxy]-4-[ (trimethylsilyl)oxy]benzeneacetal- dehyde (50%, bp 130-140°C at 0.1 mm Hg) ; 1 NMR (CDC1 3 ) δ 9.50 (s, 1 H, CHO), 7.54-7.49 (m, 2 H, Ar CH) , 7.43-7.29 (m, 3 H, Ar CH) , 7.20-7.17 (m, 2 H, Ar CH) , 6.86-6.81 (m, 2 H, Ar CH) , 4.93 (s, 1 H, -CHCHO), 0.41, 0.35, 0.26 (3 s, 15 H, SiCH 3 ) ; 13 C NMR (CDC1 3 ) δ 199.0 (CHO), 155.5 (Ar C) , 136.6 (Ar C) , 133.5 (Ar CH) , 129.9 (Ar CH) , 128.9 (Ar C) , 128.1 (Ar CH) , 127.9 (Ar CH) , 127.6 (Ar CH) , 120.3 (Ar CH) , 79.8 (-CHCHO), 0.2, -1.2, -1.4 (SiCH 3 ) ; IR
(CH 2 C1 2 ) v c=o 1733 cm '1 . Anal. Calcd for C 19 H 28 0 3 Si 2 : C, 63.63; H, 7.32%. Found: C, 63.84; H, 7.09%.
EXAMPLE V 12' (N-Methylpyrroyl) )CH .OBiMθ-.Ph. CHO (3β) . (60%, bp
110-120°C at 0.1 mm Hg) ; 'H NMR (CDC1 3 ) δ 9.60 (s, 1 H, CHO) , 7.61-7.32 (m, 5 H, Ar H) , 6.57-6.56 (m, 1 H pyrrole CH) , 607 ( , 2 H, pyrrole CH's) , 5.09 (s, 1 H, CHCHO), 3.41 (s, 3 H, NCH 3 ) , 0.38, 0.33, 0.30 (s's, 6 H, SiCH 3 ) ; 13 C NMR δ 197.1 (CHO) , 139.5 (Ar C) , 136.4 (Ar C) , 133.4
(Ar CH) , 133.3 (Ar CH) , 132.8 (Ar CH) , 129.6 (Ar CH) , 129.4 (Ar CH) , 129.0 (Ar CH) , 127.7 (pyrrole CH) , 127.6 (pyrrole CH) , 127.5 (pyrrole CH) , 125.8 (pyrrole CH) , 124.4 (pyrrole CH) , 122.8 (pyrrole CH) , 110.9 (pyrrole CH) , 108.7 (pyrrole CH) , 107.3 (pyrrole CH) , 106.3
(pyrrole CH) , 74.5 (-CHCHO0, 35.6 (NCH 3 ) , 0.7, -1.5, -1.8 (SiCH 3 ) ; IR (CH 2 C1 2 ) v c=0 1738 cm "1 . Anal. Calcd for C 15 H 19 N0 2 Si: C, 65.66; H, 7.14%. Found: C, 65.88; H, 7.02%.
EXAMPLE VI
-Σ-Thiophenyl-CH.OBiMθ.Ph.CHO (3f) . α-[ (phenyldi- methylsilyl)oxy]-2-thiopheneacetaldehyde (72%, bp 90- 100-C at 0.1 mm Hg) ; 1 H NMR (CDC1 3 ) δ 9.52 (S, 1 H, CHO), 7.57-7.27 (m, 7H, Ar CH/thiophene CH) , 7.01-6.95 (m, 1 H, thiophene CH) , 5.19 (s, 1 H, -CHCHO), 0.44, 0.40, 0.33 (3 s, 6 H, SiCH 3 ) ; 13 C NMR (CDC1 3 ) δ 196.9 (CHO), 139.4 (Ar C) , 136.1 (Ar C) , 133.5, 132.9, 130.0, 129.2, 127.5, 127.6, 127.2, 126.3, 125.3 (Ar and thiophene CH's) , 76.2 (-CHCHO), 0.8, -1.3, -1.6 (SiCH 3 ) ; IR (CH 2 C1 2 ) V c=0 1737 cm "1 . Anal. Calcd for C u H 16 0 2 SSi: C, 60.84; H, 5.83%. Found: C, 60.4; H, 6.10%.
