Rh(Ⅰ)-Catalyzed Annulations In The Presence Of Bifunctional Organoboron Reagents

This thesis focused on the Rh(â… )-catalyzed annulations in the presence of bifunctional organoboron reagents and has successfully developed two novel reaction protocols. One is the Rh(â… )-catalyzed [2+2+2] cycloadditions of 1,6-enynes with 2-bromophenylboronic acid, the other is the Rh(â… )-catalyzed [2+2+2] cycloadditions of 1,6-diynes with potassium (Z)-(2-bromovinyl)trifluoroborate.Rh(â… )-catalyzed cycloadditions of 1,6-enynes with 2-bromophenylboronic acid, which provides a facile method to construct the multi-substituted dihydronaphthalene scaffold, in which substrate 1,6-enyne works as the two 2C-components and 2-bromophenylboronic acid as one 2C-component. The deuterium-labeled experiment disclosed that a direct reductive elimination mechanism would dominate over the formation of aryl-Csp3 bond from aryl-Rh(â…¢)-Csp3 species.A new strategy for Rh(â… )-catalyzed [2+2+2] cycloadditions of 1,6-diynes with potassium (Z)-(2-bromovinyl)trifluoroborate as the third two-atom unit has been realized, which provides a facile entry to polysubstituented benzene derivatives.In this transformation, potassium (Z)-(2-bromovinyl)trifluoroborate is thought to be crucial to fulfill this new .strategy for Rh(â… )-catalyzed [2+2+2] cycloaddition due to its dual structural functions with nucleophilic vinyl borate and electrophilic vinylbromine.The outcome of control experiments disclosed that the existence of the vinyl-Rh(â… ) intermediate 3.7-C, and the reaction is really operating via Scheme 3.7,path a.