The Reaction of Butadienylphosphonates with a Oxosulfonium Ylide, Phosphonium Ylides, and Ketone Enolates

Article abstract of DOI:10.1246/bcsj.57.2127

The condensation of diethyl (ethoxycarbonylmethyl)phosphonate (1a) with cinnamaldehyde in the presence of piperidine gave a 1:1 mixture of diethyl (1E,3E)- (2a) and (1Z,3E)-(1-ethoxycarbonyl-4-phenyl-1,3-butadienyl)phosphonates (2b) in 82percent yield, while a similar reaction using diethyl phosphonates (1c) exclusively gave diethyl (1E,3E)-<1-cyano- (3) and 1-methyl-sulfonyl-4-phenyl-1,3-butadienyl>phosphonates (4) in 78percent and 93percent yields, respectively.The reaction of the butadienylphosphonates 2-4 with dimethyloxosulfonium methylide (5) gave mixtures of (E)- and (Z)-(1-substituted 2-styrylcyclopropyl)phosphonates 7-9 in good yields.Similar treatment of the butadienylphosphonate 2 with phosphonium ylides 16a-c led to (3-substituted 1-ethoxycarbonyl-2-styrylcyclopropyl)phosphonates 17a-c in moderate yields.Reduction and oxidation of 7 were studied.The reaction of the phosphonates, 2 and 4, with ketone enolates and ketones resulted in the formation of unexpected olefins 22-24 and dienes 20a, b.The reaction mechanism is discussed.