An Unusual Case of Silyl Deprotection in ortho-Carborane Derivatives. Synthesis of 1-(3′-Fluoropropyl)-ortho-carborane

The deprotection reaction of 1-tert-butyldimethylsilyl-2-(3′-iodopropyl)-ortho-carborane using Bu4NF is accompanied by a number of side reactions, leading to 1-(3′-fluoropropyl)-ortho-carborane—the product of nucleophilic substitution—as the main product. Besides 1-(3′-fluoropropyl)-ortho-carborane and the expected 1-(3′-iodopropyl)-ortho-carborane, the reaction products are the previously known 1-allyl-ortho-carborane and 1,2-μ-trimethylene-ortho-carborane. The crystalline molecular structures of 1-ClCH2CH2CH2-2-tBuMe2Si-1,2-C2B10H10 and 1-ICH2CH2CH2-2-tBuMe2Si-1,2-C2B10H10 were determined by single crystal X-ray diffraction.