Serena Gabrielli

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.

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.

Low impact synthesis of β-nitroacrylates under fully heterogeneous conditions

We report, a new synthetic approach to β-nitroacrylates by dehydration of the corresponding nitroalkanols, under fully heterogeneous conditions and with low resource consumption.

A salting out system for improving the efficiency of the headspace solid-phase microextraction of short and medium chain free fatty acids.

Given the importance of short and medium chain free fatty acids (FFAs) in several fields, this study sought to improve the extraction efficiency of the solid-phase microextraction (SPME) of FFAs by evaluating salting out agents that appear promising for this application. The salts ammonium sulfate ((NH4)2SO4) and sodium dihydrogen phosphate (NaH2PO4) were tried on their own and in combination (3.7/1), in four different total amounts, as salting out agents in the headspace-SPME-gas chromatographic (HS-SPME-GC) analysis of the FFAs from acetic acid (C2) to decanoic acid (C10). Their performance in a model system of an aqueous standard mixture of FFAs at a pH of 3.5 was compared to that of the more commonly used sodium chloride (NaCl) and sodium sulfate (Na2SO4). All of the salts and salt systems evaluated, in proper amount, gave improved results compared to NaCl (saturated), which instead gave interesting results only for the least volatile FFAs C8 and C10. For C2-C6, the salt system that gave the best results compared to NaCl was (NH4)2SO4/NaH2PO4, in the highest of the four amounts evaluated, with factor increases between 1.2 and 4.1-fold, and NaH2PO4, between 1.0 and 4.3-fold. The SPME extraction efficiency given by the mixture (NH4)2SO4/NaH2PO4 was also assessed on biological and food samples, confirming that overall it performed better than NaCl.

One-pot synthesis of alkyl pyrrole-2-carboxylates starting from β-nitroacrylates and primary amines

Herein, we present a new, efficient, one-pot synthesis of pyrrole-2-carboxylate derivatives starting from ketal-functionalized β-nitroacrylates in combination with primary amines under acidic heterogeneous conditions.

A New One-Pot Synthesis of Quinoline-2-carboxylates under Heterogeneous Conditions

Quinoline-2-carboxylates are an important subclass of quinoline derivatives largely present in a variety of biologically active molecules, as well as useful ligands in metal-catalyzed reactions. Herein, we present a new one-pot protocol for synthesizing this class of derivatives starting from β-nitroacrylates and 2-aminobenzaldehydes. In order to optimize the protocol, we investigated several reaction conditions, obtaining the best results using the 2-tert-Butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine (BEMP) as solid base, in acetonitrile. Finally, we demonstrated the generality of our approach over several substrates which led to synthesize a plethora of functionalized quinolines-2-carboxylate derivatives in good overall yields.

Nitroaldol (Henry) reaction of 2-oxoaldehydes with nitroalkanes as a strategic step for a useful, one-pot synthesis of 1,2-diketones

The nitroaldol (Henry) reaction of 2-oxoaldehydes with a variety of nitroalkanes, under basic heterogeneous conditions and microwave irradiation, affords 1,2-diketones in a one-pot way. The key step of the process involves the nitrous acid elimination from the nitroalkanol intermediates instead of the standard water elimination.

Reaction of α-amido sulfones with functionalized nitrocompounds: a new two-step synthesis of N-alkoxycarbonyl-2,5-disubstituted pyrroles

Reaction of α-amido sulfones with nitro ketals promoted by KF on alumina provides the corresponding adducts which, upon treatment with p-toluenesulfonic acid, generate the corresponding N-alkoxycarbonyl-2,5-disubstituted pyrroles. The latter transformation involves a cascade process including ketal cleavage, ring closure and final aromatization by nitrous acid elimination.

Easy and direct conversion of tosylates and mesylates into nitroalkanes

Summary Tosylates and mesylates were directly converted into the corresponding nitroalkanes, by their treatment with tetrabutylammonium nitrite (TBAN) under mild conditions.

A new, low impact and efficient synthesis of ω-nitro esters under solid heterogeneous catalysis

Herein, we report a new, efficient and sustainable synthetic protocol for the preparation of ω-nitro esters starting from cyclic 2-nitro ketones. The method involves the use of polymer bound BEMP and provides the target compounds in excellent yields and low process mass intensity and E-factor values.