Reactions of azoesters and dimethyl acetylenedicarboxylate with 3-methyl-1,2,4-triazole-5-thione

The addition of dimethyl acetylenedicarboxylate to 3-methyl-1,2,4-triazole-5-thione ( 1 ), both in alcoholic medium and in inert solvents, has been investigated. When 1 was allowed to react with diethyl azodicarboxylate a disulfide 5 was obtained.     

Heterocycles from substituted amides II. Novel behavior of a reactive thiophene in some cyelo- and acyclo-addition reactions

N,N'-Diisopropyl-N,N'-diphenyl-2,4-thiophenediamine ( 1 ) has demonstrated its remarkable electron-donating abilities and atypical behavior as a thiophene, by its facile reaction with a number of electron deficient dienophiles. Thus, β-nitrostyrene, ethoxymethylene malononitrile, diethyl azodicarboxylate and dimethyl acetylenedicarboxylate undergo Michael-type addition at the 5-position of 1 to form adducts 2, 3, 4 , and 5 . Alternatively, the dienophiles, acrylonitrile, N-phenylrnaleimide and phenyl-1,2,4-triazoline-3,5-dione gave novel cyclic materials 6, 9 , and 11 , not necessarily arising from simple Diels Alder addition. Structure proofs for the products as well as alternative mechanisms for their formation are discussed.     

Regioselective synthesis of pyrrolin-3-ones and 2,3,4,5-tetrahydro[1,3]-oxazines from N-vinylic amidines

Achiral and optically active N-vinylic amidines are obtained by simple addition of amidines to acetylenic esters. Thermal intramolecular cyclization of these substrates containing a carboxylate group in position 3 gives pyrrolin-3-ones. The enaminone character of these compounds towards propargyl bromide, diethyl azodicarboxylate, diethyl acetylenedicarboxylate, ethyl propiolate and phenyl isocyanate is studied and functionalized pyrrolin-3-one derivatives are obtained. The reaction of the pyrrolinones prepared with diethyl ketomalonate leads to new 1,3-oxazine derivatives.     

Preparation of Aminovinyl Phosphonates by Four-Component Aminoalkylation of Aldehydes Mediated by Lithium Perchlorate

Several aminovinyl phosphonates were prepared in good yield by four-component aminoalkylation of aldehydes with diethyl(trimethylsilyl)amine, triethylphosphite and dimethyl acetylenedicarboxylate mediated by a 5 molar solution of lithium perchlorate in diethyl ether.     

Catalysis of reactions of allyltin compounds and organotin phenoxides by lithium perchlorate

The effect of increase of polarity of the solvent binary mixture methanol-benzene and acetonitrile-chloroform on the selectivity and the rate of metalloene reaction of different allyltin compounds with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), diethyl azodicarboxylate (DEAD) and singlet oxygen was studied. The more polar solvent favored the production of the M-ene product. Analogous comparative studies were carried out in Et₂O and 4 mol dm⁻³ solutions of LiClO₄ in diethyl ether. All studied reactions were strongly catalysed by LiClO₄. Physicochemical studies were carried out in purpose to explain the catalytic effect of LiClO₄ on the aforementioned reactions. In case of singlet oxygen and diethyl azodicarboxylate it was presumably a result of facilitation of the formation of the polar intermediate by the ionic medium. Whereas, in case of PTAD the mentioned previously effect could be associated with lowering its LUMO by association with lithium. The analogous catalytic effect of LiClO₄ was also observed for reactions of organotin phenoxides with DEAD and bis(trichloroethyl) azodicarboxylate leading to corresponding ring-aminated phenols in excellent yield, and with diethyl acetylenedicarboxylate giving a mixture of corresponding vinyl ethers and ring ethenylated phenols. Organotin phenoxides were distinctly more active than the corresponding phenols.     

Cycloaddition reactions of 2-vinylthiophen

Cycloaddition reactions between 2-vinylthiophen and the dienophiles maleic anhydride, dimethyl acetylenedicarboxylate,' methyl propiolate, and methyl acrylate, are reported. Products include simple benzo[b]thiophen carboxylates (6, 13, 17) and reduced derivatives (3, 4, 18). The acetylenic dienophiles also gave a dihydrobenzthienyl-acrylate (16) or -fumarate (11), and the dithienylcyclohexene esters (7) and (14).     

A highly efficient cycloaddition of vinylarenes with electron-deficient alkynes affording 1,2-disubstituted-3,4-dihydronaphthalenes catalysed by N,N-dimethylformamide dimethyl acetal

1,2-Disubstituted-3,4-dihydronaphthalenes could be conveniently synthesized with high yields by the cycloaddition reactions of easily available vinylarenes with electron-deficient alkynes such as dimethyl, or diethyl acetylenedicarboxylate, methyl phenylpropiolate in the presence of DMF.DMA (N,N-dimethylformamide dimethyl acetal) as organocatalyst.     

Preparation of Isoquinolin-(2(1H)-yl)but-2-enedioate Derivatives

One-pot, three-component reactions of isoquinoline, dimethyl/diethyl acetylenedicarboxylate, and indole, carbazole, pyrazole, or imidazole gave dimethyl/diethyl 2-(1-(1H-indol-1-yl)isoquinolin-2(1H)-yl)but-2-enedioate, dimethyl/diethyl 2-(1-(9H-carbazol-9-yl)isoquinolin-2(1H)-yl)but-2-enedioate, dimethyl 2-(1-(1H-pyrazol-1-yl)isoquinolin-2(1H)-yl)but-2-enedioate, or dimethyl 2-(1-(1H-imidazol-1-yl)isoquinolin-2(1H)-yl)but-2-enedioate respectively in good to excellent yields.     

Synthesis and Complexing Properties of Alkyl (3-Oxo-2,3-dihydrothiophen-2-ylidene)- and (4-Oxothiazolidin-5-ylidene)acetate Derivatives

Condensation of dimethyl and diethyl acetylenedicarboxylate with thioacetamides gave the corresponding alkyl (3-oxo-2,3-dihydrothiophen-2-ylidene)- and (4-oxothiazolidin-5-ylidene)acetates. Treatment of these compounds with zinc in acetic acid resulted in reduction of the exocyclic double bonds. The products can be used in membrane processes as sodium cation carriers.     

Tri‐ and Tetrasubstituted N‐Phthalimidoaziridines in 1,3‐Dipolar Cycloaddition Reactions

The thermal reactions of the 2,2,3‐trisubstituted N‐phthalimidoaziridine 1a with dimethyl acetylenedicarboxylate (DMAD), thioketones 4a – 4d , and dimethyl azodicarboxylate ( 5 ) proceed even at room temperature leading to the five‐membered cycloadducts 2a, 6 – 8 , and 12 , respectively, with retention of the spatial arrangement of the aziridine substituents, in contrast to the expectation based on the conservation of orbital symmetry in concerted reactions. The analogous reactions of the tetrasubstituted phthalimidoaziridine 1b with thioketones at 40° lead to the 1,3‐thiazolidine derivatives 10 and 11 as mixtures of diastereoisomers. These unexpected results may be explained by either the isomerization of the intermediate azomethine ylides or a non‐concerted stepwise cycloaddition reaction of these ylides with the dipolarophiles. The structures of some adducts have been determined by X‐ray crystallography.     

Darstellung und Eigenschaften von Chlorozinksäuren

Contributions to the Chemistry of Hydrazine and its Derivatives. 53. Synthesis of P-, As-, and Sb-substituted Hydrazines by Addition of P? H, As? H, and Sb? H Groups to N?N Double Bonds Addition of diphenylphosphinous acid, diphenylthiophosphinous acid, methyl hydrogen phenylphosphonite, diethyl hydrogen phosphite, diphenylphosphane, dibutylphosphane, diphenylarsane, diethylarsane, and diphenylstibane to the N?N double bond of diethyl azodicarboxylate, dimethyl azodicarboxylate, ethyl phenylazocarboxylate, and azobenzene yields the P-, As-, and Sb- substituted hydrazines 1–23 . The spectroscopic data agree with the structural formulae. The course of the reactions suggests a polar reaction mechanism except in the case of the synthesis of 15 , which probably proceeds via radical intermediates. The azo systems employed show a distinct graduation in their ability to add to the element-hydrogen groups used.     

Synthesis,chemistry, and dynamic NMR study of new atropisomeric 4-dialkylamino-5-chloro-1,2-dithiole-3-thiones

[reaction: see text] Reaction of N-(2-phthalimidoethyl)-N-alkylisopropylamines and S(2)Cl(2) gave atropisomeric (by dynamic NMR) 4-N-(2-phthalimidoethyl)-N-alkylamino-5-chloro-1,2-dithiole-3-thiones that quantitatively cycloadded to dimethyl or diethyl acetylenedicarboxylate to give a novel class of stable thioacid chlorides, which in turn reacted with 1 or 2 equiv of secondary amines to give thioamides.     

Synthesis of pyridazino[3,4-b]quinoxalines and pyrazolo[3,4-b]-quinoxaline by 1,3-dipolar cycloaddition reaction

The pyridazino[3,4-b]quinoxalines 6a,b and pyrazolo[3,4-b]quinoxaline hydrochloride 9 were synthesized by the 1,3-dipolar cycloaddition reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 5 with dimethyl or diethyl acetylenedicarboxylate and 2-chloroacrylonitrile, respectively. The reaction mechanisms were postulated for the formation of 6a,b and 9 .     

Synthesis of some new nitrogen bridge-head pyrido[1,2,4]triazepines

Ring closure reactions of 1,6-diamino-4-(4-chlorophenyl)-2-oxopyridine-3,5-dicarbonitrile with various 1,3-dielectrophiles, namely, diethyl malonate, ethyl ethoxymethylenecyanoacetate, 2-cyano-3,3-bis(methylthio)acrylonitrile, dimethyl acetylenedicarboxylate, dehydroacetic acid, chromone-3-carbonitrile, and 3-formylchromone led to the formation of the target biheterocyclic 1,2,4-triaze-pines. The reactions with 3-phenylazo-2,4-pentadione, ethyl α-cyano-α-phenylazoacetate, and 3,1-benz-oxazin-4-one derivative are also described.     

