Carlo Biffi

Bio: Carlo Biffi is an academic researcher. The author has contributed to research in topics: Alcohol oxidation & Dehydrogenation. The author has an hindex of 2, co-authored 2 publications receiving 716 citations.

Fast and selective oxidation of primary alcohols to aldehydes or to carboxylic acids and of secondary alcohols to ketones mediated by oxoammonium salts under two-phase conditions

Abstract: General Oxygenation Procedure. An apparently heterogeneous mixture of an olefin (cyclohexene, 1-pentene, or styrene, 1 g), NaBH, (300 mg, 7.9 mmol), (OEP)RhnxCl (4.0 mg, 6 pmol; [Rh] = 0.6 mM), and an internal standard (p-xylene, mesitylene, or durene, appropriate amount) in dry THF (10 mL) exposed to dry air was stirred a t 20-25 \"C. The oxygenation of 1-methylcyclohexene was carried out by using the rhodium catalyst in an amount 2 or 20 times as much as that used above ([Rh] = 1.2 or 12 mM). The electronic spectra of the reaction mixture underwent no significant change even after 100 h. The formation of oxygenation products was monitored by gas chromatography. Similarly was carried out the oxygenation of 1,5-cyclooctadiene and acetylenes (1-heptyne and 3-heptyne) by using substrate (300 mg), NaBH, (300 mg), and (OEP)RhmC1 or (TPP)RhInC1 (4.0 mg) in THF (20 mL). Reaction products, after conversion if necessary to silylated derivatives, were identified by gas chromatography on the basis of coinjection with authentic samples, and their yields determined also by gas chromatography. 2-Methylcyclohexanol as a mixture of stereoisomers arising from the oxygenation of 1-methylcyclohexene was purified by preparative gas chromatography. The stereoisomer distribution was determined by 'H NMR spectroscopy by taking advantage of the characteristic signals for hydroxymethine protons a t 6 3.1 (for E isomer) and 3.75 (for 2 isomer). The following control runs were carried out by using cyclohexene as substrate: (1) without rhodium porphyrin catalyst, (2) without 02, (3) without NaBH,, and (4) with NaBH(OCHJ3 in place of NaBH,. In neither case was detected oxygenation of substrate to any significant extent. Another control run using cyclohexene oxide in place of cyclohexene under otherwise identical oxygenation conditions did not give cyclohexanol. Borane Transfer. A mixture of (0EP)Rh\"'Cl (40 mg, 0.06 mmol), NaBH4 (100 mg, 2.64 mmol), and 1-pentene (70 mg, 1.0 mmol) in T H F (2 mL) in a vessel sealed with a rubber septum was degassed by freezepumpthaw cycles and was stirred a t room temperature for 19 h. The electronic spectrum of the mixture showed A, a t 395,514, and 545 nm, indicating the formation of (OEP)RhH? Following the standard procedure for the analysis of organoboranes,28 the mixture was then subjected to gas chromatography at 170 OC on a column of silicone SE-30 (2 m), which had been treated with Silyl-8 (Pierce Chemical Co.) to mask protic sites with trimethylsilyl groups. The product was readily identified as tripentylborane on the basis of coinjection with the authentic sample prepared by hydroboration of olefin with diborane under standard conditions. The mixture was exposed to air, stirred for 20 min, and then analyzed by gas chromatography to show the formation of 1-pentanol and 2-pentanol (94:6, in a total yield of 45% based on mol of Rh complex used). Oxidation of Alkylborane. A T H F solution of (E)-bis(2methy1cyclohexyl)borane\" was prepared by the hydroboration of 1-methylcyclohexene (96 mg, 1.0 mmol) with borane-THF (1 M) (0.5 mL, 0.5 mmol) in THF (1 mL) under nitrogen. To this was added 1 N aqueous NaOH (0.5 mL), and the mixture was stirred under air atmosphere for 20 h. Gas chromatographic analysis using silicone DCQF-1 showed the formation of 2methylcyclohexanol with the stereoisomer ratio of E / Z = 7624. Another control run for the oxidation of alkylborane with O2 was carried out in the presence of NaBH, (38 mg, 1.0 mmol) instead of aqueous NaOH under otherwise identical conditions and gave the isomer ratio of E / Z = 81:19. A solution of (E)-bis(2-methylcyclohexyl)borane in THF (0.21 mL) was prepared as above starting from the olefin (15.4 mg, 0.16 mmol). This solution was added to (OEP)RhH15 (100 mg, 0.16 mmol) under nitrogen. The mixture was then allowed to contact with a gentle stream of THF-saturated air for 20 h. Gas chromatography coupled with 'H NMR analysis indicated almost exclusive formation of (E)-2-methylcyclohexanol.

Magnetically recoverable nanocatalysts.

Abstract: We gratefully acknowledge funding and support from King Abdullah University of Science and Technology (KAUST). Thanks are also due to the KAUST communication department for designing several images for this Review.

Fundamentals of green chemistry: efficiency in reaction design

Abstract: In this tutorial review, the fundamental concepts underlying the principles of green and sustainable chemistry - atom and step economy and the E factor - are presented, within the general context of efficiency in organic synthesis. The importance of waste minimisation through the widespread application of catalysis in all its forms – homogeneous, heterogeneous, organocatalysis and biocatalysis – is discussed. These general principles are illustrated with simple practical examples, such as alcohol oxidation and carbonylation and the asymmetric reduction of ketones. The latter reaction is exemplified by a three enzyme process for the production of a key intermediate in the synthesis of the cholesterol lowering agent, atorvastatin. The immobilisation of enzymes as cross-linked enzyme aggregates (CLEAs) as a means of optimizing operational performance is presented. The use of immobilised enzymes in catalytic cascade processes is illustrated with a trienzymatic process for the conversion of benzaldehyde to (S)-mandelic acid using a combi-CLEA containing three enzymes. Finally, the transition from fossil-based chemicals manufacture to a more sustainable biomass-based production is discussed.

A Versatile and Highly Selective Hypervalent Iodine (III)/2,2,6,6-Tetramethyl-1-piperidinyloxyl-Mediated Oxidation of Alcohols to Carbonyl Compounds

Abstract: Catalytic amounts of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) are used in combination with [bis(acetoxy)iodo]benzene (BAIB) as a stoichiometric oxidant in the conversion of primary and secondary alcohols to carbonyl compounds. This procedure works efficiently at room temperature in almost all common solvents and neat in some cases. This process exhibits a very high degree of selectivity for the oxidation of primary alcohols to aldehydes, without any noticeable overoxidation to carboxyl compounds, and a high chemoselectivity in the presence of either secondary alcohols or of other oxidizable moieties. This procedure allows an easy, convenient, high-yielding method for the oxidation of alcohols starting from commercially available compounds.

Highly practical copper(I)/TEMPO catalyst system for chemoselective aerobic oxidation of primary alcohols.

Abstract: Aerobic oxidation reactions have been the focus of considerable attention, but their use in mainstream organic chemistry has been constrained by limitations in their synthetic scope and by practical factors, such as the use of pure O2 as the oxidant or complex catalyst synthesis. Here, we report a new (bpy)CuI/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic, and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant. The catalyst system is compatible with a wide range of functional groups and the high selectivity for 1° alcohols enables selective oxidation of diols that lack protecting groups.

Nano-Gold Catalysis in Fine Chemical Synthesis

Abstract: the National Natural Science Foundation of China (21073208);the Chinese Academy of Sciences