Potassium thioacetate synthesis

Yield:-

Reaction Conditions:

with potassium hydroxide in ethanol at 20;

Steps:

8
Compound 75: (20S)-20-dimethylamino-16α-acetyl-3β-isobutyrylamino-9,19-cyclo-4α-methylethanethioate-4β,14α-dimethyl-5α,9β-pregnan-11-one 75 To a solution of 100 mg (1.78 mmol, 1.0 eq) of potassium hydroxide in 1.5 ml of ethanol are added 126.8 μl (1.78 mmol, 1.0 eq) of thiolacetic acid. After minutes of agitation at room temperature, the reaction mixture is evaporated and the yellow powder obtained is washed with tetrahydrofuran to yield 203 mg of potassium thioacetate in the form of a light yellow powder.166.8 mg (1.46 mmol, 7.0 eq) of potassium thioacetate thus prepared are added to 145.8 mg (0.21 mmol, 1.0 eq) of (20S)-16α-acetyl-3β-isobutyrylamino-9,19-cyclo-4α-hydroxytosylmethyl-4β,14α-dimethyl-20-dimethylamino-5α,9β-pregnan-11-one dissolved in 5 ml of anhydrous 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU). After 5 hours of agitation at 100° C., the reaction mixture is alkalinized with 20 ml of a 10% sodium hydrogen carbonate solution (pH=8) and extracted with 3×20 ml of ether. The recombined organic phases are successively dried on anhydrous sodium sulfate and evaporated under a vacuum.The residue obtained is purified by silica gel flash chromatography (eluent: 9.8/0.2 dichloromethane/methanol) to yield 70.1 mg of 75 in the form of a light yellow powder with a yield of 56%.IR (diamond) υ(cm^-1): 2930 (NH); 1730 (CO); 1666 and 1529 (CO ester, CONH and COS).MS (ESI): m/z: 603.4 ([M+H].

References:

Guillou, Catherine;Lallemand, Jean-Yves;Sauvaítre, Thibault;Molgo, Jordi;Herlem, Denyse;Guenard, Daniel;Khuong-Huu, Françoise US2012/40930, 2012, A1 Location in patent:Page/Page column 77

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