Studies on the Catalysis of Ene Reactions by Lithium Perchlorate in Different Solvents

Abstract

The catalytic effect of lithium perchlorate on ene reaction of cis-cyclooctene with diethyl azodicarboxylate, 4-phenyl-1,2,4-triazoline-3,5-dione and the metallo-ene reaction of diallyldibutyltin with diethyl azodicarboxylate has been studied in different solvents like acetonitrile, acetone, diethyl ether, dimethylformamide and ethyl acetate.     

Preparation of carbodiimides by the reaction of thioureas with diethyl azodicarboxylate

A new synthesis of disubstituted carbodiimides from N.N′-disubstituted thioureas, diethyl azodicarboxylate and triphenyl phosphine has been achieved. The intermediates of the reaction have been isolated and found to be 1:1 adducts of the thioureas and diethyl azodicarboxylate, N¹,N²-disubstituted—S—(N³,N⁴-biscarboethoxy)hydrazinoisothioureas which, on treatment with triphenyl phosphine at room temperature, afford the corresponding carbodiimides. Alternatively, the intermediates on heating under reflux in benzene or toluene, decompose to the carbodiimides, diethyl hydrazodicarboxylate and sulphur.     

Reactions of Cyclic Pseudothioureas with Acetylenedicarboxylates

Treatment of aliphatic 1,2-, 1,3- or aromatic o-diamine with carbon disulfide provided the corresponding cyclic pseudothioureas (IIb-j). Heating thiourea (IIa) or these compounds with dimethyl or diethyl acetylenedicarboxylate (IIIa, b) in ethanol resulted a nucleophilic addition of the sulfhydryl group to the C≡C bond accompanied with a ring-closure condensation. Thus a series of alkoxycarbo-methylidene derivatives of 2-imino-4-thiazolidinone (IVa), imidazolo-, benzimidazo-and tetrahydropyrimido (2, 1-b)-3-thiazolidinones (IVb-k) was produced. An orientating experiment of saponifying the ester function of these compounds has also been carried out.     

Reactions of dimethyl acetylenedicarboxylate—VI : Reaction with aldehyde and ketone phenylhydrazones

Benzaldehyde phenylhydrazone with dimethyl acetylenedicarboxylate gives dimethyl 1,3-diphenylpyrazoline-4,5-dicarboxylate, dimethyl 1,3-diphenylpyrazole-4,5-dicarboxylate and trimethyl 1-phenylpyrazole-3,4,5-tricarboxylate; p-chlorobenzaldehyde phenylhydrazone gives trimethyl 1-phenyl-3,4,5-tricarboxylate and 1,2-(bis-phenylazo)-1,2-di-p-chlorophenylethane. Under similar conditions, p-tolualdehyde phenylhydrazone gives only trimethyl 1-phenylpyrazole-3,4,5- tricarboxylate. Acetophenone phenylhydrazone with dimethyl acetylenedicarboxylate gives dimethyl 1,3-diphenylpyrazole-4,5-dicarboxylate. Benzophenone phenylhydrazone, on the other hand, gives a mixture of dimethyl 1,3-diphenylpyrazoline-4,5-dicarboxylate and dimethyl 1,3-diphenylpyrazole-4,5- dicarboxylate. Benzyl methyl ketone and dimethyl acetylenedicarboxylate gives an enamine maleate, which is the Michael addition product.     

Electrophilic substitution reactions of indole alkaloids with α,β-unsaturated carbonyl compounds in the presence of K10 montmorillonite

Reactions of indole, 1-methylindole, and 3-methylindole with dimethyl acetylenedicarboxylate in the presence of K10 montmorillonite as a catalyst led to the formation of the corresponding dimethyl 2,2-bis(indolyl)butanedioates. The reaction of 2-methylindole with dimethyl acetylenedicarboxylate gave dimethyl 2-(2-methyl-1H-indol-3-yl)maleate and dimethyl 2-methyl-1H-1-benzoazepine-3,4-dicarboxylate. Dimethyl 1,5-dimethyl-1H-1-benzoazepine-3,4-dicarboxylate was obtained by treatment of 1,3-dimethylindole with dimethyl acetylenedicarboxylate using K10 clay as a catalyst. Published in Russian in Zhurnal Organicheskoi Khimii, 2006, Vol. 42, No. 6, pp. 900–902. The text was submitted by the authors in English.     

1,3-dipolar cycloadditions to oxidopyraziniums

1,5-Dimethyl-3-oxidopyrazinium (6) undergoes cycloadditions with methyl acrylate, acrylonitrile, diethyl maleate, maleimide, methyl propiolate and diethyl acetylenedicarboxylate.