title: Tertiary carbinamine synthesis by rhodium-catalyzed [3+2] annulation of N-unsubstituted aromatic ketimines and alkynes.
abstract: A convenient and waste-free synthesis of indene-based tertiary carbinamines by rhodium-catalyzed imine/alkyne [3+2] annulation is described. Under the optimized conditions of 0.5-2.5 mol % [{(cod)Rh(OH)}(2)] (cod=1,5-cyclooctadiene) catalyst, 1,3-bis(diphenylphosphanyl)propane (DPPP) ligand, in toluene at 120 degrees C, N-unsubstituted aromatic ketimines and internal alkynes were coupled in a 1:1 ratio to form tertiary 1H-inden-1-amines in good yields and with high selectivities over isoquinoline products. A plausible catalytic cycle involves sequential imine-directed aromatic C-H bond activation, alkyne insertion, and a rare example of intramolecular ketimine insertion into a Rh(I)-alkenyl linkage.
authors.affiliation: Department of Chemistry and Molecular Biology, North Dakota State University, 1231 Albrecht Avenue, P.O. Box 6050, Fargo, ND 58108-6050, USA.
authors.forename: Zhong-Ming
authors.initials: ZM
authors.lastname: Sun
authors.forename: Shuo-Ping
authors.initials: SP
authors.lastname: Chen
authors.forename: Pinjing
authors.initials: P
authors.lastname: Zhao