The synthesis of diethyl p-tolylsulphonylethynylphosphonate and related acetylenes, and their reactions with nucleophiles, pyridinium-1-dicyanomethylides, and dienes

Abstract

Diethyl p-tolylthioethynylphosphonate (10) was synthesized from diethyl ethynylphosphonate (7) by two routes and oxidised to the corresponding sulphoxide (11) and sulphone (12). The sulphone showed no triple bond i.r. absorption, but a strong Raman band, and nucleophiles could add to either end of the triple bond. These alkynes gave indolizines with pyridinium-1-dicyanomethylides and Diels–Alder adducts with anthracenes. The orientations of the additions were deduced from ¹H, ¹H; ³¹P, ¹H; and ³¹P, ¹³C coupling constants.