ChemInform Abstract: CAL‐B Catalyzed Enantioselective Synthesis of Cyanohydrins — A Facile Route to Versatile Building Blocks.

Abstract

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Enantioselective Synthesis of Protected Cyanohydrins

“…[22] However, since the protection reaction had to be performed with the mixture obtained from the kinetic resolution, these conditions had to be reassessed. For the protection of (S)-2aϪd as TBDMS ethers, several sets of conditions were explored.…”

“…Previous work in this group had indicated low selectivity for the kinetic resolution of aliphatic cyanohydrin acetates, and so this class of compounds was not included in this work. [32] However, if the kinetic resolution of aliphatic cyanohydrins should be desired, other lipases has been used with excellent results. [33,34] In order to prevent any enzyme degradation, the protection reactions were performed after removal of the enzyme from the reaction mixture.…”

“…[21] This procedure has been optimised for the kinetic resolution of a wide range of aromatic cyanohydrin acetates, with excellent results. [22] However, the resulting (S)-cyanohydrins are relatively unaddition of vinyl butyrate, or chemically after removal of the enzyme from the reaction mixture. This process gave access to both enantiomers in pure form and in good yields, while considerably reducing the risks due to HCN.…”

An Asymmetric, Chemo‐Enzymatic Synthesis of O‐Acetylcyanohydrins

“…[28] This temperature was incompatible with its use in situ with catalyst 1, which requires ambient or lower temperatures to obtain high enantioselectivities. Fortunately, a reaction using this enzyme was found to proceed at room temperature giving a good conversion and enantioselectivity after one day (Table 1: Entry 1).…”

“…[28] [ (R)-O-Acetyl-2-hydroxy-2-(4-chlorophenyl)acetonitrile: [31] Solvent system for column chromatography: hexane/ethyl acetate, 4:1. Yield 0.60 g (81 %).…”