Phototriggered Generation of Ynol Ethers and Their Rearrangement to Ketenes.

This study developed reactions for the phototriggered generation of reactive ynol ethers using alkoxycyclopropenones. The resulting ynol ethers underwent rearrangement to ketenes, which subsequently participated in cycloaddition with alkynes and the acylation of amines. The alkoxy groups in the ynol ethers significantly influenced on the reactivity toward their rearrangement to ketenes. Reasonable transition state structures for the rearrangement reaction were found through density functional theory calculations, and the reactivity of the ynol ethers could be predicted by these calculations.