Synthetic Applications of Nitroalkanes Promoted by Solid Catalysis: Recent Results

Abstract

Solid catalysis is crucial to chemical technology. Innumerable chemical reactions are facilitated by this catalytic system and, in this context, nitroalkanes have been demonstrated a great reactivity under solid catalysis, especially in the formation of new carbon-carbon single bond. In fact, aliphatic nitrocompounds are a valuable source of stabilized carbanions since the high electron-withdrawing power of the nitro group provides an outstanding enhancement of the hydrogen acidity at the ?-position (cf. pKa, MeNO2 = 10). Nitronate anions, that can be generated from nitroalkanes, using a wide range of bases, act as carbon nucleophiles with common electrophiles such as aldehydes (Nitroaldol-Henry-reaction), and electron-poor alkenes (Michael reaction), leading to carbon-carbon bond formation. In the last few decades several solid catalyses have been efficiently proposed for the employment of the nitroalkanes in the latter reactions. Very often the use of nitroalkanes, combined with solid catalysis, offers the opportunity to perform the reactions more efficiently, with enhanced chemoselectivity, high purity, improved yields and without the use of any solvent. ? 2006 Bentham Science Publishers Ltd.