Hydroaminoalkylation of Unactivated Olefins with Dialkylamines
摘要:
The intermolecular addition of the a-C-H bonds of unactivated dialkylamines to unactivated olefins in the presence of the chloro amido complex [TaCl3(NEt2)(2)](2) (2) is described. This process forms the branched insertion products in high yields (up to 96%) and selectivities, and a rare example of an intermolecular amine-olefin coupling reaction that does not require preactivation of either substrate. The reaction is shown to encompass the addition of the primary C-H bonds in linear- and branched-methylamines, as well as secondary C-H bonds in higher dialkylamines. The related chloroanilido complex [TaCl3(NMePh)(2)](2) (4) is also shown to catalyze the addition of N-alkyl-arylamines to olefins at temperatures as low as 90 degrees C. H-1 NMR spectroscopy, identification of the catalyst structure, and deuterium-labeling experiments all suggest that reactions catalyzed by 2 and 4 occur by turnover-limiting generation of an eta(2)-imine complex. These labeling studies also imply that more favorable partitioning of the eta(2)-imine complex toward reaction with alkene versus regeneration of the starting bis-amido complex accounts for the higher reactivity of the mixed halide amido catalyst versus a homoleptic amido complex.
TaMe<sub>3</sub>Cl<sub>2</sub>-Catalyzed Intermolecular Hydroaminoalkylation: A Simple Complex for Enhanced Reactivity and Expanded Substrate Scope
作者:Zhengxing Zhang、Jean-Denys Hamel、Laurel L. Schafer
DOI:10.1002/chem.201300992
日期:2013.7.1
Tantalizingly simple: The common organometallic starting material TaMe3Cl2 can be used for the catalytic CH functionalization reaction, hydroaminoalkylation. The substrate scope for this readily accessed compound includes unactivated terminal and internal alkenes, styrene derivatives, and both alkylaryl‐ and dialkyl secondary amines (see scheme).