Alessandro Palmieri

Recent developments on the chemistry of aliphatic nitro compounds under aqueous medium

Aliphatic nitro derivatives represent an important class of useful molecules in organic synthesis. The versatility of these compounds is largely due to their easy availability and transformation into a variety of diverse functionalities. Moreover, aliphatic nitro compounds are very important building blocks (both as nucleophiles or as electrophiles) for the generation of new carbon–carbon bonds, mainly via nitroaldol-Henry reactions, Michael reactions and Diels–Alder cycloadditions. Usually, organic solvents are believed to be necessary for achieving the best efficiency in the reactions of aliphatic nitro compounds and, only recently, it has been shown that these reactions are also very efficient using water as reaction medium. Such progress in the chemistry of aliphatic nitro compounds is particularly attractive to industry since the replacement of toxic solvents still remains a crucial (and expensive) challenge. Thus, this report is focused on the chemistry of aliphatic nitro derivatives performed in aqueous media.

Use of heterogeneous catalyst KG-60-NEt2 in Michael and Henry reactions involving nitroalkanes

The N,N-diethylpropylamine supported on amorphous silica (KG-60-NEt2) catalyses the formation of carboncarbon bonds by nitroalkanes through both the nitroaldol (Henry) and Michael reactions. The catalyst shows general utility with a variety of electrophilic acceptors. Moreover, the catalyst can be reused for two further cycles without loss of the activity.

Fast, mild, eco-friendly synthesis of polyfunctionalized pyrroles from β-nitroacrylates and β-enaminones

The reaction of β-nitroacrylates with β-enaminones, at room temperature and under solvent- and promoter-free conditions, affords the one-pot synthesis of polyfunctionalized pyrroles in high yields.

Continuous flow based catch and release protocol for the synthesis of α-ketoesters

Summary Using a combination of commercially available mesofluidic flow equipment and tubes packed with immobilised reagents and scavengers, a new synthesis of α-ketoesters is reported.

Nitroalkanes as new, ideal precursors for the synthesis of benzene derivatives

Nitroalkanes have emerged, in the past few years, as powerful acyclic building blocks to synthesize polyfunctionalized benzene derivatives, avoiding any serious regiochemical ambiguities due to the activating/deactivating and orienting effects of the substituents. Many of these procedures are realized in a one-pot process or a few-step sequence. This feature article describes recent results, mainly from our group, in this field.

β -Nitroacrylates as an Emerging, Versatile Class of Functionalized Nitroalkenes for the Synthesis of a Variety of Chemicals

Modern organic synthesis requires easily obtainable synthetic building blocks that can be manipulated without the need of se- vere reaction conditions and that show high chemical versatility so that they can be employed in diverse synthetic processes.  - Nitroacrylates are a class of electron-poor alkenes having two electron-withdrawing groups in  - and  -positions. This peculiarity makes their chemical behaviour more interesting with respect to the classical conjugated nitroalkenes and, in the last few years, there has been a growing interest in the chemistry of these molecules. The aim of this report is to present, mainly, the recent synthetic applications of  - nitroacrylates, as well as the principal procedures for their preparations.

Neutral alumina catalysed synthesis of 3-nitro-1,2-dihydroquinolines and 3-nitrochromenes, under solvent-free conditions, via tandem process

It has been found that neutral alumina carries out the solvent-free reaction of 2-aminobenzaldehyde or salicylaldehyde over a range of nitroalkenes, under mild and convenient conditions, allowing the one pot synthesis of 3-nitro-1,2-dihydroquinolines and 3-nitrochromenes, respectively.

JandaJel as a polymeric support to improve the catalytic efficiency of immobilized-1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) under solvent-free conditions

JandaJel, with its greater spacing between the linear polymeric chains compared to that of polystyrene matrices, is a very efficient support for improving the catalytic efficiency of TBD under SolFC.

Synthesis of fine chemicals by the conjugate addition of nitroalkanes to electrophilic alkenes

Several aliphatic nitro compounds have been employed as stabilized carbanions in the conjugate addition to a variety of electron-poor alkenes (Michael reaction). Depending on the nature of the alkene, new carbon-carbon single or double bonds can be generated. However, all the Michael adducts can be efficiently utilized as key building blocks for the synthesis of a huge array of fine chemicals, including homo- and heterocyclic structures.

Isolute®Si-carbonate catalyzes the nitronate addition to both aldehydes and electron-poor alkenes under solvent-free conditions

It has been found that commercial ISOLUTE®Si-carbonate catalyzes both nitroaldol and Michael reactions, from nitroalkanes and under solvent-free conditions, allowing satisfactory to good yields of nitroalkanols and γ-nitro-functionalized carbonyl and cyano derivatives. In addition, a one-pot Henry–Michael reaction can be performed.