Anticholesterol Drug Enzymatic Acylation of Alcohol

Antiviral drug regioselective enzymatic acylation of ribavirin. 

Using an enzymatic diastereoselective acetylation process, tiie (5f ,3f )-alcohol 72 was prepared from racemic 73 [102]. Lipase PS-30 efficiently catalyzed the acetylation of racemic 73 (50g/l) to yield the (5R,3S)-acetate 74 and the unreacted, desired (5R,3R)-alcohol 72. A reaction yield of 46 M% and an ee of 98% were obtained for (5R,3R)-alcohol 72 when the reaction was conducted in methyl ethyl ketone in the presence of isopropenyl acetate as an acyl donor. The enzymatic process was scaled up to a 6401 preparative batch using immobilized lipase PS-30 (lipase PS-30 immobilized on Accurel PP). Product (5R,3R)-alcohol 72 was isolated with a 35 M% overall 

22 SAXAGLIPTIN ENZYMATIC SYNTHESIS OF (5S)-4,5-DIHYDRO-1H-PYRROLE-1,5 DICARBOXYLIC ACID, DIMETHYLETHYD-5-ETHYL ESTER 

An enzymatic process was developed using the CAL-B-mediated ammonolysis of (5S)-4,5-dihydro-lH-p3rrrole-l,5-dicarboxylic acid, l-(l,l-dimethylethyl)-5-ethyl ester 77 with ammonium carbamate to furnish 76 without racemization and with very low levels of side-product formation [104]. 

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