ω-BROMOALKAPOLYENYLMETHYL KETONES-I. REACTION OF 5-BROMO-3-PENTEN-2-ONE WITH TRIPHENYLPHOSPHINE

Article abstract of DOI:10.1016/S0040-4020(01)88895-5

The reaction of (E)-5-bromo-3-penten-2-one with triphenylphosphine affords a 3:1 mixture of two protomeric phosphonium salts: 4-oxo-2-pentenyltriphenylphosphonium bromide and 4-oxo-1-pentenyltriphenylphosphonium bromide, characterized by the 13C NMR spectrum of the mixture.However, the common phosphorane of these salts gives two condensation products with benzaldehyde, corresponding to α- and γ-condensation respectively.