Thermally-induced skeletal rearrangement of (Z)-O-propargylic α,β-unsaturated aldoximes to multisubstituted pyridine oxides

(Z)-Propargylic oxime ethers derived from alpha,beta-unsaturated aldehydes were converted to the corresponding 2,3,6-trisubstituted pyridine oxides in moderate to acceptable yields with high regioselectivity. The reaction proceeds via a tandem thermal [2,3] rearrangement, 4 pi electrocyclization, and ring expansion. (C) 2011 Elsevier Ltd. All rights reserved.