摘要:

AbstractThe dienone‐dianion derivatives1react with all types of electrophiles tested (alkyl halide, silyl chloride, ester, ketone, aldehyde, epoxide) to give β, γ‐unsaturated carbonyl compounds of typeA(seeFormulae2–6,13,14andTables 1–5). The α‐ and β‐hydroxyalkylation products obtained from1a–1dcan be converted to tetra‐hydrofuran and tetrahydropyran derivatives 7 and16, respectively (Tables 1 and 2), those from the sulfur analogues1eand1fto ketene thioacetals 9 and to dienone derivatives10and12.Thet‐butyl and α‐hydroxy‐ketones are cleaved to give nitriles, amides, carboxylic acids and esters (Formulae16‐25). The reagents1allow to synthesize products with distant functional groups in one step (cf.1,8‐diketones14andFormulae26–30); they correspond to the d5‐synthons31–33; inTable6, they

ISSN:0018-019X    

DOI:10.1002/hlca.19820650202

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

AbstractSechs Vinylketene (9a–9f), wovon fünf Chlor‐vinylketene (9a–e) (s.Schema 2),in situdurch 1,4‐Eliminierung von HCI aus den entsprechenden α, β‐ungesättigten Säurechloriden hergestellt, wurden mit Cyclopentadien (2) bzw. 6,6‐Dimethylfulven (3) umgesetzt. Durch [2 + 2]‐Cycloaddition entstanden fünf 7‐vinylsubstituierte Bicyclo[3.2.0]‐2‐hepten‐6‐one (10/11) bzw. drei 4‐Isopropylidenbicyclo [3.2.0]‐2‐hepten‐6‐one (12/13), wobei das Stereoisomerenverhältnis10:11bzw. 12:13 von der Grösse der Ketensubstituenten beeinflusst wurde. Die Vinylketen‐Cycloaddukte10/11und12/13enthalten einCope‐System, das entweder in einer syn‐(10und12) oder in einer anti‐Konfiguration (11und13) vorliegt. Beim Erwärmen auf 140–190° ergaben10/11bzw,12/13durchCope‐Umlagerung die entsprechend substituierten Bicyclo[4.2.1]‐3,7‐nonadien‐2‐one (14) bzw. 9‐Isopropylidenbicyclo[4.2.1]‐3,7‐nonadien‐2‐one (15). Mittels der beschriebenen Reaktionen werden d

ISSN:0018-019X    

DOI:10.1002/hlca.19820650203

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

AbstractSix unsaturated γ‐lactones, (Z)‐5‐octen‐4‐olide (1), (Z)‐5‐decen‐4‐olide (2).(Z)‐6‐nonen‐4‐olide (3), (Z)‐6‐dodecen‐4‐olide (4), (Z,Z)‐6,9‐dodecadien‐4‐olide (5), and tuberolide (6)have been identified for the first time in tuberose absolute (fromPolianthes tuberosaL.). All structures were corroborated by synthesis and all, except3and4, are new.The name ‘tuberolactone’ has been suggested for (Z,Z)‐2,7‐decadien‐5‐olide [1]. We propose the name ‘tuberolide’ for the bicyclic lactone6. (IUPAC name (1R*,5S*,Z)‐6‐(2′‐pentenyl)‐2‐oxabicyclo[3.3.0]octan‐3‐one).An improved method for the stereoselective synthesis of (±)‐cis‐bicyclo [

ISSN:0018-019X    

DOI:10.1002/hlca.19820650204

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

AbstractMethyl‐2‐acetamido‐4,6‐di‐O‐acetyl‐3‐S‐acetyl‐2‐deoxy‐3‐thio‐α‐D‐mannopy‐ranoside has been synthesized by conversion of methyl 2‐amino‐2‐deoxy‐4,6‐O‐benzylidene‐α‐D‐altropyranoside into the corresponding 3‐O‐methanesulfony1‐2‐N‐[(methylthio)thiocarbonyl]derivative followed by intramolecular displacement of the 3‐O

ISSN:0018-019X    

DOI:10.1002/hlca.19820650205

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Maltoxazine, a Tricyclic Compound from MaltA new tricyclic compound, named maltoxazine, has been isolated from malt as well as from the reaction products formed in a model reaction of maltose with proline. The structure of maltoxazine (1) has been established by1H‐ and13C‐NMR. spectroscopy. The formation of1in several model reactions is strongly correlated with the formation of maltol and 5‐hydroxy‐5,6‐dihy

ISSN:0018-019X    

DOI:10.1002/hlca.19820650206

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

(Perhalomethylthio)heterocycles XII. Preparation of Perfluoroalkylsulfonylurea Derivatives as well as CCl3−nFnX‐Substituted Heterocycles and Their Biological ActivityXI, Mitt., s.[1]In the presence of CF3SO3H (chlorodifluoromethylthio)thiophene1reacts with CClF2SCl to give the 2,5‐disubstituted thiophene2awhich on oxidation with 30% H2O2‐solution yields the corresponding sulfonyl compound2b· R1SO2NCO adds amines to give R1SO2NHC(O)NHR3a–g. Some biological properties of these compounds were in

ISSN:0018-019X    

DOI:10.1002/hlca.19820650207

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

On the Depolymerization of Poly‐(R)‐3‐hydroxy‐butanoate (PHB)From cell‐freePHBor from dried cells ofAlcaligenes eutrophus H 16, which had been grown in an aqueous fructose solution, enantiomerically pure methyl, ethyl, butyl or β‐methoxyethyl (R)‐3‐hydroxy‐butanoates are obtained in yields ranging from 75–90% (0.1 to 70 g scale). The depolymerization is achieved by heating thePHB‐containing materials to temperatures of 80–160° in the corresponding alcohol with or without the cosolvent dichloroethane in the presence of either sulfuric acid or tetraethoxytitanium catalyst. Since (S)‐3‐hydroxy‐butanoates are also readily obtained (by yeast reduction of aceto‐acetates), starting materials derived from 3‐hydroxy‐butyric acid now belong to the especially useful group of synthetic building blocks which a

ISSN:0018-019X    

DOI:10.1002/hlca.19820650208

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

AbstractInvestigation of the formation of complex reaction products in the gas‐phase system O3/NO2/(Z)‐2‐butene by combination of linear reactors with IR. matrix and microwaveStarkSpectroscopy is reported. Besides the polyatomic products observed earlier in the gas‐phase ozonolysis of (Z)‐2‐butene, the following products were identified; N2O5, HNO3, HNO4, CH3NO2, CH3ONO, CH3COONO2and CH3COO2NO2(peroxyacetyl nitrate, PAN). Matrix IR. spectra of N2O5, HNO3. CH3COONO, CH3COONO2required for reference purposes are presented. It is shown that PAN‐formation occurs already in the absence of light. A reaction scheme is proposed for explanation of the observed complex NOx‐containing products, which assumes methyldioxirane as a central intermediate. Particular reaction steps of the scheme will be discussed, including thermochemical estimates of reac

ISSN:0018-019X    

DOI:10.1002/hlca.19820650209

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

AbstractIn connection with the total synthesis of cytochalasans the cleavage of the macrocyclic system of cytochalasin D (3) was studied in order to gain useful relay compounds. Selective scission of the double bond in 19‐position was achieved by controlled ozonolysis leading to compound7(Scheme 1). Treatment of3with OsO4and subsequent acetylation gave the tetraacetoxy‐ and diacetoxy derivatives8and9, respectively.Sharplessepoxidation of3yielded the mono‐, di‐ and the two epimeric triepoxides10,11,12, and13, respectively.Further studies concerned the isomerization of the 6(12)‐double bond to 6(7)‐double bond by an allylic rearrangement. Treatment of3with mesylchloride and triethylamine led to 12‐hydroxy‐, 12‐mesyloxy‐ and 12‐chlorozygosporin (14,16, and17, resp.) (seeScheme 2). Epoxidation of14gave a mixture of the two epimeric 6,7‐epoxides21and23.Zn‐reduction of18(the corresponding bromide of17) led to zygosporin G (20).In order to convert a carbocyclic cytochalasan into a macrocyclic derivative,3was converted to32(Scheme 2). Treatment of32with H2O2in acetic acid/chloroform or with phenylselenylperacid/H2O2yielded the enollactone33.Finally, 17,18‐secocytochalasin D derivatives were prepared for the synthesis of unnatural analogs of macrolidic cytochalasans. The diol26was converted into the ketoaldehydes38and40and to the corresponding keto‐acids43and44(Scheme 3), which were reduced to the ω‐hydroxycarboxylic acids45–48.Treatment of47with 2,2/‐dipyridyldisulfide/triphenylphosphin

ISSN:0018-019X    

DOI:10.1002/hlca.19820650210

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

AbstractA series of lipophilicN,N,N′,N′‐tetrasubstituted diamides were prepared and their selectivity in solvent polymeric membranes was studied,cis‐N,N,N′,N′‐Tetraisobutylcyclohexane‐1,2‐dicarboxamide induces a selectivity in membranes for Li+over alkaline earth metal cations and other alkali metal cations by a factor of about 1000 and 100 respectively. The ionophoreN,N′‐diheptyl‐N,N′‐dimethylethylmalonamide is an attractive candidate for the use in microelectrodes for the determination of in

ISSN:0018-019X    

DOI:10.1002/hlca.19820650211

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY