Generation of Highly Electrophilic Cationic Boron Complexes and their Application toward Formation of C-B Bonds.

[摘要] The focus of our research was to achieve better understanding of the processes underlining the chemistry of highly electrophilic boron cations, and to develop the applications of such cations to C-B bond formation.The reactions of Lewis base borane complexes with potent electrophiles such as the trityl cation, bistriflimide and tris(pentafluorophenyl)borane were explored, and the product structures were assigned based on the X ray crystallographic and spectroscopic data.Hydride abstraction from Lewis base borane complexes by trityl cation was shown to be a viable method for generation of unstabilized primary borenium species, and several such L-BH2+ cations were shown to exist in the condensed phase in the form of diborane(6)-type dicationic dimers.We also explored the aliphatic and aromatic borylation chemistry involving B-H borocations, and developed a procedure for the intramolecular C-H borylation of amine boranes that uses only a catalytic amount of a strong electrophile, and produces H2 gas as the sole byproduct.Additionally, the methodology for generation of more substituted unstabilized borocations derived from 9-BBN was developed, and subsequently applied to the borylation of electron rich heteroaromatic compounds.An unusually hindered boronium cation possessing a 9-BBN cage chelated by 1,8-bis(dimethylamino)naphthalene was structurally characterized and shown to be a potent borylating reagent.

[发布机构] University of Michigan

[效力级别] C-H Activation

[关键词] Borylation;C-H Activation;Borenium;Organoboron Chemistry;Chemistry;Science;Chemistry