Background of the Invention It is widely believed that HDL is a"protective"lipoprotein [Gloria Lena Vega and Scott Grundy, Current Opinion in Lipidology, 7,209-216 (1996)] and that increasing plasma levels of HDL may offer a direct protection against the development of atherosclerosis. Numerous studies have demonstrated that both the risk of coronary heart disease (CHD) in humans and the severity of experimental atherosclerosis in animals are inversely correlated with serum HDL cholesterol (HDL-C) concentrations (Russ et al., Am.

J. Med., 11 (1951) 480-493; Gofman et al, Circulation, 34 (1966) 679-697; Miller and Miller, Lancet, 1 (1975) 16-19; Gordon et al., Circulation, 79 (1989) 8-15; Stampfer et al., N. Engl. J. Med., 325 (1991) 373-381; Badimon et al., Lab. Invest., 60 (1989) 455-461).

Atherosclerosis is the process of accumulation of cholesterol within the arterial wall which results in the occlusion, or stenosis, of coronary and cerebral arterial vessels and subsequent myocardial infarction and stroke. Angiographical studies have shown that elevated levels of some HDL particles in humans appears to be correlated to a decreased number of sites of stenosis in the coronary arteries of humans (Miller et al., Br. Med. J., 282 (1981) 1741-1744).

There are several mechanisms by which HDL may protect against the progression of atherosclerosis. Studies in vitro have shown that HDL is capable of removing cholesterol from cells (Picardo et al., Arteriosclerosis, 6 (1986) 434-441). Data of this nature suggest that one antiatherogenic property of HDL may lie in its ability to deplete tissues of excess free cholesterol and eventually lead to the delivery of this cholesterol to the liver (Glomset, J. Lipid Res., 9 (1968) 155-167). This has been supported by experiments showing efficient transfer of cholesterol from HDL to the liver (Glass et al., Circulation, 66 (Suppl. II) (1982) 102; MacKinnon et al., J. Biol. Chem., 261 (1986) 2548-2552). In addition, HDL may serve as a reservoir in the circulation for apoproteins necessary for the rapid metabolism of triglyceride-rich lipoproteins (Grow and Fried, J.

Biol. Chem., 253 (1978) 1834-1841; Lagocki and Scanu, J. Biol. Chem., 255 (1980) 3701-3706; Schaefer et al., J. Lipid Res., 23 (1982) 1259-1273). Accordingly, agents which increase HDL cholesterol concentrations are useful as anti-atherosclerotic agents, particularly in the treatment of dyslipoproteinemias and coronary heart disease.

BRIEF DESCRIPTION OF THE INVENTION The compounds of this invention which elevate plasma levels of HDL cholesterol have the general structure wherein: R1, R2, and R3 are independently hydrogen, Cl-C6 alkyl or- (CH2) 0-6Ph where Ph is phenyl is optionally substituted by halogen, cyano, nitro, Cl-C6 alkyl, C1-C6 alkoxy, trifluoromethyl, Cl-C6 alkoxycarbonyl,-CO2H or OH; R4 is hydrogen or Cl-C6 alkyl; RS is hydrogen, Cl-C6 alkyl, C3-C8 cycloalkyl, or- (CH2) 0-6Arl where Arl is phenyl, naphthyl, furanyl, pyridinyl or thienyl and Arl can be optionally substituted by halogen, cyano, nitro, Cl-C6 alkyl, phenyl, Cl-C6 alkoxy, phenoxy, trifluoromethyl, C1-C6 alkoxycarbonyl,-CO2H or OH; and Ar is phenyl, naphthyl, furanyl, pyridinyl or thienyl or Ar is optionally substituted by halogen, cyano, nitro, C1-C6 alkyl, phenyl, C1-C6 alkoxy, phenoxy, trifluoromethyl, Cl-C6 alkoxycarbonyl,-C02H or OH.

The compounds are tested in vivo in rats fed cholesterol-augmented rodent chow for 8 days according to the test protocol and blood from the rats analyzed for HDL cholesterol.

DETAILED DESCRIPTION OF THE INVENTION The compounds of this invention are conveniently prepared by the route shown in Scheme 1. Specific examples are given in the Experimental Section. These examples are for illustrative purposes only and are not to be construed as limiting to this disclosure in any way. Those skilled in the art will be aware of other methods of preparing compounds of this invention. The starting materials or intermediates are available commercially or can be prepared by standard literature procedures.

Scheme 1.

Experimental Example 1 <BR> <BR> N- [4- [ (Aminothioxomethyl) hydrazono]-4-phenylbutyl]-N- (l-methylethyl)- acetamide (a) A mixture of y-phenyl-y-butyrolactone (lO. Og, 61.7 mmol) and isopropylamine (50 ml, 587 mmol) was stirred at room temperature for approximately 26 hours. The solvent was removed under reduced pressure to give 4-hydroxy-N-isopropyl-4-phenyl- butyramide (13.71g, 100 %) as a yellow solid, mp 131-135°C.

Elemental Analysis for C13Hl9NO2 Calc'd: C, 70.56; H, 8.65; N, 6.33 Found: C, 70.24; H, 8.73; N, 6.24 (b) A solution of 4-hydroxy-N-isopropyl-4-phenyl-butyramide (12.03g, 54.4 mmol), prepared in the previous step, in 200 ml of anhydrous THF was added under nitrogen dropwise over 30 minutes to a suspension of LAH (5.18g, 136 mmol) in 200 ml of anhydrous THF at room temperature. After the addition the reaction was refluxed for approximately 19 hours. After cooling to room temperature 5.18 ml of water was added dropwise followed by the dropwise addition of 5.18 ml of 15% KOH and 15.54 ml of water. After stirring at room temperature 30 minutes the solid was removed by filtration and the filtrate concentrated under reduced pressure to remove the THF. The residue was partitioned between methylene chloride and water. The organic layer was separated and the aqueous layer extracted three times with methylene chloride. The combined organic extracts were dried (MgS04) and the solvent removed under reduced pressure to give 10.22g of a light yellow solid. The solid was dissolved in methylene chloride and extracted with 1 N HC1. The organic layer was separated and the aqueous layer extracted two times with methylene chloride. The aqueous layer was partitioned with methylene chloride and then made basic with 1 N NaOH. The organic layer was separated and the aqueous layer extracted five times with methylene chloride. The organic extracts were combined, dried (MgS04) and the solvent removed under reduced pressure to give 4- isopropylamino-l-phenyl-l-butan-l-ol (9.47g, 84%) as a white solid, mp 61-67°C.

Elemental Analysis for C13H21NO Calc'd: C, 75.32; H, 10.21; N, 6.76 Found: C, 75.26; H, 10.25; N, 6.52

(c) Acetyl chloride (4.47 ml, 62.9 mmol) in 200 ml of methylene chloride was added under nitrogen dropwise over 2 hours to a solution of 4-isopropylarnino-1-phenyl-1-butan- l-ol (13.02g, 62.8 mmol), prepared in the previous step, and triethylamine (8.75 ml, 62.8 mmol) in 250 ml of methylene chloride at ice bath temperature. After the addition the reaction was stirred at ice bath temperature for 2 hours. The ice bath was removed and the stirring continued for 20 hours (overnight). The reaction was extracted with 1 N HCI, dried (MgS04) and the solvent removed under reduced pressure to give N- (4-hydroxy-4- phenyl-butyl)-N-isopropyl-acetamide (16.29g) as a yellow oil. The material was used in the following reaction without addition purification, MS [M+] rnle 249.

Elemental Analysis for C15H23NO2-0-11 CH2CI2 Calc'd: C, 70.15; H, 9.05; N, 5.41 Found: C, 69.92; H, 8.95; N, 5.32 (d) Pyridinium chlorochromate (20.35g, 94.2 mmol) was added to a solution of N- (4- hydroxy-4-phenyl-butyl)-N-isopropyl-acetamide (15.69g, 62.9 mmol), prepared in the previous step, in 350 ml of methylene chloride and the mixture stirred at room temperature for 2 hours. The entire reaction mixture was poured onto 750g of silica gel (230-400 mesh) and the material eluted with 50% ethyl acetate-methylene chloride and then ethyl acetate. Isolation of the major fraction gave N-isopropyl-N- (4-oxo-4-phenyl-butyl)- acetamide (12.43g, 80%) as a green solid, mp 36-39°C.

