Gold-catalysed synthesis of phosphonate-substituted oxetan-3-ones – an easy access to highly strained HWE reagents

A convenient approach for the attainment of strained phosphonate-substituted oxetan-3-ones, starting from easy to synthesise alkynyl phosphonates, is presented. With the aid of a pyridine- N -oxide, in a gold-catalysed step an α-oxo carbene species is generated as a key intermediate. After formal OH-insertion, synthetically useful HWE reagents can be attained. The synthetic utility of the obtained building blocks could be demonstrated, which yielded the 2-alkenyl oxetan-3-one scaffold in high yields after the HWE reaction.