New Approach to the Synthesis of 3-Alkyl-1,2-dicarba-closo-dodecaboranes: Reaction of Alkyldichloroboranes with Thallium Dicarbollide

A number of 3-alkyl-substituted 1,2-dicarba- closo -dodecaboranes were prepared in good yields via the reaction of alkyldichloroboranes, which were generated in situ through hydroboration of the corresponding alkenes with a dichloroborane–dioxane complex, with thallium dicarbollides in anhydrous dichloromethane at room temperature. This reaction also affords insertion products with new thallium dicarbollides prepared from 3-iodo- and 9-iodo-1,2-dicarba- closo -dodecaboranes. The synthesized 3-alkyl-1,2-dicarba- closo -dodecaboranes can be selectively deboronated at the B(6) atom to form the anionic 3-alkyl-7,8-dicarba- nido -undecaborates. All compounds were characterized by NMR and MS techniques.