- Enantioselective Formal Total Synthesis of (-)-Quinagolide
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The enantioselective formal total synthesis of (-)-quinagolide has been accomplished in a linear sequence of 8 purification steps from pyridine. The key steps are (a) organocatalyzed Diels-Alder reaction for fixing all three stereocenters on piperidine ri
- Chavan, Subhash P.,Kadam, Appasaheb L.,Gonnade, Rajesh G.
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supporting information
p. 9089 - 9093
(2019/11/14)
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- Enantioselective Synthesis of Chiral Piperidines via the Stepwise Dearomatization/Borylation of Pyridines
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We have developed a novel approach for the synthesis of enantioenriched 3-boryl-tetrahydropyridines via the Cu(I)-catalyzed regio-, diastereo-, and enantioselective protoborylation of 1,2-dihydropyridines, which were obtained by the partial reduction of the pyridine derivatives. This dearomatization/enantioselective borylation stepwise strategy provides facile access to chiral piperidines together with the stereospecific transformation of a stereogenic C-B bond from readily available starting materials. Furthermore, the utility of this method is demonstrated for the concise synthesis of the antidepressant drug (-)-paroxetine. A theoretical study of the reaction mechanism is also described.
- Kubota, Koji,Watanabe, Yuta,Hayama, Keiichi,Ito, Hajime
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supporting information
p. 4338 - 4341
(2016/05/09)
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- SMALL MOLECULE INDUCERS OF GDNF AS POTENTIAL NEW THERAPEUTICS FOR NEUROPSYCHIATRIC DISORDERS
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The invention provides a compound having the structure (I), wherein A is a substituted or unsubstituted ring; Z is present or absent and when present is (II), wherein n is 0, 1, 2, 3, or 4; Y is -(CR11R12)-, -NH(CR11R12)- or -O(CR11R12)- wherein R11 and R12 are each hydrogen or combine to form a carbonyl; and wherein R1 to R10 are herein as described.
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Page/Page column 66
(2013/03/26)
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- An efficient synthesis of chiral isoquinuclidines by Diels - Alder reaction using Lewis acid catalyst
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The Diels-Alder reaction of 1,2-dihydropyridine derivatives (1-phenoxycarbonyl-1,2-dihydropyridine 1 or 1-methoxycarbonyl-1,2- dihydropyridine 4) with N-acryloyl (1S)-2,10-camphorsultam (1S)-2 {or N-acryloyl (1R)-2,10-camphorsultam (1R)-2} in the presence of Lewis acid, such as titanium tetrachloride, zirconium tetrachloride, and hafnium tetrachloride afforded the endo-cycloaddition product, 2-azabicyclo[2.2.2]octane derivatives in good yields with excellent diastereoselectivity. The absolute stereochemistry assignment of the endo-cycloaddition product (1S)-5a starting from N-acryloyl (1S)-2,10-camphorsultam (1S)-2 has been established to be (1S,4R,7S) and the reaction mechanism was proposed.
- Hirama, Masafumi,Kato, Yuji,Seki, Chigusa,Nakano, Hiroto,Takeshita, Mitsuhiro,Oshikiri, Noriko,Iyoda, Masahiko,Matsuyama, Haruo
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experimental part
p. 7618 - 7624
(2011/02/22)
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- Biogenetically inspired synthesis of marine C6N4 2-aminoimidazole alkaloids: Ab initio calculations, tautomerism, and reactivity
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(Chemical Equation Presented) A simple synthesis of the fused tetrahydro-imidazopyridine 13 was accomplished via selective addition of protected guanidine to N-carbomethoxy-1,2-dihydropyridine in the presence of bromine. Base-mediated semicleavage of the aminal gave 4-substituted 2-aminoimidazole 14. With this new method, natural marine metabolite 3-amino-1-(2-aminoimidazol-4-yl)-prop-1-ene (1) and derivatives may now be prepared from pyridine. Ab initio calculations of the energies of tautomers I-IV and deuteration experiments have provided insight into their reactivity.
