Interception of benzyne with thioethers: a facile access to sulfur ylides under mild conditions

Reactive benzyne generated from o-(trimethylsilyl) phenyl triflate under the action of CsF has been trapped in situ by thioethers to give sulfonium ylides, which in turn have been intercepted by isatins to give rise to corresponding spiroepoxy oxindoles in moderate to high yields. This reaction provides a facile and efficient synthesis of spiroepoxy oxindoles.