◆日時◆ 平成２８年３月１日（火）１5：3０～１７：00 ◆場所◆ 　　　　化研会議室　N-53１ C

◆講師◆

◆演題◆ Carbene Catalysis and the Breslow Intermediate

Albrecht Berkessel 教授　 Cologne University, Germany

　Both in B1-enzymes and in organocatalytic Umpolung, catalysis by N-heterocyclic　carbenes hinges on the formation of the so-called Breslow-intermediates [(di)aminoenols] I (Scheme, reaction a), in which the innate polarity of e.g. an aldehyde substrate is inverted from electrophilic to nucleophilic. In the related a3-d3 Umpolung ("conjugate Umpolung"; Scheme, reaction b), the diamino dienol II, a homoenolate equivalent, is assumed to be pivotal. OH-Cγ proton shift in the diamino dienol II leads to the azolium enolate III, an enolate equivalent. The lecture will report (i) the generation and characterization, by NMR and X-ray crystal structures, of intermediates I-III, (ii) the mechanism-based design of a new generation of carbene organocatalysts, and (iii) the application of the latter in hitherto impossible catalytic transformations. References: ACIE 2012, 51, 12370-12374. ACIE 2013, 52,11158-11162. Chem. Sci. 2015, 6, 3706-3711. JACS 2016, DOI: 10.1021/jacs.5b11796

◆連絡先◆ 時任宣博、小澤文幸、中村正治、山子茂、村田靖次郎、川端猛夫（内線３１９０）