EXAMPLE VII CH 3 (CH,),CH(OSiMe. ; Ph)CHO (3α) . (60%, bp 90-100°C at
0.1 mm Hg) ; 1 H NMR (CDCl 3 ) δ 9.55 (s, 1 H, CHO), 7.59-7.31 (m, 5H, ArCH) , 3.97 (dt, =6.5, 1.2 Hz, 1 H, -CHCHO),
1.81-1.30 ( , 4 H, CH 2 's) , 0.86 (t, J=7.3 Hz, 3 H, CH 3 ) , 0.43, 0.42, 0.33 (s's, 6 H, SiCH 3 ) ; 13 C NMR (CDCl 3 ) δ 203.5 (CHO) , 136.8 (Ar C) , 133.4 (Ar CH) , 133.3 (Ar CH) , 132.9 (Ar CH) , 129.9 (Ar CH) , 129.8 (Ar CH) , 129.2 (Ar CH) , 127.9 (Ar CH) , 127.8 (Ar CH) , 127.6 (Ar CH) , 78.9 (-CHCHO) , 34.3 (-CH 2 CHCHO) , 17.9 (CH 3 CH 2 -) , 13.8 (CH 3 CH 2 .) 0.8, -1.4, -1.50 (SiCH 3 ) ; IR (CH 2 C1 2 ) v c=0 1734 cm "1 . Anal. Calcd for C 13 H 20 O 2 Si: C, 66.04; H, 8.54%. Found: C, 65.82; H, 8.56%.
EXAMPLE VIII
( CH 3 ) ,CHCH ( 08 JMe 2 Ph ) CHO ( 3 h ) . (75%, bp 90 - 100 "C at
0.1 mm Hg) ; 1 H NMR (CDC1 3 ) <5 9.55 (s, 1 H, CHO) , 7.64-7.31 (m, 5 H, Ar CH) , 3.75 (dd, J=4.9 , 1.9 Hz, 1 H, -CHCHO) , 2.06-1.99 (m, 1 H, (CH 3 ) 2 CH-) , 0.93 (d, J=6 Hz, 3 H,
CHCH 3 ) , 0.91 (d, J=6 Hz, 3 H, CHCH 3 ) , 0.41 (s, 6 H, SiCH 3 ) ; 13 C NMR (CDC1 3 ) δ 203.9 (CHO) , 136.9 (Ar C) , 133.4 (Ar CH) , 133.3 (Ar CH) , 132.9 (Ar CH) , 129.8 (Ar CH) , 129.6 (Ar CH) , 129.2 (Ar CH) , 127.8 (Ar CH) , 127.6 (Ar CH) , 82.0 (-CHCHO) , 31.1 ((CH 3 ) 2 CH-) , 19.2 ((CH 3 ) 2 CH-),
18.8 ((CH 3 ) 2 CH-), 18.5 ((CH 3 ) 2 CH-), 16.8 ((CH 3 ) 2 CH-) , 14.8 ((CH 3 ) 2 CH-) , 0.8, -1.46, -1.51, (SiCH 3 ) ; IR (CH 2 C1 2 ) v c=0 1734 cm "1 . Anal. Calcd for C 13 H 20 O 2 Si: C, 66.04; H, 8.54%. Found: C, 66.15; H, 8.52%.
EXAMPLE IX
-2-Furyl-CH(OSiMe,Ph)CHO (3i) . (90%, bp 90 - 100°C at 0.1 mm Hg) ; 1 H NMR (CDC1 3 ) δ 9.63 (s, 1 H, CHO), 7.60- 7.52 ( , 2 H, Ar CH) , 7.43-7.32 (m, 4 H, Ar CH and furyl CH) , 6.34-6.32 (m, 1 H, furan CH) , 6.28-6.26 ( , 1 H, furyl CH) , 5.02 (s, 1 H, CHCHO) , 0.40, 0.35, 0.33 (s's, 6 H, SiCH 3 ) ; 13 C NMR (CDCl 3 ) δ 196.8 (CHO) , 149.3 (furyl C) , 143.3 (furyl CH) , 136.2 (Ar C) , 133.4 (Ar CH) , 132.8 (Ar CH) , 129.8 (Ar CH) , 129.1 (Ar CH) , 127.8 (Ar CH) , 127.5 (Ar CH) , 110.4 (furyl CH) , 109.7 (furyl CH) , 73.8
(CHCHO), 0.7, -1.5, -1.9 (SiCH 3 ) ; IR (CH 2 Cl 2 ) v c=0 1736 cm "
1 . Anal. Calcd for C u H 16 0 3 Si: C, 64.57; H, 6.21%. Found: C, 64.41; H, 6.24%.
