摘要:

Iminoformylation Reaction of Substituted Crotonnitriles. III. Stereochemistry and Intramolecular Mobility of 4‐Amino‐1.1‐dicyano‐buta‐1.3‐dienes1H‐ and13C‐n.m.r. spectroscopic investigations show the preference of s‐trans configuration and the push‐pull character of the investigated 4‐amino‐1,1‐dicyano‐buta‐1,3‐dienes. Dynamic1H‐ and13C‐n.m.r. data for the rotation process about the CN bond are determined. The activation energies are discussed with respect to electronic and steric effects of

ISSN:0021-8383    

DOI:10.1002/prac.19893310102

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractThe15N‐ and13C chemical shifts and1J(15Nα15Nβ) coupling constants of 3‐methyl‐1‐phenylpyrazole‐4,5‐dione 4‐phenylhydrazone (1) were measured in dimethyl sulphoxide and pyridine solutions. It was found that compound1exists fully in its hydrazone form in these two solvents, contrary to the previously published data which propose equilibrium mixture of the hydrazon

ISSN:0021-8383    

DOI:10.1002/prac.19893310103

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractFriedel‐Crafts acetylation of phenanthrene (1a) insym‐tetrachloroethane yields mixtures of 2‐, 3‐ and 9‐acetylphenanthrenes (2a, 3a, 4). The distribution of isomers is found to depend strongly upon the method of mixing the reagents. Acetylation of 9‐chlorophenanthrene (1b), performed by a variety of methods and solvents, led mainly to 3‐acetyl‐9‐chlorophenanthrene (3b) (≥85%). Previously unreported 2‐acetyl‐9‐chlorophenanthrene (2b) was found to form up to a ma

ISSN:0021-8383    

DOI:10.1002/prac.19893310104

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractThe condensation of naphthalene‐1‐ or 2‐carbaldehyde with dimethyl 2,2‐dimethyl‐succinate (Stobbe conditions) gives predominantly the (Z)‐hemiesters3and11a. The hemiester3contains a small amount of the (E)‐isomer. Similar condensation of naphthalene‐2‐carbaldehyde with dimethyl‐2‐methylsuccinate gave the hemiester (E)‐12a. Their configuration and the ratios of the (Z:E)‐hemiesters, their derived acids, anhydrides, indenones and phenanthrene derivatives are inferred by high resolut

ISSN:0021-8383    

DOI:10.1002/prac.19893310105

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractPhenacylmalononitriles2react with hydrazines, acetic‐hydrochloric acid and with diazotised primary aromatic amines to afford phenacylpyrazole (5a,b), aminofurans (6a,b) and aminopyrazole derivatives (3a,d) respectively. The synthesised derivatives (3d, 6a) were the key materials for the synthesis of isoindolinedione, (7a–c) pyrazolopyrimidine (9, 10), and pyrazolopyridazine derivatives (11). The structures of the newly synthesised heterocycles were established on the basis of elemental analyses and spectral data besides synthesis via other rou

ISSN:0021-8383    

DOI:10.1002/prac.19893310106

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

Chalcone Aziridines. IV. Comparison of Spectroscopical and Mass Spectrometrical Behavior of trans‐Chalcone Aziridines and trans‐Chalcone EpoxidesThe aziridines1were compared with epoxides2by their i.r. and n.m.r. spectroscopical behavior and the threemembered ring electron densities. In the masse spectra we found not only identical path‐ways i. e. the formation of M⊕and Ar2CH⊕ions and onium or aryl fragmentation, but also differences as the formation of [M–17]⊕ions for1and carbonyl rearra

ISSN:0021-8383    

DOI:10.1002/prac.19893310107

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

An Improved Method for the Application of the 4‐Methoxybenzyl Group to Protect the 2′‐Hydroxyl Group in the Ribonucleotide Synthesis by TFA‐acidolysisThe cleavage of the 4‐methoxybenzyl group from the 2′‐OH‐position of ribonucleosides by the hydrogenation with different Pd‐catalysts as well as trifluoracetic acid has been studied in detail. During hydrogenation, side reactions at the base residue of cytidine‐occurred which, however, could be extensively suppressed by PdCl2catalysis. More practicable results were obtained with trifluoracetic acid in the presence of cation scavengers, allowing smoothly to convert a series of 2′‐methoxybenzyl ribonucleotides to the homogeneou

ISSN:0021-8383    

DOI:10.1002/prac.19893310108

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractThe reaction of 2‐(aroyl, methylidene)‐3‐arylthiazolidine‐4‐ones1with trifluoromethylsulfenyl chloride yields a mixture of geometric (Z, E) isomers of 2(aroyl, trifluorosulfenylmethylen)‐3‐aryl‐thiazolidine‐4‐ones2. The bromination of1leads to 2‐(aroyl, methylidene)‐3‐aryl‐5‐bromothiazolidine‐4‐ones3which on reaction with nitrosobenzene formes nitrones4. The structures of the compounds2–4were determined by me

ISSN:0021-8383    

DOI:10.1002/prac.19893310109

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

Special Features in Pyrolysis Behaviour of IsoalkylaromaticsThe pyrolysis of cumene, sec. butyl‐ and tert. butylbenzene proceeds in a laboratory scale quartz vessel in the temperature range 600–750°C. Conversion occurs mainly via a radical‐chain mechanism in the side chain in proportions, determined by the dissociation energies of the CC‐ and CH‐bonds. Dealkylation was observed in greater amounts than for n‐alkylbenzenes. It is interpreted by H‐atom addition to the aromatic nucleus, followed by β‐scission to benzene and isoalkenes. It was be shown, that H‐atoms are formed by unusual reactions such as neophyl rearrangement and homolytic rupture of C

ISSN:0021-8383    

DOI:10.1002/prac.19893310110

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

Quinoxalines. XXVI. Synthesis of Bis‐azolo[a,c]‐fused Quinoxalines. I. Synthesis from 4‐Substituted 1,2,3‐Triazolo[1,5‐a]quinoxalinesThe synthesis of bis‐azolo‐fused quinoxalines of type.6is described. The new bisazolo‐fused compounds9, 10a, b, 12, and16were synthesized from the 4‐substituted 1,2,3‐triazolo‐[1,5‐a]quinoxalines7, 8, 11, and13by intramolecular cyclization reactions. The structures were determined by microanalysis, i.r.,1H

ISSN:0021-8383    

DOI:10.1002/prac.19893310111

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY