Reduction of pentafluorophenyl esters to the corresponding primary alcohols using sodium borohydride

Primary alcohols and chiral N-protected 2-amino alcohols can be obtained in high yields from the reaction of pentafluorophenyl esters of the corresponding carboxylic acids with sodium borohydride in THF under mild conditions. This reductive method is rapid and compatible with various functional groups as well as with the most common N-protective groups Z, Boc and Fmoc.     

Efficient conversion of vicinal diols to alkenes by treatment of the corresponding dimesylates with a catalytic, minimally fluorous, recoverable diaryl diselenide and sodium borohydride

In conjunction with sodium borohydride as stoichiometric reagent a catalytic quantity of bis(4-perfluorohexylphenyl) diselenide converts vicinal dimesylates to the corresponding alkenes in good yield on warming in ethanol. The diselenide is recovered in high yield by continuous fluorous extraction.     

Carbon dioxide conversion into the reaction intermediate sodium formate for the synthesis of formic acid

Research on Chemical Intermediates - Increased carbon dioxide (CO2) emissions from anthropogenic activities are a contributing factor to the growing global warming worldwide. The economical method...     

A mild method for the formation and in situ reaction of imidoyl chlorides: conversion of pyridine-1-oxides to 2-aminopyridine amides

[reaction: see text] A mild, practical, one-pot method for the generation of imidoyl chlorides and their subsequent in situ reaction with pyridine-1-oxides is described. The imidoyl chlorides were formed from the reaction of secondary amides with a stoichiometric amount of oxalyl chloride and 2,6-lutidine in CH(2)Cl(2) at 0 degrees C. Upon warming of the reaction mixture to room temperature in the presence of pyridine-1-oxides, a rapid conversion to 2-aminopyridine amides was observed in moderate to excellent isolated yields.     

The influence of sodium trifluoroacetate on the acidity function of solutions of trifluoroacetic acid in N,N-dimethylformamide

The influence of CF₃COONa on the acidity function (H ₀) and IR spectra of the CF₃COOH-N,N-dimethylformamide (DMF)-CF₃COONa system ([CF₃COOH] ≤ [DMF], [CF₃COONa] = 0–3 M) and H ₀ of solutions of the salt in 100% CF₃COOH ([CF₃COONa] = 0–1.2 M) was studied. The addition of the salt to 100% CF₃COOH insignificantly changed solution acidity; H ₀ passed a minimum at [CF₃COONa] = 0.7 M because of the formation of (CF₃COO…H…OOCCF₃)^? anions and destruction of acid associates in the presence of the salt. Changes in the acidity of solutions of CF₃COOH in DMF caused by the addition of the salt depended on the n = [CF₃COOH]/[DMF] ratio. At n = 1, the salt almost did not influence H ₀. At n < 1, a substantial decrease in the acidity of solutions was observed, because the salt increased the degree of proton transfer in CF₃COO…H…OC(H)N(CH₃)₂ quasi-ion pairs solvated by DMF molecules.     

Comparative study of mono- and dinuclear complexes of late 3d-metal chlorides with N,N-dimethylformamide in the gas phase

Mono- and binuclear complexes of N,N-dimethylformamide (DMF) with chlorides of the divalent, late 3d metals M = Co, Ni, Cu, and Zn are investigated by means of electrospray ionization (ESI). Specifically, ESI leads to monocations of the type [(DMF)(n)MCl](+) and [(DMF)(n)M(2)Cl(3)](+), of which the species with n = 2 and 3 were selected for in-depth studies. The latter include collision-induced dissociation experiments, gas-phase infrared spectroscopy, and calculations using density functional theory. The mononuclear complexes [(DMF)(n)MCl](+) almost exclusively lose neutral DMF upon collisional activation with the notable exception of the copper complex, for which also a reduction from Cu(II) to Cu(I) concomitant with the release of atomic chlorine is observed. For the dinuclear clusters, there exists a competition between loss of a DMF ligand and cluster degradation via loss of neutral MCl(2) with decreasing cluster stability from cobalt to zinc. For the specific case of [(DMF)(n)ZnCl](+) and [(DMF)(n)Zn(2)Cl(3)](+), ion-mobility mass spectrometry indicates the existence of two isomeric cluster ions in the case of [(DMF)(2)Zn(2)Cl(3)](+) which corroborates parallel theoretical predictions.     

A reaction of nitroxides with ethyl mercaptane: A mild method for the conversion of nitroxides into their corresponding amines

Summary The mild reduction of the nitroxides1 a–j to the corresponding sterically hindered amines2 a–j by means of ethyl mercaptane is reported. The reaction mixtures of1 a, b, g were analyzed by glc/ms.

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Die Reaktion von Nitroxiden mit Ethylmercaptan: Eine milde Methode für die Umsetzung von Nitroxiden zu den entsprechenden Aminen

Zusammenfassung Es wird über die milde Reduktion der Nitroxide1 a–j zu den entsprechenden sterisch gehinderten Aminen2 a–j mittels Ethylmerkaptan berichtet. Die Reaktionsmischungen von1 a, b, g wurden mittels GLC/MS analysiert.

     

Designing a safer process for the reaction of TFA with sodium borohydride in THF by calorimetric technique

Reaction of TFA with sodium borohydride in THF is a loss of thermal control involving the evolution of Hydrogen gas. The investigation of the process by RC1e and ARSST showed that the criticality class of the reaction is dependant on the addition of TFA. Heat of reaction (Q _r), adiabatic temperature rise (ΔT _ad), and MTSR data are obtained from RC1e experiment. Exothermic onset temperature, Pressure rise, and self heat rate data are obtained from ARSST experiments. The correlation of these data was utilized to define the criticality class of the reaction under different conditions. The reaction with uncontrolled addition of TFA falls in the undesirable criticality class 5. Vent size data are obtained from the adiabatic calorimeter for undesirable reaction. The criticality class can be changed to class 2 with controlled addition. Accordingly, interlock system to control the undesired reaction and appropriate vent relief system are provided.     

A general method for the rapid reduction of alkenes and alkynes using sodium borohydride, acetic acid, and palladium

Alkenes and alkynes are rapidly reduced to the corresponding alkanes using sodium borohydride and acetic acid in the presence of a small amount of palladium catalyst. The heterogeneous reaction is conducted in open air at room temperature. Reactions typically afford conversions to the alkane product of 98% or more within 15 min. The best solvent system was determined to be isopropyl alcohol, though reduction also takes place in solvents such as tetrahydrofuran, chloroform and, with some substrates, even in water. The method described is a convenient alternative to hydrogenations that require an external supply of hydrogen gas.     

An efficient method for the conversion of aromatic and aliphatic nitriles to the corresponding N-tert-butyl amides: a modified Ritter reaction

Aromatic and aliphatic nitriles react with tert-butyl acetate in the presence of a catalytic amount of sulfuric acid to give the corresponding N-tert-butyl amides in excellent yields.     

The formation of a metallacycloheptadienyl intermediate in the reaction of palladacyclopentadienyl derivatives with tetracyanoethylene

The palladium(II) derivatives of the type 1 [Pd(LL′)(C₄R₁R₂R₃R₄)] (LL′ = HNSPh:2-(phenylthiomethyl)-pyridine (A), BiPy: 2,2′-bipyridyl (B), DPPE: bis-diphenylphosphinoethane (C), NEOC: neocuproine (2,2′-dimethyl-o-phenanthroline) (D), R₁ = R₄ = COOMe, R₂, R₃ = C₁₀H₆ (a), R₁ = R₃ = C₆H₅, R₂ = R₄ = COOMe (b), R₁ = R₂ = R₃ = R₄ = COOMe (c)) react with the electron poor olefin tetracyanoethylene (TCNE) to yield under mild conditions the type 2 cycles C₆(CN)₄R₁R₂R₃R₄ and the corresponding palladium(0) olefin derivative [Pd(η²]-TCNE)(LL′)]. The olefin insertion reactions are usually fast, but in the case of the reaction of complex 1Da with TCNE accumulation of an intermediate is observed. The low temperature NOESY spectrum allows the determination of the intermediate structure which can be described as a hepta-membered metallacycle species.     

An efficient palladium-catalyzed coupling reaction of lithium alkynyltriisopropoxyborates with acid chlorides: a new access to synthesis of conjugated ynones

An efficient palladium-catalyzed protocol for the synthesis of ynones from lithium alkynyltriisopropoxyborates with acid chlorides under mild neutral conditions.     

Microflow photo-radical reaction using a compact light source: application to the Barton reaction leading to a key intermediate for myriceric acid A

The Barton reaction (nitrite photolysis) of a steroidal substrate 1, to give 2, a key intermediate for the synthesis of myriceric acid A, an endothelin receptor antagonist, was successfully carried out in a continuous microflow system using a Pyrex glass-covered stainless-steel microreactor having a one lane microchannel (Type A: 1000 μm width, 107 μm depth, 2.2 m length). We found that using a low-power black light (peak wavelength: 352 nm) and UV-LED light (peak wavelength: 365 nm) as the light source will suffice for the Barton reaction, creating a compact energy-saving photo-microreaction system. A multi-gram-scale production was attained using a multi-lane microreactor (Type B: 1000 μm width, 500 μm depth, 0.5 m length, 16 lanes) in conjunction with a black light.     

Reduction of N-acyl,N′-tosylhydrazines with diborane : A simple,convenient procedure for the conversion of the carboxylic to the methyl group

Aliphatic tosylhydrazides upon treatment with diborane followed by alkaline hydrolysis yield aliphatic hydrocarbons. Aromatic hydrocarbons are produced when aromatic tosylhydrazides undergo heating in presence of diborane and are subsequently oxidated by KIO₄. A discussion on the structures of intermediate products is reported.     

Rhodium catalyzed three-component reaction of aldehyde,boronic acid,and sulfonamides: a facile one-pot synthesis of diarylmethylamines

Rhodium(I) catalyzed three-component reaction for the one pot synthesis of diarylmethylamines in excellent yields were achieved by using aldehyde, boronic acid, and sulfonamides. The use of hyper-valent bis(trifluoroacetoxy)iodobenzene as an additive plays a key role in the chemo selective formation of amines instead of alcohols.