- Microwave-assisted NBS bromination of p-iminotoluenes: Preparation of new alcohol, mercapto, and amino protection groups
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A simple, efficient, safe, high-yielding and rapid microwave-assisted method for the preparation of protected p-bromomethyl and p- dibromomethylanilines was developed as new alcohol, thiol, and amine protection groups. The procedure involves microwave-assisted N-bromosuccinimide (NBS) radical bromination of readily available N-protected p-toluidine. The microwave-assisted radical bromination was found to be superior to the conventional NBS radical bromination. Copyright
- Upadhyay, Sunil K.,Jursic, Branko S.
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experimental part
p. 3177 - 3185
(2011/09/20)
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- 2-[(2-Aminobenzyl)sulfinyl]-1-(2-pyridyl)-1,4,5,6- tetrahydrocyclopent[d]imidazoles as a novel class of gastric H+/K+-ATPase inhibitors
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Substituted 2-sulfinylimidazoles were synthesized and investigated as potential inhibitors of gastric H+/K+-ATPase. The 4,5-unsubstituted imidazole series 6-11 and the 1,4,5,6-tetrahydrocyclopent[d]imidazole series 12 were found to be potent inhibitors of the acid secretory enzyme H+/K+- ATPase. Structure-activity relationships indicate that the substitution of 2- pyridyl groups at the 1-position of the imidazole moiety combined with (2- aminobenzyl)sulfinyl groups at the 2-position leads to highly active compounds with a favorable chemical stability. Other substitution patterns in the imidazole moiety result in reducing biological activities. 2-[(2- Aminobenzyl)sulfinyl]-1-[2-(3-methylpyridyl)]-1,4,5,6- tetrahydrocyclopent[d]imidazole (12h, T-776) was selected for further development as a potential clinical candidate. Extensive study on the acid degradation of 12h indicates a mechanism of action different from that of omeprazole, the first H+/K+-ATPase inhibitor introduced to the market.
- Yamada,Yura,Morimoto,Harada,Yamada,Honma,Kinoshita,Sugiura
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p. 596 - 604
(2007/10/03)
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- Exploration of N-Phosphonoalkyl-, N-Phosphonoalkenyl-, and N-(Phosphonoalkyl)phenyl-Spaced α-Amino Acids as Competitive N-Methyl-D-aspartic Acid Antagonists
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A series of N-substituted α-amino acids containing terminal phosphonic acid groups has been synthesized as potential N-methyl-D-aspartate (NMDA) receptor antagonists.NMDA receptor affinity was determined by displacement of a known ligand (CPP) from crude rat brain synaptic membranes; an antagonists action was demonstrated by the inhibition of glutamate-induced accumulation of (45Ca2+> in cultured rat cortical neurons.Receptor affinity was significantly correlated with antagonist activity (Figure 1).Moderate affinity (IC50 = 1-2 μM) was retained for analogues (31 and 32, Table I; and 59 and 66, Table II) with reduced flexibility in their phosphonate side chains and is consistent with entropy playing a role in determining receptor affinity.Modeling studies suggest a folded conformation that brings the distal phosphonic acid group into close proximity with the α-carboxylate is required for binding.Each of the active analogues possess entropy-limiting features (double bonds, phenyl rings) in their side chains that allows the superposition of their key NH2, α-COOH, and distal PO3H2 groups with those of known competitive antagonists.Affinity decreased for analogues with α-carbon substitution, presumably because the α-substituent inhibits the folding of these structures into a bioactive conformation and occupies receptor-excluded volume.A complete description of the NMDA antagonist pharmacophore model is provided in a companion paper.
- Bigge, Christopher F.,Johnson, Graham,Ortwine, Daniel F.,Drummond, James T.,Retz, Daniel M.,et al.
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p. 1371 - 1384
(2007/10/02)
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- Pyrrolo- and Pyridoindoles via An Intramolecular Wittig Reaction
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Several pyrrolo- and pyridoindoles were prepared via an intramolecular Wittig reaction in good yields.This reaction sequence represents a facile entry into the mitosene ring system.
- Crenshaw, Michael D.,Zimmer, Hans
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p. 623 - 624
(2007/10/02)
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- Organphosphorus Compounds. XVIII. Synthesisi of 2-Phenyl-2,3-dihydro-1H-1,2-benzazaphosphole 2-Sulfide by Pyrolysis of (2-Aminobenzyl)phenyldithiophosphonic Acid
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Reaction of 2-phthalimidobenzyl bromide (12b) with the dialkyl phenylphosphonites (13a-c) afforded the corresponding alkyl phosphinates (14a-c) which upon hydrazinolysis yielded the respective (2-aminobenzyl)phenylphosphinates (16a-c).Reduction of the phosphinates (16a) or (16b) with lithium aluminium hydride gave (2-aminobenzyl)phenylphosphine (15), characterized by its conversion into crystalline 2,3-diphenyl-1,2,3,4-tetrahydro-1,3-benzazaphosphorine (18). (2-Aminobenzyl)phenylphosphine (15) was heated with sulfur in benzene under reflux for 30 min to give 80percent of (2-aminobenzyl)phenyldithiophosphinic acid (20) which when heated between 100-200 deg in vacuum underwent elimination of hydrogen sulfide to yield 2-phenyl-2,3-dihydro-1H-1,2-benzazaphosphole 2-sulfide (22a).Several other new phosphorus compounds are described.An attempt to prepare a 1H-1,2-benzazaphosphole derivative by photolysis of methyl benzylphosphonic azide (7) was unsuccessful.
- Collins, David J.,Drygala, Peter F.,Swan, John M.
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p. 2095 - 2110
(2007/10/02)
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