- Abou-Jneid, Robert,Ghoulami, Said,Martin, Marie-Therese,Dau, Elise Tran Huu,Travert, Nathalie,Al-Mourabit, Ali
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p. 3933 - 3936
(2007/10/03)
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- Stereospecific synthesis of azetidine-cis-2,3-dicarboxylic acid
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Electrocyclic reaction product of 1-(methoxycarbonyl)-1,2-dihydropyridine was stereospecifically converted by RuO4 oxidation into azetidine-cis-2,3-dicarboxylic acid.
- Arakawa, Yasushi,Murakami, Tomoaki,Arakawa, Yukimi,Yoshifuji, Shigeyuki
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- HETEROCYCLIC COMPOUNDS AND THEIR USE
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The present invention relates to therapeutically active heterocyclic compounds and to pharmaceutical compositions comprising the compounds. The novel compounds are useful in treating diseases in the central nervous system caused by malfunctioning of the muscarinic cholinergic system.
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- Thermal and induced decompositions of N′-alkoxycarbonyldihydropyridines: End product analysis and EPR spectra of azacyclohexadienyl radicals
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Hydrogen abstraction from N-alkoxycarbonyldihydropyridines generated azacyclohexadienyl radicals (pyridinyl radicals) which are characterised by EPR spectroscopy. In the presence of peroxide initiators, N-alkoxycarbonyl-1,2-dihydropyridines decomposed with production of pyridine, the corresponding alkyl formate, alkyl benzoate and alkanol being formed as the major products. Absence of cyclised products in experiments with substrates containing hex-5-enyl, pent-4-enyloxy etc. units demonstrates that radical production must be minor and that N-alkoxycarbonylazacyclohexadienyl radicals do not readily undergo ss-scission of the exocyclic N-C bond. The most probable mechanism is a direct 1,2-elimination of formate. The alcohols which accompanied the other products are probably formed by hydrolysis of the formates and benzoates. Analogous chemistry is displayed by N-alkoxycarbonyl-1,4-dihydropyridines at higher temperatures where 1,4-elimination of formate is too rapid for homolytic radical production to compete.
- Baguley, Paul A.,Walton, John C.
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p. 1423 - 1429
(2007/10/03)
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- Photochemical Reaction of 2-Azabicyclohex-3-ene: The Formation of 1-Azahexatrienes and the Cyclization to 1,2-Dihydropyridine
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The irradiation of homopyrrole gives rise to 1-azahexatrienes which are thermally cyclized to 1,2-dihydropyridine and provide the methanol-adducts in the presence of methanol.The photolysis of dihydropyridine at low temperature affords a mixture of the same azatrienes. Keywords: photolysis; homopyrrole; dihydropyridine; azahexatriene; electrocyclization
- Kumagai, Tsutomu,Saito, Shue,Ehara, Takashi
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p. 6895 - 6898
(2007/10/02)
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- A NEW METHOD FOR REGIOSELECTIVE SYNTHESIS OF 2-SUBSTITUTED 1-(METHOXYCARBONYL)-1,2-DIHYDROPYRIDINES
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2-Substituted 1,2-dihydropyridines including an optically active one were regioselctively prepared from 2-substituted piperidines through three intermediates, that is, (a) 1,2,3,4-tetrahydropyridines, (b) 5-bromo-6-methoxypiperidines, and (c) 1,2,3,4-tetrahydro-6-methoxypyridines.
- Shono, Tatsuya,Matsumura, Yoshihiro,Onomura, Osamu,Yamada, Yasufu
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p. 4073 - 4074
(2007/10/02)
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- A Synthesis of N-Acyl-1,2-dihydropyridines
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A new approach to the synthesis of N-acyl-1,2-dihydropyridines based on the cyclization of N-acyl-1-azatrienes is introduced.These latter compounds were not isolated but were produced in the gas phase as transient intermediates by the flash vacuum pyrolysis of O-methoxycarbonyl N-penta-1,3-dien-5-yl hydroxamic acid derivatives 8.
- Wyle, Michael J.,Fowler, Frank W.
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p. 4025 - 4029
(2007/10/02)
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