James K. Heeren

Studies in phosphinemethylene chemistry : XIII. Routes to triphenylphosphine-halomethylenes and -dihalomethylenes☆

Abstract The action of phenyllithium on (bromomethyl)triphenylphosphonium bromide results in a nearly equimolar mixture of triphenylphosphinebromomethylene (formal H ÷ abstraction) and triphenylphosphinemethylene (formal Br ÷ abstraction). With (iodomethyl)triphenylphosphonium iodide a mixture of triphenylphosphineiodomethylene and triphenylphosphinemethylene is formed in which the latter is favored by a factor of about three. A new route to haloolefins based on phenyl(halomethyl)mercurial reagents is summarized by the equations below (X  Cl and Br). C 4 H 3 HgCX 2 Br ÷ (C 6 H 5 ) 3 P ÷ RR′CO → RR′CCX 2 ÷ C 6 H 5 HgBr ÷ (C 6 H 5 ) 3 PO C 6 H 5 HgCHXBr ÷ (C 6 H 5 ) 3 P ÷ RR′CO → RR′CCHX ÷ C 6 H 5 HgBr ÷ (C 6 H 5 ) 3 PO

Studies in phosphinemethylene chemistry : IX. The reaction of organolithium reagents with tert-butyltriphenylphosphonium bromide☆

Abstract Methyllithium attacks tert -butyltriphenylphosphonium bromide principally at the phosphorus atom, giving benzene (68%) and tert -butyldiphenylphosphinemethylene (46% as methylenecyclohexane after its reaction with cyclohexanone). Ethyllithium shows reaction in this sense to a lesser degree, giving benzene and tert -butyldiphenylphosphineethylidene in yields of 30% and 25% respectively. With lithium piperidide formation of 9-phenyl-9-phosphafluorene in 42.4% yield was found; some 16% β -elimination also was observed in this reaction. Thus in the RLi ÷ [(C 6 H 5 ) 3 PC(CH 3 ) 3 ]Br reactions electronic factors appear to be more important than steric factors.