Enantioselective Cyanosilylation of Ketones with Amino Acid/BINAP/Ruthenium(II)‐Lithium Phenoxide Catalyst Systems

Abstract

AbstractEnantioselective reactions of simple ketones, α,α‐ and β,β‐dialkoxy ketones, and α‐alkoxy ketones with trimethylsilyl cyanide catalyzed by the bimetallic systems of amino acid/BINAP/ruthenium(II) complexes and lithium phenoxide have been studied [BINAP=2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl]. The Ru(PhGly)2(BINAP)‐lithium phenoxide system showed high enantioselectivity for the reaction of acetophenone derivatives to afford the cyanated products in up to 90% ee [PhGly=phenylglycinate]. For the cyanosilylation of dialkoxy ketones and α‐alkoxy ketones, the Ru(t‐Leu)2(BINAP)‐lithium phenoxide system exhibited the best catalyst performance to produce the cyanohydrin derivatives in up to 99% ee and 98% ee, respectively [t‐Leu=tert‐leucinate]. The excellent catalytic activity resulted in complete conversion in the reaction with a substrate‐to‐catalyst molar ratio (S/C) of 10,000 in the best cases.