ISSN:0165-0513    

DOI:10.1002/recl.19891080502

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractA new and convenient route for the synthesis of several heterotetra‐ and pentacyclic compounds is presented. Heating the 2‐vinyl‐N,N‐dialkylanilines3a‐h, synthesized from the aldehydes2a‐f,hor the acetophenone2gand malononitrile or ethyl cyanoacetate, in refluxing 1‐butanol yields selectively the tetra‐ and pentacyclic compounds4a‐h. This cyclization proceeds via a 1,5 hydrogen shift, followed by an addition of the carbanion to the iminium double bond. The benzo[f]thieno[3,2‐a]quinolizine4cand the benzo[f]thieno[2,3‐a]quinolizine4drepresent new classes of heterocycles.The first example of formation of a six‐membered ring via carboncarbon bond formation, starting from 2‐vinyl‐substituted enamines, was the conversion of5aand5binto the benzo[h]pyrrolo[1,2‐a]‐quinoline6aand the naphtho[2,1‐c]quinolizine6b, respectively. Most probably, the cyclization of5aand5bproceeds in the same way as does the cyclization of the 2‐vinylN,N‐disubstituted aniline derivatives.Heating the tricyano compound5cin refluxing 1‐butanol gave both the benzo[g]pyrrolo[1,2‐a]indole 7 and malononitrile. This cyclization proceeds probably via a 1,6 hydrogen shift, followed by a 1,5 electrocyclization, and a s

ISSN:0165-0513    

DOI:10.1002/recl.19891080503

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

Abstract11B and1H NMR spectroscopy studies have revealed that the apparent association constants for borate esters of 2‐amino 1,3‐diols are pH dependent, whereas such a pH dependence is not found in the case of methyl‐substituted diols or 3‐amino‐1,2‐propanediol. These studies have also shown that boric acid ester formation can be detected u

ISSN:0165-0513    

DOI:10.1002/recl.19891080504

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe epoxidation of alkenes by hypochlorite catalysed by manganese(III) tetraarylporphyrins in a two‐phase water/dichloromethane system is accelerated by lowering the pH of the aqueous phase. This effect is explained by a faster formation of the active [(P)MnO]+species from a (P)MnOCl complex for all types of porphyrin catalysts and additionally by a suppression of dimerization phenomena for non‐sterically hindered cataly

ISSN:0165-0513    

DOI:10.1002/recl.19891080505

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractA new synthesis of 6‐demethoxy‐N‐formyl‐N‐northebaine (1) and its spectacular rearrangement to dibenzazonine8are described.N‐Demethylation of codeine (2) gaveN‐norcodeine (3) which was converted into the mesyl compound5byN‐formylation with ethyl formate, followed by reaction with mesyl chloride in pyridine. A short treatment of5with lithium bromide afforded7which, upon reaction with potassiumtert‐butoxide, yielded1. Reaction of7with zinc in ethanol gave morphinan‐5,7‐diene9. Prolonged treatment of morphinan5with lithium bromide gave dibenzazonine8, which could also be obtained by reaction of1with hydrogen bromide. A mechanism for this rearrangement is proposed.The1H and13C NMR spectra of the new co

ISSN:0165-0513    

DOI:10.1002/recl.19891080506

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe minimum energy conformations of quinine, quinidine, ephedrine andN‐methyl‐ephedrine have been calculated using molecular mechanics and semi‐empirical techniques. Conformational data for quinine and quinidine in solution have been obtained by 2D‐NMR. No evidence has been found for an earlier proposed conformational change of the catalysts3in the asymmetric Michael addition between cycloalkenones and aromatic thiols. The preferred orientations between 4‐methylbenzenethiol and quinine have been predicted with molecular docking calculations; they are in good agreement with NOESY NMR data. The results obtained by this combined NMR and molecular modelling approach suggest a new model for the transition state of alkaloid‐catalyzed addition of aromatic thiols to 2‐

ISSN:0165-0513    

DOI:10.1002/recl.19891080507

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19891080509

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19891080511

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19891080501

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY