摘要:
The Pd(PPh3)(4)-catalyzed reaction of 1-iodo-6-phenylethynyl-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-hexaborane(6) (1a) with in situ generated arylzinc reagents (from arylbromides) leads to 1-bromo-6-phenylethynyl-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-hexaborane(6) (2a) and a trace amount of nido-(EtC)(4)(BC CPh)(2) (3a). 3a is separately synthesized by a Pd-catalyzed Negishi-type coupling reaction of la with phenylethynyl-zincchloride. This is confirmed by the Pd-catalyzed reactions of 1-iodo-6-tert-butylethynyl-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-hexaborane(6) (1b) with n-BuBr and PhZnCl, respectively, which produce the brominated carborane 2b and nido-(EtC)(4)(BC CtBu)(2) (3b). With a dialkynylzine reagent, a similar reaction of 1-iodo-6-ptolylethynyl-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-hexaborane(6) (1c) gives the linked compound 4, and a very small amount of ZnI2(OPPh3)(2) is formed. The selective basal halogen exchange of 1,6-diiodo-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-hexaborane(6) (5) with an excess of AgF leads to 1-iodo-6-fluoro-2,3,4,5-tetraethyl-2,3,4,5-tetracarba-nido-hexa-borane(6) (6). The composition of the products follows from NMR and MS data and a single crystal X-ray analysis of 2a. The X-ray structure of Znl2(OPPh3)2 is reported. (c) 2005 Elsevier B.V. All rights reserved,