Studies On The Regioselective Alkenylation And Acetoxylation Of O-Carboranes Via Electrophilic B-H Activation

This paper carried out the "regioselective alkenylation and acetoxylation of o-carboranes".The main contents include the following two parts:First,based on the characteristic that H-B(8,9,10,12)bond of o-carborane susceptible to electrophilic reaction,take the palladium catalyzed electrophilic boron hydrogen activation as breakthrough point,for the first time get the coupling of H-B(8)and H-B(9)with olefins using steric effects of the reaction transition state,provide a new way synthesis of monofunctional o-carborane.According to the experimental results,we proposed a Pd?/Pd? mechanism of the reaction.The reaction avoids traditional method using pre functionalization of iodo-carborane,with high atom economy and important application value.Second,based on the characteristic that H-B(8,9,10,12)bond of o-carborane susceptible to electrophilic reaction,use iodobenzene diacetate as acetoxylation reagent,for the first time get the B(8,9,10,12)regioselectivity tetra-acetoxylation of o-carborane.This reaction use only 2 mol%catalyst can be realized four B-H bonds acetoxylation at the same time,has a high catalytic efficiency.According to the experimental results,we proposed a step by step Pdll/PdIV catalyzed reaction mechanism.At the same time,the reaction is further verified that we present the effect of transition state of the reaction steric on B-H bond selective functionalization and Ccage substituent play an important role of controlling H-B(8,9,10,12)bonds selective functionalization.