Elemental Analysis for C15H21NO2 Calc'd: C, 72.84; H, 8.56; N, 5.66 Found: C, 73.11; H, 8.42; N, 5.60 (e) Thiosemicarbazide (6.1901g, 67.9 mmol) was added to a solution of N-isopropyl- N- (4-oxo-4-phenyl-butyl)-acetamide (11.20g, 45.3 mmol), prepared in the previous step, in 160 ml of methanol plus 12.2 ml of 1 N HCI, plus 12.2 ml of water and the reaction stirred at room. temperature for 22 hours (overnight). The reaction was concentrated under reduced pressure to remove the methanol. The residue was partitioned between methylene chloride and water. The organic layer was separated, washed five times with water, dried (MgS04) and the solvent removed under reduced pressure to give 14.54g of a yellow foam. The foam was crystallized from ethyl acetate to give 10.28g (71%) of the title compound as a white solid, mp 141-147°C.

Elemental Analysis for C16H24N4OS Calc'd: C, 59.97; H, 7.55; N, 17.48 Found: C, 59.96; H, 7.46; N, 17.46 Example 2 N- [4- [ (Aminothioxomethyl) hydrazono]-4-phenylbutyl] acetamide (a) A mixture of y-phenyl-y-butyrolactone (10.30g, 63.5 mmol) and an excess of ammonia was stirred under nitrogen and a dry ice trap for 8 hours. The dry ice trap was removed and after evaporation of the ammonia 11.27g of a tan solid remained.

Recrystallization of this solid from ethyl acetate-hexane gave 4-hydroxy-4-phenyl- butyramide (8.56g, 75%) as a white solid, mp 85-87°C.

Elemental Analysis for CloHl3NO2 Calc'd: C, 67.02; H, N, 7.82 Found: C, 67.27; H, 7.25; N, 7.84 (b) A solution of 4-hydroxy-4-phenyl-butyramide (26.0g, 0.145 mol), prepared in the previous step, in 400 ml of anhydrous THF was added under nitrogen dropwise over 1.5 hours to a suspension of LAH (11. 0g, 0.290 mol) in 300 ml of anhydrous THF at room temperature. After the addition the reaction was refluxed for approximately 21 hours.

After cooling to room temperature 11 ml of water was added dropwise followed by the dropwise addition of 11 ml 15% KOH and 33 ml of water. After stirring at room temperature for 30 minutes the solid was removed by filtration and the filtrate concentrated under reduced pressure to remove the THF. The residue was partitioned between methylene chloride and water. The organic layer was separated and the aqueous layer extracted three times with methylene chloride. The combined organic extracts were dried (MgS04) and the solvent removed under reduced pressure to give 18.38g of a waxy yellow solid. Recrystallization of the solid from ethyl acetate gave 4-amino-l-phenyl-butan-1-ol (4.95g, 21%) as a white solid, mp 94-96°C.

Elemental Analysis for CloHIsNO Calc'd: C, 72.69; H, 9.15; N, 8.48 Found: C, 72.49; H, 9.04; N, 8.24

(c) Acetyl chloride (4.26 ml, 59.9 mmol) in 200 ml of methylene chloride was added under nitrogen dropwise over 3 hours to a solution of 4-amino-1-phenyl-butan-1-ol (9.90g, 5.99 mmol), prepared in the previous step, and triethylamine (8.35 ml, 59.9 mmol) in 300 ml of methylene chloride at ice bath temperature. After the addition the reaction was stirred at ice bath temperature for 1 hour. The ice bath was removed and the stirring continued for 18 hours (overnight). The reaction was extracted with 1 N HCI, dried (MgS04) and the solvent removed under reduced pressure to give 9.04g of a yellow oil. Purification of this oil on 700g of silica gel (230-400 mesh) using ethyl acetate and then 1% to 5% methanol-ethyl acetate as the eluent gave N- (4-hydroxy-4-phenyl-butyl)- acetamide (6.30g, 51%) as a light yellow oil, MS [M+] m/e 207.

Elemental Analysis for C12Hl7NO2'0. 04 CH2CI2'0-06 C4H802 Calc'd: C, 68.30; H, 8.20; N, 6.49 Found: C, 66.98; H, 8.32; N, 6.27 (d) Pyridinium chlorochromate (10.08g, 46.8 mmol) was added to a solution of N- (4- hydroxy-4-phenyl-butyl)-acetamide (6.46g, 31.2 mmol), prepared in the previous step, in 200 ml of methylene chloride and the mixture stirred at room temperature for 1.5 hours.

The entire reaction mixture was poured onto 200g of silica gel (230-400 mesh) and the material eluted with ethyl acetate. Isolation of the major fraction gave N- (4-oxo-4-phenyl- butyl)-acetamide (4.35g, 68%) as a light brown solid, mp 92-95°C.

Elemental Analysis for Cl2Hi5N02 Calc'd: C, 70.22; H, 7.37; N, 6.82 Found: C, 69.70; H, 7.38; N, 6.75 (e) Thiosemicarbazide (2.85g, 31.3 mmol) was added to a solution of N- (4-oxo-4- phenyl-butyl)-acetamide (4.28g, 20.9 mmol), prepared in the previous step, in 75 ml of methanol plus 5.6 ml of 1 N HCI, plus 5.6 ml of water and the reaction stirred at room temperature for 42 hours. The reaction was concentrated under reduced pressure to remove the methanol. The residue was partitioned between methylene chloride and water. The organic layer was separated, washed five times with water, dried (MgS04) and the solvent removed under reduced pressure to give 4.77g of a yellow solid. Recrystallization of this solid from ethyl acetate gave the title compound (3.53g, 61%) as an off-white solid, mp 74-83°C.

Elemental Analysis for Cl3HlgN4OS0.79 C4HgO2 Calc'd: C, 55.78; H, 7.04; N, 16.10 Found: C, 55.72, H, 6.90; N, 15.97 Example 3 N- [4- [ (Aminothioxomethyl) hydrazonol-4- phenylbutyl]-N- (1-methylethyl)- benzamide In the manner as described in Example 1 and substituting benzoyl chloride for acetyl chloride in step c, the title compound was obtained (3.75g, 75%) as an off-white solid, mp 107-109°C.

Elemental Analysis for C2lH26N4oS0.25 C4HaO2 Calc'd: C, 65.32; H, 6.98; N, 13.85 Found: C, 65.24; H, 6.88; N, 13.76 Example 4 N- [4- [ (Aminothioxomethyl) hydrazono]-4-phenylbutyl]-N- (1-methylethyl)- cyclohexanecarboxamide In the manner as described in Example 1 and substituting cyclohexanecarbonyl chloride for acetyl chloride in step c, the title compound was obtained (1.48g, 40%) as a white solid, mp 112-114°C.

Elemental Analysis for C2lH32N4oS0 07 C6H1400. 22 C4H8O2 Calc'd: C, 64.70; H, 8.46; N, 13.53 Found: C, 64.72; H, 8.63; N, 13.10 Example 5 N- [4- [ (Aminothioxomethyl) hydrazono]-4-phenylbutyl] cyclohexane- carboxamide In the same manner as described in Example 2 and substituting cyclohexanecarbonyl chloride for acetyl chloride in step c, the title compound was obtained (2.19g, 51%) as a light yellow solid after recrystallization from isopropyl alcohol, mp 158-159°C.

Elemental Analysis for C18H26N4OS Calc'd: C, 62.40; H, 7.56; N, 16.17 Found: C, 62.37; H, 7.39; N, 15.87 Example 6 N- [4- [ (Aminothioxomethyl) hydrazono]-4-phenylbutyl] hexanamide In the same manner as described in Example 2 and substituting hexanoyl chloride for acetyl chloride in step c, the title compound was obtained (3.48g, 53%) as a light yellow solid, mp 125-127°C.

Elemental Analysis for C17H26N4OS Calc'd: C, 61.05; H, 7.84; N, 16.75 Found: C, 61.10; H, 7.59; N, 16.89 Example 7 N-[4-[[(Methylamino) thioxomethyl] hydrazono]-4-phenylbutyl] benzamide In the same manner as described in Example 2 and substituting benzoyl chloride for acetyl chloride in step c, the title compound was obtained (1.47g, 64%) as a white solid, mp 114- 118°C.

