| Autor: |
Magis D; CNRS, Bordeaux INP, Institut des Sciences Moléculaires (ISM, UMR 5255), Université de Bordeaux, 351 Cours de la Libération, 33400 Talence, France., Cabrera-Trujillo JJ; E2S-UPPA, CNRS, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux (IPREM, UMR 5254), Université de Pau et des Pays de l'Adour, Hélioparc, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France., Vignolle J; CNRS, Bordeaux INP-ENSMAC, Laboratoire de Chimie des Polymères Organiques (LCPO, UMR 5629), Université de Bordeaux, 16 Avenue Pey-Berland, 33607 Pessac Cedex, France., Sotiropoulos JM; E2S-UPPA, CNRS, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux (IPREM, UMR 5254), Université de Pau et des Pays de l'Adour, Hélioparc, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France., Taton D; CNRS, Bordeaux INP-ENSMAC, Laboratoire de Chimie des Polymères Organiques (LCPO, UMR 5629), Université de Bordeaux, 16 Avenue Pey-Berland, 33607 Pessac Cedex, France., Miqueu K; E2S-UPPA, CNRS, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux (IPREM, UMR 5254), Université de Pau et des Pays de l'Adour, Hélioparc, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France., Landais Y; CNRS, Bordeaux INP, Institut des Sciences Moléculaires (ISM, UMR 5255), Université de Bordeaux, 351 Cours de la Libération, 33400 Talence, France. |
| Abstrakt: |
A library of novel structurally related singlet carbenes, namely, acyclic amino(haloaryl)carbenes, was designed by a high-yielding two-step procedure, and their chemical stability explored both experimentally and theoretically. Thanks to a careful selection of both the amino and the aryl substitution pattern, these carbenes exhibit a wide range of stability and reactivity, spanning from rapid self-dimerization for carbenes featuring ortho -F substituents to very high chemical stability as bare carbenes, up to 60 °C for several hours for compounds carrying ortho -Br substituents. Their structure was determined through NMR and X-ray diffraction studies, and their reactivity evaluated in benchmark reactions, highlighting the ambiphilic character of this novel class of singlet carbenes. In contrast with previously reported aryl substituents incorporating o -CF 3 and t -Bu groups, which were considered "spectator", the high chemical stability of some of these carbenes relates to the stabilization of the σ-orbital of the carbene center by the π-accepting haloaryl substituent through delocalization. Kinetic protection of the carbene center is also provided by the ortho -halogen atoms, as demonstrated computationally. This push-pull stabilization effect makes acyclic amino(haloaryl) carbenes among the most ambiphilic stable carbenes reported to date, holding promise for a variety of applications. |
