摘要:

AbstractEquilibrium constants for oxidations of cyclanols by cyclohexanone in benzene have been determined in the presence of aluminium isopropoxide. The free energies of the equilibrium (ΔGox) are correlated with equilibrium constants for dissociation of cyanohydrins, rate constants for cyclanol oxidation with chromic acid, ketone reduction with sodium borohydride and trifluoroethanolysis of tosylates

ISSN:0018-019X    

DOI:10.1002/hlca.19800630702

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

AbstractThe primary solvent isotope effects on theASE‐2 type hydrolyses of α‐diazocarbonyl compoundsp‐XC6H4CN2CH3(X = NO2, H, OCH3and C6H5CON(CH3)2) are found to be identical despite large differences in their overall hydrolysis rates. The secondary solvent isotope effects diminish considerably with diminishing substrate reactivity, and for two substrates they are smaller than those normally anticipated for a simple proton transfer from the lyonium species. An analysis is presented of these and other abnormal secondary isotope effects found elsewhere, involving consideration of the solvation of the reaction c

ISSN:0018-019X    

DOI:10.1002/hlca.19800630703

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Synthesis of Sugar Derivatives Bearing a Spiro HeterocycleviaNucleophilic CyclizationTreated with the 1,4‐binucleophiles 1,2‐diaminoethane, 2‐aminoethanol, 2‐aminoethanethiol,L‐cysteine,o‐phenylenediamine,o‐aminophenol oro‐aminothiophenol the ketosugar derivative1gave in good yields the corresponding spiro derivatives2–8. In each case, the reaction was stereospecific leading to the isomer bearing the N‐atom on theendoface of the bicyclic starting material. Starting from the sugar enone9, the aromatic 1,4‐binucleophiles led stereospecifically to the spirobenzo [b]‐diazepine10, ‐oxazepine11or ‐thiazepine12. In one case, an imine(13)was isolated. As13cyclized to6, the intermediate formation of these kind of derivatives could be considered as a common s

ISSN:0018-019X    

DOI:10.1002/hlca.19800630704

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

AbstractThe spirolactam5was reduced to the spiro[naphthalene, pyrrolidine]7which wasN‐aralkylated to give9and17. Cyclization of9gave the phenanthridines10and11; similarly,17afforded the 7‐ and 8‐membered heterocycles18and19. Compounds10, 18and19when subjected to an intramolecularHofmannelimination yielded the 9‐, 10‐ and 11‐membered ring systems, respectively

ISSN:0018-019X    

DOI:10.1002/hlca.19800630705

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

AbstractThe synthesis of the naturally occurring 1′,2′‐epoxy‐1′,2′‐dihydro‐β, δ‐carotene and 1′,2′‐epoxy‐1′,2′‐d

ISSN:0018-019X    

DOI:10.1002/hlca.19800630706

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Hydrazinolysis ofN‐(3‐Oxo‐1‐isoindolinyliden)alanin Ethyl Ester, Structure of the ProductTreatment ofN‐(3‐oxo‐1‐isoindolinyliden)alanin ethyl ester(6)with hydrazine hydrate leads to 4‐methyl‐2,3,4,6‐tetrahydro[1,2,4]triazino[3,4‐a]isoindole‐3, 6‐dione (8,Scheme 3) and not to the previously postulated 6‐hydroxy‐2‐methyl‐2,3‐dihydro‐imidazo [2,1‐a]phthalazin‐3‐one (7,cf.[2]). The structure of8has been established by an independent synthesis as well as by the X‐ray analysis of the reaction product11from8and 3‐dimethylamino‐2,2‐dimethyl‐2H‐azirine (1,Scheme 4). A reaction me

ISSN:0018-019X    

DOI:10.1002/hlca.19800630707

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Synthesis of 7‐Aminoxanthopterin7‐Aminoxanthopterin (II) is obtained in good yield and purity by the transformation of isomer‐free xanthopterin‐7‐carboxylic acid (I) with NH3followed by oxidation with MnO2. The Frontier Orbital Theory contributes to a better understanding of the reactio

ISSN:0018-019X    

DOI:10.1002/hlca.19800630708

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

AbstractThe synthesis of 1‐bicyclo[3.2.2]nonene(2)and of 1 (7)‐bicyclo [3.2.2]nonene(3), two isomeric bridged (E)‐cycloheptenes, by intramolecularWittigreaction is described. These ‘Bredtolefins’ could not be isolated, but dimerized rapidly. In both cases, the main product was shown to be a head‐to‐tail dimer with a cyclobutane ring. The ‘Bredtolefins’ were also trappedin situwith furan or 2,5‐dip

ISSN:0018-019X    

DOI:10.1002/hlca.19800630709

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

Photochemical Reaction of Optically Active 2‐(1′‐Methylallyl)anilines with MethanolIt is shown that (−)‐(S)‐2‐(1′‐methylallyl)aniline ((−)‐(S)‐4) on irradiation in methanol yields (−)‐(2S, 3R)‐2, 3‐dimethylindoline ((−)‐trans‐8), (−)‐(1′R, 2′R)‐2‐(2′‐methoxy‐1′‐methylpropyl)aniline ((−)‐erythro‐9) as well as racemic (1′RS, 2′SR)‐2‐(2′‐methoxy‐1′‐methylpropyl) aniline ((±)‐threo‐9) in 27.1, 36.4 and 15.7% yield, respectively (seeScheme 3). By deamination and chemical correlation with (+)‐(2R, 3R)‐3‐phenyl‐2‐butanol ((+)‐erythro‐13; seeScheme 4) it was found that (−)‐erythro‐9has the same absolute configuration and optical purity as the starting material (−)‐(S)‐4. Comparable results are obtained when (−)‐(S)‐N‐methyl‐2‐(1′‐methylallyl)aniline ((−)‐(S)‐7) is irradiated in methanol,i.e.the optically active indoline (+)‐trans‐10and the methanol addition product (−)‐erythro‐11along with its racemicthreo‐isomer are formed (cf. Scheme 3). These findings demonstrate that the methanol addition products arise from stereospecific, methanol‐induced ring ope

ISSN:0018-019X    

DOI:10.1002/hlca.19800630710

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY

摘要:

AbstractOn triplet excitation (E)‐2isomerizes to (Z)‐2and reacts by cleavage of the C(γ), O‐bond to isomeric δ‐ketoester compounds (3and4) and 2,5‐dihydrofuran compounds (5and19, s.Scheme 1). ‐ On singulet excitation (E)‐2gives mainly isomers formed by cleavage of the C(γ), C(δ)‐bond (6–14, s.Scheme 1). However, the products3–5of the triplet induced cleavage of the C(γ), O‐bond are obtained in small amounts, too. The conversion of (E)‐2to an intermediate ketonium‐ylideb(s.Scheme 5) is proven by the isolation of its cyclization product13and of the acetals16and17, the products of solvent addition tob. ‐ Excitation (λ = 254 nm) of the enol ether (E/Z)‐6yields the isomeric α, β‐unsaturated ε‐ketoesters (E/Z)‐8and9, which undergo photodeconjugation to give the isomeric γ, δ‐unsaturated ε‐ketoesters (E/Z)‐10. ‐ On treatment with BF3O(C2H5)2(E)‐2isomerizes by cleavage of the C(δ), O‐bond to the γ‐ketoester (E)‐20(s.Scheme 2). Conversion

ISSN:0018-019X    

DOI:10.1002/hlca.19800630711

出版商:WILEY‐VCH Verlag GmbH    

年代:1980

数据来源: WILEY