Complete multinuclear magnetic resonance characterization of a set of polyfluorinated acids and alcohols

A complete ¹H, ¹⁹F, and ¹³C NMR assignment of a homologous series of polyfluorinated acids and alcohols is reported. These assignments were obtained chiefly through single and multiple‐bond ¹H–¹³C and ¹⁹F–¹³C correlation experiments (HSQC, HMBC). ¹⁹F NOESY experiments were required for assignment of two compounds with diastereotopic ¹⁹F nuclei in the CF₂chain of the molecule. Copyright © 2008 John Wiley & Sons, Ltd.     

A convenient method for the synthesis of polyfluorinated β-diimines

The higher internal perfluoroak-2-enes react with ammonium hydroxide at atmospheric pressure to give the corresponding iminoenamines, whose further transformations yield heptafluoroacetylacetone analogs. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1710–1712, September, 1999.     

An infrared spectroscopic method for quantitative analysis of fatty alcohols and fatty acid esters in machinery oils

A new infrared spectroscopic method suitable for determining total fatty alcohol and fatty acid ester concentrations in industrial oils has been developed. Oil samples were diluted with toluene (1:3 w/w), the toxicity and volatility of which are relatively low compared with more commonly used IR solvents, like carbon tetrachloride or carbon disulfide. Mixture standards were prepared from dodecanol, tetradecanol, octadecanol, methyl stearate and methyl palmitate. Some analytical and statistical tests were performed on the developed method. The recoveries and the repeatability of the method proved to be sufficient for the quantitative determination of fatty alcohol and fatty acid ester additives in industrial oils. Reproducibility testing in another laboratory also produced satisfactory results. The developed method also proved to be relatively quick and simple. This method was developed to satisfy industry’s need to determine the concentrations of these oil additives, and it has already been applied successfully in machinery oil analysis.     

Regio- and stereoselective double alkylation of β-enamino esters with organolithium reagents followed by one-pot reduction: convenient method for the synthesis of tertiary γ-amino alcohols

An easy, high yielding and stereoselective procedure for the preparation of tertiary γ-amino alcohols starting from β-enamino esters is presented. In this procedure, the double alkylation of β-enamino esters with organolithium reagents is followed by one-pot reduction with sodium borohydride in methanol/acetic acid. A hypothesis of mechanism is given, explaining the observed diastereoselectivity through molecular modeling. The configuration of the products was determined by ¹H NMR spectroscopy coupled with conformational analysis.     

Palladium-catalyzed direct coupling reaction of propargylic alcohols with arylboronic acids

The direct coupling of propargylic alcohols with arylboronic acids has been achieved using palladium catalyst. Various propargylic alcohols and arylboronic acids can be coupled to afford the corresponding allenic and propargylic arenes, which are selectively produced depending on the substituent on the propargylic alcohol, respectively.     

Thioethynyl esters of phosphorus acids

The results of searching for the methods of synthesis of substituted thioethynyl monothio- and dithiophosphates, which are of interest as physiologically active compounds, are summarized. The preparative method for the synthesis of thioesters of O,O-dialkylmonothiophosphoric acids of a specific type was developed: the reaction of substituted ethynyl bromides with potassium salts of the corresponding monothiophosphoric acids in the presence of an equimolar amount of CuCl. These reactions occur through the stage of formation of Cu^I salts of the corresponding monothiophosphoric acids and are accompanied by redox processes leading to the formation of free radicals. The modified method for the synthesis of substituted thioethynyl monothio- and dithiophosphates is the reaction of Cu^I salts of these acids with the corresponding ethynyl bromides.     

A robust NNP-type ruthenium (II) complex for alcohols dehydrogenation to esters and pyrroles

A Ru (II) complex bearing pyridyl-based benzimidazole-phosphine tridentate NNP ligand was synthesized and structurally characterized by NMR, IR. The complex can efficiently and selectively catalyze the acceptorless dehydrogenation of primary alcohols to esters under relatively mild conditions and the synthesis of pyrroles by means of the reactions of secondary alcohols and β-amino alcohols through acceptorless deoxygenation condensation.     

An effective synthesis of β-aryl substituted isotetronic acids via Suzuki coupling

Isotetronic acids are of great agricultural and pharmacological relevance and occur in a number of natural products. A convenient synthetic pathway to β-aryl substituted isotetronic acid derivatives was developed via Suzuki cross-coupling of the corresponding β-bromo substituted isotetronic acid derivatives with arylboronic acids under palladium acetate catalysis. Good to excellent yields have been achieved     

An effective synthesis of β-aryl substituted isotetronic acids via Suzuki coupling

lsotetronic acids are of great agricultural and pharmacological relevance and occur in a number of natural products.A convenient synthetic pathway to β-aryl substituted isotetronic acid derivatives was developed via Suzuki cross-coupling of the corresponding β-bromo substituted isotetronic acid derivatives with arylboronic acids under palladium acetate catalysis.Good to excellent yields have been achieved.     

Fluorinated acrylates via alkoxycarbonylation of 1-alkynes with fluorinated alcohols

The system formed by combining in situ Pd(OAc)₂ with (2-pyridyl)diphenylphosphine (PyPPh₂) and CH₃SO₃H catalyzes efficiently the carbonylation of terminal alkynes (phenylacetylene or 1-hexyne) with alcohols having perfluorinated segments of the type CF₃(CF₂)_m(CH₂)_n–OH (m=1 or 3, n=1, 2 or 3) or with pentafluorophenol. Good carbonylation rates accompanied by high regioselectivity towards acrylate ester formation are obtained under mild reaction conditions (T=60–80 °C, P(CO)=30 atm). The influence of the CO pressure, the catalyst composition, the temperature and the number (n) of protonated methylene groups on the catalysis has been studied.     

