Improved preparation of alkyl 2-(3-indolyl)-3-nitroalkanoates under fully heterogeneous conditions: stereoselective synthesis of alkyl (E)-2-(3-indolyl)-2-alkenoates |
| |
Authors: | Roberto Ballini Serena Gabrielli Alessandro Palmieri Marino Petrini |
| |
Institution: | aDipartimento di Scienze Chimiche, Università di Camerino, via S. Agostino, 1. I-62032 Camerino, Italy |
| |
Abstract: | Ethyl 3-nitro-2-alkenoates can be generated starting from nitroalkanes and ethyl 2-oxoacetate under heterogeneous conditions that minimize work-up procedures, avoid any purification step and direct manipulation of the nitroalkene system. Reaction of ethyl 3-nitro-2-alkenoates, formed in situ from their acetoxy precursors, with indoles in the presence of basic alumina affords ethyl 2-(3-indolyl)-3-nitroalkanoates that are central intermediates for the preparation of tryptamines and carboline alkaloids. A base promoted elimination of nitrous acid from these nitroindolyl derivatives readily produces ethyl 2-(3-indolyl)-2-alkenoates with high E stereoselectivity. The latter compounds can be used as Michael acceptors in intra- and intermolecular reactions with nucleophilic reagents. |
| |
Keywords: | Conjugate addition Heterogeneous catalysis Indoles Nitroaldol reaction Nitroalkenes |
本文献已被 ScienceDirect 等数据库收录! |