A novel multistep mechanism for the stereocontrolled ring opening of hindered sulfamidates: Mild, green, and efficient reactivity with alcohols
Cyclic hindered sulfamidates exhibited an outstanding performance in their ring-opening reactions with alcohols and in the absence of any external activator. The mechanism of this unprecedented transformation was thoroughly studied both experimentally and theoretically. As a result, a nontrivial ste...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2009 |
| País: | España |
| Institución: | Universidad de La Rioja (UR) |
| Repositorio: | RIUR. Repositorio Institucional de la Universidad de La Rioja |
| OAI Identifier: | oai:portal.dialnet.es:doc/5bbc69a7b750603269e81f11 |
| Acceso en línea: | https://investigacion.unirioja.es/documentos/5bbc69a7b750603269e81f11 |
| Access Level: | acceso abierto |
| Palabra clave: | Alcohols Neighboringgroup effects Nucleophilic substitution Reaction mechanisms Sulfamidates |
| Sumario: | Cyclic hindered sulfamidates exhibited an outstanding performance in their ring-opening reactions with alcohols and in the absence of any external activator. The mechanism of this unprecedented transformation was thoroughly studied both experimentally and theoretically. As a result, a nontrivial stepwise pathway involving solvent-induced conversion of the sulfamidates to activated aziridinium and then to oxazolinium cations, which are finally opened at their 5-position with inversion of configuration, is proposed. The presence of the SO 3 moiety in the sulfamidate was revealed as a "built-in activator". In fact, the spontaneous SO 3 cleavage takes place under the reaction conditions and avoids the subsequent step of hydrolysis after the ring opening of the sulfamidates. This is another important improvement of this meth-odology with respect to the standard basic conditions, allowing a greater compatibility with other functional groups. Furthermore, the carbamate group plays a key role in this mechanism. Briefly, a highly chemoselective and stereoespecific formal solvolysis of hindered sulfamidates with alcohols without further activation is described. This reaction takes place exclusively at the quaternary center with inversion of configuration, providing a new straightforward synthetic route to O-substituted α-methylisoserines. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA. |
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