Convenient preparation of (Z)-α-halo-α,β-unsaturated aldehydes: synthesis of a Laurencia flexilis toxin
摘要:
The CrCl(2)-mediated two-carbon halo-homologation of aryl, alkenyl, and aliphatic aldehydes with chloral ethyl hemiacetal or bromal affords (Z)-alpha-chloro- and (Z)-alpha-bromo-alpha,beta-unsaturated aldehydes, respectively, in good to excellent yields and high stereoselectivity. The utility of this methodology was illustrated by a synthesis of 2-chloropentadec-2(Z)-enal, a toxin isolated from the marine red alga Laurencia flexilis. (C) 2008 Elsevier Ltd. All rights reserved.