New metal-free one-pot synthesis of substituted allenes from enones.

A new metal-free, one-pot synthesis of substituted allenes from enones was discovered for the first time, in which a tertiary amine as a base was found to be an effective promoter in such novel transformations. The present synthetic protocol proceeded readily with high compatibility of sensitive functional groups, and it provides a new efficient way to access a series of synthetically important allenes without the use of metallic reagents or catalysts.