| Autor: |
de Los Santos JM; Departamento de Química Orgánica I, Facultad de Farmacia, Centro de Investigaciones y Estudios Avanzados 'Lucio Lascaray', Universidad del País Vasco UPV/EHU, Paseo de la Universidad 7, 01006 Vitoria, Spain. francisco.palacios@ehu.es., Rubiales G; Departamento de Química Orgánica I, Facultad de Farmacia, Centro de Investigaciones y Estudios Avanzados 'Lucio Lascaray', Universidad del País Vasco UPV/EHU, Paseo de la Universidad 7, 01006 Vitoria, Spain. francisco.palacios@ehu.es., Sbai ZE; Departamento de Química Orgánica I, Facultad de Farmacia, Centro de Investigaciones y Estudios Avanzados 'Lucio Lascaray', Universidad del País Vasco UPV/EHU, Paseo de la Universidad 7, 01006 Vitoria, Spain. francisco.palacios@ehu.es., Ochoa de Retana AM; Departamento de Química Orgánica I, Facultad de Farmacia, Centro de Investigaciones y Estudios Avanzados 'Lucio Lascaray', Universidad del País Vasco UPV/EHU, Paseo de la Universidad 7, 01006 Vitoria, Spain. francisco.palacios@ehu.es., Palacios F; Departamento de Química Orgánica I, Facultad de Farmacia, Centro de Investigaciones y Estudios Avanzados 'Lucio Lascaray', Universidad del País Vasco UPV/EHU, Paseo de la Universidad 7, 01006 Vitoria, Spain. francisco.palacios@ehu.es. |
| Abstrakt: |
The behavior of phosphinyl nitrosoalkenes with indole, pyrrole and 2,5-dimethylpyrrole is described. The reaction of nitrosoalkenes with indole leads to the formation of 3-substituted indoles. While a concerted asynchronous [4 + 2] cycloaddition process may explain the formation of 3-substituted indole when a methyl group is present at the 3-position of nitrosoalkene, the presence of a 3-methoxycarbonyl group at the same position of nitrosoalkene increases its electrophilic character, and both mechanisms, an electrophilic aromatic substitution and a [4 + 2] cycloaddition process, are predicted to be competitive, although thermodynamically the cycloaddition is favoured. Phosphinyl nitrosoalkenes react with pyrrole leading to the corresponding 2-substituted pyrroles, while the treatment of 2,5-dimethylpyrrole with these nitrosoalkenes gives rise to the formation of bicyclic 1,2-oxazines. The mechanism of the reaction of phosphinyl nitrosoalkenes with pyrrole and 2,5-dimethylppyrrole may be explained by an initial hetero-Diels-Alder cycloaddition in both cases, but only subsequent rearomatization in the case of pyrrole. Theoretical studies show very good agreement with the experimental findings and the proposed mechanisms. |
