摘要:

A Simple Route for the Synthesis of Chlorosubstituted Arylazobenzenes, Arylazonaphthalenes, and ArylazopyrazolesThe reaction of arylazophenoles and arylazohydroxypyrazoles (or their tautomer hydrazones)10, 11, and15with POCl3in dimethylformamide yields chlorosubstituted arylazobenzenes or arylazopyrazoles12, 13, and16, resp., in moderate to high yields.The substitution of the OH‐group by the Cl‐moiety is favoured by acceptor substituents in the aryl fragments ortho‐ and/or para‐linked to the azo group.In case that arylazocompounds derived from resorcinol are used the substitution reaction runs in a stepwise manner giving raise to the formation of o‐hydroxy‐p‐chlorosubstituted azo compounds18primarily and then of dichlorosubstituted az

ISSN:0021-8383    

DOI:10.1002/prac.19873290602

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

On the Application of the N.M.R. Shift Reagent Technique to Substances with Two Different Association SitesThe competition of two potential association sites of the same substrate molecule for the shift reagent is described by a simple association model. The relative equilibrium constants are determined by the dependence of the induced shifts observed on the amount of the added shift reagent. An example of 3.17‐bifunctionalized steroids demonstrates the applicability of the metho

ISSN:0021-8383    

DOI:10.1002/prac.19873290603

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Liquid Crystalline trans‐4‐(ω‐Cyanalkyl)cyclohexylester and 4‐(ω‐Cyanalkyl)phenylestersThe synthesis of the title esters1and2a–e(n = 0 – 3) and their mesomorphic properties are described. When the alkyl‐spacer n between the polar CN‐group and the cyclohexane ring of cyanalkyl‐cyclohexylesters1is increased the difference of the clearing points between the phenylesters2and the cyclohexylesters1decreases to nearly zero. The reason of higher clearing temperatures of2is a dynamic conformational effect of ring inversion of cyclohexane in the ester1with two polar sub

ISSN:0021-8383    

DOI:10.1002/prac.19873290604

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Pyrylium Compounds. 37. Arylbenzenes from 2,4,6‐Triarylpyrylium Salts and Carboxylic Acid AnhydridesRefluxing 2,4,6‐triarylpyrylium salts1with excess carboxylic acid anhydrides (RCH2CO)2O (2a: R = H,2b: R = Me) in the presence of condensing agents like sodium or potassium acetate, sodium carbonate or methoxide, triethylamine or pyridine results in 1,3,5‐triarylbenzenes3(R = H, Me). Under similar conditions, phenylacetic acid anhydride (2c), generated in situ from sodium phenylacetate and excess2aor2b, yields 1,2,3,5‐tetraarylbenzenes3(R = Ph). Thus, the reaction1+2→3represents a new and simple method for replacing the pyrylium heteroatom =O⊕– by the =CR– moiety (R = H, Me, Ph). The structure of the arylbenzenes3was proved by spectroscopic methods, by comparison with literature data or by independent synthesis. As by‐products 2‐acyloxy‐benzophenones10are formed. Reaction of 3,5‐dimethyl‐2,4,6‐triphenyl‐pyrylium perchlorate (11) with acetic acid anhydride/sodium acetate (or sodium phenylacetate) takes another course leading to 2‐acetoxy‐3,5‐dimethyl‐4,6‐diphenyl‐benzophenone (15), whereas treatment of11with propionic acid anhydride/sodium acetate follows the reaction scheme1+2→3giving 1,3,5‐trimethyl‐2,4,6‐triphenylbenzene (16). The mechanisms of the diff

ISSN:0021-8383    

DOI:10.1002/prac.19873290605

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Reaction of (Z/E)‐1‐Aryl‐4‐arylmethylene‐pyrrolidine‐2,3,5‐triones with Enaminocarbonyl CompoundsTreatment of the α, β‐unsaturated ketones (Z/E)‐1a–ewith alicyclic or aliphatic enamines afforded cyclic Michael adducts2and3a–e, respectively. By dehydration of the N,O‐hemiacetals3b–dthe corresponding 1,4‐dihydropyridines4a–cwere obtained.The acid‐catalyzed reaction of aminosubstituted maleimides with (Z/E)‐1e, aldehydes or indan‐1,2,3‐trione led to5a–c,6a–c,7a–cand8. O‐Methylation of the aryl‐bis(maleinimidyl)methanes5c,6cby using diazomethane gave5d,6d, whereas5acyclized spontaneously to the 1,4‐dihydropyridine9a. Further 1,4‐dihydropyridines were prepared by cyclocondensation of6a,bin the presence of ammon

ISSN:0021-8383    

DOI:10.1002/prac.19873290606

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Three Component Reactions. XVII. Terminal Reactive Oligooxyethylene Structures from Alkenes, Chlorine and O‐Nucleophiles and Their Transformation into OxathiaalkanesThe reaction of alkenes, chlorine and oxirane, dioxane, ethyleneglycole, oligoethylenglycoles, the monoethers of oligoethyleneglycoles, ethylene chlorohydrine or α‐hydro‐ω‐chloro‐oligooxyethylenes leads to compounds6‐‐9, which contain mono or oligoether functions and one or two reactive terminal chlorine atoms. Oxathiaalkanes (10and12) were obtained in the reaction of such compounds with sod

ISSN:0021-8383    

DOI:10.1002/prac.19873290607

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Substituted 5‐Imino‐3,3‐pentamethylene‐1,2,4‐thiadiazolidines by Amination of Thiourea DerivativesN‐Acylthioureas2a–band thiosemicarbazones of aldehydes, ketones, and esters4a–gare aminated at the potential SH‐group by 3,3‐pentamethyleneoxaziridine yielding substituted 5‐imino‐3,3‐pentamethylene‐1,2,4‐thiadiazolidines3and6the latter via the intermediates5.The reaction of the thiosemicarbazones4is a very general one, but only two acylthioureas2could be conve

ISSN:0021-8383    

DOI:10.1002/prac.19873290608

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Photochemical Primary Processes of Xanthene Dyes. VIII. Influence of Mixed Micelles on the Photochemical Primary Processes of Selenopyronine and Erythrosine and the Sensitized Photolysis of Diazonium SaltsThe influence of the nonionic detergent dodecyltriglycol (DTG) on the escape rate of dye ions from cationic and anionic micelles is investigated. The rate constant of the escape of selenopyronine ions (Sp⊕) from mixed micelles of sodium dodecylsulfate (NDS) and DTG (1:1) (kA≈︁ 3,2 · 104s−1) is, as a result of the lower charge density, higher by the factor 10 than that from clean NDS‐micelles (kA≈︁; 2,8 · 103s−1). Erythrosine ions (Et2⊖) are tightly fixed to cetyltrimethylammoniumbromide (CTAB)‐micelles (kA≈︁; 0,25 · 103s−1) and to mixed micelles of CTAB and DTG (1:1). This may be a result of the twofold negative charge of the erythrosine ions. Properties of the mixed micelles (polarity, average aggregation numbers) are determined by using the dyes and pyrene as probes. The sensitized photolysis of diazonium salts by electron transfer from photoexited selenopyronine under aerobic conditions is more effective by a factor of 3–5 in the presence of anionic micelles

ISSN:0021-8383    

DOI:10.1002/prac.19873290609

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe aldol reaction of the substituted cyclopentane carbaldehydes1with heptan‐2‐one was demonstrated to offer an effective alternative to the carbonyl olefinations generally used for the build‐up of the (E)‐3‐oxooct‐1‐enyl side chain of 11‐deoxyprostaglandins. In this case dimethyl 2‐oxoheptylphosphonate can be substituted advantageously by the cheaper heptan‐2‐one as

ISSN:0021-8383    

DOI:10.1002/prac.19873290610

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

Resolution of the Enantiomers of (S,R)‐1,1′‐Bi‐2,2′‐naphthylhydrogenphosphate by (1R,2R)‐ and (1S,2S)‐2‐Amino‐1‐(4‐nitrophenyl)‐propane‐1,3‐diolThe resolution of the diastereoisomeric salts of the title compounds was possible in the presence of a ketone, especially acetone, which forms oxazolidines (3a–d) with the chiral bases. These oxazolidines afforded separable salts with the (S,R)‐1,1′‐Bi‐2,2′‐naphthylhydrogenphosphate (4). The structures of these salts

ISSN:0021-8383    

DOI:10.1002/prac.19873290611

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY