The syntheses of 5-amino-3-t-butylisothiazole and 3-amino-5-t-butylisothiazole

A general synthesis of 3-amino-3-alkylpropenenitriles is described. These intermediates are further transformed to 5-amino-3-alkylisothiazoles. Also described is the synthesis of the novel isomer, 3-amino-5-t-butyl-isothiazole.     

One-pot synthesis of 3-amino-4-aryl- and 3-amino-4-hetarylfurazans

A “one pot” method for the synthesis of 3-amino-4-aryl- and 3-amino-4-hetarylfurazans from β-aryl- and 4-β-hetaryl-β-oxo acid esters was developed. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1030–1032, April, 2005.     

Synthesis of 2-amino-3-methoxypyrazinc

A new synthesis of 2-amiuo-3-methoxypyrazine, an intermediate in the synthesis of sulfalene, via 2-carbamido-3-hydroxy pyrazine and subsequent Hofmann rearrangement of 2-carhamido-3-methoxypyrazine, is described.     

Structure and reactivity of 2-amino-3-carbamoylchromone

The structure of 2-amino-3-carbamoylchromone has been studied by 1D and 2D NMR spectroscopy. Selective hydrolysis of this compound gives 3-carbamoyl-4-hydroxycoumarin, whereas the reactions with acetic anhydride and hydrazines, 2-methyl-4H-chromeno-[2,3-d]pyrimidine-4,5(3H)-dione and 3-aminochromeno[4,3-c]pyrazol-4-ones, respectively.

     

Thermal decomposition of 2-amino-3-aziridino-1,4-naphthoquinones

The course of the thermal decomposition of various 2-amino-3-substituted aziridino-1,4-naphthoquinones (Ia-g) was investigated. In all the cases, the thermal decomposition gave variable amounts of 2,3-diamino-1,4-naphthoquinone (II) and of substituted 1,2,3,4,5,10-hexahydrobenzo[g]quinoxaline-5,10-diones (IIIa-g) with complete stereospecificity. The decomposition of the aziridines Ib,f also gave significative amounts of 2-amino-3-allylamino-1,4-naphthoquinones (IVb,f). In the case of 2-amino-3-(2′-phenyl-3′-ethylaziridino)-1,4-naphthoquinone (Ig), the formation of trans-1-phenyl-1-butene (V), 2-(1-phenylpropyl)-1H-naphtho-imidazole-4,9-dione (VI), 2-phenyl-3-ethyl-3,4,5,10-tetrahydrobenzo[g]quinoxaline-5,10-dione (VII), 2-phenyl-3-ethyl-5,10-dihydrobenzo[g]quinoxaline-5,10-dione (VIII), and a mixture of cis- and trans-4H-2,3,5,6-tetra-hydro-2-phenyl-3-ethyl-5-iminonaphtho[1,2-b]oxazin-6-one (IX) also occurred. Hypotheses concerning the mechanism and the steric course of this reaction are given. The reaction is a general method for the stereospecific synthesis of 2,3-disubstituted 1,2,3,4,5,10-hexahydrobenzo[g]quinoxalines.     

Reactions of 3-amino-1,2,4-triazoles with cinnamic aldehydes

The reaction of 3-amino- and 3-amino-5-methylthio-1,2,4-triazoles with cinnamaldehyde takes two directions to form mixtures of 5-[N-(3-phenylpropenylideneamino)]-1H-1,2,4-triazoles and 5-phenyl-4,5,6,7-tetrahydro[1,2,4]triazolo[1,5-a]pyrimidin-7-ols.     

An alternative synthesis of 3-amino-1,2,3,4-tetrahydrocarbazoles

3-Amino-1,2,3,4-tetrahydrocarbazoles are easily prepared from the readily available 3-hydroxy-1,2,3,4-tetrahydrocarbazoles by conversion of the latter to the p-toluene- or methanesulfonate ester, followed by nu-cleophilic displacement with azide ion. The resulting 3-azido-1,2,3,4-tetrahydrocarbazoles are then catalytically hydrogenated to their 3-amino counterparts.     

