Reactions of 4-ethoxyflavylium, 4-ethoxychromylium,and 4-ethoxyfurochromylium salts with several amines

The reactions of 4-ethoxyflavylium, 4-ethoxychromylium, and 4-ethoxyfurochromylium salts in acidic media with several acids were investigated. In the reaction with hydrazine the furochromylium salt forms pyrazole, whereas both α,β-substituted benzopyrylium salts are converted to azines. The reaction of hydroxylamine with the flavylium salt gives a flavone oxime, whereas the reaction with the furochromylium salt gives an isoxazolylbenzofuranol.     

Catalytic conjugate additions of carbonyl anions under neutral aqueous conditions

The conjugate addition of carbonyl anions catalyzed by thiazolium salts that is fully operative under neutral aqueous conditions has been accomplished. The combination of alpha-keto carboxylates and thiazolium-derived zwitterions produces reactive carbonyl anions in a buffered protic environment that readily undergo conjugate additions to substituted alpha,beta-unsaturated 2-acyl imidazoles. The scope of the reaction has been examined and found to accommodate various alpha-keto carboxylates and beta-aryl substituted unsaturated 2-acyl imidazoles. The optimal precatalyst for this process is the commercially available thiazolium salt 5, a simple analogue of thiamin diphosphate. In this process, no benzoin products from carbonyl anion dimerization are observed. The corresponding 1,4-dicarbonyl compounds can be efficiently converted into esters and amides by way of activation of the N-methylimidazole ring via alkylation.     

6-(2-furyl)imidazolo[2, 1-b]thiazole and its derivatives

Imidazolo[2, 1-b]thiazoles have been obtained by cyclizing thiazolium salts synthesized by the reaction of 2-aminothiazole and 2-amino-4-methylthiazole with 2-haloacetylfurans.     

Facile Synthesis of 1, 2-Diazepine Derivatives under Microwave Irradiation

An efficient and convenient synthesis of 3, 5, 7-triaryl-4H-1, 2-diazepine from 2, 4,6-triarylpyrylium salts and hydrazine in water under microwave irradiation is reported. The same reaction can be conducted using 2, 4, 6-triarylthiopyrylium salts and hydrazine.     

Studies with 1‐functionally substituted alkyl azoles: Novel synthesis of functionally substituted azolylbenzimidazoles and functionally substituted azolyl‐1,2,4‐triazoles

ω‐Azolylacetophenones 1 and 2 react with dimethylformamide dimethylacetal to yield enaminones 7,8 that were converted into azolylazoles via reaction with hydrazine and with hydroxylamine. Compounds 1,2 also coupled with aromatic diazonium salts to yield arylhydrazones and reacted with nitrous acid to yield corresponding oximes.     

Polymer-Attached Thiazolium Salts-Catalyzed Addition of Aldehydes to α, β-Unsaturated Carbonyl Compounds

A homogeneous catalyst, 3-benzyl-5-(2-hydroxyethyl)-4-methyl-1,3-thiazolium chloride, for addition of aldehydes to activated double bond, was attached to 20% cross-linked polystyrene-divinylbenzene copolymer. The attached catalysts could be easily removed from the reaction mixture. Polymer-attached thiazolium salts in the presence of triethylamine are active catalysts for addition of aromatic and aliphatic aldehydes to α,β-unsaturated ketones to yield γ-diketones.     

General synthesis of: 5-substituted-3-acyl-4-carbethoxypyrazoles 3,6-subslituted-5-carbethoxy-4(h)pyridazinones and 3,7-substitutedpyrazoio[3,4-d] pyridazine-4(5h)ones via reactions between 2-hydroxy,methoxy, and acetoxy-3(2h)furanones and hydrazine

Synthesis of substituted 3-acyl-4-carbethoxypyrazoles, 5-earbethoxy-4(1H)pyridazinones and pyrazolo[3,4-d]pyridazine-4(5H)ones is described. They involve the reaction of the 2,5-substituted-4-earbelhoxy-2-hydroxy, methoxy and acetoxy-3(2H)furanones with hydrazine hydrate. The reaction was found to be dependent on the hydroxy, methoxy or acetoxy substituents of these furanones and proceeds with ring opening followed by cy clisation. Pyrazoles were formed with hydroxy or methoxy substituents while pyridazinones are afforded with acetoxy group. The pyrazoles so formed were readily converted to pyrazolo[3,4-d] pyridazinones by condensation with excess hydrazine.     

Ring transformations of heterocyclic compounds. XVII, 2-(2,4,6-Triarylphenyl) substituted dihydro-1H-imidazolium,dihydrothiazolium and thiazolium salts from 2-methyl derivatives by pyrylium and thiopyrylium ring transformations

The synthesis of hitherto unknown 2-(2,4,6-triarylphenyl) substituted 4,5-dihydro-1H-imidazolium perchlorates 6 , 4,5-dihydrothiazolium perchlorates 8 and thiazolium perchlorates 9 from their 2-methyl derivatives 2 , 4 and 5 , respectively, by a 2,6-[C₅+C] ring transformation of 2,4,6-triarylpyrylium and -thiopyrylium salts 1/10 in ethanol in the presence of an appropriate base ( 6 : sodium ethanolate; 8,9 : anhydrous sodium acetate) is reported. Spectroscopic data of the transformation products and structural influences on their formation via anhydrobases of the salts 2 , 4 and 5 are discussed.     

Synthesis of c-17 trans β-lactams of the androstane series

3,3′-Ethylenedioxyandrost-4-en-17β-ol 1 was converted into the ethyl ester 2 by reaction with potassium metal and ethyl chloroacetate. The ethyl ester 2 on reaction with hydrazine gave the hydrazide 3 . Condensation of 3 with aryl aldehydes gave the Schiff bases 4 . The reaction of Schiff bases 4 with mono-chloroacetyl chloride in the presence of triethylamine afforded the β-lactams 5 .     

Reactions of functionally substituted benzo[c]pyrylium salts. Synthesis of 5h-benzo-2,3-diazepines

5H-Benzo-2,3-diazepine derivatives are formed in the reaction of 4-ethoxycarbonylbenzo[c]pyrylium perchlorates with excess hydrazine hydrate. It was established that the key intermediate in the reaction is the 2-aminoisoquinolinium cation. A method for the recyclization of 4-cyanobenzo[c]pyrylium salts to 5H-benzo-2,3-diazepine derivatives was found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1475–1477, November, 1993.     

Functionalization and cyclization reactions of 4-benzoyl-1,5-diphenyl- 1H-pyrazole-3-carboxylic acid

The 1H-pyrazole-3-carboxylic acid 2 or its remarkably stable acid chloride 3 can easily be converted into the corresponding ester or amide derivatives 4 or 5, respectively, from reaction with alcohols or N-nucleophiles. Pyrazolo[3,4-d]pyridazines 6a,b are obtained from cyclocondensation reactions of the pyrazoles 2 and 3, respectively, with phenylhydrazine or hydrazine hydrate, while 6c is formed in an one-pot procedure from the furan-2,3-dione 1 and hydrazine hydrate.     

A New Route for the Synthesis of Substituted Pyridazines

Condensation of 4‐acetyl‐5,6‐diphenyl‐2,3‐dihydropyridzin‐3‐one (1) with dimethylformamide dimethylacctal (DMFDMA) afforded the enaminone 2. This could be converted into the pyrazolylpyridazine derivative 4 on reaction with hydrazine hydrate and into pyridazinylpyridazinone 7a,b via coupling with aromatic diazonium salts and subsequent treatment with active methylene compounds. The reaction of 6 with dimethyl acetylenedicarboxylate in the presence of triphenylphosphine afforded the pyridazinylpyridazine derivative 8. Compound 1 converted into 9 upon reflux in acetic acid in the presence of ammonium acetate and afforded 10 on reflux in acetic acid.     

The Chemistry of Stable Carbenes. Part 2. Benzoin-type condensations of formaldehyde catalyzed by stable carbenes

Stable carbenes derived from thiazole, 1H-imidazole, and 4H-1,2,4-triazole are efficient catalysts for benzointype condensations of formaldehyde. Catalysts derived from N-substituted thiazolium salts trimerize formaldehyde to dihydroxyacetone ( II ). Catalysts based on 1,4-disubstituted 4H-1,2,4-triazol-1-ium salts give glycolaldehyde ( I ) as the main product and no II , whereas N,N′-disubstituted 1H-imidazol-3-ium salts yield mixtures of both products. The isolation of several intermediates in the catalytic cycle provide a better insight into the reaction mechanism.     

