Synthesis of new arylcarboranes as precursors for oligomers

Some new aryl o-carboranes have been synthesized. From methyl 3-iodo-5-(tri methylsilyl-ethynyl)-benzoate (1) or butyl 3-(3,3-diethyltriazeno)-5-ethytl yl-benzoate (2), 5-ethynyl-3-iodo-benzoates (3a, 3b) were obtained, which a fter the reaction with the decaborane-acetonitrile complex led to the corre sponding 5-(1'-(1',2'-dicarba-closo-dodecaboranyl))-3-iodo-benzoates (4a, 4 b). Furthermore, the methyl 3-iodo-5- (trimethylsilyl-ethynyl)-benzoate (1) is the starting material for the synthesis of a bis-carborane. Compound 1. is modified to the methyl 3,5-bis(trimethylsilyl-ethynyl)-benzoate (5), wh ich is deprotected to give the methyl 3,5-bis(ethynyl)-benzoate (6). Compou nd 6 reacted with the decaborane-acetonitrile complex to the methyl 3,5-bis (1'-(1',2'-dicarba closo-dedecaboranyl))-benzoate (7), which wets partially degraded to the bis(tetramethylammonium)-3,5-bis(7'-(8'-dicarba-nido-undec aboranyl))methoxycarbonylphenyl (8). (C) 1999 Elsevier Science S.A. All rig hts reserved.