Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 11.1 Unexpected generation and rearrangement of acetyl benzotriazolyl carbene

Abstract

Seventeen novel α-benzotriazolyl-β-oxo phosphorus ylides 2 have been prepared and characterised. Flash vacuum pyrolysis (FVP) of these generally leads to loss of both R¹₃PO and N₂ to give intractable products but, in one case, 2l, extrusion of Bu₃P is observed to give 3-acetyl-1,2,4-benzotriazine 6 and 2′-cyanoacetophenone 7, products apparently derived from rearrangement of the initially formed carbene 11, and involving in the latter case a novel 1,3-acetyl migration process.