title: Metal-induced coordination inversion and carbon-nitrogen bond rearrangement. Structurally characterized phenyl isocyanate inserted into aluminum methyl compounds and O- and N-bound aluminum compounds.
abstract: [C(4)H(3)N(CH(2)NMe(2))-2]AlMe(2) (1) is prepared in 88% yield by the reaction of substituted pyrrole [C(4)H(4)N(CH(2)NMe(2))-2] with 1 equiv of AlMe(3) in methylene chloride. Reaction of compound 1 with 1 equiv of phenyl isocyanate in toluene generates a seven-membered cycloaluminum compound [C(4)H(3)N[CH(2)NPh(CONMe(2))]-2] AlMe(2) (2). The phenyl isocyanate was inserted into the aluminum and dimethylamino nitrogen bond and induced an unusual rearrangement which results in C-N bond breaking and formation. A control experiment shows that the reaction of substituted pyrrole [C(4)H(4)N(CH(2)NMe(2))-2] with 1 equiv of phenyl isocyanate in diethyl ether yields a pyrrolyl attached urea derivative [C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NHPh]-1] (3). The demethanation reaction of AlMe(3) with 1 equiv of 3 in methylene chloride at 0 degrees C afforded O-bounded and N-bounded aluminum dimethyl compounds [C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NPh]-1]AlMe(2) (4a) and [C(4)H(3)N(CH(2)NMe(2))-2-[CO(=NPh)]-1]AlMe(2) (4b) in a total 78% yield after recrystallization. Both 4a and 4b are observed in (1)H NMR spectra; however, the relative ratio of 4a and 4b depends on the solvent used. Two equivalents of AlMe(3) was reacted with 3 in methylene chloride to yield a dinuclear aluminum compound AlMe(3)[C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NPh]-1] AlMe(2) (5). Reaction of 5 with another equivalent of ligand 3 results in the re-formation of compounds 4a and 4b.
authors.affiliation: Department of Chemistry, National Changhua University of Education, Changhua, Taiwan 50058.
authors.forename: Chia-Fu
authors.initials: CF
authors.lastname: Tsai
authors.forename: Hsing-Jen
authors.initials: HJ
authors.lastname: Chen
authors.forename: Jr-Chiuan
authors.initials: JC
authors.lastname: Chang
authors.forename: Cheng-Hsiang
authors.initials: CH
authors.lastname: Hung
authors.forename: Chun-Chia
authors.initials: CC
authors.lastname: Lai
authors.forename: Ching-Han
authors.initials: CH
authors.lastname: Hu
authors.forename: Jui-Hsien
authors.initials: JH
authors.lastname: Huang