摘要:

AbstractFor the assignment of the configuration at C(8) and C(15) of the natural oviposition‐deterring pheromone1inRhagoletis cerasiL., the four possible stereoisomers of1are synthesized. By condensing the C6building blocks (5R)‐4and (5S)‐4with the boron enolates of the C10building blocks (4S)‐13and (4R)‐13, followed by decarboxylative dehydration, all stereoisomers of16are available (Scheme 5). Glucosylation of 16 followed by formation of the taurin amide gives, after deprotection, the four stereoisomers (8R,15S)‐1, (8R,15R)‐1, (8R,15S)‐1, and (8S,1

ISSN:0018-019X    

DOI:10.1002/hlca.19890720122

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

A New Aminoazirine Reaction. Formation of 3,6‐Dihydropyrazin‐2(1H)‐onesThe reaction of 3‐(dimethylamino)‐2H‐azirines1and 2‐(trifluoromethyl)‐1,3‐oxazol‐5(2H)‐ones5in MeCN or THF at 50–80° leads to 5‐(dimethylamino)‐3,6‐dihydropyrazin‐2(1H)‐ones6(Scheme 3). Reaction mechanisms for the formation of6are discussed: either the oxazolones5react as CH‐acidic heterocycles with1(Scheme 4), or the azirines1undergo a nucleophilic attack onto the carbonyl group of5(Scheme 6). The reactionviaintermediate formation ofN‐(trifluoroacetyl)

ISSN:0018-019X    

DOI:10.1002/hlca.19890720123

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

Abstract18‐O‐Methylchaenorpine (1a) and iso‐18‐O‐methylchaenorpine (1b) two novel stereoisomeric spermine alkaloids were isolated from the roots ofAphelandra tetragona(VAHL) NEES.Their structures were established by chemical and spectroscopi

ISSN:0018-019X    

DOI:10.1002/hlca.19890720124

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

ISSN:0018-019X    

DOI:10.1002/hlca.19890720125

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

ISSN:0018-019X    

DOI:10.1002/hlca.19890720101

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY