Two highly enantioselective methods for hydrocyanation of aldehydes were developed by using chiral alkoxytitanium reagents. Treatment of benzaldehyde with cyanotrimethylsilane in the presence of a chiral alkoxytitanium affords mandelonitrile in good chemical and optical yields. By the use of the chiral cyanotitanium reagent generated in situ from the chiral alkoxytitanium and cyanotrimethylsilane, aliphatic aldehydes are converted into the corresponding cyanohydrins in a highly enantioselective manner.
The asymmetric hydrocyanation of aldehydes with cyanotrimethylsilane proceeds by the use of a chiral alkoxy titanium(IV) to give the corresponding cyanohydrins with good enantioselectivity.
The enzyme catalyzed synthesis of aliphatic (S)-cyanohydrins has been accomplished for the first time by application of a hydroxynitrile lyase from leaves of Hevea brasiliensis. The optical purities of (S)-cyanohydrins are in a range between 60-97%.
[EN] PROCESS FOR THE CYANATION OF ALDEHYDES<br/>[FR] PROCÉDÉ DE CYANATION D'ALDEHYDES
申请人:NPIL PHARMACEUTICALS UK LTD
公开号:WO2007093765A1
公开(公告)日:2007-08-23
[EN] The present invention relates to a process for the cyanation of aldehydes, particularly to the asymmetric cyanation of aldehydes, including the synthesis of chiral cyanohydrins and derivatives thereof, such as chiral O-acyl cyanohydrins. The process of the present invention comprises: reacting the aldehyde with a cyanating agent in the presence of a chiral catalyst and less than a stoichiometric amount of an ionic cyanide source. Chiral catalysts employed in the process according to the present invention are of the formula: (1), (3a), (3b). [FR] La présente invention concerne un procédé de cyanation d'aldéhydes, en particulier la cyanation asymétrique d'aldéhydes, qui inclut la synthèse de cyanhydrines chirales et de leurs dérivés, par exemple des O-acylcyanhydrines chirales. Le procédé selon la présente invention comprend : la réaction de l'aldéhyde avec un agent de cyanation en présence d'un catalyseur chiral et d'une quantité sous-stoehiométrique d'une source ionique de cyanure. Les catalyseurs chiraux employés dans le procédé selon la présente invention sont de formule : (1), (3a), (3b).