摘要:

Studies on the Autoxidation of cis‐ und trans‐β‐Methyl StyreneIn the autoxidation of cis‐ and trans‐β‐methyl styrene at temperatures between 80 and 120°C the CC‐double bond is preferably attacked: 35–60% of epoxides and their consecutive products and 25–50% of benzaldehyde are obtained. Products of allylic oxidation are formed only with yields lower than 1%; high‐boiling or polymeric products, respectively, which could not be detected gaschromatographically are formed with yields lower than 20%. The ratio of cis‐ to trans‐epoxides in the case of cis‐β‐methyl styrene oxidation amounts to about 0.04, in the case of trans‐β‐methyl styr

ISSN:0021-8383    

DOI:10.1002/prac.19803220302

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Wechselwirkung zwischen Eisen(III)‐Ionen und einigen Cannabinoiden und verwandten VerbindungenDie Reaktion zwischen Orcinol, Olivetol oder Cannabidiol und dreiwertigem Eisen wurde spektroskopisch untersucht. Zwischen Eisen(III)‐Ionen und Orcinol bzw. Olivetol bilden sich in Methanol 1:3 Komplexe (Dissoziationskonstanten 1,5 × 10−5bzw. 2,5 × 10−7). Keine Wechselwirkung konnte unter analogen Bedingungen zwischen Fe3+‐ionen und Cannabidiol beobac

ISSN:0021-8383    

DOI:10.1002/prac.19803220303

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Zur Bildung von 4,4‐Dialkyl‐2‐oxo‐morpholinium‐chloridenDialkylaminoethanole2reagieren mit Chloracetaten1zu den N,N‐Dialkyl‐2‐oxo‐morpholinium‐salzen6. Es wird gezeigt, daß die Reaktion zweistufig und über die Ester 3–5 verläuft, welche zu den Salzen6cyclisieren. Das Zwischenprodukt5awurde isoliert, seine Struktur aufgeklärt und ein Reaktionsmechanismus vorgeschlagen.2‐Oxo‐morpholiniumsalze6hydrolysieren in wäßriger Lösung zu den entsprechenden Betainen7. Der Hydrolysegrad wurde bestimmt. Die Betaine7können in umgekehrter Weise zu den 2‐Ox

ISSN:0021-8383    

DOI:10.1002/prac.19803220304

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Syntheses of New Salts of Thieno[2′,3′;4,5]imidazo[1,2‐a]pyridinesMesomeric 1‐[2‐amino‐1‐cyano‐2‐thio‐]ethene‐pyridinium ylides1are cyclizized to imidazo[1,2‐a]pyridinium ylides2in the presence of HgO. S‐alkylation of2leads to derivatives of 1‐R1‐2‐thio‐3‐cyano‐imidazo[1,2‐a]pyridinium halides3or4. Alkylation products from2with α‐haloketones are cyclizized to thieno

ISSN:0021-8383    

DOI:10.1002/prac.19803220305

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Proton‐Catalyzed Disulfide Exchange of S‐Alkylthio Cysteine DerivativesAlthough N‐unprotected S‐alkylthio cysteine derivatives are relatively stable in acid solutions, N‐acylsubstituted and N‐urethane protected S‐alkylthio cysteines react easily by disulfide exchange. As a rule the frequently used tert.‐butyloxycarbonyl amino protecting group, present in ethylthio cysteine derivatives can′t be removed selectively without disulfide cleavage, whilst the 2‐(p‐biphenylyl)isopropyloxycarbonyl and the 2‐phenyl‐isopropyloxycarbonyl amino protecting groups are removable without any structure change of the alkylthio thiol protecting groups. It is advisable to realize this acid demasking of the amino groups by means of weak deblocking reagents. Comperative experiments in acid solution prove S‐tert.‐butylthio group to be the most stable protecting function, whilst isopropylthio cysteine derivatives are more stable than the corresponding S‐ethylthio compounds. All these results and experiments with addition of different thiols as well as u.v.‐spectroscopic investigations indicate, that the observed acid catalyzed disulfide exchange proceeds via a carbonyl neighbouring group effect and formation of thiazolidinium and thiazol

ISSN:0021-8383    

DOI:10.1002/prac.19803220306

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Three‐Component Reactions. VIII. Chlorination of Olefines in N‐MethylpyrrolidoneThe chlorination of cyclohexene, styrene and 1‐dodecene in NMP gives immonium‐chlorides5reacting with water to β‐chloralkyl‐γ‐N‐methylaminobutyrat‐hydrochlorides. With cyclohexene the reaction proceeds stereospecifically as trans‐addition. From styrene there is only formed the Markovnikov product, and from dodecene a mixture of isomeres is obtained containing about 30% of the ant

ISSN:0021-8383    

DOI:10.1002/prac.19803220307

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

1,2,3‐Triazabutadienes. XI. Investigation of the Iodine‐induced Photoisomerization of 1‐Aryl‐3‐(3‐methyl‐benzthiazolin‐2‐yliden) triazenescis‐1‐Aryl‐3‐(3‐methyl‐benzthiazolin‐2‐yliden)triazenes isomerize induced photo‐chemically by iodine to the trans‐isomer. The wavelength of the used irradiation light was 546 nm so that only I2absorb. The dependence of the quantum yields on the concentration of the cis‐isomer and on the intensity of the irradiation light was investigated. The influence of the light intensity on the quantum yields shows, that the primary step is the dissoziation of I2‐molecules to I·

ISSN:0021-8383    

DOI:10.1002/prac.19803220308

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Substituted 1,4,2‐Dithiazoline‐3‐ylidene‐aroylacetonitrilesA convenient method for the preparation of new 2,5‐disubst‐1,4,2‐dithiazoline‐3‐ylidene‐aroylacetonitriles4is presented. The compounds4are formed during reaction of substituted thioacetamides1with α‐bromo‐α‐thiocyanatoketones2. The mechanism of formation as well as the mass and i.r.‐spectra of the synthe

ISSN:0021-8383    

DOI:10.1002/prac.19803220309

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Photocatalytic Systems. XXXIV. On the Photoreduction of Carboxylato(cuproine) Copper (II) Chelates in AlcoholsIn contrast to the behaviour in nonpolar aprotic solcents, the photolysis of cuproine copper(II) chelates of the type Cu(NN) (RCOO)2(R  CH3, C(CH3)3; NN = sterically hindered heterocyclic 1, 2‐diimine ligand) in alcohols does not lead to formation of free radicals.A two‐step mechanism with non‐radicalic intermediates is derived from e.s.r. spin trapping and microsecond flash photolysis

ISSN:0021-8383    

DOI:10.1002/prac.19803220310

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Azoperoxides. VII. Thermolysis of α‐AlkylazoalkylhydroperoxidesThe thermal decomposition of 1‐methylazo‐1‐hydroperoxycyclohexane1and 1‐tert.‐butylazo‐1‐hydroperoxycyclohexane2was studied in ethylbenzene and in the case of2also in other solvents. Decomposition products and decomposition rates of the azo and the peroxy groups were selectively estimated. The title compounds decompose faster than the analogous azo compounds and alkylhydroperoxides. A induced homolysis of both initiator groups is proposed; the compounds are not „bifunct

ISSN:0021-8383    

DOI:10.1002/prac.19803220311

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY