摘要:

AbstractThe transverse relaxation rate of H2O in Al(H2O) 63+has been measured as a function of temperature (255 to 417 K) and pressure (up to 220 MPa) using the17O‐NMR line‐broadening technique, in the presence of Mn(II) as a relaxation agent. At high temperatures the relaxation rate is governed by chemical exchange with bulk H2O, whereas at low temperatures quadrupolar relaxation is prevailing. Low‐temperature fast‐injection17O‐NMR was used to extend the accessible kinetic domain. The samples studied contained Al3+(0.5m), Mn2+(0.2–0.5m),H+(0.2–3.1m) and17O‐enriched (20–40%) H2O. Non‐coordinating perchlorate was used as counter ion. The following H2O exchange parameters were obtained:k ex298= (1.29 ± 0.04) s−1, ΔH* = (84.7 ± 0.3) kJ mol−1, ΔS* = +(41.6 ± 0.9)J K−1mol−1, and ΔV ex*= +(5.7 ± 0.2) cm3mol−1, indicating a dissociative interchange,Id, mechanism. These results of H2O exchange on Al(H2O) 63+are discussed together with the available complex‐formation rate data and permit also the assign

ISSN:0018-019X    

DOI:10.1002/hlca.19850680302

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractTwo new saponins, β‐D‐glucopyranosyl 3‐O[O‐βD‐xylopyranosyl‐(1→3)‐O‐(β‐D‐glucopyranosyluronic acid)]oleanolate (1) and 3‐O‐[O‐β‐D‐xylopyranosyl‐(1→3)‐O‐(β‐D‐glucopyranosyluronic acid)]oleanolic acid (2), have been isolated from the tubers ofTalinum tenuissimum. The structures have been established mainly by13C‐NMR and FAB‐MS. The monodesmosidic saponin2exhibits very strong molluscicidal activity against the sch

ISSN:0018-019X    

DOI:10.1002/hlca.19850680303

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

(E)‐3‐(1H‐Pyrrol‐3‐yl)‐2‐propenoic Acid and (E)‐3‐(1H‐Pyrrol‐3‐yl)‐2‐propenamide fromStreptomyces parvulus, Strain Tü 2480The title compounds were isolated from cultures ofStreptomyces parvulus. They give a deep blue colour reaction withEhrlichreagent. Their structures were elucidated by spectroscopy and comparison with synthetic samples. They do not sho

ISSN:0018-019X    

DOI:10.1002/hlca.19850680304

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractPhase‐transfer glycosylation of 4‐methoxy‐1H‐pyrazolo[3,4‐d]pyrimidine with the 2‐deoxyribofuranosyl chloride9formed the N(1)‐β‐nucleoside10aas main product (39%). As by‐products the α‐D‐anomer11a(7%) and the N(2)‐isomer12a(18%) were isolated. Assignment of these isomers was made on the basis of their1H‐ and13C‐NMR spectra. Removal of the sugar‐protecting groups yielded the 4‐methoxy‐nucleosides10b, 11b, and12b, respectively. Nucleophilic displacement of the 4‐MeO‐group gave the 2‐deoxyribofuranosides1–4of allopurin

ISSN:0018-019X    

DOI:10.1002/hlca.19850680305

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Abstract1‐O‐Acetyl‐1‐O‐demethylcolchicine, and acylated 1‐O,2‐O‐didemethylthiocolchicines, in contrast to 2‐O‐acetyl‐, 2‐O,3‐O‐diacetyl‐ and 3‐O‐acetyl analogs, showed after standing in CHCl3solution significant changes in optical rotation, a duplication of1H‐NMR signals, and the formation of new isomers on TLC. Solid‐state X‐ray diffraction ofO‐acetylated colchinoids and thio analogs, showed out of planar arrangements of the aromatic substituents, but the analysis could not help to explain the structures of

ISSN:0018-019X    

DOI:10.1002/hlca.19850680306

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractThe structure of the title compound obtained from 2(1H)‐quinoxalinone oxime by the template effect of Co(II) and Ni(II) ion has been determined by three dimensional X‐ray analy

ISSN:0018-019X    

DOI:10.1002/hlca.19850680307

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Photochemical Syntheses of 3‐Oxazolines which Possibly Exhibit Hypoglycemic ActivityReactions of photochemically generated benzonitrile methylides2with carbonyl compounds3yielded 3‐oxazolines of the types5and6(Scheme 1). Photooxidation of 5‐[p‐(dimethylamino)phenyl]‐2,2‐dimethyl‐4‐phenyl‐3‐oxazoline (5a) gave 4′‐(2,2‐dimethyl‐4‐phenyl‐3‐oxazolin‐5‐yl)‐N‐methylformanilide (6r) which could be transformed to 2,2‐dimethyl‐5‐[p‐(methylamino)phenyl]‐4‐phenyl‐3‐oxazoline (6s) by photodecarbonylation. Thirty 3‐oxazolines of types5and6have been synthesized and tested by oral and/or intraperitoneal

ISSN:0018-019X    

DOI:10.1002/hlca.19850680308

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Synthesis and Reactions of 5‐[p‐(Dimethylamino)phenyl]‐2,2‐dimethyl‐4‐phenyl‐3‐oxazolineThe title compound8has been synthesized in a one‐pot reaction of 4′‐(dimethylamino)benzoin (4) with 2‐propanone and NH3. The preparation of the intermediate4from3is the first example of an acid‐catalyzed transformation of the stable benzoin3into the corresponding less stable benzoin4. Structures and yields of various by‐products occurring under different reaction conditions during the synthesis of8from4are given. The O‐atom of the 3‐oxazoline ring in8could be replaced by S from P2S5yielding the 3‐thiazoline14. Separation of the enantiomers of the racemate8could only be performed by transforming them into the trimethylanilinium salts8band8cof (−)‐ and (+)‐10‐camphorsulfonic acid, respectively. Solid NaOAc in boiling toluene caused the precipitation of the 10‐camphorsulfonic acids from the quaternary ammonium salts as sodium salts and the removing of the third methyl group from the quaternary ammonium salts as AcOMe to give the enantiomers (−)‐(5S)‐8and (+)‐(5R)‐8. Their absolute c

ISSN:0018-019X    

DOI:10.1002/hlca.19850680309

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Photochemical and Chemical Syntheses of Biologically Active 3‐OxazolinesUsing the photoreaction of 2H‐azirines with carbonyl compounds, the 2,2‐dimethyl‐3‐oxazolines5a, 5b, and6ahave been obtained which bear a mono‐ or dichlorophenyl substituent at C(4) of the five‐membered heterocycle and pyridyl at C(5). These compounds exhibit interesting activities against phytopathogenic fungi. Because6ahad been selected for field testing, its photochemical preparation was supplemented by a chemical synthesis. However, the overall performance of6ain the field was inferior to some of the recently introduced agricultural fungicides of the ergosterol biosynthesis inhibitor type. Although 16 additional 3‐oxazolines with varied substituents have been prepared, the fungicidal activity found with6acould

ISSN:0018-019X    

DOI:10.1002/hlca.19850680310

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractLiquid crystals with negative Δϵ can be obtained by incorporating a cyano group in the terminal alkyl substituent or in an ethylene bridge between the cyclic units of the rigid core. The clearing points of such compounds are higher than those of the corresponding derivatives where the cyano group is laterally attached to a phenyl moiety. In compounds where both cyclic units of the rigid core are cyclohexyl, this type of substitution leads to an optimal contribution to ϵ⟂ in contrast to the cyanophenyl derivat

ISSN:0018-019X    

DOI:10.1002/hlca.19850680311

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY