Michael L. Wood

Synthesis and scintillating efficiencies of 4-functionalised-2,5-diphenyloxazoles

Abstract A series of 4-functionalised-2,5-diphenyloxazoles has been synthesised. Each member of the series has been assessed for the ability to scintillate in the presence of ionising radiation. The scintillation counting efficiency of each member of the series has been determined relative to 2,5-diphenyloxazole, a widely used scintillant molecule.

AN EASY SYNTHESIS OF 3-AMINO- AND 3-NITROTHIOPHENE

Abstract 3-Amino- and 3-nitrothiophene are readily made by the decarboxylation of the corresponding thiophene-2-carboxylic acids which are easily prepared from the commercially available methyl 3-aminothiophene-2-carboxylate.

A RAPID CONVERSION OF 3-OXOTHIOLANES INTO 3-AMINOTHIOPHENES

ABSTRACT 3-Oxotetrahydrothiophenes can be rapidly converted into 3-aminothiophenes by refluxing with hydroxylamine hydrochloride in a polar solvent, usually acetonitrile.

Dehalogenation of 1-halogenothienyl-di- and -tetra-hydroisoquinolines by sodium methoxide in dimethyl sulphoxide

On treatment with sodium methoxi-dimethylsulphoxide (NaOMe–DMSO) 1-(5-halogeno-2-thienyl)-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinolines suffer loss of halogen and are converted into the related 1-hydroxytetrahydroisoquinolines. The reaction fails with comparable 1-bromophenyl- and 1 -(halogeno-3-thienyl)tetrahydroisoquinolines. A similar transformation takes place with (5-halogeno-2-thienyl)phenylmethoxymethanes, leading to the dimethyl acetal of the 5-dehalogenated-2-thienyl phenyl ketone. α-Halogenated-2- and 3-thienyl-3,4-dihydroisoquinolines undergo dehalogenation-aromatisation with NaOMe–DMSO. Mechanisms for these conversions are proposed.

3,3′-Azothiophene

Methyl 3-nitrothiophene-2-carboxylate was reduced with bismuth(III) chloride/potassium borohydride to give an unstable hydroxylamine which was oxidised without isolation using iron(III) chloride to give methyl 3-nitrosothiophene-2-carboxylate. Condensation of this with methyl 3-aminothiophene-2-carboxylate furnished the azodiester. This was more conveniently obtained by manganese dioxide oxidation of the aminoester. Hydrolysis of the azodiester to give the diacid followed by decarboxylation gave 3,3′-azothiophene which could be oxidised to 3,3′- azoxythiophene with hydrogen peroxide. The azodiester was oxidised to the corresponding azoxydiester with urea-hydrogen peroxide/trifluoroacetic anhydride and reduced to the related hydrazothiophenediester with diimide.

Nitration of methyl-3-hydroxy- and 5-methyl-3-hydroxy-thiophene-2-carboxylate, and some chemistry of the products

The nitration of methyl-3-hydroxythiophene-2-carboxylate furnishes two products, the lower melting of which was previously thought to be the 4- (3) and the other the 5-isomer (2); these assignments have been reversed on the basis of carbon-13 NMR. data and the revised structures have been confirmed both by O to N acyl migrations and by the preparation of the first examples (20) and (23) of the thieno[3,4-b][1,4]oxazine ring system from derivatives of the 4-nitro isomer.

A SYNTHESIS OF 2-ACYL-3-HYDROXYTHIOPHENES

Abstract 2-Acyl-3-hydroxythiophenes have been made by the reaction of the anion of a mercaptoketone with dimethyl acetylenedicarboxylate to give a hydroxythiophene ester which is then hydrolysed and decarboxylated.

DEHALOGENATION OF 1-HALOTHIENYLDI- AND -TETRAHYDROISOQUINOLINES BY SODIUM METHOXIDE IN DIMETHYL SULFOXIDE

Int. Cl. ... A61K31/505; A61K31/44; A61K31/47; A61K31/38 U.S. Cl. ......................... 514/259; 514/340; 514/345; 514/349; 514/312; 514/311; 514/313; 514/314; 514/269; 514/309; 514/307: 514/444; 514/445; 514/.447; 514/249; 514/248; 514/252; 514/375 Field of Search ..................................... 514/259,340, 514/345, 349, 312, 311, 313, 314, 269, 309, 307, 444, 445, 447, 249, 248,252, 375