The enantioselective addition of trimethylsilyl cyanide to a variety of aldehydes proceeded by the aid of a catalyst prepared in situ from titanium tetraisopropoxide [Ti(O-i-Pr)4] and chiral Schiff bases and gave the corresponding cyanohydrins in high optical yield (up to 96% e.e.). A remarkable rate enhancement was brought about by the addition of the Schiffbase to the titanium alkoxide mediated
METHOD FOR PRODUCING OPTICALLY ACTIVE 5-HYDROXY-3-KETOESTER
申请人:NISSAN CHEMICAL INDUSTRIES, LTD.
公开号:US20160185734A1
公开(公告)日:2016-06-30
The object of the present invention is to provide a method for producing in high yield with high stereoselectivity an optically active 5-hydroxy-3-ketoester compound which is useful as an intermediate for a pharmaceutical. A novel method for producing an optically active 5-hydroxy-3-ketoester compound in which an asymmetric aldol reaction by use of 1,3-diene compound is carried out in the presence of an optically active binaphthol-titanium complex together with a substituted nitrogen-containing 5 or 6-membered aromatic heterocyclic compound to obtain an optically active 5-hydroxy-3-ketoester compound in high yield with high stereoselectivity; and a novel production intermediate having a crystalline form.
New chloramphenicol Schiff base ligands for the titanium-mediated asymmetric aldol reaction of α,β-unsaturated aldehydes with diketene: a short synthesis of atorvastatin calcium
Several novel chiral Schiff base ligands were prepared from a commercially available chloramphenicol base and applied to the titanium-mediated asymmetricaldolreaction of diketene with various α,β-unsaturated aldehydes. This reaction proceeded in good yield with high enantioselectivity. The synthetic utility of this methodology was demonstrated in the short synthesis of atorvastatin calcium.
Novel enantioselective reaction of diketene with aldehydes promoted by chiral Schiff base–titanium alkoxide complex
作者:Masahiko Hayashi、Tetsuya Inoue、Nobuki Oguni
DOI:10.1039/c39940000341
日期:——
Reaction of a variety of aldehydes with diketene in the presence of chiral Schiff baseâtitanium alkoxide complexes proceeds with high enantioselectivity to afford the corresponding 5-hydroxy-3-oxoesters.
Enantioselective addition Of diketene to aldehydes promoted by chiral schiff base—titanium alkoxide complex. Application to asymmetric synthesis of potential inhibitors of HMG coenzyme reductase
Highly enantioselective addition of diketene to aldehydes was achieved by using novel Schiff base—titanium alkoxide complexes. Up to 92% ee of 5-hydroxy-3-oxoesters was obtained. This procedure provides an efficient method for the asymmetric synthesis of potential inhibitors of HMG coenzyme reductase.