Synthesis and electronic properties of poly(aniline-co-2-amino-4-hydroxybenzenesulfonic acid)

Poly(aniline- co-2-amino-4-hydroxybenzenesulfonic acid) (PAAHB) was first synthesized via the electrochemical copolymerization of aniline and 2-amino-4-hydroxybenzenesulfonic acid (AHB) in the presence of an ionic liquid. The conductivity of PAAHB in the oxidized state is 0.45 S cm(-1). The conductivity and ESR spectra of PAAHB are slightly affected by water. The cyclic voltammograms of PAAHB reveal excellent redox activity from pH<1 to pH 11.0. This is attributed to the synergistic effect of the -SO3- and -OH functional groups in the copolymer chain and the ionic liquid incorporated into the PAAHB film. It is evident that the pH dependence of the redox activity and conductivity of PAAHB is much better than that of polyaniline. The proton NMR spectra of PAAHB and AHB demonstrate that the -SO3- group exists in the copolymer chain instead of the -SO3H group. Therefore, PAAHB can be used for the determination of dopamine in the presence of ascorbic acid as a result of the -SO3- group, which plays an important role in the selectivity.     

Friedel-crafts reactions of 2-amino-4-(alkyl or aryl)oxazoles with acid chlorides and acid anhydrides: Synthesis of 5-acyl-2-amino-4-alkyloxazoles

Acid chlorides and anhydrides react with 2-amino-4-alkyloxazoles in the presence of aluminum chloride to produce 5-acyl substituted 2-amino-4-alkyloxazoles in modest yields. However, in the absence of the Lewis acid reaction occurs at the amino group to give the corresponding amides. This provides a viable entry for functionalising and making carbon-carbon bond at C-5 of this heterocyclic system.     

Asymmetric synthesis of nonproteinogenic amino acids with l-amino acid transaminase: synthesis of (2S)-2-amino-4-oxo-4-phenylbutyric and (3E,2S)-2-amino-4-phenylbutenoic acids

2,4-Dioxo-4-phenylbutyric acid and 2-oxo-4-phenylbut-3-enoic acid are converted to the corresponding (S)-2-amino acids by recombinant Escherichia coli whole cells over-expressing aromatic transaminase from Enterobacter sp. BK2K-1 (AroATEs) in high yields (68–78%) and high enantiomeric purity (>99%) using l-aspartic acid as an amino donor.     

Synthesis of 10-propargylfolic acid from 2-amino-6-(bromomethyl)-4(1h)-pteridinone

6-(Bromomethyl)-2,4-pteridinediamine hydrobromide (1) is readily converted to 2-amino-6-(bromomethyl)-4(1H)-pteridinone hydrobromide (2) by treatment with 48% hydrobromic acid. Compound 2 is of interest for direct attachment of the (2-amino-3,4-dihydro-4-oxo-6-pteridinyl)methyl group to appropriate side-chain precursors of analogues of folic acid, particularly those bearing functional groups incompatible with conditions required for hydrolytic deamination of the corresponding 2,4-diaminopteridine analogues. An example of the use of 2 in this connection is demonstrated through synthesis of 10-propargylfolic acid.     

Synthesis of derivatives of 4-amino-2-trifluoromethylnicotinic acid

The method for the synthesis of ethyl 4-R-amino-2-trifluoromethylnicotinates from a diphenylboron complex of ethyl 2-acetyl-3-amino-4,4,4-trifluorobut-2-enoate was developed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2221–2223, October, 2004.     

Synthesis of protected （2S,4R）-2-amino-4-methyldecanoic acid,a proposed component of culicinins

The protected （2S,4R）-2-amino-4-methyldecanoic acid, a proposed component of culicinins has been synthesized over 10 steps and in total 28% yields using Wittig reaction and Schollkopf amino acid synthesis as key steps.     

（2R，4S）-N-叔丁酰基-4-氨基-2-四氢吡咯甲酸甲酯的合成

以(2R,4S)-4-羟基-2-四氢吡咯甲酸为起始原料,经甲酰化,酰化引入叔丁氧羰基,手性反应,甲磺酰化,叠氮化及三苯基膦还原等7步反应合成了(2R,4S)-N-叔丁酰基-4-氨基-2-四氢吡咯甲酸甲酯(总收率29%),其结构经1H NMR和LC-MS表征.     

Synthesis of 3-amino-4-(thienyl-2)furazan

3-Amino-4-(thienyl-2)furazan (3) has been synthesized from 2-acetylthiophene (4) by several routes. Nitrosation of 4, followed by oximation of the resulting oxime salt 5, gave a 6:1 mixture of the E,E and E,Z isomers of thienylglyoxime (1). Estimation of differences and analogies of these isomers' reactivity have been carried out. Oxidation and dehydration of 1 gave furoxan 11 and furazan 2, respectively. Conversion of 2, 12, 13, and 11a, b into the target amine 3 by base-promoted reaction with hydroxylamine has been reported. © 1997 John Wiley & Sons, Inc.     

Reactions of polyfunctional amines with 3-amino-4-(anilinothio-methylidene)-2-cyano-2-pentenedioic acid diethyl ester

3-Amino-4-(anilinothiomethylidene)-2-cyano-2-pentenedioic acid diethyl ester reacts with ethylenedi-amine, 1,3-propylenediamine and 1,4-butylenediamine affording bicyclic cyclocondensation products. The title compound reacts with diethylenetriamine and 2-(2-aminoethylamino)ethanol to give new seven membered ring tricyclic compounds. The mechanism for these reactions is discussed.     

Synthesis of 4(5)-substituted 2-amino-5(4)-hydroxyimino-5(4)H-imidazoles and their transformation into the corresponding 3-substituted 5-amino-1,2,4-oxadiazoles

Treatment of 4(5)-phenyl(or alkyl)-2-aminoimidazoles with isoamyl nitrite in acetic acid afforded the corresponding 4(5)-substituted 2-amino-5(4)-hydroxyimino-5(4)H-imidazoles which by heating in water were transformed into 3-benzoyl(or acyl)-5-amino-1,2,4-oxadiazoles.     

An efficient multi-component synthesis of (2-amino-3-cyano-4H-chromen-4-yl) phosphonic acid diethyl ester

(2-Amino-3-cyano-4H-chromen-4-yl) phosphonic acid diethyl esters are prepared via a single-step multi-component reaction of structurally diverse salicylaldehydes with malononitrile and triethyl phosphite using a catalytic amount of potassium phosphate in ethanol at ambient temperature. Use of potassium phosphate as an inexpensive catalyst makes the protocol more economical. Mild reaction conditions, simple work-up procedure are the added advantages of the present method.     

Rearrangement of 2-amino-4-(trifluoromethyl)oxazoles to hydantoins

Reaction of 2-amino-4-trifluoromethyloxazoles with excess bromine in acetic acid/sodium acetate gives 5-acetoxyhydantoins. The 5-bromooxazoles are intermediates in the reaction.     

New synthetic methods for 4-amino-2(5H)-furanones

Two new efficient methods are disclosed for the synthesis of the title compounds: (1) base-promoted ring closure of 2-acyloxy alkanenitrile and (2) acid-mediated lactonization of t-butyl 4-alkoxy-3-amino-2-alkenoates.