Reactions of heterocyclic cations with nitrogen-containing nucleophiles. 11. Reaction of 2,6-diphenylpyrylium perchlorate with primary amines,hydrazine, and hydroxylamine

The reaction of 2,6-diphenylpyrylium perchlorate with methylamine and various anilines in acetic acid leads to pyridinium salts; 3,4-bispyridinium perchlorates were obtained in dimethylformamide. The reaction of 2,6-diphenylpyrylium perchlorate with hydrazine and the sodium salt of hydroxylamine leads to 3-phenyl-5-phenacyl-2-pyrazoline and -2-isoxazoline.See [1] for Communication 10.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 461–464, April, 1982.     

Facile synthesis of highly substituted 3-aminofurans from thiazolium salts, aldehydes, and dimethyl acetylenedicarboxylate

[reaction: see text] A facile preparation of 3-aminofuran derivatives via multicomponent reactions of thiazole carbenes, aldehydes, and dimethyl acetylenedicarboxylate (DMAD) is reported. In this process, the thiazole carbenes, generated in situ from thiazolium salts, reacted with aldehydes and DMAD at -78 to 0 degree C in CH(2)Cl(2) to afford the substituted furans in moderate to good yields. Eight substituted thiazolium salts were employed as carbene precursors in the reaction. Besides aryl aldehydes, alpha,beta-unsaturated aldehydes, aliphatic aldehydes, and arenedial were also investigated and found to be applicable to this reaction.     

Synthesis of new thiazolium betaines and the ring expansion reaction via 1,4-dipolar cycloaddition

The 1,4-dipolar cycloaddition of 3-phenyl-7-[N-pheny(carbamoyl)]-5,6-dihydroimidazo[2,1-b]thia-zolium betaine (7d) with a series of aliphatic alkylating agents such as ethyl bromoacetate, α-chloroacetone, and ethyl 4-chloroacetoacetate gave a variety of new ring-expanded cycloadducts 10a-c instead of ring transformation compounds 9 . This result was derived from the difference of reactivity between N- and S-alkylations of thiazolium betaines 7a,d. The advantage of our method is to prepare the triheterocyclic compounds 10a-c of complicated structure using reactive thiazolium betaine 7d in a one-pot without isolation of intermediates. Treatment of N-bridged thiazolo compounds 1a-c with benzoyl isothiocyanate led to new thiazolium betaines 2a-c , which were reacted with methyl iodide to afford the S-alkylated quarternary ammonium salts 3a-c. Synthesis of new 2-iminothiazolinium betaines 5a,b also was carried out.     

Synthesis of condensed heterocycles via cyclopropylimine rearrangement of cyclopropylazoles

Thermal cyclopropylimine rearrangement of cyclopropylazoles into condensed heterocycles and factors affecting the regioselectivity and conversion are reported. A method of conducting the reaction in the absence of solvents is developed. A series of 2-cyclopropylazoles, including novel examples, is synthesized and their transformations into the corresponding condensed heterocyclic compounds (2,3-dihydro-1H-pyrroles and 6,7-dihydro-5H-pyrrolo[2,1-b]thiazolium salts) are studied.     

Synthesis and some reactions of indolo[2,1-c]-1,4-oxazinium perchlorates

Summary The reaction of acyl perchlorates with 1 phenacylskatole affords the previously unknown 1-R-lamethyl-3phenylindolo[2,1-c1-1,4oxazinium salts, which undergo recyclization by the action of ammonia to the corresponding indolo[2,1-alpyrazines. It is found that the salts (R = CHj, CZHS) also form dimers of their anhydro bases. The perchlorate (R = Ph) is converted to indolo[2,141-1, 2, S-triazepine by the action of hydrazine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1041-1047, August, 1994.     

4-(取代嘧啶-2-基)-1-芳磺酰基氨基脲化合物的合成与表征

以取代的苯磺酰肼与(取代嘧啶-2-基)-氨基甲酸苯酯在非亲核性碱存在下合成了12个4-(取代嘧啶-2-基)-1-芳磺酰基氨基脲化合物5和3个5与碱形成的有机盐5as, 5bs和5cs. 所有合成化合物均经过元素分析和¹H NMR的结构确证. ¹H NMR数据证明, 在5as～5cs中, 磺酰氨基脲起到提供质子的作用.     

5-Azacinnolines

Adducts of 4-phenyl-1,2,4-triazoline-3.5-dione with 2-vinylpyridines were converted to 5-azacinnolines and 4-hydrazino-5-azacinnolines on reaction with hydrazine hydrate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 976–981, July, 1976.