- Pyridazine N-Oxides as Precursors of Metallocarbenes: Rhodium-Catalyzed Transannulation with Pyrroles
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Pyridazine N-oxides are used for the first time as precursors of metallocarbenes. These nitrogen-rich heterocycles led to the discovery of a novel acceptor and donor-acceptor enalcarbenoids. The synthetic utility of these metallocarbenes was demonstrated in the rhodium-catalyzed denitrogenative transannulation of pyridazine N-oxides with pyrroles to the valuable alkyl, 7-aryl, and 7-styryl indoles. The transannulation strategy was applied to the synthesis of a potent anticancer agent.
- Kanchupalli, Vinaykumar,Joseph, Desna,Katukojvala, Sreenivas
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supporting information
p. 5878 - 5881
(2015/12/11)
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- Design, synthesis, and structure-activity relationships of a series of 3-[2-(1-benzylpiperidin-4-yl)ethylamino]pyridazine derivatives as acetylcholinesterase inhibitors
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Starting from the 3-[2-(1-benzylpiperidin-4-yl)ethylamino]-6-phenylpyridazine 1, we performed the design, the synthesis, and the structure-activity relationships of a series of pyridazine analogues acting as AChE inhibitors. Structural modifications were achieved on four different parts of compound 1 and led to the following observations: (i) introduction of a lipophilic environment in the C-5 position of the pyridazine ring is favorable for the AChE-inhibitory activity and the AChE/BuChE selectivity; (ii) substitution and various replacements of the C-6 phenyl group are possible and led to equivalent or slightly more active derivatives; (iii) isosteric replacements or modifications of the benzylpiperidine moiety are detrimental to the activity. Among all derivatives prepared, the indenopyridazine derivative 4g was found to be the more potent inhibitor with an IC50 of 10 nM on electric eel AChE. Compared to compound 1, this represents a 12-fold increase in potency. Moreover, 3-[2-(1-benzylpiperidin-4-yl)ethylamino]-5-methyl-6-phenylpyridazine 4c, which showed an IC50 of 21 nM, is 100-times more selective for human AChE (human BuChE/AChE ratio of 24) than the reference compound tacrine.
- Contreras,Parrot,Sippl,Rival,Wermuth
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p. 2707 - 2718
(2007/10/03)
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- Pyridazine derivatives
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The present invention relates to pyridazine derivatives of formula: STR1 which are useful as ligands of cholinergic receptors, in particular, receptors of the M1 type.
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- One-pot preparation of 6-substituted 3(2H)-pyridazinones from ketones
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A one-pot process for the preparation of 6-phenyl-3(2H)-pyridazinone from acetophenone and glyoxylic acid has been investigated and shown to have wide utility in the preparation of 6- and 5,6-substituted 3(2H)-pyridazinones. Limitations to the process encountered with 2'-hydroxyacetophenone and with basic hetero-aromatic ketones have been overcome, and the processes described offer the rapid and efficient synthesis of many 6-substituted pyridazinones from readily available ketones.
- Coates,McKillop
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p. 334 - 342
(2007/10/02)
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- USE OF 5-ALKYLPYRIDAZINE DERIVATIVES AS DRUGS ACTIVE ON THE CHOLINERGIC SYSTEM
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The invention relates to the use of 5-alkylpyridazine derivatives of the formula STR1 in which R 1 is a C 1-C 4 alkyl group or a phenyl group and R 2 and R 3 independently are a C 1-C. sub. 4 alkyl group, or R 2 and R 3, taken with the nitrogen atom to wh
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- Synthesis and Structure-Activity Relationships of Series of Aminopyridazine Derivatives of γ-Aminobutyric Acid Acting as Selective GABA-A Antagonists
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We have recently shown that an aryloaminopyridazine derivarive of GABA, SR 95103 , is a selective and competitive GABA-A receptor antagonist.In order to further explore the structural requirements for GABA receptor affinity, we synthesized a series of 38 compounds by attaching various pyridazinic structures to GABA or GABA-like side chains.Most of the compounds displaced GABA from rat brain membranes.All the active compounds antagonized the GABA-elicited enhancement of diazepam binding, strongly suggesting that all these compounds are GABA-A receptor antagonists.None of the compounds that displaced GABA from rat brain membranes interacted with other GABA recognition sites (GABA-B receptor, GABA uptake binding site, glutamate decarboxylase, GABA-transaminase).They did not interact with the Cl- ionophore associated with the GABA-A receptor and did not interact with the benzodiazepine, strychnine, and glutamate binding sites.Thus these compounds appear to be specific GABA-A receptor antagonists.In terms of structure-activity, it can be concluded that a GABA moiety bearing a positive charge is necessary for optimal GABA-A receptor recognition.Additional binding sites are tolerated only if they are part of a charge-delocalized amidinic or guanidinic system.If this delocalization is achieved by linking a butyric acid moiety to the N(2) nitrogen of a 3-aminopyridazine, GABA-antagonistic character is produced.The highest potency (ca.250 times bicuculline) was observed when an aromatic ? system, bearing electron-donating substituents, was present on the 6-position of the pyridazine ring.
- Wermuth, Camille-Georges,Bourguignon, Jean-Jacques,Schlewer, Gilbert,Gies, Jean-Pierre,Schoenfelder, Angele,et al.
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p. 239 - 249
(2007/10/02)
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- Hypotensive alkyl-3-[6-(aryl)-3-pyridazinyl]-carbazates
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This disclosure describes novel alkyl 3-[6-(aryl)-3-pyridazinyl]-carbazates useful as hypotensive agents in mammals. SP CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of our copending application Ser. No. 692,254, filed June 3, 1976 now abandoned, which in turn is a continuation-in-part of our abandoned application Ser. No. 552,024, filed Feb. 24, 1975 now abandoned.
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