An enantioselective synthesis of natural (-)-huperzine a via cinchona alkaloids-promoted asymmetric michael reaction

Heterocycles

Volumn 46, Issue 1, 1997, Pages 27-30

  Kaneko, Satoru ^a   Yoshino, Toshiharu ^a   Katoh, Tadashi ^a   Terashima, Shiro ^a  

^a SAGAMI CHEMICAL RESEARCH CENTER   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0002004240     PISSN: 03855414     EISSN: None     Source Type: Journal    
DOI: 10.3987/com-96-s4     Document Type: Article

References (24)

1. Visiting scientist from Exploratory Chemistry Research Laboratory, Sankyo Co., Ltd.
2. Present address: Exploratory Research Laboratories Daiirhi Pharmaceutical Co., Ltd.
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18. The representative enantiomeric excesses observed for the reactions employing other chiral amines in dichloromethane at 20 °C were as follows: N-methylephedrine (12% ee), (S)-(+)-l-(2-pyrrolidinyl-methyOpyrrolidine (14% ee), (R)-(+)-2-methoxymethylpyrrolidine (17% ee), (R)-α-pnenylethylamine (43% ee).
19. CHIRALCEL OD-H (DAICEL CHEMICAL INDUSTRIES, LTD) was used. Eluent (hexane : 2-propanol = 20 : 1) was flown by 0.5 ml/min and the products were detected by UV (254 nm).
20. Neither sonification nor decrease of the amount of catalyst ( 20 mol% ) affects the enantiomeric excess.
21. The asymmetric Michael reaction did not proceed below -20°C.
22. 15 the transition state model shown below may be postulated based on the observed enantiomeric excess and absolute configuration of the products. Figure presented
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