Convenient One-Pot Synthesis of Spiro- (E) -?-Ethylidene-?-Butyrolactones

Abstract
Treatment of the di-anion (5) derived from N, 2-dimethyl-2-(E), -butenamide (4) with cycloalkanones, followed by acid-catalysed hydrolysis and cyclodehydration of the resulting adducts, in a ‘one-pot’ procedure, provides a convenient stereospecific synthesis of spiro-(E), -α-ethylidene-γ-butyrolactones, e.g., (6), (7), and (9).