Vinylphosphonium Salt Mediated Reaction between Alkyl Propiolates and Aminophenols or Hydroxyphenols

Addition of catechol to methyl propiolate or ethyl phenylpropiolate in the presence of Ph 3 P leads to methyl 2-(1,3-benzodioxol-2-yl)acetate or 3-(1-phenylmethylidene)-1,4-benzodioxin-2-one. 2-Aminophenols react with alkyl propiolates in the presence of Ph 3 P to produce a nearly 1:1 mixture of 3-methyl-2H-1,4-benzoxazin-2-one derivatives and methyl (E)-3-(2-aminophenoxy)-2-propenoates.