α-alkylation of serine with self-reproduction of the center of chirality
作者:Dieter Seebach、Johannes D. Aebi
DOI:10.1016/s0040-4039(01)81227-2
日期:1984.1
The lithiumenolate 6 of methyl (2R,4S)-2--butyl-3-formyl-oxazolidine-4-carboxylate (4b) derived from (s)-(+)-serine can be generated with LDA in THF solution at −75°C. Alkylations (→ 9) and hydroxyalkylations (→ 10, 11) occur preferentially (>95:5) from the Re-face of the donor center (relative topicity lk). This stereochemical course is derived from the absolute configuration of 2-deuterio- and 2-methyl-serine
New fast and practical method for the enantioselective synthesis of α-vinyl, α-alkyl quaternary α-amino acids
作者:Marcello Di Giacomo、Valerio Vinci、Massimo Serra、Lino Colombo
DOI:10.1016/j.tetasy.2007.12.012
日期:2008.2
We describe a fast and practical enantioselective synthesis of (S)-N-Cbz-alpha-vinyl, phenylalanine, suitable for the preparation of different N-Cbz-alpha-vinyl aminoacids of both configurations. The new protocol exploits a Wittig reaction on highly enantiomeric enriched N-Cbz-alpha-formyl-alpha-alkyl amino esters, readily accessible from (L)-serine through a stereoselective alkylation of Seebach's oxazolidine, carried out with a significant improvement of the previously reported method. The synthetic scheme is suitable for gram scale preparation of the desired product with a 94% ee. (C) 2008 Elsevier Ltd. All rights reserved.