143621-72-1Relevant articles and documents
One-Pot Synthesis of Optically Active Cyanohydrin Acetates from Aldehydes via Lipase-Catalyzed Kinetic Resolution Coupled with in Situ Formation and Racemization of Cyanohydrins
Inagaki, Minoru,Hiratake, Jun,Nishioka, Takaaki,Oda, Jun'ichi
, p. 5643 - 5649 (2007/10/02)
A novel one-pot synthesis of optically active cyanohydrin acetates from aldehydes has been accomplished by lipase-catalyzed kinetic resolution coupled with in situ formation and racemization of cyanohydrins in an organic solvent.Racemic cyanohydrins 2, generated from aldehydes 1 and acetone cyanohydrin in diisopropyl ether under the catalysis of basic anion-exchange resin (OH- form), were acetylated stereoselectively by a lipase from Pseudomonas cepacia (Amano) with isopropenyl acetate as an acylating reagent.The (S)-isomer of 2 was preferentially acetylated by the lipase, while the unreacted (R)-isomer was continuously racemized through reversible transhydrocyanation catalyzed by the resin.These processes thus enabled one stage conversion of various aldehydes 1a-n into the corresponding (S)-cyanohydrin acetates 3a-n with up to 94 percent ee in 63-100 percent conversion yields.The racemization of the optically active cyanohydrin 2e by Amberlite IRA-904 (OH- form) was found to be much faster then the enzymatic acetylation, confirming the effective second-order asymmetric transformation.Enzymatic deacetylation of (S)-cyanohydrin acetates in an organic solvent and the synthesis of optically active pyrethroids are also described.
