HETEROCYCLES

Heterocycles has a pay-per-view service for Non-subscribers.
You will be able to directly purchase the full text article through PayPal.
Your purchased Paper can be downloaded after the payment is completed.
An e-mail will be sent the URL to download the paper.
If you have any questions, please contact: purchase@heterocycles.com

Price: ¥ 4,400 (Yen only)
Period: This Article can be accessed for 7 days.

■ Asymmetric Synthesis of Octahydro-2H-pyrido[1,2-a]pyrazines

Olivier Froelich, Françoise Cossart, Martine Bonin, Jean-Charles Quirion,* and Henri-Philippe Husson*

*Laboratoire d'Hétérochimie Organique, Associé au C.N.R.S., IRCOF, INSA de Rouen, Place Emile Blondel, P08, 76131 Mont-Saint-Aignan Cedex, France

Abstract

A series of optically pure octahydro-2H-pyrido[1,2-a]pyrazines has been prepared from (-)-2-cyano-6-phenyloxazolopiperidine (4). 2H-Pyrido[1,2-a]pyrazin-3-(4H)-one (7) and octahydro-2H-pyrido[1,2-a]pyrazine (14) were obtained from diamino alcohol (5) by cyclization of bromo- or chloroamides (6) and (10). (4R,9aS)-1,1,4-Triphenyloctahydro-2H-pyrido[1,2-a]pyrazine (16) was synthesized by cyclization of amino alcohol (15c). The formation of cyclic urea (8aS)-diphenyl-3-oxooctahydroimidazo[1,5-a]pyridine (18) was observed during the hydrogenolysis of the corresponding carbamate (17).