The reaction of 2-aminomethylphenols and their copper(II) complexes with esters of phosphorus acids

2-Alkyl- and 2-dialkylaminomethylphenols (AMP) with different hydrophobic substituents at the nitrogen atom and their copper(II) complexes (CAMP) react with the esters of phosphorus acids in aqueous solutions of ethanol in two stages: phosphorylated AMP (PAMP) are formed at the first stage and then hydrolyzed to the corresponding acids. The reactivity of AMP and PAMP significantly decreases when the hydrophobicity and steric hindrances of substituents at the nitrogen atom increase. An inverse dependence was found for CAMP. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1355–1360, August, 2000.     

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.     

Reaction of allylic and benzylic alcohols and esters with PPh3/I2: one-pot synthesis of β,γ-unsaturated compounds

The treatment of tertiary and secondary allylic alcohols containing a terminal double bond, and their acetyl derivatives, with triphenylphosphine and iodine under mild conditions leads regiospecifically and in high stereoselectivity to the corresponding primary allylic iodides, which can react ‘in situ’ with diverse nucleophiles. Primary allylic alcohols and benzyl alcohols and acetates are also transformed into the corresponding iodides under these conditions.     

Development and application of an analytical method for the determination of storage lipids, fatty acids and fatty alcohols in Calanus finmarchicus

A method was developed for the determination of the major storage lipids, wax ester and triglycerides, in the copepod Calanus finmarchicus. A variation of the Folch method was used to extract the lipid. The method was scaled down to enable the extraction of either pooled (-1 mg) or individual (approximately 200 microg) copepods. The major lipid classes were identified using TLC and quantified using HPLC coupled with evaporative light scattering detection. Analysis of laboratory reference materials indicated that this method underestimated the minor triglyceride component, but gave a good estimate of the major wax ester component. The fatty acid and fatty alcohol composition of the C. finmarchicus were determined following trans-esterification of the lipid extract in methanol. Fatty acids and fatty alcohols were initially identified by comparison with authentic standard and by mass spectroscopy. Using GC with flame ionisation detection the normalised area percentage of the fatty alcohols and fatty acid methyl esters was determined simultaneously in one run for either pooled or individual copepod samples. These methods were applied to C. finmarchicus collected from the Irminger Sea, North Atlantic in 2001 and 2002.     

Some approaches to the synthesis of fluorinated alcohols and esters. I. Completely fluorinated esters from the hunsdiecker reaction of silver F-alkanoates with iodine

A completely fluorinated ester of the type R_FCO₂CF₂R_F′ was obtained from reaction of silver 3,6,9-trioxa-F-undecanoate and iodine with a diluent at 130°. This new substance resembled closely the previously prepared 1,1-dichloro-F-alkyl esters and was hydrolytically and thermally labile. Substitution products, R_FCOY (Y = nucleophile) and pyrolysis products, R_FCOF and R_F′COF were isolated and characterized. It appears probable that the acyl hypoiodite and the iodo-F-alkane reacted by an S_Ei-type process to give the completely fluorinated ester.     

A concise synthesis of glycosyl-α-amino acid derivatives via homologation of dialdoses into bromo uronic acids and esters

The synthesis of the compounds of the title involves three steps from dialdoses. The reaction between potassium dibromoacetonitrile carbanion and protected dialdoses provides corresponding β-bromo-α-ketonitriles that are easily transformed into α-bromo esters by treatment with methanol or isopropanol or α-bromo acids by treatment with t-BuOH. Substitution of the bromine by sodium azide onto these last compounds and subsequent catalytic hydrogenation of the azide group afford the targeted glycosyl-α-amino acid derivatives. This methodology represents the most rapid access to the key α-amino acid moiety of polyoxins.     

The green and effective oxidation of alcohols to carboxylic acids with molecular oxygen via biocatalytic reaction

A clean and effective alcohol oxidizing system using three enzymes has been developed. Regeneration of NAD⁺ by NADH oxidase with molecular oxygen enabled to oxidize alcohols to carboxylic acids in good yield under mild conditions (25 °C, 1 atm).     

Cobalt phthalocyanine catalyzed aerobic oxidation of secondary alcohols: an efficient and simple synthesis of ketones

A variety of activated and non-activated secondary alcohols have been efficiently oxidized to their corresponding ketones in excellent yields with molecular oxygen using cobalt phthalocyanine as catalyst in the presence of powdered potassium hydroxide.     

An improved Pfitzinger reaction for the direct synthesis of quinoline-4-carboxylic esters/acids mediated by TMSCl

An efficient and facile synthesis of quinoline-4-carboxylic esters/acids by TMSCl-promoted reaction of easily available N,N-dimethylenaminones and isatins in alcohols/water has been developed. The improved Pfitzinger reaction involves esterification and cyclization in one-step process, and in situ formed a carboxylic ester/acid group (CO₂R or COOH) at the 4-position of quinoline ring. Moreover, the key features of this protocol are readily available starting materials, good functional group tolerance, mild reaction conditions, operational simplicity, and feasibility of scale up.