EXAMPLE XI tn g -C.-H. r -Fe--7 5 -C : H t CH(OBiMeP-_)CHO- (3i) . α-[ (phenyl- dimethylsilyl)oxy]ferroceneacetaldehyde (88%, purified by flash chromatography through deactivated flourosil) ; 1 H NMR (CDC1 3 ) δ 9.61, 9.62 (s's, 1 H, CHO), 7.59-7.34 (m, 5 H, phenyl CH's) , 4.74 (S, 1 H, CHCHO), 4.21-4.17 (m, 3 H, Cp CH's), 4.11 (s, 5 H, Cp) , 4.04-4.03 (m, 1 H, Cp CH) , 0.40, 0.38, 0.33 (3s, 6H, SiCH 3 ) ; 13 C NMR (CDC1 3 ) δ 196.9 (CHO), 136.9 (Ar C) , 133.5 (Ar CH) , 132.9 (Ar CH) , 129.8 (Ar CH) , 129.2 (Ar CH) , 127.9 (Ar CH) , 127.6 (Ar CH) , 82.1 (Cp C) , 75.6 (Cp CH) , 68.8 (CHCHO), 68.6 (Cp CH) , 68.4 (Cp CH) , 68.3 (Cp CH) , 67.5 (Cp CH) , 66.6 (Cp CH) , 0.8, -1.0, -1.1 (SiCH 3 ) ; IR (CH 2 C1 2 ) v c=0 1734 cm- 1 . Anal. Calculated for C 20 H 22 O 2 SiFe: C, 63.49; H, 5.86%. Found: C, 63.26; H, 6.10%.
EXAMPLE XII
Preparation of N-benzvl-α-r (phenyldimethylsilyl)- oxy]benzeneacetaldehyde i ine (4) . A THF (8 mL) solution of the compound of EXAMPLE I (0.05 g, 1.85 mmol) was treated with benzylamine (0.20 g, 1.85 mmol) in the presence of molecular sieves (4 A) at 0°C for 15 min. The mixture was filtered and the solvent removed under reduced pressure to afford pure 4.H NMR (CDC1 3 ) δ 7.66 (d, J=5.9 Hz, 1 H, CH=N) , 7.54 (d, J=7.7 Hz, 2 H, phenyl CH's), 7.43-7.15 ( , 13 H, phenyl CH's), 5.33 (d, J=5.9 HZ, 1 H, PhCH(OSiMe 2 Ph)C=N-) , 4.49 (s, 2 H, PhCH 2 N=) , 0.38, 0.37 (s's, 6 H, SiCH j ) ; 13 C NMR (CDC1 3 ) <S 166.1 (CHN) , 140.3, 138.6, 133.5, 129.7, 128.4, 128.0, 127.8, 127.7, 127.0, 126.2 (Ar C's) , 76.8 (CH(OSiMe 2 Ph) ) , 64.3 (CH 2 N=) , -1.0, -1.3 (SiCH 3 ) ; IR (CH 2 C1 2 ) v c=n 1655 cm "1 .
EXAMPLE XIII l4-(Acetoxy)C £ H t ICH(OSiMePh)CHO (5) . α-[(phenyl- dimethylsilyl)oxy]-4-(acetoxy)benzeneacetaldehyde (70%, purified by flash chromatography through deactivated flourosil) ; 1 H NMR (CDC1 3 ) δ 9.49 (s, 1 H, CHO), 7.53 (dd, J=7.5, 1.8 Hz, 2 H, Ar) , 7.40-7.34 (m, 5 H, Ar) , 7.09 (D, J=8.4 Hz, 2 H, Ar) , 4.98 (d, J=1.8 HZ, 1 H, CHCHO), 2.27 (S, 3H, CH 3 ) , 0.44, 0.39 (s's, 6 H, SiCH 3 ) ; 13 C NMR (CDC1 3 ) <S 198.5 (CHO), 169.0 (0 2 CCH 3 ) , 150.6 (Ar C) , 133.5 (Ar C) , 133.3 (Ar CH) , 132.8 (Ar CH) , 129.9 (Ar CH) , 127.9 (Ar CH) , 127.5 (Ar CH) , 122.2 (Ar CH) , 121.8 (Ar CH) , 79.4 (CHCHO), 20.8 (CH 3 ) , -1.4, -1.5 (SiCH 3 ) ; IR (CH 2 C1 2 ) V c=0 1736 cm "1 .
EXAMPLES XIV to XVII
Other monohydridic silane reducing reagents such as Et 3 SiH, Et0 3 SiH, MePh 2 SiH and Ph 3 SiH were tested and were found not to be effective reagents for the rhodium(I) catalyzed silaformylation of aldehydes at the mild temperatures employed. Triethylsilane and MePh 2 SiH were recovered intact and the triphenylsilane and triethoxysilane decomposed to unidentified products.
References herein to specific Examples or embodi- ents should not be interpreted as limitations to the invention's scope which is determined by the claims.
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