Jr. Mahajan et Is. Resck, A NEW SYNTHESIS OF MEDIUM RING AND MACROCYCLIC ACETYLENIC LACTONES FROM OXABICYCLOALKENONES VIA THEIR TOSYLHYDRAZONES, Journal of the Chemical Society, Chemical Communications, (23), 1993, pp. 1748-1749
Tosylhydrazones 4a-d of vinylogous lactones 1a-d on treatment with N-b
romosuccinimide, under strictly controlled conditions, give the title
acetylenic compounds 5a-d in 65-90% yield.