Titanium mediated asymmetric aldol reaction with α-fluoropropionimide enolates
摘要:
Aldol reaction utilising Evans N-(alpha-fluoropropyl)-2-oxazolidinones with TiCl4 have been explored. Reactions of N-(alpha-fluoropropyl)-2-oxazolidinones with aliphatic aldehydes generated (x-fluoro-p-hydroxy-aldol products with high diastereoselectivities. When (alpha R)- and (alpha S)-N-(alpha-fluoropropyl)-2-(4S)-oxazolidinones were explored as substrates they gave rise to identical aldol diastereoisomer products. Examination of the enolates formed in each case by F-19 NMR, after treatment with TiCl4, indicated that both preparations gave the same predominant enolate. This was assumed to be the E-enolate. The alpha-fluoro-beta-hydroxy-aldol products were removed from the auxiliary either by alcoholysis or reduction and converted to the corresponding alpha,beta-difluoro products by treatment with Deoxofluor (TM) (C) 2007 Elsevier B.V. All rights reserved.
[EN] PROCESS FOR PREPARING 2-FLUOROPROPIONALDEHYDE<br/>[FR] PROCÉDÉ DE PRÉPARATION DE 2-FLUOROPROPIONALDÉHYDE
申请人:SANDOZ AG
公开号:WO2016016446A1
公开(公告)日:2016-02-04
A process comprising (i) providing a 2-fluoropropionic acid halide; (ii) hydrogenating the 2-fluoropropionic acid halide by contacting it with a heterogeneous hydrogenation catalyst in an atmosphere comprising hydrogen, obtaining a mixture comprising 2-fluoropropionic aldehyde.