Affordable Access

Publisher Website

SnCl2-mediated carbonyl allylation in fully aqueous media

Authors
Journal
Tetrahedron
0040-4020
Publisher
Elsevier
Publication Date
Volume
60
Issue
29
Identifiers
DOI: 10.1016/j.tet.2004.05.046
Keywords
  • Allylation
  • Sncl2
  • Aqueous Medium
  • Green Chemistry
  • Barbier Reaction

Abstract

Abstract Systematic studies were performed on SnCl 2-mediated carbonyl allylation reaction between aldehydes and allyl halides in fully aqueous media. Totally three valuable reaction systems were discovered, which were SnCl 2/CuCl 2, SnCl 2/TiCl 3, and SnCl 2/PdCl 2. They all provided good to excellent yields in the allylation of aliphatic and aromatic aldehydes under very mild and convenient conditions. SnCl 2, by itself, was also found to be effective for the allylation reaction when allyl bromide was employed. However, the SnCl 2-only reaction could only tolerate very small amount of water as the solvent. The SnCl 2/CuCl 2, SnCl 2/TiCl 3, and SnCl 2/PdCl 2-mediated reactions exhibited good regioselectivity favoring the γ-adduct when cinnamyl halides were employed as the allylation reagent. The same reactions with cinnamyl halides also showed good diastereoselectivity favoring the anti-product. Mechanistic studies using proton NMR techniques suggested that the additive (i.e., CuCl 2, TiCl 3, PdCl 2) could accelerate the formation of allyltin intermediate, but this step was shown not to be the most important for the allylation. Thus we proposed that the Lewis acid catalysis effect exerted by the additive was the main reason for the observed reactivity enhancement.

There are no comments yet on this publication. Be the first to share your thoughts.