Acylation of 5-amino-3H-1,3,4-thiadiazolin-2-one

Acylation of 5-amino-3H-1,3,4-thiadiazolin-2-one (2) was undertaken selectively at either the 3-NH position or at 5-amino group depending on reaction conditions. The 3-NH is highly acidic and acylation takes place with acid anhydrides at this position in high yields in the presence of pyridine or triethylamine. The diacylation of both the 3-position and the 5-amino group was only possible via the 5-amino-3-acyl-1,3,4-thiadiazolin-2-one intermediates 4 . Under neutral conditions, acylation only occurs at the 5-amino group with acyl chlorides forming 5-acylamino-3H-1,3,4-thiadiazolin-2-ones 5 . 5-Acetylamino-3H-1,3,4-thiadiazolin-2-one can also be synthesized by the thermal transformation of 5-amino-3-acetyl-1,3,4-thiadi-azolin-2-one in acetic acid.     

1H and 31P NMR studies of rotational isomerism in phosphorus analogues of aspartic acid, 3-amino-3-phosphonatopropionic and 3-amino-3-(methylphosphinato) propionic acids

By the use of the ¹H? ¹H and ¹H? ³¹P coupling constants in two analogues of aspartic acid i.e. 3-amino-3-phosphonatopropionic and 3-amino-3-(methylphosphinato) propionic acids, it was shown that the six parameter formulation for the evaluation of mole fractions of three staggered ethanic rotamers is not necessarily better than the two parameter formulation in this system. The results allowed the recommendation of the following values for the two vicinal proton parameters i.e. J(HH)g=2.3, J(HH)t=13.9 and for the two vicinal proton-phosphorus parameters i.e. J(HP)g=4.2, J(HP)t=33.0 Hz.     

Synthesis and anticonvulsant activity of 3-amino-4(3H)-quinazolinones

Several 3-amino-4(3H)-quinazolinones were prepared from o-aminobenzoylhydrazines and triethyl orthoformate or from isatoic anhydrides, hydrazines and triethyl orthoformate. o-Aminobenzoylhydrazine intermediates were obtained by reaction of isatoic anhydrides with hydrazines. Some of the aminoquinazolinones displayed anticonvulsant activity in mice.     

Novel benzopyranopyridine derivatives of 2-amino-3-formylchromone

Enol lactones such as 4-hydroxy-6-methyl-2H-pyran-2-one (triacetic acid lactone, TAL) and 4-hydroxycoumarin when treated with 2-amino-3-formylchromone under basic conditions afforded 3-acetoacetyl benzopyranopyridones and benzopyranopyridines, respectively. A series of pyrazole derivatives was prepared by the reaction of 3-acetoacetyl benzopyranopyridones with different hydrazines. All compounds were characterised on the basis of spectral data and their antibacterial activity evaluated.     

Synthesis of 2-amino-3-hydroxy- and of 2,3-diamino-3H-1,4-benzodiazepines

A new synthesis of 7-chloro-2,3-diamino-5-phenyl-3H-1,4-benzodiazepines is described, which allows for the preparation of compounds bearing the same or different substituents at the 2 and 3 positions, starting from 2-amino-7-chloro-3-hydroxy-5-phenyl-3H-1,4-benzodiazepines.     

Aroylation of 5-amino-2H-1,2,4-thiadiazolin-3-ones

2-Aroyl-5-aroylamino-1,2,4-thiadiazolin-3-ones ( 2 ) have been synthesized through aroylation of 5-arruno-2H-1,2,4-thiadiazolin-3-one ( 1 ) as an analog of cytosine. The aroylation was carried out with a substituted aroyl chloride in pyridine at 56～58°C. It has been established that the intermediates of the reactions are 2-aroyl-5-amino-1,2,4-thiadiazolin-3-ones ( 3 ) on the basis of the spectral data, additional experimental information and ab initio molecular orbital calculations.     

Synthesis of substituted 2-amino-3-cyano-4-methylpyrroles

A facile route for the synthesis of substituted 2-amino-3-cyano-4-methylpyrroles from N-acetyl-α-amino ketones and malononitrile is reported.     

Cyclecondensation of 3-amino-1,2,4-triazole with substituted methyl cinnamates

The reaction of 3-amino-1,2,4-triazole ( 1 ) with substituted methyl cinnamates 2a-h leads selectively to the formation of 7-aryl-6,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-5(4H)-ones 3a-h . The structure eluci dation of the products is based on ir, ¹H and ¹³C nmr measurements and X-ray diffraction.     

Synthesis of 3-acetyl-2-amino-4-pyridone

A method hxsynthesizing 3-acetyl-2-amino-4-pyyridone has been suggested. The synthesis involves the condensation of dimethylformamide dimethylacetal at the NH₂ group of diphenylboron chelate diacetylketene aminal followed by its intramolecular cyclization under the action of NaOMe in MeOH.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 177–179. January, 1996.     

Unusual heterocyclization of chalcone podands with 3-amino-1,2,4-triazole

A new type of intramolecular cyclization of 1,5-bis[2-(E-3-oxo-3-phenylprop-1-enyl)-phenoxy]-3-oxapentane with 3-aminotriazole promoted by potassium ions was discovered. A cascade mechanism for the formation of crownophane with 4,7-dihydro[1,2,4]triazolo[1,5-a]-pyrimidine fragment was suggested. Effects of oligooxyethylene fragment of the chalcone podand and acid-base catalysis on the selectivity of the cyclocondensation processes and degree of oxidation of triazolopyrimidine fragments were studied. The product structures were confirmed by IR, ¹H and ¹³C NMR spectroscopy and X-ray diffraction study.     

Synthesis of 2-amino-6-chloro- and 2,6-diammopunne 3-oxides

N-Oxidation of 2-amino-6-chloropurine to the 3-oxide provided a convenient intermediate for the synthesis of 2-amino-6-substituted purine 3-oxides, including the previously unavailable 2,6-diaminopurine 3-oxide. Thiation of the 6-halogen was accompanied by reduction of the N-oxide. The properties of the 1- and 3-oxides of 2,6-diaminopurine are compared.     

Synthesis of 3-amino-5-nitrobenzaldehyde oxime and its conversion into 3,4-bis(3-amino-5-nitrophenyl)furoxan and isomeric 3(4)-(3-amino-5-nitrophenyl)-4(3)-nitrofuroxans

The oxime of the hitherto unknown 3-amino-5-nitrobenzaldehyde was synthesized by the reaction of 3-amino-5-nitrobenzaldehyde phenylhydrazone with excess of (NH₂OH)₂·H₂SO₄. The oxime obtained was used as the starting compound for the synthesis of novel diaryl- and arylnitrofuroxans. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2232–2235, December, 1997.     

Synthesis of 3-nitro-4-amino- and 3,4-diaminothiocoumarins

Nitration of 4-hydroxythiocoumarin gave 3-nitro-4-hydroxythiocoumarin, which was converted to 3-nitro-4-chlorothiocoumarin by the action of phosphorus oxychloride in dimethylformamide. The corresponding 3-nitro-4-aminothiocoumarins were synthesized by reaction of 3-nitro-4-chlorothiocoumarin with ammonia or amines. The 3-nitro-4-aminothiocoumarins were hydrogenated in alcohol over Raney nickel to give 3,4-diaminothiocoumarins. The-aminovinylcarbonyl form of the 4-substituted 3-aminothiocoumarins was established on the basis of the UV, IR, and PMR spectra.See [1] for our preliminary communication.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 43–47, January, 1978.