摘要:

AbstractThe crystal structure of the title compound has been determined by X‐ray crystallographic analysis from diffractometer data. The compound is found to exist in the crystalline state as the mono‐cisisomer (a). The conjugated chain is in a folded configuration and the two sulfur atoms are on opposing sides. It is the first time such a mono‐cisisomer has been analysed by X‐ray crystall

ISSN:0018-019X    

DOI:10.1002/hlca.19740570102

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractThe structure ofdes‐boron‐des‐valine‐boromycin C40H68O14· H2O (DBDVB), the product obtained by hydrolysis of the antibiotic boromycin C45H74BNO15, has been determined by X‐ray analysis. The molecule is remarkably similar in constitution, configuration and even in conformation to those of boromycin anddes‐valine‐boromycin determined previously [2], showing that the overall molecular shape is retained on removal of the sp

ISSN:0018-019X    

DOI:10.1002/hlca.19740570103

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractThe gas phase thermal decomposition of triallylamine was studied in the temperature range 531 to 620 K. The major products observed in the reaction were propylene and 3‐picoline. The first order rate constants for depletion of triallylamine, obtained using the internal standard technique, are found to be independent of pressure and conversion, and fit theArrheniusrelationship\documentclass{article}\pagestyle{empty}\begin{document}$$ \log ({\rm k}/{\rm s}^{ - 1}) = 11.74 \pm 0.07 - (38.27 \pm 0.19)/\theta \,\,{\rm where}\,\theta = 2.303\,{\rm RT}\,{\rm kcal/mol} $$\end{document}The reaction appears to be homogeneous, as a 15‐fold change in thc surface‐to‐volume ratio of the vessel left the rate constants unchanged. The Arrhenius parameters are consistent with a molecular elimination reaction involving a six‐center transition state, yielding propylene and N‐allyl‐prop‐2‐enaldimine. It is proposed that the latter product undergoes a 1,5‐hydrogen transfer, followed by a ring closure reaction to yield dihydropicoline, which in turn reacts forming 3‐picoline via a self‐initiated

ISSN:0018-019X    

DOI:10.1002/hlca.19740570104

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

Abstract3‐Benzoyl‐thiocarbazic acid O‐methyl ester7aand 3‐benzoyl‐dithiocarbazic acid methyl ester7bare methylated, in presence of alkali, at the SH group of1a, the ene‐thiol tautomer of1, to give the 3‐benzoyl‐isothiocarbazic acid O, S‐dimethyl ester8aand the 3‐benzoyl‐isodithiocarbazic acid dimethyl ester8bresp., which clearly differ from the N‐methylated compounds11aand12aor11band12bprepared from the two N‐methyl benzohydrazides9and10resp. (melting points, thin‐layer chromatography and NMR. spectra).The previously reported [1] ring closure of 3‐(ω‐chloroalkanoyl)‐thiocarbazic acid O‐alkyl esters and ‐dithiocarbazic acid alkyl esters can be interpretated as an intramolecular auto‐alkylation of CONHNHCSYR: the 3‐(chloroacetyl)‐compounds2areS‐alkylated(enethiol form) to the six‐membered thiadiazinones4, but the 3‐(3‐chloropropionyl)‐compounds3areN‐alkylatedto the pyrazolidinones6, the five‐membered ring being preferred in the latter case to the seven‐membered ring5which would be formed by S‐alkylation. Hence the position of alkylating attack depends on the size of the ring to be formed.As a consequence, starting from 3‐(4‐chlorobutyryl) compounds13, an alternative between the two N‐alkylation products14(five‐membered ring) and15(six‐membered ring) would be expected. On the contrary however, a combination of 1,3,4‐thiadiazole ring closure and chlorine elimination predominates, giving the 5‐(3‐hydroxypropyl)‐1,3,4‐thiadiazoles16. This reaction may proceedviathe butyrolacto

ISSN:0018-019X    

DOI:10.1002/hlca.19740570105

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractThe absolute configurations of (+)‐cantharic acid, a chiral derivative of the achiral insect defensive substance cantharidin (1), and of palasonin, a lower homologue of1occurring in the plantButea frondosa, were shown to be represented by formulas2and3, respectively (scheme 1). These results were obtained by application of theHoreaumethod (table 1) on the (+)‐cantharic acid derivatives (+)‐5, (−)‐7, and (−)11(scheme 2), and the palasonin derivatives (+)‐29and (+)‐30(scheme 4), as well as by comparison of the chiroptical properties (tables 2and3) of a number of derivatives, prepared from either cantharic acid or palasonin. – Attempts to incorporate various radioactively labelled precursors into palasonin (3), using young and adult plants, have been so

ISSN:0018-019X    

DOI:10.1002/hlca.19740570106

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractTreatment of keto‐sugarp‐nitrophenylhydrazones with lead tetraacetate led to the correspondinggem‐azo‐acetates. The reaction is highly stereoselective, only one of the two possible epimers at the new asymmetric carbon being formed in measurable quantity. Catalytic de‐acylation of thesegem‐azo‐acetates yielded, quantitatively, representatives of a new class of nitrogen‐containing sugars: thegem‐azo‐alcohols. When treated with potassiumt‐butylate, thegem‐azoacetates underwent a rearrangement with ring expansion le

ISSN:0018-019X    

DOI:10.1002/hlca.19740570107

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractThe four isomeric dithymidine monophosphates βTd‐βTd(1), αTd‐βTd(2), βTd‐αTd(3) and αTd‐αTd(4), differing only by the anomeric configurations of the nucleoside units, were prepared from the suitably protected nucleosides and nucleotides. The four dinucleoside monophosphates were tested as substrates of snake venom phosphodiesterase and spleen phosphodiesterase. Both enzymes accept all four compounds as substrates, however, the rate of the hydrolysis is considerably smaller if the enzymic attack takes place at the α‐nucleoside moiety of the dinucleo

ISSN:0018-019X    

DOI:10.1002/hlca.19740570108

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractDurch Umsetzung vonSchiff'schen Basen aus 4‐(2H‐Arenotriazol‐2‐yl)‐benzaldehyden undp‐Chloranilin mitp‐tolyl‐substituierten Heterocyclen aromatischen Charakters mit mindestens einem Ring‐Stickstoffatom können in Dimethylformamid in Gegenwart von Kaliumhydroxid die entsprechenden, in 4′‐Stellung heterocyclisch substituierten 4‐(2H‐Arenotriazol‐2‐yl)‐stilbene darg

ISSN:0018-019X    

DOI:10.1002/hlca.19740570109

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractIt has been found that difluorocarbene undergoes extensive addition to theendo‐face of norbornadiene, yeilding the cheletropic adduct, 4.4‐difluorotetracyclo[3.3.0.02,8.03,6]‐octane. Similar behaviour has been observed for fluorochlorocarbene. Possible mechanisms to rationalize this novel behaviour of carbenes are disc

ISSN:0018-019X    

DOI:10.1002/hlca.19740570110

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractFrom saprophytic cultures of a strain ofClaviceps paspali Stevens et Hall, which produces as main metabolite 6‐methyl‐Δ8,9‐ergolen‐8‐carboxylic acid, three new alkaloids of the clavine type were isolated. One is a dihydro derivative of setoclavine, the two others, which are named paspaclavine and paliclavine, represent new struct

ISSN:0018-019X    

DOI:10.1002/hlca.19740570111

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY