Base Catalysed Rearrangements involving Ylide Intermediates. Part 7. The Rearrangements of Allyl(pentadienyl)- and Propionyl(pentadienyl)-ammonium Cations. The Sigmatropic Rearrangement.

Article abstract of DOI:10.1039/P19800002033

The base catalysed rearrangements of the cations (7), (17), (22), and (27) gave the enamines (9), (18), (23), and (28), which on hydrolysis yielded the aldehyde (10), (19), (24), and (29) respectively.The reactions are shown to be concerted <5,4> sigmatropic rearrangements proceeding via a nine-membered transition state involving 10? electrons.The base catalysed rearrangements of the 3-phenylprop-2-ynyl (pentadienyl) ammonium cations (51), (52), (60), and (61), however yield only the products of <1,2>, <3,2>, and <5,2> sigmatropic rearrangements.