Regioselective synthesis of 1-aryl-3,4-substituted/annulated-5-(methylthio)pyrazoles and 1-aryl-3-(methylthio)-4,5-substituted/annulated pyrazoles

[reaction: see text] Highly efficient and regioselective synthesis of 1-aryl-3,4-substituted/annulated-5-(methylthio)pyrazoles and 1-aryl-3-(methylthio)-4,5-substituted/annulated pyrazoles has been reported via cyclocondensation of arylhydrazines with either alpha-oxoketene dithioacetals or beta-oxodithioesters.     

Regioselective rapid analog synthesis of 1,3-(or 1,5-)diphenyl-4-aryl/heteroaryl-5-(or 3-)(methylthio)pyrazoles via Suzuki cross-coupling

Regioselective routes for the synthesis of 1,3-(or 1,5-)diphenyl-4-aryl/heteroaryl-5-(or 3-)(methylthio)pyrazoles via Suzuki cross-coupling of 4-bromo (or 4-iodo)-1,3-(or 1,5-)diphenyl-5-(or 3-)(methylthio)pyrazoles have been reported.     

Highly regioselective synthesis of 1-aryl-3 (or 5)-alkyl/aryl-5 (or 3)-(N-cycloamino)pyrazoles

[Reaction: see text]. An efficient highly regioselective protocol for the synthesis of isomeric 1,3-diaryl (or 1-aryl-3-alkyl) and 1,5-diaryl (or 1-aryl-5-alkyl)-5 (or 3)-(N-cycloamino)pyrazoles has been reported by cyclocondensation of common alpha-oxoketene N,S-acetal precursors with arylhydrazines by variation of reaction conditions.     

Regioselective synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles

An efficient and simple method for the synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles has been developed. It consists in the condensation of α-diketone monooximes with aromatic amines and formaldehyde on the presence of boron trifluoride etherate, leading to the formation of stable boron trifluoride complexes of N-oxides. Further reduction of these complexes led to the corresponding imidazoles. This method permits broad variations of substituents in the aryl part of these compounds.     

4-Functionally-substituted 3-heterylpyrazoles: XIX. 3-aryl-4-(5-isoxazolyl)pyrazoles

Oximes of 4-(4-pyrazolyl)-3-buten-2-onees obtained by successive reaction of 3-aryl-4-formylpyrazoles with acetone and hydroxylamine at the treatment with iodine suffered an oxidative cyclization yielding 3-aryl-4-(5-isoxazolyl)pyrazoles.     

Regioselective synthesis of 3-aryl-5-(1H-indole-3-carbonyl)-4-hydroxyfuroic acids as potential insulin receptor activators

3-Methoxy-4-aryl-furan-2,5-dicarboxylic acid (8) is selectively converted into its C-5 methylester (6) by treatment with methyl chloroformate followed by decarboxylation in one flask. Acylation of the resulting half ester with a 7-substituted indole was performed under mild conditions to afford 3-aryl-5-(1H-indole-3-carbonyl)-4-methoxy-2-furoic acid (11). The synthetic utility of the resulting furoic acids as a skeleton in the synthesis of potential insulin receptor activators is established.     

Regioselective synthesis of 4-alkyl- and 4-aryl-6-(perfluoroalkyl)salicylic acid derivatives by formal [3+3] cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 3-silyloxy-1-(perfluoroalkyl)prop-2-en-1-ones

4-Alkyl- and 4-aryl-6-(perfluoroalkyl)salicylic acid derivatives were regioselectively prepared by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 3-silyloxy-1-(perfluoroalkyl)prop-2-en-1-ones.     

Regioselective synthesis of 6-aryl-5-(chloroethyl)salicylates by domino ‘[3+3] cyclization/homo-Michael’ reactions of 1,3-bis(silyloxy)-1,3-butadienes with 1-formyl- and 1-acetyl-1-aroyl-cyclopropanes

Functionalized 3-aryl-4-(chloroethyl)phenols are regioselectively prepared by domino ‘[3+3] cyclization/homo-Michael’ reactions of 1,3-bis(silyloxy)-1,3-butadienes with 1-formyl- and 1-acetyl-1-aroyl-cyclopropanes.     

Simple one-pot multicomponent approach to polyfunctionalized 2-amino-1-methyl-6-(methylthio)-5-nitro-4-aryl-1,4-dihydropyridine-3-carbonitriles

A series of polyfunctionalized 2-amino-1-methyl-6-(methylthio)-5-nitro-4-aryl-1,4-dihydropyridine-3-carbonitriles have been prepared using a multicomponent condensation reaction between aromatic aldehydes, malononitrile, and (Z) N-methyl-1-(methylthio)-2-nitroethenamine in the presence of Et₃N in acetonitrile.     

Polyfunctional pyrazoles 5*. preparative synthesis of 1-aryl-4-formylpyrazole- 3-carboxylic acids

Treatment of methyl pyruvate N-arylhydrazones with the Vilsmeier-Haack reagent gave methyl 1-aryl-4-formylpyrazole-3-carboxylates, basic hydrolysis of which yielded the corresponding acids.     

Cyclocondensation of α-hydroxyimino-β-alkyl/arylimino-β-methylthioketones with hydrazine hydrate: Synthesis of 3(5)-aryl-5(3)-alkyl/arylamino-4-nitroso (or amino) pyrazoles

The title pyrazoles were synthesized through cyclocondensation of hydroxyiminoimine derivatives 1a-j with hydrazine hydrate.     

Synthesis of 5-Amino-1-aryl-4-(4-aryl-1,3-thiazol-2-yl)- 2,3-dihydro-1H-pyrrol-3-ones*

Reactions of 2-(4-aryl-1,3-thiazol-2-yl)-3-oxo-4-chlorobutyronitriles with primary aromatic amines result in nucleophilic substitution of the chlorine atom by amino group, followed by intramolecular addition of the secondary amino group to the cyano group. The products are 5-amino-1-aryl-4-(4-aryl-1,3-thiazol-2-yl)- 2,3-dihydro-1H-pyrrol-3-ones which are structurally related to the known antiischemic drugs.     

Palladium-catalyzed ring expansion reaction of (Z)-1-(1,3-butadienyl)cyclobutanols with aryl iodides. stereospecific synthesis of (Z)-2-(3-aryl-1-propenyl)cyclopentanones

[reaction: see text] A novel type of cascade ring expansion process has been developed by the palladium-catalyzed reaction of (Z)-1-(1,3-butadienyl)cyclobutanols with aryl iodides. The reaction proceeds in a stereospecific manner to produce (Z)-2-(3-aryl-1-propenyl)cyclopentanones. It has also been found that regioselective alpha-arylation of alkenyl cyclopentanones proceeds to afford the alpha-arylated cyclopentanones.     

5-(α-Fluorovinyl)tryptamines and 5-(α-Fluorovinyl)-3-(N-methyl-1′,2′,5′,6′,-tetrahydropyridin-3′- and -4′-yl)indoles—5-(α-Fluorovinyl)tryptamines

5-(α-Fluorovinyl)tryptamines 4a, 4b and 5-(α-fluorovinyl)-3-(N-methyl-1′,2′,5′,6′-tetrahydropyridin-3′- and -4′-yl) indoles 5a, 5b were synthesized using 5-(α-fluorovinyl)indole ( 7 ). The target compounds are bioisosteres of 5-carboxyamido substituted tryptamines and their tetrahydropyridyl analogs.