Sequential cycloaddition and ring expansion reaction of arynes and methylenebenzothiopheneones: synthesis of a benzo-fused eight-membered ring via sulfonium ylides.

A sequential cycloaddition and ring expansion of arynes and methylenebenzothiopheneones has been disclosed. This strategy proceeds through a sulfonium ylides intermediate and allows for the efficient synthesis of a sulfur-containing benzo-fused eight-membered ring.