摘要:

AbstractFourteen peptides, analogues of bradykinin and (des‐Arg9)bradykinin, have been synthesized by the solid‐phase method or have been obtained through chemical modification. In all these peptides an aromatic residue has been substituted by (4′‐NO2)Phe, (4′‐NH2)Phe, (4′‐N3)Phe or (4′‐NH2‐3′, 5′‐I2)Phe. These peptides will be used as photoaffinity labelling or affinity labelling probes fo

ISSN:0018-019X    

DOI:10.1002/hlca.19810640302

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractA comparison ofMössbauerisomer shifts and direct Sn, Sn‐coupling constants for a series of di‐ and polytin compounds indicates that the s‐electron density at the Sn‐atom has little influence on this

ISSN:0018-019X    

DOI:10.1002/hlca.19810640303

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

Synthesis and Characterization of the 8 Stereoisomeric Royleanones with One or Two Hydroxy Groups in Ring BThe partial syntheses of 6α, 7α‐dihydroxyroyleanone (6a), 6α, 7β‐dihydroxyroyleanone (7a) and 6β, 7β‐dihydroxyroyleanone (9a) are described. Thus, all in ring B mono‐ and dihydroxylated royleanones are now known (see [2–11]), being fully characterized by extensive spectroscopic, chiroptic and chromatographic (HPLC.) methods. An opening of the epoxyroyleanone11ayieldscis‐ andtrans‐diols together with their corresponding mono‐ and di‐O‐acetyl derivatives. We postulate a reversible addition of the acetate ion at C(8) of the quinone system, followed by a neighbouring group participat

ISSN:0018-019X    

DOI:10.1002/hlca.19810640304

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractThe title compound4is generated from the phosphoric amide5in tetrahydrofuran with butyllithium. The lithium reagent4is stable at room temperature; its reactions with electrophiles furnish the products6–22,26,27, seeTable 1and theScheme. A second alkylation is also possible, see23–25. The cleavage to tetrahydroisoquinolines is accomplished in refluxing aqueous‐methanolic hydrochloric acid, seeTable 2. Phosphinoylation, lithiation, reaction with electrophiles and cleavage constitute an efficient sequence for 1‐alkylation of the isoquinoline

ISSN:0018-019X    

DOI:10.1002/hlca.19810640305

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

3‐Ethyl‐2‐tetrazo‐6‐X‐benzo[d]thiazolines and Their Reactivity: A Contribution to the Chemistry of Nucleophilic CarbenesThe synthesis of 3‐ethyl‐2‐tetrazo‐6‐X‐benzo[d]thiazolines3‐ a new class of azohomologous diazo compounds ‐ by addition of azide ions to azidinium salts4is described, their structure and some of their reactions are disscussed. The thermolysis of3atca.270Kin DMFA or THF generates nucleophilic carbenes1, whose trapping by electrophilic compounds such as3,4, diazonium salts, diazo compounds, methanol, sulfur and tetracyanoethylene could be studied. Direct dimerisation of1to2(without acid/base catalysis) could not be found, as demons

ISSN:0018-019X    

DOI:10.1002/hlca.19810640306

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

ISSN:0018-019X    

DOI:10.1002/hlca.19810640307

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractA chiral macrocyclic crown ether exhibits an enantiomer‐selectivity of 2.6 for α‐phenylethylammonium ion when incorporated in solvent polymeric membranes. The sequence of selectivity of these membranes clearly differs from that of lipophilicity for the different biogenic ammonium ions studied, indicating a significant structural contribu

ISSN:0018-019X    

DOI:10.1002/hlca.19810640308

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

Preparation of Styryl and Stilbenyl Derivatives of 1H‐Benzotriazoles1‐(p‐Tolyl)‐substituted 1H‐benzotriazoles react with anils of aromatic aldehydes in the presence of dimethylformamide and potassium hydroxide to yield the corresponding 1‐(styr‐4′‐yl)‐1H‐benzotriazoles and 1‐(stilben‐4′‐yl)‐1H‐benzotriazoles, respectively (‘anil synthesis’). Further, under the same reaction conditions, theSchiff's bases derived fromp‐chloroaniline and 4‐(1′H‐benzotriazol‐1′‐yl)benzaldehydes give, withp‐tolyl‐substituted heterocycles, the corre

ISSN:0018-019X    

DOI:10.1002/hlca.19810640309

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractAromatization in the series of optically active 1‐benzyltetrahydroisoquinolines has been accomplished with (—)‐(S)−(N‐nor)‐reticuline (1b) and analogs. Direct catalytic or chemical reduction of the isoquinoline4obtained could not be achieved in a practical way but4was converted into1in three steps (4 → 8 → 9 → 1), in 55% overall yield. PartialO‐methylation of the isoquinoline4gave the isoquinoline alkaloid palaudine (5), before papave

ISSN:0018-019X    

DOI:10.1002/hlca.19810640310

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

Chiral Electrophilic Synthetic Building Blocks with Four Different Functional Groups from Tartaric Acid, 2, 3‐ and 3, 4‐Epoxy‐butanediol Derivatives in All Four Stereoisomeric FormsEfficient and simple procedures have been developed for the preparation of thethreo‐ anderythro‐3, 4‐epoxy‐1, 2‐butanediol derivatives3and8and of thecis‐ andtrans‐2, 3‐epoxy‐1, 4‐butanediol derivatives7and9in both enantiomeric forms from tartaric acid (seeScheme 2). These epoxides should prove versatile as alkylating reagents in syntheses of enantiomerically pure natural products and of physiol

ISSN:0018-019X    

DOI:10.1002/hlca.19810640311

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY