N-aryl Effects On The Catalyst Reactivity Of Imidazolylidene In A3→d3-umpolung Addition: Structural Study And Mechanistic Investigation | 74003
Like us on:
Our Group organises 3000+ Global Conferenceseries Events every year across USA, Europe & Asia with support from 1000 more scientific Societies and Publishes 700+ Open Access Journals which contains over 50000 eminent personalities, reputed scientists as editorial board members.
N-Heterocyclic carbenes (NHCs) have become widely utilized as organocatalysts in the formation of challenging C-C bonds. Conjugated Breslow intermediates, derived from the reaction of αβ-enal and NHCs, have emerged as a powerful tool for a variety of transformations. Since the concept of conjugated umpolung through the intermediacy of catalytically generated homoenolates and activated carboxylates, many investigations have revealed their utility to synthesize various heterocycles such as γ-butyrolactones, γ-lactams and cyclopentenes. However, there are few methods for tuning the catalytic reactivity of NHCs by either rational design of NHC catalysts or appropriate additives for cooperative catalysis. This is particularly true of imidazolylidene catalysts, only a few members of which are utilized effectively for NHC catalysis. In this study, structural and kinetic investigation of a series of imidazolyli-dene catalysts with various N-aryl groups for homoenolate-mediated -butyrolactone formation. Our study revealed that the reaction rate and catalytic reactivity can be clearly increased by the combination of 2,6-diethylphenyl groups as N-aromatic rings and a small excess amount of DBU as base compared to the originally reported conditions. Details of the structural studies, mechanistic investigations including parallel KIE experiments, and applications to the design of novel imidazolylidene catalysts will be discussed.
Tetsuo Narumi has completed his PhD from Kyoto University with Prof. Nobutaka Fujii. He spent a year in US as a JSPS Postdoctoral Fellow with Prof. Jeffrey W Bode at the University of Pennsylvania. In 2009, he began his academic career in Japan, at Tokyo Medical and Dental University with Prof. Hirokazu Tamamura. In 2013, he began his independent career at Shizuoka University, in Japan, as an Associate Professor in the Bioorganic Chemistry. He has published more than 50 papers in reputed journals and serves as a Leading Researcher in the field of Peptidomimetic Science.
Peer Reviewed Journals
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals