854886-64-9Relevant academic research and scientific papers
Chiral osmium complexes with sterically bulky schiff-base ligands. Crystal structures of Os(IV) derivatives and the reactivity and catalytic cyclopropanation of alkenes with EDA
Zhang, Jing,Liang, Jiang-Lin,Sun, Xian-Ru,Zhou, Hai-Bing,Zhu, Nian-Yong,Zhou, Zhong-Yuan,Chan, Philip Wai Hong,Che, Chi-Ming
, p. 3942 - 3954 (2005)
The syntheses and reactivities of sterically encumbered trans-dioxoosmium(VI) complexes containing Schiff-base ligands bis(3,5-di-tert-butylsalicylidene)-1,2-cydohexane-diamine (H2Bu- salch) and bis(3,5-dibromosalicylidene)-1,2-cyclohexane-diamine (H 2Br-salch) are described. Reactions of [OsVI(Bu-salch) O2] (1a) and [OsVI(Br-salch)O2] (1b) with PPh3, p-X-arylamines (X = NO2, CN), N2H 4·H2O, Ph2NNH2, SOCl 2, CF3CO2H, Br2, and I2 under reducing conditions gave [OsII(Br-salch)(OPPh3) 2] (2), [OsVI(Br-salch)(p-X-C6H 4NH)2] (3), [μ-O{OsIV(Bu-salch)(p-NO 2C6H4-NH)}2] (4), [Os II(Br-salch)(N2)(H2O)] (5), [Os IV(Bu-salch)(OH)(Cl)] (6), [OsIV(Bu-salch)(OH) 2] (7), [OsIV(Bu-salch)-Cl2] (8), [Os IV(Bu-salch)(CF3CO2)2] (9), [Os IV(Bu-salch)Br2] (10), and [OsIV(Bu-salch) I2] (11), respectively. X-ray crystal structure determinations of [OsIV(Br-salch)(p-NO2C6H4NH) 2] (3a), [OsIV(Br-salch)(p-CNC6H 4NH)2] (3b), 6, 8, 9, and 11 reveal the Os-N(amido) distances to be 1.965(4)-1.995(1) A for the bis(amido) complexes, Os-Cl distances of 2.333(8)-2.3495(1) A for 6 and 8, Os-O(CF3CO 2) distances of 2.025(6)-2.041(6) A for 9, and Os-I distances of 2.6884(6)-2.6970(6) A for 11. Upon UV irradiation, (1S,2S)-(1a) reacted with aryl-substituted alkenes to give the corresponding epoxides in moderate yields, albeit with no enantioselectivity. The (1R,2R)-6 catalyzed cyclopropanation of a series of substituted styrenes exhibited moderate to good enantioselectivity (up to 79% ee) and moderate trans selectivity.
