Highly Selective Boron‐Wittig Reaction: A Practical Method to Synthesize Trans‐Aryl Alkenes

Abstract

AbstractOlefins play an essential role in synthetic chemistry, serving not only as important synthons but also as key functional groups in numerous bio‐active molecules. Consequently, there has been considerable interest in the development of more powerful methods for olefins. While the Wittig reaction stands as a prominent choice for olefin synthesis due to its simplicity and the ready availability of raw materials, its limitation lies in the challenge of controlling cis‐trans selectivity, hampering its broader application. In this study, a novel Boron‐Wittig reaction has been developed utilizing gem‐bis(boryl)alkanes and aldehydes as starting materials. This method enables creating favourable intermediates, which possess less steric hindrance, and leading to trans‐olefins via intramolecular O−B bonds elimination. Notably, synthesis studies have validated its good efficacy in modifying bioactive molecules and synthesizing drug molecules with great trans‐selectivity. Furthermore, the reaction mechanism was elucidated based on intermediate trapping experiments, isotope labelling studies, and kinetic analyses.