Efficient and library-friendly synthesis of furo- and thieno[2,3-d] pyrimidin-4-amine derivatives by microwave irradiation

A new, divergent, efficient, and selective synthesis of furo- and thieno[2,3-d]pyrimidin-4-amine derivatives by microwave irradiation has been developed starting from readily available amines and substituted 2-aminofuran-3-carbonitrile or 2-aminothiophene-3-carbonitrile, which are converted into corresponding formamidines in DMF using benzenesulfonyl chloride.     

Convenient synthesis and anticancer evaluation of novel pyrazolyl-thiophene,thieno[3,2-b]pyridine,pyrazolo[3,4-d]thieno[3,2-b]pyridine and pyrano[2,3-d]thieno[3,2-b]pyridine derivatives

The newly synthesized 3-(3-amino-5-(phenylamino)-4-(phenylcarbamoyl)thiophen-2-yl)-3-oxopropanoate was utilized as a precursor for the synthesis of pyrazolyl-thiophene derivative, which undergoes cyclization upon treatment with benzaldehyde derivatives to provide pyrazolo[3,4-d]thieno[3,2-b]pyridines. Basic treatment of pyrazolyl-thiophene derivative with phenyl isothiocyanate followed by subsequent addition of chloroacetone and/or ethyl bromoacetate yielded the thiazolylidene-pyrazolyl thiophenes. In addition, the building block 3-(3-amino-5-(phenylamino)-4-(phenylcarbamoyl)thiophen-2-yl)-3-oxopropanoate was converted into the corresponding thieno[3,2-b]pyridine compounds through its reactions with (DMF-DMA) and/or heating in sodium ethoxide. Moreover, the reaction of 7-hydroxy-5-oxo-N-phenyl-2-(phenylamino)-4,5-dihydrothieno[3,2-b]pyridine-3-carboxamide with 2-arylidenemalononitrile produced the new annulated pyrano[2,3-d]thieno[3,2-b]pyridines. The prepared thiophene-based compounds were evaluated against HepG2, PC3, and MCF-7 cancer cells, and normal fibroblast cell (WI38). The pyrazolo[3,4-d]thieno[3,2-b]pyridine and pyrano[2,3-d]thieno[3,2-b]pyridine compounds substituted with chlorophenyl group presented promising cytotoxic activities against HepG2 cancer cell line without any human toxicity. Docking study for the synthesized thiophene compounds delivered valuable insights about the binding interactions with the crystal structure of NS5B enzyme with PDB ID (4TLR).     

An efficient route for synthesis of 2-alkylamino benzo[b]thieno[3,2-d]pyrimidin-4(3H)-one

The carbodiimide 2,obtained from the aza-Wittig reactions of iminophosphorane 1 with alkyl isocyanates,reacted with primary amino to give 2-alkylamino benzo[b]thieno[3,2-d]pyrimidin-4(3H)-ones 4 and 5.The formation mechanism of the title compounds has been investigated.     

Synthesis of condensed derivatives of 2-substituted thieno[2,3-d]pyrimidin-4-ones

A preparative method of synthesis of 2-substituted thieno[2,3-d]pyrimidin-4-ones involving deamination of the corresponding 3-amino derivatives, by sodium nitrite in acidic medium is proposed. A possible reaction mechanism is considered.A. L. Mndzhoyan Institute of Fine Organic Chemistry. Academy of Sciences of the Republic of Armenia, Erevan 375014 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 941–944, July, 1999.     

Syntheses of functionalized thieno[3,4-d]imidazoles and thieno[3,2-d]pyrimidines from chlorine-containing enamidonitriles

Enamidonitriles of the general formula Cl(X)C=C(CN)NHCOR readily react with methyl sulfanylacetate to give tri-or tetra-substituted thiophenes, which can be converted into new functional derivatives of thieno[3,2-d]pyrimidine and thieno[3,4-d]imidazole.     

Synthesis of substituted thieno[2,3-d]thiazoles and indolo[3,2-d]thiazoles

Alkylene-, halo-, and aryl-substituted 2-methylthieno[2,3-d]thiazoles were obtained by the action of phosphorus pentasulfide on the corresponding 2-acetylamino-3-bromo- or 2-acetylamino-3-hydroxythiophenes in an organic solvent with heating. 2-Oximes of halo- and methyl-substituted isatins were converted by reduction and acylation into 2-hydroxy-3-acetylaminoin-doles, from which 2-methylindolo[3,2-d]-thiazoles were obtained by the action of phosphorous pentasulfide with heating in xylene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 410–417, March, 1987.     

