A novel improved synthesis of 3-aminopyrazine-2-carboxylic acid

A three step synthesis of 3-aminopyrazine-2-carboxylic acid ( 1 ) starting from pyrazine-2,3-dicarboxylic acid ( 5 ) is described. Diacid 5 is converted via the anhydride 6 into the ammonium salt of the half acid amide 7 which on Hofmann rearrangement gives the title compound in 55% overall yield.     

A novel synthesis of 3-cyanoindoles and a new route to indole-3-carboxylic acid derivatives

2-Alkyl-3-cyanoindoles are obtained when 1-alkylmethyl-2-chloro-(or 2-phenylsulfonyl)-3-phenylsulfonylindoles are reacted with excess azide ion (90°/DMF). The reaction is considered to occur by a fragmentation recombination process in which the Schiff's base $\text{12}$ is of central importance. This proposal is supported by the formation of 2-substituted indole-3-carboxylates $\text{17}$ from aldehydes and the α-phenylsulfonyl-$\text{o}$-aminophenylacetic acid ester derivative $\text{16}$.     

A novel synthesis of (±)-3-aminonocardicinic acid

(±)-3-Aminonocardicinic acid (3-ANA, 2), which is an important material for the synthesis of nocardicin A (1) and other biologically active analogues, has been synthesized by the application of a new method for the synthesis of α-methylene-β-lactams.     

A novel synthesis of 3H-pyrroles

Reaction of isopropylphenyl- and isopropyl-2-thienylketoximes with acetylene, catalyzed by the system MOH (M=Na, K)-DMSO, gave 2-phenyl- and 2-(2-thienyl)-3,3-dimethyl-3H-pyrroles as well as the reaction intermediates O-vinylisopropylphenylketoxime and 2-phenyl-3,3-dimethyl-5-hydroxypyrroline. The yield of the condensation products depends on the structure of the ketoximes and the conditions for the reaction with acetylene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1371–1374, October, 1991.     

O-Protected 3-hydroxy-oxazolidin-2,4-diones: novel precursors in the synthesis of alpha-hydroxyhydroxamic acids

O-Protected 3-hydroxyoxazolidin-2,4-diones have been prepared in a novel one-pot reaction by subsequent treatment of cyanohydrins with 1,1'-carbonyldiimidazole and O-protected hydroxylamines followed by acidic hydrolysis of the intermediate 4-imino-oxazolidin-2-ones. Decarbonylation of O-protected 3-hydroxyoxazolidin-2,4-diones by catalytic amounts of sodium methoxide, lithium hydroxide, sodium carbonate and caesium carbonate in methanol afforded O-protected alpha-hydroxyhydroxamic acids in excellent yields. Their deprotection provided a series of novel alpha-hydroxyhydroxamic acids.     

Efficient synthesis of multifunctional furanoid C-glycoamino acid precursors

Ready access to constrained, multifunctionalized, hydrolytically stable amino acids has been established by the synthesis of their direct precursors using 2,5-anhydro-3-azido-3-deoxy-d-altrose (a ‘formyl azido-C-glycofuranoside’), or its readily available, stable synthetic equivalent [(1R) and (1S)-2,5-anhydro-3-azido-4,6-O-benzylidene-3-deoxy-1-fluoro-1-O-methyl-d-altritol], as novel molecular scaffolds.     

A novel synthesis of acrylic acid containing polymers

A novel synthesis of linear acrylic acid containing polymers, poly(styrene-co-acrylic acid) and poly(acrylic acid), was accomplished through hydrolysis of the respective parent polymers, i.e. poly(styrene-co-methyl acrylate) and poly(methyl acrylate), with trimethylsilyl iodide under mild conditions. Combination of ¹H NMR, ¹³C NMR, FTIR, DSC and chemical titration confirms that the conversion from methoxycarbonyl to carboxyl is almost complete. This method is further successfully applied to synthesize poly-(ethyl methacrylate-co-acrylic acid) through selective hydrolysis of the methyl acrylate units in poly(ethyl methacrylate-co-methyl acrylate).     

N-Benzylhydroxylamine addition to beta-aryl enoates. Enantioselective synthesis of beta-aryl-beta-amino acid precursors

Chiral Lewis acid catalyzed N-benzylhydroxylamine addition to pyrrolidinone-derived enoates afforded beta-aryl-beta-amino acid derivatives in high enantiomeric purity with moderate to very good chemical efficiency.     

A novel synthesis of substituted 3-aminopenems

Displacement of phenol leaving groups at the C-3 position of penems by amines provides a general route to substituted 3-aminopenems     

A novel synthesis of (±)-trans-chrysanthemic acid

A novel approach to ± $\text{trans}$ chrysanthemic acid, from commercially available 2,5-dimethyl 3 hexyne 2–5 diol (30 % overall yield) is described.     

A novel synthesis of 3-bromo-1,2,4-oxadiazoles

A novel synthesis of 3-bromo-1,2,4-oxadiazoles by 1,3-dipolar cycloaddition between bromocyanogen oxide and alkyl and aryl nitriles is described.     

A novel approach to the synthesis of 5-trifluoromethyl-3-substituted pyrazoles

The 3-cyano-4-trifluoromethyl-6-phenyl or substituted phenyl 2(1H) pyridones (1) on reaction with hydrazine hydrate, gave exclusively in 5-trifluoromethyl-3-substituted pyrazoles (3) through a novel method. A possible mechanistic pathway for change in the site of nucleophilic attack due to the CF₃ group in 2(1H) pyridones is described.     

A novel synthesis of amino acid derivatives of phospholene oxides

A convenient synthetic approach is established to prepare a new class of 1-l-α-amino acid derivatives of phospholene oxides by amination of (±)-1-chloro-2-phospholene-1-oxides with several optically pure l-α-amino acid esters. All compounds obtained as a diastereomeric mixture in good to high yields. The two diastereomers were successfully separated by column chromatography and structurally identified by their spectral analyses.     

A novel synthesis of 1-aryl-3-piperidone derivatives

A novel method to construct the 1-aryl-3-piperidone scaffold is described here. Starting from 3,5-dichloroaniline, a seven-step synthesis, without the use of protecting groups, generates the desired 3-piperidone ring in an overall yield of 30% through a key Morita–Baylis–Hillman reaction and ring-closing metathesis, providing easy access to diverse and useful heterocycles.     

One-step synthesis of alpha-chloro acetophenones from acid chlorides and aryl precursors

A direct and efficient method was developed for the preparation of a variety of substituted acetophenone derivatives from readily available arene precursors and acid chlorides. This method has significant generality and affords access to substitution patterns on aryl rings not directly achievable by Friedel-Crafts chemistry. [reaction: see text].