Stereoselective Synthesis of Tetraalkyl Cyclobutene-1,2,3,4-tetracarboxylates. Synthesis of Tetraalkyl (Z,Z)-Buta-1,3-diene-1,2,3,4-tetracarboxylates
Abstract
Tetraalkyl cyclobutene-1,2,3,4-tetracarboxylates, prepared by intramolecular Wittig reaction between a vinylphosphonium salt and diethyl 2-oxobutanedioate, undergo electrocyclic ring-opening reactions, in boiling toluene, to produce highly electron-deficient 1,3-dienes.