Efficient synthesis of substituted thieno[3,2-e]indoles

Efficient cyclization reactions of 5-aminobenzothiophene derivatives with internal and terminal acetylenes, giving 7- and 8-substituted thieno[3,2-e]indoles, are described. The reaction of 4-iodo-5-(methylsulfonamido)benzothiophene with terminal alkynes gave 7-substituted thienoindoles using general Sonogashira reaction conditions. Reaction of 5-amino-4-iodobenzothiophene with internal acetylenes, using Larock's heterocyclization reaction conditions, gave 7,8-disubstituted thieno[3,2-e]indoles.     

Preparation of a 7-arylthieno[3,2-d]pyrimidin-4-amine library

A focused kinase library of 7-arylthieno[3,2-d]pyrimidin-4-amine analogues is readily prepared via solution-phase parallel synthesis. This strategy relies on a key cyclization of a 3-aminothiophene-2-carboxamide with a formamide to construct the thienopyrimidine core. Further elaborations of this core via substitution and Suzuki coupling reactions allow the introduction of other diversity points. This methodology is demonstrated through the preparation of a 72-membered library of 7-arylthieno[3,2-d]pyrimidin-4-amines in good yields and high purities.     

Synthesis of pyrido[2,3-d]pyrimidin-4-one derivatives

This paper describes one-pot synthesis of 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e]pyrimidin-5-one 4 , 5H-dipyri-do[1,2-a:3′,2′-e]pyrimidin-5-one 10 and 5H-pyrido[3,2-e]pyrimido[1,2-a]pyrimidin-5-one 15 and some of their derivatives, starting with 2-chloro-3-pyridine carboxilic acid 1. Compounds 4 and 10 reacted with phosphorus pentasulfide to give the respective 5-thione analogues, 5 from 4 and 11 from 10 . Boiling the 5-thione derivatives with hydrazine hydrate, the respective 5-hydrazono derivatives 6 from 5 and 12 from 11 were obtained. The 5-acetyl hydrazono, 7 , and the 5-isopropylidenehydrazono, 8 , derivatives were also prepared from 6 , and the 5-propionylhydrazono derivatives, 13 , from 12 . Compound 4 reacted with hydrazine to give an adduct with two molecules of hydrazine and the probable structure 16 . Treating this adduct with acetone a monohydrazone 17 was obtained. Boiling a suspension of this adduct in DMF, it gave 6,10-dihydro-6H-pyrido[3′,2′:5,6]pyrimido[2,1-c][1,2,4]triazin-5-one 20 .     

Zn(OAc)2 catalyzed microwave irradiated synthesis of substituted thieno[2,3-d]pyrimidin-4(3H)-one

Different Lewis acids were screened to catalyze the reaction of 2-amino-thiophene-3-carboxylate, orthoformate and aryl amine to form 2-substituted thieno[2,3-d]pyrimidin-4(3H)-one. Zn(OAc)₂ was demonstrated to efficiently catalyze the reaction. 20 substituted thieno[2,3-d]pyrimidines were synthesized by adding 0.5% mol Zn(OAc)₂ as catalyst under microwave irradiation.     

Derivatives of condensed thieno[2,3-d]-pyrimidines. 20. Synthesis of 2-substituted 5,6-dihydro-8H-pyrano[4′,3′:4,5]thieno[2,3-d]pyrimidin-4(3H)-ones and 5,6,7,8-tetrahydrobenzo-[b]thieno[2,3-d]pyrimidin-4-ones

We have developed a method for obtaining 2-substituted 3-amino-6,6-dimethyl-5,6-dihydro-8H-pyrano[4′,3′:4,5]-and 5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4(3H)-ones, converted by deamination to the corresponding dihydropyranothieno-3H-pyrimidinones. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 441–444, March, 2006.     

Synthesis of 2-mercaptothieno[3,2-d]- and 2-mercaptobenzo[4, 5]thieno[2,3-d]thiazoles

2-Mercaptothieno[3,2-d]- and 2-mercaptobenzo[4, 5]thieno[2,3-d]thiazoles were synthesized by reduction of bis(3,3′-nitro-2,2′-thienyl) and bis(2,2′-nitrobenzo[b]thien-3,3′-yl) disulfides, respectively, with sodium hydrosulfite or sodium sulfide in the presence of carbon disulfide.     

