摘要:

Determination of the Chirality Sense of the Enantiomeric 2,6‐AdamantanediolsThe enantiomers of 2,6‐adamantanediol (1) are resolvedviathe diastereoisomeric camphanoates. The (2R,6R)‐chirality sense for (−)‐1and (2S,6S) for (+)‐1was determined by chemical correlation with (−)‐(1R,5R)‐bicyclo[3.3.1]nonan‐2,6‐dion ((1R,5R)‐3) of known absolute configuration in the following way: alkylation of the bis(pyrrolidine enamine) of (−)‐(1R,5R)‐3with CD2I2and hydrolysis of the product gives the enantiomer4of (4,4‐D2)‐2,6‐adamantanedione. Reduction of4with LiAlH4leads to one enantiomer (Scheme 2) of each of the three diols5–7of known absolute configuration. The three diols are themselves configurational isomers due to the presence of the CD2group, but correspond otherwise entirely to the enantiomeric diols1. Accordingly, they can also be separated by means of their diastereoisomeric camphanoates to give the diols5/6and7. These samples are easily distinguished and identified by their characteristic1H‐NMR spectra (cf. Fig. 2). This allows to identify the (2R,6R)‐ and (2S,6S)‐enantiomer of1on the basis of their behavior in the resolution experiment analogous to that of the diols5/6and7, respectively. The diol (−)‐1must have the (2R,6R)‐configuration because it forms, like the diols5/6, with (−)‐camphanic acid the diastereoisomeric ester less soluble in benzene. The diol (+)‐1has (2S,6S)‐configuration, because it forms, like7, with (+)‐camphanic acid the diastereoisomeric ester less soluble in benzene. The bis(4‐methoxybenzoate) of (−)‐(2R,6R)‐1shows chiroptical properties which are in accordance withNakanishi's rule for two chromophores having coupled electric

ISSN:0018-019X    

DOI:10.1002/hlca.19850680702

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Anion‐Selectivity of Distannyl Derivatives in MembranesA series of distannyl derivatives (2,2‐bis(trimethylstannyl)‐1,3‐dithiane, 2,2‐bis(tributylstannyl)‐1,3‐dithiane, hexamethyldistannane, hexabutyldistannane, hexaphenyldistannane, bis(triphenylstannyl)sulfide,o‐bis(trimethylstannyl)benzene) has been studied in view of their applicability as anion‐selective ionophores in solvent polymeric membranes. None of these compounds induces significant changes in the anion‐selectivity pattern as compared with the membranes containing no organotin compound. Representatives with tributylstannyl groups, however, undergo chemical reactions leading to highly active anion ionophores of the type Bu3SnX, several of which (e.g.Bu3SnCl and Bu3SnOH) may be present in equilibrium in the membrane phase depending on the m

ISSN:0018-019X    

DOI:10.1002/hlca.19850680703

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Synthesis of Some 8‐Substituted 2‐Methyl‐1,2,3,4‐tetrahydroisoquinolinesA general route to 8‐substituted tetrahydroisoquinolines is exemplified by the preparation of the 2‐methyl‐1,2,3,4‐tetrahydroisoquinolin‐8‐ol (11), the ‐8‐carbaldehyde oxime (12) and the ‐8‐carbonitrile (13). It involves the conversion of isoquinoline (1) by partially modifiedSteps 1,2,3, and5(see theScheme) into the 5‐bromo‐8‐nitro derivative5, reduction of the latter to the 8‐amino derivative8and replacement of the NH2‐group with an appropriate substituent by aSandmeyer‐like reaction. The selective reductions of the N‐containing ring in6(Steps 5,6, and8) and of the NO2

ISSN:0018-019X    

DOI:10.1002/hlca.19850680704

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Hetero‐Cope‐Rearrangements, Regio‐Controlled Synthesis of IndolesThe reaction ofO‐deprotonatedN‐phenylhydroxylamines1with various electron‐deficient allenes2,14,16gives,via Michaeladdition andCope‐rearrangement, substituted anilines5, which are easily convertible into indoles6. In this manner, sulfoxides17, serve as equivalents of 2‐vinylindoles.Diels‐Alderreaction with this 2‐vinylindole equivalent followed by indolisation affords isoquinuclidine derivative21which may be a useful precursor for the preparation

ISSN:0018-019X    

DOI:10.1002/hlca.19850680705

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractNitrogen adsorption isotherms at 77K and enthalpies of immersion into water at 293K have been measured for a series of artificial and natural calcium carbonates. It appears that the external surface area and the micropore system can be fully characterized if a non‐porous sample, present in the series, is used as an internal reference. Data are given for the reference isotherm. Owing to high specific interactions, immersion into water only provides information on the total surface area of the sample

ISSN:0018-019X    

DOI:10.1002/hlca.19850680706

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractUsing the ‘permutation of indices’ method proposed byKaplanandFraenkel, we could formulate the density‐matrix equations required to fit the temperature‐dependent13C‐NMR spectra observed with the title compounds. For6Li13CHBr2(1) and6Li13CH2SC6H5(2) an exchange mechanism is proposed by which monomers interchange C‐ and Li‐atomsviaa non‐observed dimeric intermediate; the activation parameters of these intermolecular dynamic processes have been found to be ΔH≠= 10.2 kcal/mol, ΔS≠= 13.7 cal/mol·K for1and ΔH≠= 11.1 kcal/mol, ΔS≠= 20.6 cal/mol·K for2((D8)THF as solvent). In the case of (6Li)butyllithium (3), the observed low‐temperature spectra indicate that dimeric (3b) and tetrameric (3a) species are in dynamic equilibrium interchanging the C3H 713CH2groups (and THF molecules) bonded to the6Li‐atoms. The relative concentrations of the dimer and of the tetramer have been determined by peak integration or by line‐shape fitting; the ‘pseudo’‐ equilibrium constant, defined byK′eq= [3b]2/[3a], was found to be 2.6·10−2mol/1 (at −88°) and corresponds to ΔGR(−88°) = 2 ΔG°f(3b) – ΔG°f(3a) = 1.34 kcal/mol. The activation parameters of the dynamic process responsible for the exchange were estimated as ΔH≠= 3.78 kcal/mol and ΔS≠= −31.3 cal/mol·K. Tentati

ISSN:0018-019X    

DOI:10.1002/hlca.19850680707

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Synthesis of the (R)‐ and (S)‐Glycerol Acetonides. Determination of the Optical PurityThe optical purity of (R)‐glycerol acetonide (1) and (S)‐glycerol acetonide (1′) has been determined with great accuracy by gas chromatography after derivatization. The optical purity of (S)‐glycerol actonide prepared fromD‐mannitol was>99.4% while for (R)‐glycerol acetonide obtained fromL‐

ISSN:0018-019X    

DOI:10.1002/hlca.19850680708

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractThe isolation and characterisation of [CoCl(en)(L)]ZnCl4, L = NH2CH2CHNCH2CH2NH2(1,4,7‐triazahept‐3‐ene), as a by‐product (∼ 8% yield) from the H2O2synthesis oftrans‐CoCl2(en) 2

ISSN:0018-019X    

DOI:10.1002/hlca.19850680709

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractMethyl hydrodisulfide and methyl deuterodisulfide have been prepared in a four‐step synthesis. These compounds have been characterized spectroscopically including microwave spectr

ISSN:0018-019X    

DOI:10.1002/hlca.19850680710

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Abstractα‐MSH and ACTH(1–24) were tritiated to high specific radioactivity (>100 Ci/mmol) using a new tritiation apparatus with which the tritiation reaction can be performed at slightly elevated pressure. This allows short reaction times with the least possible damage to the molecule. The starting compounds for the tritiation were [13‐propargylglycine]α‐MSH and [2,23‐Bis(3′,5′‐diiodotyrosine)]ACTH(1–24). Both tritiations were quantitative and yielded products of high purity, full biological activity, and with a specific radioactivity of 115 Ci/mmol and 100 Ci

ISSN:0018-019X    

DOI:10.1002/hlca.19850680711

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY