Proline-Catalyzed One-Step Asymmetric Synthesis of 5-Hydroxy-(2E)-hexenal from Acetaldehyde
摘要:
For the first time, the L-proline-catalyzed direct asymmetric self-aldolization of acetaldehyde is described affording (+)-(5S)-hydroxy-(2E)-hexenal 2 with ee's ranging from 57 to 90%. Further transformations of 2 into synthetically valuable building blocks are presented. A mechanism for the formation of 2 is proposed.
A simple highly concise protective group-free synthesis of botryolide-E from (R)-propylene oxide was developed using Hoveyda Grubbs cross metathesis, Still's modified Horner-Wadsworth-Emmons reaction, and Sharpless asymmetric dihydroxylation, as key steps. (C) 2012 Elsevier Ltd. All rights reserved.