Solvent- and temperature-controlled diastereodivergent [4+2] cyclization of p-QMs and 4-benzylidene-pyrazolones

Abstract

A solvent- and temperature-controlled diastereodivergent [4+2] cyclization between para-quinone methides (p-QMs) and 4-benzylidene-pyrazolones has been developed. This method enabled the synthesis of three diastereomers of a spirochromene skeleton with three contiguous chiral centers. The scalability of the reaction was demonstrated through gram-scale experiments.