Alkali carbonates phosphonium ylide synthesis

Phosphonium salts that bear substituted vinyl groups on the a-carbon atom are the usual precursors of semi-stabilized ylides in carotenoid synthesis. Alkali metal alkoxides, generally as a solution in the corresponding alcohol, are frequently the bases of choice. A two-phase system is also sometimes employed, e.g. dichloromethane/aqueous NaOH solution (see Section F). 

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