摘要:

AbstractThe syntheses of fluorenone derivatives having one to three glycidyl groups and related compounds are reported. Their activity against experimental tumors in vitro in relation to the molecular structure is discussed.

ISSN:0021-8383    

DOI:10.1002/prac.19903320102

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

Spectroscopic Studies on 4‐Nitrophenylhydrazones of Secondary and Tertiary α‐Ketoamides4‐Nitrophenylhydrazones of secondary and tertiary α‐ketoamides both exist in two stable isomeric forms (E/Z) with respect to the position of the substituents at the CN‐Bond. But whereas the Z‐form of the secondary amides can be easily assigned by means of intramolecular hydrogen bond, this criterion in case of most the derivatives of tertiary amides fails. As shown by derivatives of glyoxylic acid this deviation is evidently caused by steric facts due to the double substituted amide group and the alkyl residue

ISSN:0021-8383    

DOI:10.1002/prac.19903320103

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

Galacturonic Acid Derivatives. I. Galacturonates from Acetyl‐ and Isopropylidene‐D‐galactopyranosesGalacturonic acid derivatives to be employed as glycosyl donors in saccharide synthesis are prepared from galacturonic acid itself or from galactose. Various syntheses of 1,2,3,4‐tetra‐O‐acetyl‐D‐galactopyranuronic acids (6) with differently protected carboxyl group and attempts of their conversion into galacturonpyranosyl bromides are described. The starting materials were 1,2;3,4‐di‐O‐isopropylidene‐α‐D‐galactopyranose and acetylated galactopyrano

ISSN:0021-8383    

DOI:10.1002/prac.19903320104

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

Calix[n]arenes. III. Calix[n]aren Derivates with Antioxidation EffectivityThe new tert.‐butylcalix[n]arenes compounds4and5are synthesized by esterification with carboxylic acid chlorides of hindered phenolic derivatives.These new calix[4]arenes connected with inhibitor groups act as antioxidants in tetraline and low density polyethylene (Mirathen Al 21 FAR). Compound5shows better antioxidative efficiency than tert.‐butylcalix[4]are

ISSN:0021-8383    

DOI:10.1002/prac.19903320105

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

Heterocyclic Substituted Arenediazonium Salts with a Long‐wave‐length Range of Sensitivity. II. 4‐(1‐Heterocycliden‐2,3‐diaza‐prop‐2‐en‐3‐yl)‐arenediazonium tetrafluoroboratesThe title compounds (3) are obtained by reaction of aromatic bis‐diazonium salts with substituted 2‐benzylidene‐1,3‐dithioles and 2‐benzylidene‐1,3‐diselenole, respectively. The maximum of the long wave‐length absorption band of3varies from 580 nm up to 665 nm depending on the structure of the compound.The quantum yields of the photolysis of the diazonium salts3are low (1 · 10−4to 7 · 10−3). The azo dyes obtained from3with usual azo‐couplers absorb in a shorter wave‐length range than the corresponding d

ISSN:0021-8383    

DOI:10.1002/prac.19903320106

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

1,3,4‐Thiadiazoles by Reaction of Dithiocarboxylic Esters with Carbonic Hydrazides1,1‐Dithiooxalic esters1and heteroaryl dithiocarboxylic esters2react with carbonic hydrazides yielding 1,3,4‐thiadiazoles. The 1‐thiooxamoyl semicarbazides3or 1‐heteroylthiocarbonyl semicarbazides4, primarily formed by thioacylation of semicarbazide, where isolated. By cyclocondensation they yield 1,3,4‐thiadiazole‐2(3 H) ones5,6, or in the presence of acetic anhydride 3‐acetyl‐1,3,4‐thiadiazol‐2‐ones‐7,8, respectively.2‐Amino‐ or 2‐methylthio‐1,3,4‐thiadiazoles11,12or13,14are formed by reaction of the dithioesters1,2with thiosemicarbazide or methyl dithiocarbazinate. By this way 1,3,4‐thiadiazoles with heteroaryl‐ or carbamoylresidues in position

ISSN:0021-8383    

DOI:10.1002/prac.19903320107

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

On the Reaction of Oxalic Amidines with Carbonic Acid Derived Heterocumulenes to Imidazolidine‐DerivativesA useful synthetic route to nonsymmetric derivatives of imidazolidine (derivatives of parabanic acid) is demonstrated by the reaction of tetraarylated oxalic amidines1with different alkyl‐ and aryl substituted isothiocyanates4, isoselenocyanates31, and carbodiimides30.Acylisothiocyanates9react differently leading to a mixture of three cycloacylation products12,13and14. Silylated heterocumulenes such as25and26react with1to give28and29transsilylation. Based on the13C‐n.m.r. spectroscopic investigation of the reaction between1aand methyl isothiocyanate and phenyl isothiocyanate respectively a mechanism is pro

ISSN:0021-8383    

DOI:10.1002/prac.19903320108

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

Inter‐ and Intramolecular Acyl Transfer on 1(9)H‐Imidazo[1,2‐a]benzimidazolesThe new imidazo[1,2‐a]benzimidazoles (3) react with electrophiles like aroyl chlorides, isocyanates, cyanates, chloroformates and chlorothioformates to give the 9‐acyl derivatives (4a–1).At higher temperatures intermolecular acyl transfer takes place to give the l‐acyl compounds (5a–m). In the case of 1‐carbamoyl imidazo[1,2‐a]benzimidazoles (5) was observed intramolecular acyl transfer in the presence of strong bases and 1‐benzimidazol‐2‐yl‐hydantoins (6) were isolated.The structures of the prepared compounds could be inferred from their1H and13C n.m.r., mass spectra and were corroborated by the comparison with the data of similar derivatives a

ISSN:0021-8383    

DOI:10.1002/prac.19903320109

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA number of 2‐ and 3‐methoxy‐substituted‐4‐N.N‐diethylaminoazobenzenes have been prepared and their absorption maxima in ethanol and toluene compared with the corresponding 4‐N.N‐diethylaminoazobenzenes. Both the 2‐ and 3‐methoxy groups cause a bathochromic shift, but the bathochromic shift of a 3‐methoxy group depends on the substituents in the diazo component. With increasing electron‐withdrawing strength of the substituents in the diazo component a progressive enhancement of bathochromic shift appears. In toluene all 3‐methoxy‐substituted dyes absorb at longer wavelengths compared with the

ISSN:0021-8383    

DOI:10.1002/prac.19903320110

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0021-8383    

DOI:10.1002/prac.19903320111

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY