摘要:

AbstractThe wood ofAnodendron paniculatumcontains a large number of cardenolides; 14 of such compounds could be spottet in PC. and TLC. withKeddereagent. Five of these (A, E 1, E 2, F, and G) could be isolated in crystalline form and two other ones (B 1 and B 2) as an amorphous mixture. A crystalline aromatic ketone (compound α) was obtained as by‐product. The isolated cardenolides, named as anodendrosides A‐G, were found to be glycosides containing unusual sugars. According to UV. and IR. spectra the genin portion in anodendroside E 1 (probably also in F and B 2) contains a cardenolide structure with saturated ring D and normal butenolide side‐chain, while the anodendrosides A, E 2 and G (probably also B 1) contain an additional double bond at C‐16. The four compounds for which IR. spectra could be taken (A, E 1, E 2, and G) possess a ke

ISSN:0018-019X    

DOI:10.1002/hlca.19700530602

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractIn a new approach, unstable carbenium ions produced in strong protic media could be trapped by thioethers yielding sulfonium compounds. The method has successfully been applied to the rearrangement reactions ofsec‐butyl alcohol and pinacol, where carbenium ions could be trapped before their rearrangement.In the case of the pinacol‐pinacon rearrangement the carbenium ion13has already been discussed but for the first time its existence is proved.Since compound16has been found, a new mechanism for the pinacol‐pinacon rearrangement is postulated starting with diprotonated pi

ISSN:0018-019X    

DOI:10.1002/hlca.19700530603

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractThe syntheses of ergonine and ergoptine, two new analogues of ergot alkaloids possessing the stereochemistry of the already known peptide type alkaloids, are described. The synthetic pathway corresponds to that used already for the synthesis of the natural ergot peptide alkaloids.

ISSN:0018-019X    

DOI:10.1002/hlca.19700530604

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractA new synthetic zeolite, (CH3)4NA1Si3O8, H2O, has been synthesized and shown to be an isotype of the mineral gismondine, CaAl2Si2O8,4H2O. Sodium and other cations can be introduced by ion exchange after thermal decomposition of the organic cation. A continuous structural change to «cubic» NaPhas thereby been recorded, which indicates that the latter is also based on a gismondine‐type aluminosilicate framework.The crystal structure of tetramethylammonium‐gismondine has been determined using X‐ray powder data supplemented by electron diffraction. The crystals are tetragonal,a= 9.84 andc= 10.02 Å, with 4 formula units per unit cell. The apparent symmetry of the framework structure isI41/amd, however, this is violated by the organic cation. Two of the methyl groups are pointing to oxygen atoms of the framework and the short methyl‐oxygen distances indicate CH ⃛

ISSN:0018-019X    

DOI:10.1002/hlca.19700530605

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractThe kinetics of the diazo coupling reactions of diazotized sulfanilic acid with 9 derivatives of 2‐naphthol, each containing a substituent in the 8‐position, have been measured. The reactions proceed by general base catalysis. The rate constants (k1) for the formation of the steady‐state intermediate in the presence of varying concentrations of a base (pyridine) have been evaluated from rate measurements. Similarly the ratiosk2/k1(wherek2is the rate constant for proton transfer from the steady‐state intermediate to the base, andk−1is the rate constant for the dissociation of the intermediate) have been determined. The dependence of logk1on σ+mand of the ratiok2/k−1on a steric parameterRf(defined in this paper) is interpreted as evidence for the steady‐state intermediate existing as a benzodienone σ‐complex with thesp3‐bound hydrogen in a pseudo‐equatorial position and the electrophile pseudo‐axial. A sterically caused destabilisation of the intermediate can be excluded. The steric influence on the ratiok2/k−1is therefore due to the steric influence onk2only. Diazo coupling of 8‐(2′‐pyridyl)‐2‐naphthol is subject to intramolecular base catalysis, as demonstrated

ISSN:0018-019X    

DOI:10.1002/hlca.19700530606

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractThe isomerisation of 2‐naphthol‐1‐sulfonic acid (potassium salt) into 2‐naphthol‐6‐sulfonic acid has been studied using labelled sulfuric acid (H235SO4). In 40 to 50% aqueous sulfric acid the reaction takes place exclusively by an intermolecular mechanism (protio‐desulfonation and resulfonation). In glacial acetic acid, in the presence of an excess of sulfuric acid, the rearrangement is partly intramolecular. With an equimolar amount of sulfuric acid the rearrangement is completely intramolecular. This reaction is first order with respect to 2‐naphthol‐1‐sulfonic acid and zeroth order with respect to excess of sulfuric acid. A mechanism for the r

ISSN:0018-019X    

DOI:10.1002/hlca.19700530607

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractStarting from cyclohexene and 2, 2′, 5, 5′‐tetramethylbiphenyl the linear bisindenofluorene 12, 15‐dihydro‐6H‐diindeno [1.2‐b; 2′.1′‐h] fluorene (XX) has been synthesized in 5 steps (overall yield 27%). As an intermediate product the 6, 12, 15‐trioxo‐derivative XIX (greyish green crystals, blue alcaline vat) was obtained. By a side way, the 6‐oxo‐derivative of XX and the already known monoangular bis‐indenofluorene 14, 15‐dihydro‐8H‐diindeno [2.1‐a; 2′.1′ ‐h] fluorene (XXVII) were also obtained. XX can also be prepared in several steps

ISSN:0018-019X    

DOI:10.1002/hlca.19700530608

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

Abstracto‐Di‐isobutenyl‐benzene (4) on irradiation in hexane with a low‐pressure mercury lamp gives 4 photoproducts in an overall yield of 24%. Three of these products were identified as 4, 4, 6, 6‐tetramethyl‐benzobicyclo [3.1.0] hex‐2‐ene (5, main product, 14%), 1.1‐dimethyl‐2‐isopropenyl‐indane (6, 8%) and 1‐isopropenyl‐2, 2‐dimethyl‐indane (10, 2%).6is also for

ISSN:0018-019X    

DOI:10.1002/hlca.19700530609

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

Abstract2‐Benzothiazole‐carbaldehyde is transformed into di‐O‐acetyl‐enol‐(benzothiazolecarboxyl‐2)‐oin in the presence of acetic anhydride and of pyridine as catalyst. Without pyridine or with 2,6‐lutidine no reaction occurs. A mechanism of this reaction is proposed. No reaction was observed in the case of benzaldehyde.Choral reacts with acetic anhydride in the presence of pyridine as well as of 2,6‐lutidine as catalyst to give 1,1‐diacetoxy‐2,2,2‐trichloro‐ethane. A mechanism is proposed, in which in an intermediate state the acetate ion (and not pyridine, for steric reasons) attacks the carbon of the carbonyl function of the conjugate acid with the acetylium cation to yield 1,1‐diacetoxy‐2,2,2‐trichloro‐ethane.These two reactions occur only with aldehydes whose carbonyl is very electrophilic, and seem to be a possible way to point out the presence of a

ISSN:0018-019X    

DOI:10.1002/hlca.19700530610

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractAus β‐Pentaacetyl‐D‐glucose wurde unter Variation und methodischer Verbesserung der Reaktionsbedingungen über die bekannten Zwischenprodukte II, III, IIIa die eben‐falls bekannte α‐Acetobro n‐D‐chinovose (IV) hergestellt. Der Übergang in die 1‐Thio‐D‐chinovose‐Reihe, V, Va, VI bis VIc, erfolgte in durchwegs sehr guten Ausbeuten aus der Acetohalogenose IV mit Kalium‐äthylxanthogenat und Folgeraktionen, bzw. mit Kaliumthioacetat. Die krist., wenig beständige 1‐Thio‐D‐chinovose

ISSN:0018-019X    

DOI:10.1002/hlca.19700530611

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY