title: Insertion, reduction, and carbon-carbon coupling induced by monomeric aluminum hydride compounds bearing substituted pyrrolyl ligands.
abstract: A monomeric aluminum hydride complex bearing substituted pyrrolyl ligands, AlH[C(4)H(3)N(CH(2)NMe(2))-2](2) (1), was synthesized and structurally characterized. To further confirm the presence of Al--H bonds, the compound AlD[C(4)H(3)N(CH(2)NMe(2))-2](2) ([D]1) was synthesized by reacting LiAlD(4) with [C(4)H(4)N(CH(2)NMe(2))-2]. Compound 1 and [D]1 react with phenyl isothiocyanate yielding Al[C(4)H(3)N(CH(2)NMe(2))-2](2)[eta(3)-SCHNPh] (2) and Al[C(4)H(3)N(CH(2)NMe(2))-2](2)[eta(3)-SCDNPh] ([D]2) by insertion. The reactions of 1 with 9-fluorenone and benzophenone generated the unusual aluminum alkoxide complexes 3 and 4, respectively, through intramolecular proton abstraction and C-C coupling. A mechanistic study shows that 9-fluorenone coordinates to [D]1 and releases one equivalent of HD followed by C-C coupling and hydride transfer to yield the final product. Reduction of benzil with 1 affords aluminum enediolate complex 5 in moderate yield. Mechanistic studies also showed that the benzil was inserted into the aluminum hydride bond of [D]1 through hydroalumination followed by proton transfer to generate the final product [D]5. All new complexes have been characterized by (1)H and (13)C NMR spectroscopy and X-ray crystallography.
authors.affiliation: Department of Chemistry, National Changhua University of Education, Changhua, Taiwan.
authors.forename: Che-Yu
authors.initials: CY
authors.lastname: Lin
authors.forename: Chia-Fu
authors.initials: CF
authors.lastname: Tsai
authors.forename: Hsing-Jen
authors.initials: HJ
authors.lastname: Chen
authors.forename: Chen-Hsiung
authors.initials: CH
authors.lastname: Hung
authors.forename: Ru-Ching
authors.initials: RC
authors.lastname: Yu
authors.forename: Pei-Cheng
authors.initials: PC
authors.lastname: Kuo
authors.forename: Hon Man
authors.initials: HM
authors.lastname: Lee
authors.forename: Jui-Hsien
authors.initials: JH
authors.lastname: Huang