Reactions of o-quinones with 2,5-dimethylthiophene-3,4-diylbis(methylenetriphenylphosphonium chloride) in the presence of lithium hydroxide. Application of phase transfer catalysis

Abstract

The reactions of the 1,4-bisphosphoniumsalt (1) withquinones (4), (8), (14), and (25), in the presence of lithium hydroxide did not afford bis-Wittig products, with exception of compound (6). The quinone (4) in addition to compound (6) gave the o-quinomethane derivative (7), quinone (14) gave compounds (17), (18), and (19), via a simple Wittig reaction, followed by Michael addition of a second ylide species, while quinone (25) gave the 1,3-benzodioxole (26). A deviation of the typical Wittig procedure can account for the formation of compound (12) from the quinone (8). The reaction of the 1,4-bisphosphonium salt (20) with the dione (14) is also described. Significant hydrolysis of the formed ylide groups was observed in all reactions.