New access to 7,17-seco norditerpenoid alkaloids via reduction of the corresponding 8-chloro derivatives

New access to the 7, 17-seco norditerpenoid alkaloids 9 (60%) from yunnaconitine (5), as well as 14 (46%) and 15 (22%) from isotalatizidine (10), via selective hydrolysis, chlorination and reduction with NaBH4 is described.     

Electrosynthesis of 4-chloro derivatives of pyrazole and alkylpyrazoles

Electrosynthesis of 4-chloro-substituted derivatives of pyrazole and its alkyl derivatives is carried out via the chlorination of original pyrazoles on a Pt anode in aqueous NaCl solutions under conditions of galvanostatic diaphragm electrolysis. The efficiency of this process is shown to depend on the structure of starting pyrazoles, particularly, the donor-acceptor properties of substituents, the position of the latter in the pyrazole ring, and the concomitant contribution of side reactions. Thus the yield of 4-chlorosubstituted products at the chlorination of pyrazole, 3,5-dimethylpyrazole, 1,5-dimethylpyrazole, and 3-nitropyrazole is 68, 92, 53, and 79%, respectively. By the example of 1,5-dimethylpyrazole, the possibility of electrochemical chlorination to the side chain of pyrazoles was demonstrated.     

Azolyl derivatives of nitrohalobutadienes: IV. Synthesis of 4-amino derivatives of 1-azolyl-1-arylamino-2-nitrotrihalo-1,3-butadienes

Reactions of l-(benzotriazol-l-yl)-l-(4-R-phenylamino)- and l-(3,5-dimethylpyrazol-l-yl)-l-(4-R-phenylamino)-2-nitro-3,4,4-trichloro-l, 3-butadienes and also l-(benzotriazol-l-yl)-l-(4-R-phenylamino)- and l-(3,5-dimethylpyrazol-l-yl)-l-(4-R-phenylamino)-2-nitro-4-bromo-3,4-dichloro-l,3-butadienes (R = EtO, MeO, Me) with amines proceed with replacement of the terminal chlorine in the trichlorovinyl group or of bromine in the bromodichlorovinyl group by an amine rest to yield the corresponding l-azolyl-4-amino-l-arylamino-2-nitro-3,4-dichloro-l,3-butadienes. When binucleophilic reagents (ethylenediamine and 2-aminoethanol) are used only one N-nucleophilic site of the nucleophile takes part in the reaction. For communication III, see [1].     

Vibrational and electronic absorption spectra of 4-chloro 2-methyl, 4-chloro 3-methyl and 6-chloro 3-methyl phenols

The infrared spectra of 4-Cl 2-Me, 4-Cl 3-Me and 6-Cl 3-Me phenols have been recorded. The vibrational spectrum has been analysed assuming that the molecules belong toC _s point group and a tentative assignment of the observed frequencies to various modes of vibration has been proposed. The near ultraviolet absorption spectrum of these compounds has also been recorded. Assuming the transition to be electronically allowed the strongest band on the longer wavelength side has been assigned as the (0, 0) band in each case. The spectrum has been analysed in terms of several excited state frequencies which have been correlated with the ground state frequencies observed in the infrared spectrum.     

Rearrangement of 4-aryl-1,2,4-triazine into the 4-amino derivatives

The action of hydrazine on 3-methylmercapto-5-oxo-4-aryl-4,5-dihydro-1,2,4-triazines led to a novel rearrangement and gave 3-arylamino-4-amino-5-oxo-4,5-dihydro-1,2,4-triazines. The mechanism of this rearrangement was discussed.     

Synthesis of 2-amino derivatives of levoglucosenone

2-Amino derivatives of levoglucosenone were prepared by reaction of the 2-methanesulfonyl (or p-toluenesulfonyl) derivatives with ammonia, methylamine, or octylamine under various conditions. The analogous reaction did not occur for saturated derivative 15. The 2-amino-3,4-dihydro derivative was prepared by catalytic hydrogenation of unsaturated amine 9.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 429–432, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis and reactions of 3-aminothiazolidine-2-thion-4-one derivatives. 1. Conversion of 3-aminothiazolidine-2-thion-4-one derivatives to substituted mercapto-1,3,4-thiadiazoles

The corresponding carboxymethylthiothiadiazoles are formed by the action of formic acid on 3-aminorhodanine and 3-(3-phenylthioureido)rhodanine, and the action of rhodanineaniline on 3-(3-phenylthioureido)rhodanine leads to 2-anilino-5-carboxy-methylthiothiadiazole anilide, whereas similar treatment of 3-ureidorhodanine leads to a semicarbazide derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 51–53, January, 1981.     

Reaction of 2-aroyl-1-cyclohexanones and their 6-amino derivatives with hydrazines

The reaction of 2-aroyl-1-cyclohexanones and their amino derivatives with hydrazines gives substituted 4,5,6,7-tetrahydroindazoles.     

Specific features of the reactions of quinazoline and its 4-hydroxy and 4-chloro substituted derivatives with C-nucleophiles

Reactions of quinazoline 1 with indole, pyrogallol and 1-phenyl-3-methylpyrazol-5-one in the presence of acid led to C-4 adducts 2, 3 and 5. Adduct 4 is formed by heating 1 with 1,3-dimethylbarbituric acid without acid catalysis. 1-Phenyl-3-methylpyrazol-5-one reacts with 1 without acid catalysis to form dipyrazolylmethane 6. 4-Chloroquinazoline 8 reacts with 1-phenyl-3-methylpyrazol-5-one to form 4-(1-phenyl-3-methyl-5-oxopyrazol-4-yl) quinazoline 9 and dipyrazolylmethane 6. Heating 8 with 2-methylindole leads to the formation of 4-(2-methylindol-3-yl) quinazoline 10 and tris(2-methylindol-3-yl)methane 11.     

Access to 2-fluoroacrylates and their 3-chloro derivatives by chemical hydrogenolysis of 3,3-dichloro-2-fluoroacrylates

The formation of 3-chloro-2-fluoroacrylates 2 and 2-fluoroacrylates 3 by hydrogenolysis of 3,3-dichloro-2-fluoroacrylates 1 was studied by using Bu₃SnH, zinc, the sodium sulphite/sodium formate mixture or iron pentacarbonyl in the presence of a hydrogen donor (Et₃SiH or CH₃OH). The two last couples can be used to prepare the 3-chloro derivatives 2, whereas for the preparation of the 3,3-dihydro derivatives 3, zinc is the most appropriate reducing agent. Keywords: 2-Fluoroacrylate; 3-Chloro-2-fluoroacrylate; 3,3-Dichloro-2-fluoroacrylate; Tributyltin hydride; Zinc; Sodium sulphite; Sodium formate; Iron pentacarbonyl; NMR spectroscopy; IR spectroscopy     

One-pot synthesis of 5-amino 4-cyano pyrrole derivatives

One-pot synthesis of 5-amino 4-cyano pyrrole derivatives is herein disclosed. The described method consists of four steps and gives new pyrrole derivatives in moderate to good yields. This synthesis can be used for a large scale preparation.     

Synthesis of 6-amino and 6-ethoxy-2(1H)-pyridone derivatives

An efficient route allowing the synthesis of 6-amino and 6-ethoxy-2(1H)-pyridone derivatives by reaction of ethyl cyanoacetimidate, ethyl ethoxycarbonylacetimidate and related acetamidines with diethyl ethoxymeth-ylenemalonate (EMME) is reported. The formation of dienamino derivatives as intermediates and their heterocyclization to the 2(1H)-pyridone derivatives is described.     

A direct approach to α-hydroxy and α-chloro trifluoromethyl derivatives

S-1-Acyloxy-2,2,2-trifluoroethyl and S-1-chloro-2,2,2-trifluoroethyl dithiocarbonates add efficiently to various functionalised olefins to give the corresponding adducts via a radical chain reaction initiated by a small amount of lauroyl peroxide.     

The addition of methylhypobromite to 4-acetamido-3-bromo-2-pyridone

Bromination of 4-acetamido-3-bromo-2-pyridone in methanol results in the addition of methylhypobromite to the 5,6 double bond of the pyridone.     

Conversion of 9-substituted adenines to the corresponding purines: a simple deamination method for adenine derivatives

An effective procedure for the replacement of an amino group in nucleic acid bases with hydrogen is described. The method provides a direct synthesis of the antibiotic, nebularine, from adenosine.     

Conversion of 5-hydroxy to 5-amino and 5-alkoxypyrazolidines

1-Acyl-5-hydroxypyrazolidines readily exchange their hydroxyl group when treated with primary amines or alcohols to form the corresponding 5-amino or 5-alkoxypyrazolidines. An acid catalyst is needed for the preparaton of the 5-alkoxypyrazolidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 484–487, April, 1987.