Phosphine alkylation by a -functionalized alkyl halide

The same kind of addition can be carried out on the ethynylphosphonium salt 26, generated in situ from the 1,2-vinylenebisphosphonium salt 25, and, depending on the experimental conditions, the vinylphosphonium salt produced can eventually undergo a second addition of YH to produce the / -acetalized or-thioacetalized salt. The same type of /Mieterosubstituted vinylphosphonium salt can also undergo an acidic hydrolysis that leads to the ketonic salt itself335 (reaction 74). 

Buta-l,4-dienylenebisphosphonium salts behave like bisvinylphosphonium salts and can undergo a double addition in the 2,3-position (reaction 75)335. 

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