- Biologically Active Compounds through Catalysis: Efficient Synthesis of N-(Heteroarylcarbonyl)-N′-(arylalkyl)piperazines
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A practical route for the synthesis of new biologically active 5-HT 2A receptor antagonists has been developed. In only three catalytic steps, this class of central nervous system (CNS) active compounds can be synthesized efficiently with high diversity. As the initial step, an anti-Markovnikov addition of amines to styrenes provides an easy route to N-(arylalkyl)piperazines, which constitute the core structure of the active molecules. Here, base-catalyzed hydroamination reactions of styrenes with benzylated piperazine proceeded in high yield even at room temperature. After catalytic debenzylation, the free amines were successfully carbonylated with different aromatic and heteroaromatic halides and carbon monoxide to yield the desired compounds in good to excellent yields. The two key reactions, base-catalyzed hydroamination of styrenes and palladium-catalyzed aminocarbonylation of haloarenes/heterocycles, showed tolerance towards various functional groups, thereby demonstrating the potential to synthesize a wide variety of new derivatives of this promising class of pharmaceuticals.
- Kumar, Kamal,Michalik, Dirk,Castro, Ivette Garcia,Tillack, Annegret,Zapf, Alexander,Arlt, Michael,Heinrich, Timo,Boettcher, Henning,Beller, Matthias
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p. 746 - 757
(2007/10/03)
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- Non-imidazole histamine H3 ligands. Part I. Synthesis of 2-(1-piperazinyl)- and 2-(hexahydro-1H-1,4-diazepin-1-yl)benzothiazole derivatives as H3-antagonists with H1 blocking activities
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New 2-(1-Piperazinyl)- and 2-(hexahydro-1H-1,4-diazepin-1-yl)benzothiazoles were prepared and tested as H1- and H3-receptor antagonists. A number of compounds showed weak H1-antagonistic activity, with pA2 values ranging from 5.5 to 6.1. The simple alkyl substituted, 2-[1-(4-methyl and 4-ethyl)piperazinyl] analogues show increasing, moderate H3-antagonistic activity (pA2=6.0, and pA2=7.0). The compounds with 4-phenylalkyl substitution, for both the piperazinyl and the hexahydro-1H-1,4-diazepin-1-yl homologues series, regardless of the different physicochemical properties of the para substituents at the phenyl ring, showed weak H3-antagonistic activity with pA2 values ranging from 4.4 to 5.6. Copyright (C) 1999 Elsevier Science S.A.
- Walczynski, Krzysztof,Guryn, Roman,Zuiderveld, Obbe P.,Timmerman, Henk
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p. 684 - 694
(2007/10/03)
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