Elemental Analysis for Cl9H22N40S0.5 H20 Calc'd: C, 62.79; H, 6.38; N, 15.41 Found: C, 62.64; H, 6.39; N, 15.10 Example 8 2-[2-(Benzylcarbonylamino)-l-phenyl-butylidene]-hydrazinecar bothioamide In the same manner as described in Example 2 and substituting phenylacetyl chloride for acetyl chloride in step c, the title compound was obtained (2.52g, 62 %) as a white solid after recrystallization from isopropyl alcohol, mp 121-124°C.

Elemental Analysis for ClgH22N40S Calc'd: C, 64.38; H, 6.26; N, 15.81 Found: C, 64.33; H, 6.23; N, 15.71

Example 9 N- [4- [ (Aminothioxomethyl) hydrazono]-4- (4-fluorophenyl) butyl]-N- (l- methylethyl) acetamide In the same manner as described in Example 1 and substituting y-(4-fluorophenyl)-Y- butyrolactone for y-phenyl-y-butyrolactone in step 1, the title compound was obtained (2.10g, 49%) as a white solid after recrystallization from isopropyl alcohol, mp 155-157°C.

Elemental Analysis for C, 6H23FN4OS0.36 C3H8O Calc'd: C, 56.97; H, 7.24; N, 15.56 Found: C, 56.52; H, 7.18; N, 15.08 PHARMACOLOGY In Vivo Assav: Male Sprague-Dawley rats weighing 200-225 g are housed two per cage and fed Purina Rodent Chow Special Mix 5001-S supplemented with 0.25% cholic acid and 1.0% cholesterol and water ad libitum for 8 days. Each test substance is administered to a group of six rats fed the same diet with the test diet mixed in as 0.005-0.1 % of the total diet. Body weight and food consumption are recorded prior to diet administration and at termination. Typical doses of the test substances are 5-100 mg/kg/day.

At termination, blood is collected from anesthetized rats and the serum is separated by centrifugation. Total serum cholesterol is assayed using the Sigma Diagnostics enzymatic kit for the determination of cholesterol, Procedure No. 352, modified for use with ninety-six well microtiter plates. After reconstitution with water the reagent contains 300 U/I cholesterol oxidase, 100 U/I horse radish peroxidase, 0.3 mmoles/14- aminoantipyrine and 30.0 mmoles/1 p-hydroxybenzenesulfonate in a pH 6.5 buffer. In the reaction cholesterol is oxidized to produce hydrogen peroxide which is used to form a quinoneimine dye. The concentration of dye formed is measured spectrophotometrically by absorbance at 490 nm after incubation at 25 °C for 30 minutes. The concentration of cholesterol was determined for each serum sample relative to a commercial standard from Sigma.

HDL cholesterol concentrations in serum are determined by separation of lipoprotein classes by fast protein liquid chromatography (FPLC) by a modification of the method of Kieft et al., J. Lipid Res., 32 (1991) 859-866.25 gel of serum is injected onto Superose 12 and Superose 6 (Pharmacia), in series, with a column buffer of 0.05 M Tris (2-amino-2-hydroxymethyl-1,3-propanediol) and 0.15 M sodium chloride at a flow rate of 0.5 ml/min. The eluted sample is mixed on line with Boehringer-Mannheim cholesterol

reagent pumped at 0.2 ml/min. The combined eluents are mixed and incubated on line through a knitted coil (Applied Biosciences) maintained at a temperature of 45° C. The eluent is monitored by measuring absorbance at 490 nm and gives a continuous absorbance signal proportional to the cholesterol concentration. The relative concentration of each lipoprotein class is calculated as the per cent of total absorbance. HDL cholesterol concentration, in serum, is calculated as the per cent of total cholesterol as determined by FPLC multiplied by the total serum cholesterol concentration.

TABLE I Cholesterol Fed Rat Example % Increase in HDL (Dose) Example 1 87 % (50 mg/kg) Example 2 81 % (33 mg/kg) Example 3 26.1 % (50 mg/kg) Example 4 59.7 % (50 mg/kg) Example 5 58.1 % (50 mg/kg) Example 6 56.7 % (50 mg/kg) Example 7 27.2 % (50 mg/kg) Example 8 44.5 % (100 mg/kg) Example 9 80.2 % (50 mg/kg) PHARMACEUTICAL COMPOSITION Compounds of this invention may be administered neat or with a pharmaceutical carrier to a patient in need thereof. The pharmaceutical carrier may be solid or liquid.

