부산대학교 도서관

The reaction of the bulky aminophenol 2-(CH2NMe2)-4-Me-6-CPh3-C6H3OH (1) with Al(ⁱBu)3 yields via isobutane elimination the formation of the diisobutyl Al complex {6-(CH2NMe2)-2-CPh3-4-Me-C6H2O}Al(ⁱBu)2 (2) in high yield. Reaction of 2 with B(C6F5)3 in the presence of NMe2Ph affords, along with isobutene, the salt compound [{6-(CH2NMe2)-2-CPh3-4-Me-C6H2O}Al(ⁱBu)(NMe2Ph)][HB(C6F5)3] (3), consisting of a four-coordinate Lewis acidic Al cation associated with the borohydride HB(C6F5)3^-, whose solid-state structure was determined by X-ray crystallography. When complex 2 is reacted with B(C6F5)3 (1 and 0.05 equiv) in the presence of benzophenone and benzaldehyde, the quantitative conversion to the hydroalumination products 4 and 5, respectively, is observed. This B(C6F5)3-catalyzed hydroalumination reaction, via a B(C6F5)3-mediated hydride abstraction/transfer reaction, represents a new type of reactivity for Al alkyl cations and illustrates the higher reactivity of Al cation/HB(C6F5)3^- salts versus the classical Al cation/MeB(C6F5)3^- and B(C6F5)4^- salts.