摘要:

AbstractMononitration of coumaran has been achieved by the use of acetyl chloride and silver nitrate in acetonitrile solution. Nmr decoupling experiments have served to establish the structures of the two products as the 5‐ and 7‐nitrocoumarans. Attempted nitration with nitronium tetrafluoroborate resulted in extensive ring open

ISSN:0022-152X    

DOI:10.1002/jhet.5570050101

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

AbstractThe Pariser‐Parr‐Pople approximation was used to predict the properties of compounds I, 3‐oxo‐2H‐1,2,3‐triazolo[3,4‐a]pyridine, and II, 3‐oxoisoxazolo[2,3‐a]pyridine, originated by joining a pyridine ring to two sydnone‐like heterocyclic systems not yet reported in the literature. A parallel computation was carried out for two known compounds of similar structure, to give the predictions a better reliability through the comparison with observed spectral data and chemical behaviour. Compound I is expected to be stable, with an absorption spectrum similar to III, 2‐oxo‐1,3,4‐oxadiazolo[4,5‐a]pyridine, and chemical properties analogous to IV, 1‐methyl‐3‐oxo‐1,2,4‐triazolo‐[4,3‐a]pyridine. A reaction path is suggested for obtaining from I the unknown isomeric structure V, 3‐oxo‐1H‐1,2,3‐triazolo[3,4‐a]pyridine. Compound II is predicted as an unstable orange‐red substance

ISSN:0022-152X    

DOI:10.1002/jhet.5570050102

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

AbstractThe synthesis of 5‐chloro‐8‐(ω‐dialkylaminoalkylamino)pyrazino[2,3‐d]pyridazine (II) proceeded smoothly when 5,8‐dichloropyrazino[2,3‐d]pyridazine (I) was allowed to react with ω‐dialkylaminoalkylamines. Similarly, the reaction of 5,8‐dichloropyrido[2,3‐d]pyridazine (IV) with ω‐dialkylaminoalkylamines gave the two expected products 8‐chloro‐5‐(ω‐dialkylaminoalkylamino)pyrido[2,3‐d]pyridazine (V) and 5‐chloro‐8‐(ω‐dialkylaminoalkylamino)pyrido[2,3‐d]pyridazine (VI) in a 2:3 ratio. 4,7‐Dichloroimidazo[4,5‐d]pyridazine (XII) was found to be much less reactive towards nucleophilic substitutions and more vigorous conditions resulted in disubstituted products (XIII). 7‐Chloroimidazo[4,5‐c]pyridazine (XVIII) was also found to be much less reactive towards nucleophilic substitution. In both of these cases one of the imidazole nitrogen atoms was blocked by a tetrahydropyranyl group which increased the reactivities and led to the desired monosubstituted products XVII from

ISSN:0022-152X    

DOI:10.1002/jhet.5570050103

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

AbstractA number of 1‐(tetrahydro‐2‐furyl)uracils, cytosines and related compounds were synthesized by a modified Hilbert‐Johnson method from 2‐chlorotetrahydrofuran and the corresponding 2,4‐dimethoxypyrimidines. The relative stability in acid of tetrahydrofuryl and tetrahydropyranyl moieties in compounds of this type was discussed. 2‐Oxo‐4‐methoxy‐1,2‐dihydropyrimidine, a compound which has been erroneously reported, has now been prepared and its structure confirmed by con

ISSN:0022-152X    

DOI:10.1002/jhet.5570050104

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

AbstractIt has been shown that theN‐methylation, with methyl iodide, ofs‐triazolo[4,3‐a]pyridines affords a mixture of the N‐1 and the N‐2 methiodides. The N‐2 methiodides can be thermally rearranged to the N‐1 methiodides. The 8‐methyl N‐1 methiodides exhibitperiinteraction between the two methyl groups. This interaction is reflected in greater stability of the N‐2 methiodide v

ISSN:0022-152X    

DOI:10.1002/jhet.5570050105

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

AbstractThe synthesis of 6‐methoxyimidazo[1,2‐b]pyridazine and its 2‐methyl analog is reported. Carboxylic acids, esters and quaternary salts derived from this ring system are described and the heterocyclic system is shown to undergo the Mannich reaction. A condensation reaction of the 2‐methyl group is reported and nuclear magnetic resonance (nmr) spectra and acidity constants of some imidazo[1,2‐b]pyridazines are

ISSN:0022-152X    

DOI:10.1002/jhet.5570050106

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

AbstractPyrolysis or ultraviolet photolysis of difluorodiazirine in the presence of boron trifluoride produced polydifluoromethylene. Like polymethylene derived from diazomethane, the polydifluoromethylene so produced possesses “living polymer” properties. The mechanism of polymerization is discussed and is thought to involve the formation of a linear intermedi

ISSN:0022-152X    

DOI:10.1002/jhet.5570050107

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

Abstract2,2′‐Dinitro‐3,3′‐biselenienyl‐4,4′‐dicarboxylic acid (VI), the first recorded compound of the 3,3′‐biselenienyl series, has been prepared and resolved into its optical antipodes by fractional crystallization of its brucine salt.On the basis of the quasi‐racemate method of Fredga and the O.R.D. spectra, to the dextrorotatory acid is assigne

ISSN:0022-152X    

DOI:10.1002/jhet.5570050108

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

AbstractThe action of bases on 3‐aryl (or alkyl)‐5‐acyl‐2‐isoxazolines has been shown to give rise to the corresponding aromatic (or aliphatic) nitriles and α‐diketones by cleavage of the O‐N and C3C4bonds of the heterocyclic ring. This fragmentation reaction has been extended to other 2‐isoxazolines substituted in the 5‐position with electr

ISSN:0022-152X    

DOI:10.1002/jhet.5570050109

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY

摘要:

AbstractThe synthetic chemistry of the relatively unknown pyridazino [4,5‐d]pyridazine ring system has been extended. 1,4‐Diaminopyridazino [4,5‐d]pyridazine (VIII) has been prepared by two routes, the most interesting of these being the one‐step conversion of 4,5‐dicyanopyridazine into VIII with hydrazine. Upon nitration VIII gave only the mononitramine (X). Attempts to prepare 1,4‐dichloropyridazino [4,5‐d]pyridazine gave only 4‐chloro‐2H‐pyridazino [4,5‐d]pyridazin‐1‐one (XII). Pyrimido [4,5‐d]pyridazine‐1,3‐dione (XIV) was prepared from pyridazine‐4,5‐dicarboxamide (IV). The hydrolysis of 5,8‐dichloropyrazino [2,3‐d]pyridazine (XV) gave 5‐chloropyrazino [2,3‐d]pyridazin‐8‐one (XVII) and likewise the ammonolysis of XV gave 5‐amino‐8‐chloropyrazino [2,3‐d]pyridazine (XX). As expected the hydrolysis of 5,8‐dibromo‐pyrazino [2,3‐d]pyridazine (XXI) gave 5‐bromopyrazino [2,3‐d]pyridazin‐8‐one (XXII). Attempted catalytic dechlorination of 5‐chloropyrazino [2,3‐d]pyridazin

ISSN:0022-152X    

DOI:10.1002/jhet.5570050110

出版商:Wiley‐Blackwell    

年代:1968

数据来源: WILEY