Acylaminophosphonium salt

Acid halides react with vinylphosphoranes (56) to afford isolable N-acylaminophosphonium salts (57), which are hydrolyzed by alkali to N-vinylamides (58). By treatment with triethylamine and phenol the halogen in 57 can be nucleophilically exchanged for phenolate. Thiophenol, secondary amines, and hydrazones can be employed instead of phenol this leads to diverse 1-hetero-substituted 2-aza-1,3-dienes 59 (Scheme 31) (90TL3497). 

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