One-pot synthesis of imidazo[1,2-b]pyrazole,imidazo[1,2-b]-1,2,4-triazole,imidazo[1,2-a]pyridine,imidazo[1,2-a]pyrimidine,imidazo[1,2-a]benzimidazole,and 1,2,4-triazolo[4,3-a]benzimidazole derivatives

Hydrazonoyl bromides 1a-c react with 5-amino-3-phenyl-1H-pyrazole, 5-amino-1H-1,2,4-triazole, 2-aminopyridine, and 2-aminobenzimidazole to afford the corresponding imidazol[1,2-b]pyrazoles 10, imidazo[1,2-b]-1,2,4-triazoles 11, imidazo[1,2-a]pyridines 16, imidazo[1,2-a]pyrimidines 17, and imidazo[1,2-a]benzimidazoles 20, respectively. Compounds 1a-c reacted also with 2-methylthiobenzimidazole to give 1,2,4-triazolo[4,3-a]benzimidazole derivatives 21. © 1997 John Wiley & Sons, Inc.     

Regiospecific synthesis of 3-substituted imidazo[1,2-a]pyridines,imidazo[1,2-a]pyrimidines,and imidazo[1,2-c]pyrimidine

3-Substituted imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, and imidazo[1,2-c]pyrimidine were obtained regiospecifically in yields of 35-92% in one pot by reaction of 2-aminopyridines or 2-(or 4-)aminopyrimidines, respectively, with 1,2-bis(benzotriazolyl)-1,2-(dialkylamino)ethanes.     

One-pot synthesis of imidazo[1,2-α]pyridine thioethers using imidazo[1,2-α]pyridines,arylsulfonyl chlorides and hydrazine

Abstract

A one-pot reaction of making RS-substituted imidazo[1,2-α]pyridine derivatives by directly using aryl or alkylsulfonyl chloride and hydrazine was developed, selectively giving good yields of the expected products. Compared with previously reported methods of using ArSO₂NHNH₂ as a sulfur source, this method is much cheaper, more practical and convenient and enriches current methods to make thioether-containing compounds, providing a good example of green chemistry.     

2-(2-furyl)imidazo[1,2-a]pyrimidine synthesis and electrophilic substitution reactions

The synthesis of 2-(2-furyl)imidazo[1,2-a]pyrimidine has been carried out. Azocoupling, nitrosation, and bromination by 1 mole of bromine occur at position 3 of the bicycle. Reaction with 2 mol of bromine gives the 3,5‰-disubstituted derivative. Bromination using 1 mol of bromine in 40% hydrobromic acid and sulfonation occur initially at the 5‰ position of the furyl group. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 565–570, April, 2006.     

A practical and improved synthesis of (3S,5S)-3-[(tert-butyloxycarbonyl)methyl]- 5-[(methanesulfonyloxy)methyl]-2- pyrrolidinone

A practical and improved synthesis of (3S,5S)-3-[(tert-butyloxycarbonyl)methyl]-5-[(methanesulfonyloxy)methyl]-2-pyrrolidinone (1) is described. The key transformations involve a highly efficient reaction sequence consisting of ethoxycarbonylation, alkylation, hydrolysis, and decarboxylation to produce compound 10. The process described herein is practical, robust, and cost-effective, and it has been successfully implemented in a pilot plant to produce a multikilogram quantity of mesylate 1.     

Synthesis of 1-[(1,2-dithiol-3-ylidene)methyl]pyrrolo[1,2-a]pyrazines and 2-[(1,2-dithiol-3-ylidene)methyl]pyridines from 1,2-dithiole-3-thiones

Benzo- and pyridoannulated 1,2-dithiole-3-thiones react with compounds containing an activated methyl group such as 1-methyl-3,4-dihydropyrrolo[1,2-a]pyrazine and 2-methylpyridines to furnish substituted 1,2-dithiol-3-ylidenes.     

新型(Z)-2-[(2-碘苯氧基)(芳基)]次甲基-2-丁烯酸酯类化合物的合成

以三苯基膦为催化剂,苯为溶剂,氮气保护下取代邻碘苯酚和联烯经β'-位极化亲核加成反应合成了10个新型(Z)-2-[(2-碘苯氧基)(芳基)]次甲基-2-丁烯酸酯类化合物,收率79%~98%,其结构经1H NMR,13C NMR和ESI-MS表征。     

Hydrated ferric sulfate catalyzed synthesis of 3-[(alkyl/arylthio)(aryl)methyl]-1H-indole derivatives through one-pot reaction

A wide variety of 3-[(alkyl/arylthio)(aryl)methyl]-1H-indole derivatives (4a–z) were synthesized through a one-pot three-component reaction from indoles, aromatic aldehydes, and thiols at room temperature using hydrated ferric sulfate as a Lewis acid catalyst. The key features of the present protocol are mild and simple reaction procedure, moderate to good yields, requirement of inexpensive and reusable catalyst, no formation of dithioacetals derivatives from the corresponding aldehydes as well as bis-(indolyl) methane derivatives.     

