摘要:

AbstractComparison of PE. spectroscopic data for four series of enamines (including azetidine and some aziridine derivatives) for studying the influence of amine‐ring size on electronic structure show the pyrrolidino group to exhibit the strongest amine/double bond coupling in sterically unconstrained enamines. However, the azetidino group accommodates best steric congestion due to dialkyl substitution at the β‐position of the enamine unit. Quantum‐chemical calculations of equilibrium structures and energy profiles for amine rotations in model enamines by the PRDDO SCF method agree satisfactorily with experimental results. Notable exceptions are pyrrolidine derivatives for which PRDDO overestimates the amount of N‐pyra

ISSN:0018-019X    

DOI:10.1002/hlca.19810640802

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractThe photoelectron (PE.) spectra ofN‐vinylaziridine (1) and some methyl and ethyl substituted derivatives are discussed in the light of quantum‐chemical model calculations using the PRDDO SCF method. All aziridine enamines are found to exist as equilibrium mixtures of variable compositions, with an enamine‐type conformation (I) generally as the major and atrans‐bisected form (II) as the minor co

ISSN:0018-019X    

DOI:10.1002/hlca.19810640803

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

Abstractp‐Nitrobenzenesulfonyl nitroimidazole (p‐NBSNI) (5) has been shown to be an efficient and convenient condensing agent in the coupling of protected nucleotide fragments. Its utility has been demonstrated by a direct comparison with previously‐described condensing agents in the synthesis of various di‐ and tetradeoxy‐nu

ISSN:0018-019X    

DOI:10.1002/hlca.19810640804

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractN‐Substituted 9‐fluorenimines1are easily prepared from primary amines or aminoesters and 9‐fluorenimine: their conjugate carbanions2are formed by the action of alkoxides and are reprotonated to1or to the tautomeric 9‐alkylidenamino‐fluorenes3depending upon sub

ISSN:0018-019X    

DOI:10.1002/hlca.19810640805

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractAnchimerically assisted rearrangement, observed in the fluorination of some α‐amino acids with 70 : 30 (w/w) hydrogen fluoride/pyridine (by weight) in the presence of NaNO2, is substantially or fully suppressed by using the less acidic reagent 48 : 52 (w/w) hydrogen fluoride/pyridi

ISSN:0018-019X    

DOI:10.1002/hlca.19810640806

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractDisubstituted acetylenes are oxidized with PhIO in presence of Ru‐catalysts to afford α‐diketones in 65–85% yield. Under the same conditions terminal acetylenes are cleaved to carboxylic

ISSN:0018-019X    

DOI:10.1002/hlca.19810640807

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractThe regioselectivity of the hydroperoxidation of tetrasubstituted olefins by singlet oxygen is rationalized in terms of the zwitterionic peroxide model.

ISSN:0018-019X    

DOI:10.1002/hlca.19810640808

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractThe synthesis of several 14‐hydroxymorphinans, using oxymorphone (= 3, 14‐dihydroxy‐4,5‐epoxy‐N‐methylmorphinan‐6‐one,1) as starting material, is described. The antinociceptive potency of theN‐methyl substituted 14‐hydroxy‐morphinans was determined. Thus, in order of antinociceptive potency, 14‐hydroxy‐4‐methoxy‐N‐methylmorphinan‐6‐one (5)>4,5‐epoxy‐14‐hydroxy‐N‐methyl‐morphinan‐6‐one (3)>4, 14‐dihydroxy‐N‐methylmorphinan‐6‐one (4)>14‐hydroxy‐4‐methoxy‐N‐methylmorphinan (11) ≈4, 14‐dihydroxy‐N‐methylmorphinan (12). The most potent compound in this series,14‐hydroxy‐4‐methoxy‐N‐methyl‐morphinan‐6‐one (5)

ISSN:0018-019X    

DOI:10.1002/hlca.19810640809

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractSingle crystals of the title compound are monoclinic, space groupP21/nwith two formula units per cell of the following dimensions:a= 18.209,b= 19.076,c= 4.075 Å, β = 92.43°. The crystals show metallic conductivity along the needle axis from room temperature down toca. 180K, the maximum conductivity at room temperature being 455 (Ω cm)−1.The unoxidized (iodine free) parent compound crystallizes n the monoclinic space groupP21/cwith 2 molecules per cell of dimensions:a= 4.988,b= 20.192,c= 11.871 Å, β =

ISSN:0018-019X    

DOI:10.1002/hlca.19810640810

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractAnother representative of this group of alkaloids, aristoteline (2), was also isolated fromA. peduncularis. This natural compound has previously been isolated fromA. serrataandA. chilensis.

ISSN:0018-019X    

DOI:10.1002/hlca.19810640811

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY