Umpolung with Sulfur Dioxide: Carbon-Carbon Cross-Coupling of Electron-Rich 1,3-Dienes and Alkenes; Application to the Enantioselective Synthesis of Long-Chain Polyketide Fragments

Synthesis 2009
Māris Turks, Claudia Exner, Cotinica Hamel, Pierre Vogel

At low temperature and in the presence of an acid catalyst, sulfur dioxide undergoes hetero-Diels-Alder additions with 1-oxy-1,3-dienes, giving unstable sultines, which are ionized into zwitterionic species and react as 1-oxyallylic cation intermediates (Umpolung with SO2) with electron-rich alkenes such as allylsilanes or enoxysilanes. The β,γ-unsaturated silyl sulfinates so-obtained can be desulfinylated in situ to generate polyketide fragments containing up to three contiguous stereogenic centers in one-pot operations. This reaction cascade can be applied in two-directional chain elongation approaches for the asymmetric synthesis of long chain polyketide fragments using 1-[(S)- or (R)-1-phenylethoxy]-1,3-dienes.

Keywords
hetero-Diels-Alder of sulfur dioxide - asymmetric synthesis of polyketides - reaction cascade - allylic cation - allylsilane - enoxysilane
DOI
10.1055/s-0028-1088011
Hyperlink
https://www.thieme-connect.de/DOI/DOI?10.1055/s-0028-1088011

Turks, M., Exner, C., Hamel, C., Vogel, P. Umpolung with Sulfur Dioxide: Carbon-Carbon Cross-Coupling of Electron-Rich 1,3-Dienes and Alkenes; Application to the Enantioselective Synthesis of Long-Chain Polyketide Fragments. Synthesis, 2009, No.7, pp.1065-1074. ISSN 1065-1074. Available from: doi:10.1055/s-0028-1088011

Publication language
English (en)