A new conjugated addition of trialkyl phosphites and alkylidenephosphoranes to 3-ω-azideoacetyl coumarin synthesis of some 1,2,3,4-triazaphospholes, triazoles, and azido-coumarin derivatives

Abstract

A new and efficient conjugate addition of trimethyl and triethyl phosphites to 3-ω-azidoacetylcoumarin (1) has been studied. The reaction proceeded smoothly at r.t. furnishing 1,2,3,4-triazaphosphole coumarin derivatives 4a, 4b in ∼75% yields. Linear substituted triazoles 10b, 11a were also obtained from the reactions of 1 with α-keto ylides, acetyl- and benzoylmethylene triphenylphosphoranes. Contrary to these results, Wittig reaction was occurred when 1 was allowed to react with α-alkoxycarbonylmethylene- and cyanomethylenetriphenylphosphoranes 7c, 7d, 7e as well as with methylidene- and benzylidenetriphenylphosphoranes 8b, 10a resulting in the formation of the corresponding olefins either as an intermediate 14b or as final products 11b, 11c, 12a. J. Heterocyclic Chem., (2011).