Novel and highly efficient synthesis of 3-(alkyl/benzylthio)-9b-hydroxy-1H-imidazo[5,1-a]isoindole-1,5(9bH)-dione derivatives

The oxidation of 3a,8a-dihydroxy-2-(alkyl/benzylthio)indeno[1,2-d]imidazol-8(3H)-ones to give the corresponding 3-(alkyl/benzylthio)-9b-hydroxy-1H-imidazo[5,1-a]isoindole-1,5(9bH)-dione derivatives in good to excellent yields at room temperature using two oxidants, periodic acid in aqueous ethanol and lead(IV) acetate in acetic acid, has been reported.     

Synthesis of 6-[[(hydroxyimino)phenyl]methyl]-1-[(1-methylethyl)sulfonyl]-1H-imidazo[4,5-b]pyridin-2-amine. An aza analogue of enviroxime

6-[[(Hydroxyimino)phenyl]methyl]-1-[(1-methylethyl)sulfonyl]-1H-imidazo[4,5-b]pyridin-2-amine ( 1 ), an aza analogue of enviroxime, was synthesized in eight steps from 6-hydroxynicotinic acid ( 2 ). Acid 2 was nitrated, chlorinated with phosphorus pentachloride, and subjected to Friedel-Crafts aroylation to give 6-chloro-5-nitro-3-pyridyl phenyl ketone ( 5 ). Amination of 5 was followed by reduction of the nitro group and condensation with ethoxycarbonylisothiocyanate to give 6-benzyl-2-ethoxycarbonylamino-1H-imidazo[4,5-d]pyridine ( 8 ). The ethoxycarbonyl moiety of 8 was cleaved, N-1 was isopropylsulfonylated, and the carbonyl moiety was condensed with hydroxylamine to give 1 . Compound 1 was inactive against rhinovirus 1B and poliovirus type 1 .     

The synthesis of 3-[(dimethylamino)(2-phenyl-5-oxo-2-oxazolinyl-idene-4)methyl]imidazo[1,2-x]azines and related compounds,intermediates in the formation of azaaplysinopsin derivatives

4-(2-Bromo-1-dimethylaminoethylidene)-2-phenyl-5(4H)-oxazolone ( 5 ) reacts with N,N-dimethyl-N'-heteroarylformamidines 7 to form imidazoazine derivatives 9 with the oxazolone ring connected through a conjugated double bond to the fused imidazole system at position 3. Compounds 9 were transformed with sodium methoxide in methanol into 2-benzoylamino-3-dimethylamino-3-imidazoazinylpropenoates 10 , while by treatment with hydrochloric acid in methanol, 3-(benzoylaminoacetyl)imidazoazines 12 were formed. The synthesis of compounds 9 represents a facile route to intermediates in the synthesis of azaaplysinopsin and related systems.     

Synthesis of Some New 3-Oxo-2-[(Z)-1-phenylmethylidene]-5H-[1,3]thiazolo[3,2-a]-and N-Acetylated Pyrimidines

3-Oxo-2-[(Z)-1-phenylmethylidene]-5H-[1,3]thiazolo[3,2-a] pyrimidine derivatives 2a–f were synthesized by the reaction of an appropriate 3,4-dihydro-2(H)-pyrimidone 1 , chloroacetic acid, sodium acetate and benzaldehyde. Reaction of 1 with acetic anhydride under heating afforded only 3-N-acetylated 3,4-dihydro-2(H)-pyrimidines 3a–f . The yields of the products after recrystallization from ethanol were of the order of 60–92 %. IR, ¹ H NMR spectroscopy, and elemental analysis were used for the identification of these compounds.     

A novel method for the synthesis of imidazo[5,1-f][1,2,4]triazin-4(3H)-ones

[reaction: see text] Imidazo[5,1-f][1,2,4]triazinones, as isosteres of purine, are of interest for pharmaceutical research. The syntheses reported in the literature generally require several steps. We report a novel method to access a broad range of diversely substituted derivatives. The key step is the electrophilic N-amination of 3H-imidazoles containing a 4-carbonyl group. Several different substituted imidazoles have been N-aminated in this manner. The resulting N-aminoimidazoles were cyclized under different conditions to the corresponding imidazotriazinones, which allowed for additional diversification. This novel method was applied in a formal synthesis of vardenafil, a well-known representative of this class of compounds. Furthermore, we report the first synthesis of a 7-aryl-imidazotriazinone via bromination of an unsubstituted imidazotriazinone followed by a Suzuki coupling.