- Reaction of benzophenone triplet with aliphatic amines. What a potent neurotoxin can tell us about the reaction mechanism
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A photochemical model study of benzophenone triplet (3BP) with the MAO-B substrate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine [MPTP (1)] and two of it's derivatives, 1-cyclopropyl-4-phenyl-1,2,3,6-tetrahydropyridine (2) and (±)-[trans-2-phenylcyclopropyl-4-phenyl-1,2,3,6-tetrahydropyridine (3) were performed. Literature precedent and calculations reported herein suggest that the barrier to ring opening for aminyl radical cations derived from N-cyclopropyl derivatives of tertiary amines (such as MPTP) will be low. The LFP results reported herein demonstrate that pathways for the reaction of 3BP with 1, 2, and 3 are very similar. In each instance, disappearance of 3BP is accompanied solely by appearance of bands corresponding to the diphenylhydroxylmethyl radical and neutral radical derived from MPTP and it's two derivatives 2 and 3. These results suggest that the reaction between benzophenone triplet and tertiary aliphatic amines proceed via a simple hydrogen atom transfer reaction. Additionally these model examinations provide evidence that oxidations of N-cyclopropyl derivatives of MPTP catalyzed by MAO-B may not be consistent with a pure SET pathway.
- Grimm, Michelle L.,Allen, William J.,Finn, Meghan,Castagnoli Jr., Neal,Tanko, James M.
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- Metal-free reduction of unsaturated carbonyls, quinones, and pyridinium salts with tetrahydroxydiboron/water
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A series of unsaturated carbonyls, quinones, and pyridinium salts have been effectively reduced to the corresponding saturated carbonyls, dihydroxybenzenes, and hydropyridines in moderate to high yields with tetrahydroxydiboron/water as a mild, convenient, and metal-free reduction system. Deuterium-labeling experiments have revealed this protocol to be an exclusive transfer hydrogenation process from water. This journal is
- Li, Tiejun,Peng, Henian,Tang, Wenjun,Tian, Duanshuai,Xu, Guangqing,Yang, He
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p. 4327 - 4337
(2021/05/31)
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- Synthesis of substituted 4-acetylamino-4-phenylpiperidines from the corresponding 4-piperidols under ritter reaction conditions
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The reaction of substituted 4-phenyl-4-piperidols with acetonitrile under Ritter reaction conditions leads to formation of mixtures of the corresponding 4-acetylamino-4-phenylpiperidines and 1,2,5,6-tetrahydropyridines, from which we isolated the target amides by fractional crystallization. 1997 Plenum Publishing Corporation.
- Sokolova,Cherkaev,Boiko,Moskovkin
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p. 676 - 679
(2007/10/03)
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- Selective reductions of 1-methyl-4-phenyl-2-pyridone
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We have explored the reactions of 1-methyl-4-phenyl-2-pyridone (5) with various reducing agents in an effort to develop synthetic approaches to specifically deuterium-labeled 1,4-disubstituted 1,2,3,6-tetrahydropyridine analogs needed for metabolic and enzyme mechanistic studies. Reactions with NaBH4 in CH3OH or THF, LiAl(O-t-Bu)3H in THF, and Al(i-Bu)2H (DIBALH) in THF resulted in quantitative recovery of starting material. On the other hand, treatment with BH3 in THF unexpectedly led to the formation of 4-phenylpyridine (7) in 98% yield. LiAlH4 in THF or Et2O and Red-Al in THF gave varying amounts of the 3,6-dihydro-2-pyridone 8 and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (1). In the presence of TiCl3, LiAlH4 in THF at 0°C converted 5 to 1 in 97% yield. LiB(s-Bu)3H (L-Selectride) in THF gave exclusively the 1,4-reduction product 8. Base catalyzed isomerization of 8 provided the conjugated 5,6-dihydro-2-pyridone 4. The applications of these reactions with deuterated reagents provide insights into the reaction pathways and several avenues for the regioselective synthesis of the required deuterium-labeled compounds.
- Mabic,Castagnoli Jr.
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p. 309 - 313
(2007/10/03)
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- POTENTIAL NEUROLEPTICS OF THE ORTHOPRAMIDE SERIES; SYNTHESIS OF N-SUBSTITUTED 5-(AMINOSULFONYL)-2-METHOXYBENZAMIDES
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The mixed anhydride of 5-(aminosulfonyl)-2-methoxybenzoic acid (VII) and monoethyl carbonate reacted with benzylamine, 1-methylpiperazine, and 1-benzylpiperazine to give the 5-(aminosulfonyl)-2-methoxybenzamides II, IV, and V.Heating the ethyl ester X with 4-amino-1-methylpiperidine resulted in the amide III.Reaction of 5-(chlorosulfonyl)-2-methoxybenzoyl chloride (XI) with 1-benzylpiperazine afforded 5-(4-benzylpiperazinosulfonyl)-2-methoxybenzoic acid 4-benzylpiperazide (VI).Compounds II-VI are analogues of the antidopaminergic and antiemetic agent sulpiride (I) but only the benzylpiperazides V and VI showed indications of psychotropic activity of the neuroleptic type.
- Valenta, Vladimir,Protiva, Miroslav
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p. 2095 - 2106
(2007/10/02)
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- Synthesis and toxicity toward nigrostriatal dopamine neurons of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) analogues
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Six compounds having structural features in common with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were synthesized and tested in mice for the ability to produce a prolonged decrease in nigrostriatal dopamine (DA) and DA metabolites. The compounds that were prepared and tested include the ester elimination products of the analgetic drugs α-prodine and trimeperidine. None of the compounds in this study, except for MPTP, produced significant neurotoxic effects in the mouse model. The study shows that minor changes in the tetrahydropyridine ring of MPTP result in a marked decrease in neurotoxicity.
- Fries,De Vries,Hazelhoff,Horn
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p. 424 - 427
(2007/10/02)
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- REDUCTION OF PHENYL-SUBSTITUTED PYRIDINIUM METHOIODIDES WITH SODIUM BOROHYDRIDE. FORMATION OF AMINE-BORANE COMPLEXES IN WATER.
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Reduction of phenyl-substituted pyridinium methoiodides with sodium borohydride in water afforded besides the desired tetrahydropyridines substantial amounts of amine-borane complexes.Reduction in methanol afforded tetrahydropyridines in high yield, with almost no amine-boranes formed.
- Gessner, Wieslaw,Brossi, Arnold
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p. 911 - 916
(2007/10/02)
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