DFT studies on mechanisms for dearomatization of pyridine and reactions involving o-carborane, borylene and diborane(4) compounds

Abstract

DFT studies on the reaction mechanisms for Cu(I)-catalyzed dearomatization of pyridine, Pd(II)-catalyzed B-H bond activation of o-carborane, stoichiometric reactions of borylene with different nucleophiles, and stoichiometric reactions of diborane(4) with different Lewis bases are reported in this thesis. The detailed reaction mechanisms, selectivity and structure analysis have been explored. Chapter 1 gave a short introduction of DFT methods, background information on dearomatization, and chemistry of o-carborane, borylene and diborane(4) compounds. Chapter 2 dealt with 1,4-dearomatization reactions of pyridine catalyzed by Cu(I) complexes. One-copper catalyst system can 1,4-dearomatize pyridine through consecutive structural rearrangement of the styrene-inserted species. The selectivity between 1,2- and 1,4- dearomatization reactions was also explored. Chapter 3 studied selective functionalization of o-carborane B(3)-H and B(4)-H bonds. The mechanisms of B(3)-H and B(4)-H acetoxylation of o-carboranes catalyzed by Pd(II) complexes and B(3)-H and B(4)-H amination of 1-COOH-2-CH₃-C₂B₁₀H₁₀ catalyzed by Ir(III) and Rh(III) complexes were examined and discussed. Chapter 4 was about the structure and bonding analysis of different three-coordinate borylenes and mechanistic studies of borylene with 9-BBN and H₂. And the regioselectivity for the reactions of borylene with different nucleophiles was also studied. In Chapter 5, the reactions of tetra(o-tolyl)diborane(4) with different Lewis bases, such as isocyanides, cyanides, pyridazine and phthalazine, have been carefully explored. The influence of the different substituents on isocyanides and cyanides on the reaction outcomes was studied and addressed. Activation of the N=N double bond in pyridazine or phthalazine was also calculated and discussed. Finally, a short summary was given in Chapter 6.

Date of Award	2019
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology