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

A number of 3-alkyl-substituted 1,2-dicarba-<i>closo</i>-dodecaboranes were prepared in good yields via the reaction of alkyldichloroboranes, which were generated <i>in situ</i> 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-<i>closo</i>-dodecaboranes. The synthesized 3-alkyl-1,2-dicarba-<i>closo</i>-dodecaboranes can be selectively deboronated at the B(6) atom to form the anionic 3-alkyl-7,8-dicarba-<i>nido</i>-undecaborates. All compounds were characterized by NMR and MS techniques