Transition-metal-free synthesis of aryl-substituted tert-butyl ynol ethers through addition/elimination substitution at an sp centre.

Nucleophilic attack of an alkoxide on an alkynyl sulfonamide leads to displacement of the sulfonamide at the sp centre and isolation of the ynol ether in good yield in a single operation. The mechanistic pathway has been probed by the use of coordinating additives, (13)C-labelling experiments and ab initio calculations, which indicated that an addition/elimination mechanism is in operation.