New method for the synthesis of substituted thieno[3,2-b]pyridines and 5H-pyrano[2,3-d]thieno[3,2-b]pyridines derived from them

A new highly selective method was developed for the synthesis of substituted thieno[3,2-b]-pyridines based on the domino reaction of monopotassium salt (rather than dipotassium one) of carbamoylcyanodithioacetic acid with ethyl 4-chloroacetoacetate. Substituted 5H-pyrano[2,3-d]-thieno[3,2-b]pyridines were synthesized based on these thieno[3,2-b]pyridines.     

One-pot synthesis of thieno [2,3-d] pyrimidin-4-ol derivatives mediated by polyphosphonic anhydride

An efficient synthesis of thiopyrimidines with different substituents in position 2 is described. A rapid, mild and high yielding microwave-assisted one-pot cyclization of 5-substituted 2-amino thiophene-3-carboxamide derived from Gewald reaction¹ with T3P and different acids gives the corresponding thiopyrimidines. The significant feature of this method includes less reaction time, high purity and reduced toxicity of the reaction.     

Microwave assisted synthesis of 2,3-dihydro-4H-benzo[4,5]thiazolo[3,2-a]furo[2,3-d]pyrimidin-4-ones and 6,7-dihydro-5H-furo[2,3-d]thiazolo[3,2-a]pyrimidin-5-ones using Mn(OAc)3

2-Hydroxy-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-one 2a and 7-hydroxy-5H-thiazolo[3,2-a]pyrimidin-5-one 2b, were obtained in high yields under mild conditions from the cyclization reactions of bis-(2,4,6-trichlorophenyl) malonate and 2-aminobenzothiazole or 2-aminothiazole, respectively. A new class of compounds, 2,3-dihydro-4H-benzo[4,5]thiazolo[3,2-a]furo[2,3-d]pyrimidin-4-ones and 6,7-dihydro-5H-furo[2,3-d]thiazolo[3,2-a]pyrimidin-5-ones, were synthesized via the microwave assisted radical addition of compounds 2a and 2b to various alkenes using manganese(III) acetate. A preliminary acetylcholine esterase (AchE) inhibition test of compound 4e showed excellent (92%) inhibitory potential, comparable with the standard drug Donapezil®.     

Synthesis of 2-mercapto-substituted thieno[2,3-d]thiazoles and ben zothieno[3,2-d] thiazoles

2-Mercaptothieno[2, 3-d]thiazoles were synthesized from bis(2-nitro-3-thienyl) disulfide by successive reduction of, initially, the disulfide bond and the nitro group in the presence of carbon disulfide without isolation of the intermediate 2-nitro-3-mercaptothiophene. 2-Mercaptobenzo-[b]thieno[3, 2-d]thiazole was synthesized by reaction of 3-aminobenzo[b]thiophene hydrochloride with sulfur monochloride and cleavage of the resulting benzo[b]thienothiazothionium chloride with sodium sulfide in the presence of carbon disulfide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1355–1356, October, 1976.     

Preparation of reissert compounds derived from the thieno[3,2-c]pyridine,thieno[2,3-d]pyridazine and the thieno[2,3-d]pyrimidine ring systems

The use of tributyltin cyanide, trimethylsilyl cyanide and potassium cyanide in the Reissert reaction is contrasted in the furo[3,2-c]pyridine, thieno[3,2-c]pyridine, thieno[2,3-dpyridazine, and thieno[2,3-d]pyrimidine ring systems.     

Efficient Synthesis of 3,5,6,8-Tetrahydro-4H-thiopyrano[4',3':4,5]thieno[2,3-d]pyrimidin-4-ones via an Iminophosphorane

3,5,6,8-Tetrahydro-4H-thiopyrano[4',3':4,51thieno[2,3-d]pyrimidin-4-ones(7) were synthesized via the base catalytic reactions of amines or phenols with carbodiimides(5),which were obtained from the aza-Wittig reactions of iminophosphoranes(4) with aromatic isocyanates.     

Cyclisierungsreaktionen zu Thiazolo[3,2—a]thieno[2,3-d]pyrimidinen

Cyclisation of 2-(-oxo-alkylthio)-thieno[2.3-d]pyrimidin-4(3H)-ones gave separable mixtures of the title substances and their [2.3-b]-isomers. The structure of the two isomers were be proved by comparison with a linear product synthesized by an unambiguous method. Similar cyclisations were achieved by reactions of 2-mercapto-thieno[2.3-d]pyrimidin-4(3H)-ones with chloroacetone, 1.2-dibromoethane or 1.3-dibromopropane.