摘要:

Synthesis and Oxydation of 1‐(1,3‐Thiazol‐2‐yl)‐pyrazolidin‐3‐onesThe 1‐(1,3‐thiazol‐2‐yl)‐pyrazolid‐3‐ones4are synthesized by reaction of 1‐thiocarbamoyl‐pyrazolidin‐3‐one2with α‐halogenaldehydes and α‐halogenketones, respectively. The structure of4is proved by their1H‐n.m.r. and mass spectra. Oxydative dimerisation of4leads to the bisazomethinimines10. The compounds10represent a new type

ISSN:0021-8383    

DOI:10.1002/prac.19823240602

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Ionisation of Triphenylmethylbromide in NitromethaneDissolving triphenylmethylbromide in nitromethane leads to the formation of HBr which complicates conductivity and spectroscopic measurements of carbenium ion absorption. As a result of addition of bromide ions (as tetraethylammonium bromide = Et4NBr) the triphenylmethylabsorption totally disappeares. It can be concluded that Ph3CBr in nitromethane is partially present in form of free (solvated) ions. The carbenium ion concentration has been determined as a function of gross concentration and temperature.

ISSN:0021-8383    

DOI:10.1002/prac.19823240603

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

The Dependence of Fluorescence Quantum Yields of Donor Substituted 4′‐Diphenylphosphinyl trans‐Stilbenes on Temperature and Viscosity in Low Viscous Solvents of Different PolarityThe dependence of fluorescence quantum yields of donor substituted 4′‐diphenylphosphinyl trans‐stilbenes1on temperature was investigated between 15–65°C in toluene and n‐propanol. It is concluded that the fluorescence quantum yield dependence on temperature is due to the dependence of nonradiative deactivation on solvent viscosity. The nonradiative deactivation is attributed to the ethylene bond rotation in1. The rotation around the ethylenic bond and the fluorescence are the two most important deactivation processes detected up to now for the first excited singlet of1in

ISSN:0021-8383    

DOI:10.1002/prac.19823240604

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Hydroxybromination of NorcaraneTreatment of norcarane (1) with N‐bromosuccinimide (NBS) and water results mainly in Markovnikov addition of the elements of hypobromous acid to the cyclopropane ring forming trans‐2‐(bromomethyl)cyclohexanol (2) (52%) and cis‐2‐(bromomethyl)cyclohexanol (3) (7%). In addition a deprotonation of the intermediately cationic species leads to the not isolated 3‐(bromomethyl)cyclohexene (12), which gives with a second mol of NBS and water t‐2‐bromo‐t‐3‐(bromomethyl)cyclohexan‐r‐1‐ol (4) (28%) and three isomeric minor compounds5, 6, 7. The stereochemistry of the major products has been established by spectroscopic tech

ISSN:0021-8383    

DOI:10.1002/prac.19823240605

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Azomethineimines. V.1H‐N.M.R. Spectra and Steric Properties of Arylsubstituted Pyrazolidone‐AzomethineiminesFrom the results of1H‐n.m.r.‐spectroscopic investigations we tried to draw conclusions regarding the steric properties of pyrazolidone‐azomethineimines1a–k. The influence of aromatic systems on chemical shift of the methineproton of the 1,3‐dipolar centre was calculated using the ring current model. Without the twisted 9‐anthryl‐substituted compound1fexperimental results show a good correspondence to the values of chemical shift calculated for two of four possible is

ISSN:0021-8383    

DOI:10.1002/prac.19823240606

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Reaction of α‐Cyano‐β‐aryl Acrylic Acid Ethylesters with Hydrazine, a Retro‐Knoevenagel‐ReactionWe tried to obtain 4‐cyano 5‐aryl pyrazolidones‐(3)3a, band related azomethine imines4a, b. However the reaction of α‐cyano β‐aryl acrylic acid ethylesters2a, bwith hydrazine yields the familiar cyano acetic acid arylidene hydrazides5a, bby cleavage of the carbon‐carbon double bond.5a, breact with pyrene‐1‐aldehyde to7a, b. Formation of5a, bis proved by an independent synthesis.5a, band7a, bare inve

ISSN:0021-8383    

DOI:10.1002/prac.19823240607

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Synthesis and Chemical Behaviour of 2,6‐Disubst.‐5‐acyl‐4H‐1,3‐oxazine‐4‐thionesNew 2,6‐disubst.‐5‐acyl‐4H‐1,3‐oxazine‐4‐thiones4are synthesized by addition‐cyclocondensation reaction between 1,3‐diketones and acylisothiocyanates.With perchloric acid ring opening of4takes place and N‐acyl‐acylthioacetamides5are obtained. The compounds5can be S‐alkylated by alkyl halides to form6. 2‐Aroyl‐1‐aroylamino‐1‐arylaminoethenes7are prepared from5or6with primary am

ISSN:0021-8383    

DOI:10.1002/prac.19823240608

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Synthesis and Structure of Novel 1‐Imino‐1λ4,2,4,6‐thiatriazinesO,O′‐Dimethyldiisobiurete1is cyclisized with N‐arylsulfonyl sulfinyl amines4a–cto 1λ4,2,4,6‐thiatriazines9a–c. The reaction with corresponding sulfur diimides7a–cleads to identical 1λ4,2,4,6‐thiatriazines9a–c. Methylation products from9cwith diazomethane are isolated by column chromatography. The cyclization mechanism with a substituted imido sulfurous diamide

ISSN:0021-8383    

DOI:10.1002/prac.19823240609

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

About the Deactivation Behaviour of Photoexcited Aryltropyliumions. II. Fluorescence Quenching of AryltropyliumionsThe properties of aryltropyliumions in the excited singlet state were studied. These ions are very strong acceptors. So the fluorescence is quenched by aromatic donors. The rates of fluorescence quenching depend on the ionization potential of the donor. This fact is discussed in terms of mechanisms derived by WELLERet al. The results were related to the light stability of aryltropyliumions.

ISSN:0021-8383    

DOI:10.1002/prac.19823240610

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Reaction of Methylene Active Nitriles and Cyanamide with Acylated EnaminesThe addition products from enamines onto isocyanates and isothiocyanates, i.e. substituted β‐aminoacrylo amides1and thioamides2, react with malononitrile to yield the 6‐amino‐1‐aryl‐5‐cyano‐pyridin‐2‐ones3and ‐thiones4among them 5,6,7,8‐tetrahydroisoquinolin‐1‐ones and ‐thiones. From ethyl cyanoacetate the 5‐cyano‐6‐hydroxy‐pyridin‐2‐ones7and from benzoyl acetonitrile the 6‐phenyl‐pyridin‐2‐ones8are formed. The replacement of malononitrile by cyanamide yields the 2‐amino‐3‐aryl‐pyrimidin‐4‐ones5and ‐thiones6among them 5,6,7,8‐tetrahydroquinazolin‐4‐ones and ‐thiones. The not isolated β‐acyl enamines derived from enamines and acid chlorides react with malononitrile or cyanamide to form

ISSN:0021-8383    

DOI:10.1002/prac.19823240611

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY