- Br?nsted acid-mediated cyclization-dehydrosulfonylation/reduction sequences: An easy access to pyrazinoisoquinolines and pyridopyrazines
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An efficient and alternative synthetic approach has been developed to prepare various N-(arylethyl)piperazine-2,6-diones from 4-benzenesulfonyliminodiacetic acid and primary amines using carbonyldiimidazole in the presence of a catalytic amount of DMAP at ambient temperature. Piperazine-2,6-diones are successfully transformed to pharmaceutically useful pyridopyrazines or pyrazinoisoquinolines and ene-diamides via an imide carbonyl group activation strategy using a Br?nsted acid. Subsequent dehydrosulfonylation reactions of the ene-diamides, in a one pot manner, smoothly transformed them to substituted pyrazinones. A concise synthesis of praziquantel (1) has also been achieved through this method.
- Rao, Ramana Sreenivasa,Ramanathan, Chinnasamy Ramaraj
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supporting information
p. 428 - 440
(2017/03/14)
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- 4-BENZYL-1-PHENETHYL-PIPERAZINE-2,6-DIONE PREPARATION METHOD, AND INTERMEDIATE AND PREPARATION METHOD THEREOF
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The present invention provides a key new intermediate (a compound of formula III) of 4-benzyl-1-phenethyl-piperazine-2,6-dione (formula IV compound), a pharmaceutically acceptable salt thereof and a preparation method thereof. The present invention additi
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Paragraph 0043
(2016/06/06)
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- 4-BENZYL-1-PHENETHYL-PIPERAZINE-2,6-DIONE PREPARATION METHOD, AND INTERMEDIATE AND PREPARATION METHOD THEREOF
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The present invention provides a key new intermediate (a compound of formula III) of 4-benzyl-1-phenethyl-piperazine-2,6-dione (formula IV compound), a pharmaceutically acceptable salt thereof and a preparation method thereof. The present invention additi
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Paragraph 0051; 0052
(2017/01/05)
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- Synthesis and Anthelmintic Activity of a Series of Pyrazinobenzazepine Derivatives
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A series of 1,2,3,4,6,7,8,12b-octahydropyrazinobenzazepine derivatives was prepared and the cestocidal activity of the compounds evaluated in an in vitro Taenia crassiceps screen.Many of these derivatives proved to be highly active, and 2-(cyclohexylcarbonyl)-4-oxo-1,2,3,4,6,7,8,12b-octahydropyrazinobenzazepine, epsiprantel (BAN) (22), was selected for further development.The structure-activity relationships are discussed.
- Brewer, Malcolm D.,Burgess, Malcolm N.,Dorgan, Roderick J. J.,Elliott, Richard L.,Mamalis, Patrick,et al.
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p. 2058 - 2062
(2007/10/02)
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