摘要:

AbstractCondensation of a nitrile with benzene, furan and thiopheneortho‐aminonitriles in the presence of dry hydrogen chloride yields condensed 4‐chloropyrimidines, condensed 4‐aminopyrimidines or a mixture of the two condensed pyrimidines in varying proportions depending upon the nature of the nitrile and the substrate,ortho‐amino

ISSN:0022-152X    

DOI:10.1002/jhet.5570270201

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

AbstractNovel 4‐arylsulfonylthiophene‐ and furan‐2‐sulfonamides are prepared from the 3‐arylsulfonyl heterocycleviachlorosulfonation with chlorosulfonic acid/phosphorus pentachloride. Free radical bromination affords bromomethyl analogues that are precursors to amine derivatives of the parent thiophenesulfonamides. Instability of the furansulfonyl chlorides to free radical bromination necessitated a sequence employing bromomethyl group generation prior to chlorosulfonation. Demethylation of methoxyl substituted sulfonamides afforded phenols that underwent efficient mono‐ and bis‐alkylation with Man

ISSN:0022-152X    

DOI:10.1002/jhet.5570270202

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

AbstractThe electron impact mass spectra (75 eV) of the β‐diazopyrroles always show the molecular ions and undergo as the main fragmentation process the elimination of nitrogen followed by ring opening reactions leading to benzonitrile either as neutral or charged species. The peaks at 26 amu below the molecular ions, which are a general feature of these spectra, are due to the presence of the corresponding pyrroles which are formed by reductive reactions during the vaporization process of the sampl

ISSN:0022-152X    

DOI:10.1002/jhet.5570270203

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

AbstractFacile synthesis of 2‐n‐dodecylthio‐4‐phenylthiomethyl‐1,3,4‐thiadiazole‐5‐thione6, starting from 2,5‐dimercapthothiadiazolevia2‐n‐dodecylthio‐1,3,4‐thiadiazole‐5‐thione2, 2‐n‐dodecylthio‐4‐hydroxymethyl‐1,3,4‐thiadiazole‐5‐thione4and 2‐n‐dodecylthio‐4

ISSN:0022-152X    

DOI:10.1002/jhet.5570270204

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

AbstractFour isomeric 4,7‐dimethyl‐6‐phenyl‐5,6,7,8‐tetrahydro‐4H‐1,3,6‐dioxazocin‐2‐ones and four isomeric 4,7‐dimethyl‐6‐phenyl‐5,6,7,8‐tetrahydro‐4H‐1,3,2,6‐dioxathiazocine 2‐oxides were prepared. On the basis of the nmr chemical shifts due to the γ‐effect, the

ISSN:0022-152X    

DOI:10.1002/jhet.5570270205

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

AbstractThe synthesis oftrans‐(±)‐N‐methyl‐N‐[2‐[methyl[2‐(3‐pyridyl)ethyl]amino]cyclohexyl]‐4‐benzofuranacetamide dihydrochloride,1which is a 3‐[2‐(methylamino)ethyl]pyridyl derivative of the kappa opioid analgesictrans‐(±)‐N‐methyl‐N‐[2‐(1‐pyrrolidinyl)cyclohexyl]benzofuran‐4‐acetamide monohydrochloride,2is described. The key intermediate istrans‐(±)‐N,N'‐dimethyl‐N‐[2‐(3‐pyridyl)ethyl]‐1,2‐cyclohexanediamine,9which is formed by nucleophilic addition of 3‐[2‐(methylamino)ethyl]pyridine6to the aziridine, 7‐methyl‐7‐azabicyclo[4.1.0]heptane,4. During attempts to prepare the 2‐ or 4‐isomeric pyridyl derivatives of1it was discovered that both 2‐ or 4‐[2‐(methylamino)ethyl]pyridine,5or7are converted toN‐methyl‐N,N‐di‐[2‐(2‐pyridyl)ethylamine]11andN‐methyl‐N,N‐di[2‐(4‐pyridyl)ethylamine]13respectively by refluxing in toluene in the presence of ammonium chloride. The 3‐isomer,6is unchanged after treatment under identical conditions. Careful control of the reaction conditions enabled the aziridine4to be ring opened with the pyridyl amines5or7to give the 1,2‐diaminestrans‐(±)‐N,N′‐dimethyl‐N‐[2‐(2‐

ISSN:0022-152X    

DOI:10.1002/jhet.5570270206

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

AbstractThe new pyrimido[5,4‐b][1,4]oxazinones4a‐cand6a,b, 7a,cwere obtained from 6‐amino‐2,3‐dimethyl‐4(3H)‐pyrimidone (1) and 4‐substituted pyrimido[5,4–6][1,4]oxazinones5, 7a, respectively, while derivatives 8a‐e of the novel ring system 1,4‐dioxino[2,3‐d]pyrimidine were prepared starting from2b.Compounds4a, 4cand7ashowed po

ISSN:0022-152X    

DOI:10.1002/jhet.5570270207

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

AbstractThe regioselective synthesis of pyrido[2,3‐b]‐ and [3,4‐b]pyrazine derivativesIIby the Hinsberg reaction is reported starting from 2,3 and 3,4‐diaminopyridine and excess of pyruvic acid or ethyl pyruvate as reactants. Good yields (higher than 90%) were obtained for pyrido[2,3‐b]pyrazine derivatives at room temperature using anhydrous methanol and chloroform as solvents which promote regioselective reactions to give 2‐methylpyrido[2,3‐b]pyrazin‐3(4H)‐one (3a) and 3‐methylpyrido[2,3‐b]pyrazin‐2(1H)‐one (4a) respectively. On the other hand, when the same procedure was applied to 3,4‐diaminopyridine results were not so encouraging for the formation of 2‐methylpyrido[3,4‐b]pyrazin‐3(4H)‐one (3b) and 3‐methylpyrido[3,4‐b]‐pyrazin‐2(1H)one (4b). Kinetic studies were performed in aqueous buffers (pH ‐0.89 to 11.5) and different organic solvents trying to improve yields and achieve regioselectivity. The course of the reactions was followed by uv spectrophotometry being those with ethyl pyruvate 2 to 800 times faster than with pyruvic acid. This investigation involves the kinetics and mechanism of this reaction studying its factibility when π‐deficient substrates are used and its regioselectivity accordi

ISSN:0022-152X    

DOI:10.1002/jhet.5570270208

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

Abstract4,4′‐Divinyl‐2,2′‐bipyridine (2) was prepared in 12% overall yield from 4,4′‐dimethyl‐2,2′‐bipyridine (3)viaa5step reaction sequence involving the intermediate 4,4′‐R2‐2,2′‐bipyridines: R = COOH,4; CO2CH3,5; CH2OH,6; CHO,7. The newly synthesized compounds2, 6and7were characterized by melting point, infrared,1H nmr, mass spectr

ISSN:0022-152X    

DOI:10.1002/jhet.5570270209

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY

摘要:

AbstractTwo new tetraazacycloalkane‐N‐acetic acids containing 4‐(phenylethynyl)pyridine subunit as a part of macrocycle have been prepared. Two methods for the cyclisation reaction were investi

ISSN:0022-152X    

DOI:10.1002/jhet.5570270210

出版商:Wiley‐Blackwell    

年代:1990

数据来源: WILEY