Applicable solid carriers can include one or more substances which may also act as flavoring agents, lubricants, solubilizers, suspending agents, filles, glidants, compression aids, binders or tablet-disintegrating agents or an encapsulating material. In powders, the carrier is a finely divided solid which is in admixture with the finely divided active ingredient. In tablets, the active ingredient is mixed with a carrier having the necessary compression properties In suitable proportions and compacted in the shape and size desired. The powders and tablets preferably contain up to 99% of the active ingredient.

Suitable solid carriers include, for example, calcium phosphate, magnesium stearate, talc,

sugars, lactose, dextrin, starch, gelatin, cellulose, methyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidine, low melting waxes and ion exchange resins.

Liquid carriers may be used in preparing solutions, suspensions, emulsions, syrups and elixirs. The active ingredient of this invention can be dissolved or suspended in a pharmaceutically acceptable liquid carrier such as water, an organic solvent, a mixture of both or pharmaceutically acceptable oils or fat. The liquid carrier can contain other suitable pharmaceutical additives such a solubilizers, emulsifiers, buffers, preservatives, sweeteners, flavoring agents, suspending agents, thickening agents, colors, viscosity regulators, stabilizers or osmo-regulators. Suitable examples of liquid carriers for oral and parenteral administration include water (particularly containing additives as above, e. g., cellulose derivatives, preferable sodium carboxymethyl cellulose solution), alcohols (including monohydric alcohols and polyhydric alcohols, e. g., glycols) and their derivatives, and oils (e. g., fractionated coconut oil and arachis oil). For parenteral administration the carrier can also be an oily ester such as ethyl oleate and isopropyl myristate. Sterile liquid carriers are used in sterile liquid form compositions for parenteral administration.

Liquid pharmaceutical compositions which are sterile solutions or suspensions can be utilized by, for example, intramuscular, intraperitoneal or subcutaneous injection.

Sterile solutions can also be administered intravenously. Oral administration may be either liquid or solid composition form.

The compounds of this invention may be administered rectally in the form of a conventional suppository. For administration by intranasal or intrabronchial inhalation or insufflation, the compounds of this invention may be formulated into an aqueous or partially aqueous solution, which can then be utilized in the form of an aerosol. The compounds of this invention may also be administered transdermally through the use of a transdermal patch containing the active compound and a carrier that is inert to the active compound, is non-toxic to the skin, and allows delivery of the agent for systemic absorption into the blood stream via the skin. The carrier may take any number of forms such as creams and ointments, pastes, gels, and occlusive devices. The creams and ointments may be. viscous liquid or semi-solid emulsions of either the oil in water or water in oil type. Pastes comprised of absorptive powders dispersed in petroleum or hydrophilic petroleum containing the active ingredient may also be suitable. A variety of occlusive devices may be used to release the active ingredient into the blood stream such as a semipermeable membrane covering a reservoir containing the active ingredient with or without a carrier, or a matrix containing the active ingredient. Other occlusive devices are known in the literature.

The dosage to be used in the treatment of a specific patient suffering from high density lipoprotein insufficiency must be subjectively determined by the attending physician. The variables involved include the severity of the dysfunction, and the size, age, and response pattern of the patient.. Treatment will generally be initiated with small dosages less than the optimum dose of the compound. Thereafter the dosage is increased until the optimum effect under the circumstances is reached. Precise dosages for oral or parenteral administration will be determined by the administering physician based on experience with the individual subject treated and standard medical principles.

Preferably the pharmaceutical composition is in unit dosage form, e. g., as tablets or capsules. In such form, the composition is sub-divided in unit doses containing appropriate quantities of the active ingredient; the unit dosage form can be packaged compositions, for example packed powders, vials, ampoules, prefilled syringes or sachets containing liquids. The unit dosage form can be, for example, a capsule or tablet itself, or it can be the appropriate number of any such compositions in package form.