Recent Advances in o-Benzyne Chemistry: Aryne C¬–C Bond Insertions, Regioselective Syntheses with Benzdiyne Equivalents, and the Hexadehydro–Diels–Alder Reaction

Benzynes, as intermediates, have been known to chemists since the 1940’s through studies published by Wittig, Gilman, Horning, and Roberts.  The methods of generating this intermediate have evolved over time from using strong bases at low temperatures to milder conditions.  The most common method for generating o-benzyne is by the elimination of o-(trimethylsilyl) triflates with a fluoride anion source, the process of which was developed by Kobayashi and co-workers in 1983.  This method is convenient due to the use of a weaker base at ambient temperatures.  Once thought to be too reactive to offer any chance for chemoselectivity and regioselectivity, benzyne has been tamed by chemists, and, through mild methods of generation, there is now a chance to utilize benzyne intermediates in refined ways.  There is great diversity in the kinds of reactions that arynes can do, including nucleophilic and electrophilic additions, pericyclic reactions, and transition metal catalysis.  With a plethora of ways for the intermediate to react, in addition to having more predictable reactivity, benzynes have found themselves to be key intermediates in synthetic methodology and natural product synthesis. For this seminar, recent studies with benzynes including C-C bond insertions, regioselective benzdiyne equivalents, and the hexadehydro-Diels-Alder reaction will be discussed.