Construction of Fully Substituted Cyclobutanes by Tandem Reaction of 1,4-Diyn-3-ols and Anhydrides

A concise and efficient synthesis of fully substitutedcyclobutanederivatives from 1,4-diyn-3-ols and anhydrides was developed. Mechanisticstudies indicated that a tandem esterification, isomerization to giveallenyl ester, and homointermolecular [2+2] cycloaddition might beinvolved. The features of this protocol are its operational practicality,mild reaction conditions, and high regio- and stereoselectivity, andit is a readily accessible gram-scale synthesis.