Department of Chemistry - PhD Student Seminar - Harnessing Carbenoid and Nitrenoid Intermediates: Precision Control in Modern Organic Synthesis
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Student: Mr. Hiroshige Ogawa
Department: Department of Chemistry, HKUST
Supervisor(s): Prof. Hugh NAKAMURA
Abstract
Featuring a highly reactive carbon atom with two bonds (a divalent center), carbenes serve as powerful intermediates that enable advanced chemical reactions and the rapid assembly of complex molecular structures. Historically, their unique ability to follow multiple reaction routes—such as forming three-membered rings (cyclopropanation) and inserting into other molecules—has made them essential in modern organic chemistry.
Despite their clear advantages, the broad use of carbenes has been limited by problems with traditional starting materials. Common reagents, such as diazo compounds (which contain two nitrogen atoms linked together) and gem-diiodoalkanes (alkanes with two iodine atoms attached to the same carbon), are often unsafe and may not work well with various functional groups. Also, the excessively reactive carbenes can cause unwanted reactions. Therefore, controlling this strong reactivity and achieving selective results remain major challenges for chemists.
In response to these challenges, this seminar highlights state-of-the-art strategies intended to overcome these long-standing limitations. First, recent advances covering two fundamental pillars of this field will be discussed: (1) the development of highly versatile carbene generation methods that bypass hazardous precursors,1 and (2) the accurate control of carbene reactivity through advanced catalytic systems.2, 3 These modern protocols allow for unrivaled precision in maneuvering complex molecular environments.
Progressing from these advances, the expanding role of carbenes in the fast-growing field of "skeletal editing" will be explored.4 Unlike classic peripheral functionalization, skeletal editing allows direct manipulation of core molecular frameworks. I will introduce recent landmark examples exhibiting how carbene intermediates are uniquely suited for these demanding transformations, thereby reshaping the logic of molecular synthesis and unlocking new chemical space.