- Birch-Type Photoreduction of Arenes and Heteroarenes by Sensitized Electron Transfer
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The direct reduction of arenes and heteroarenes by visible-light irradiation remains challenging, as the energy of a single photon is not sufficient for breaking aromatic stabilization. Shown herein is that the energy accumulation of two visible-light photons allows the dearomatization of arenes and heteroarenes. Mechanistic investigations confirm that the combination of energy-transfer and electron-transfer processes generates an arene radical anion, which is subsequently trapped by hydrogen-atom transfer and finally protonated to form the dearomatized product. The photoreduction converts planar aromatic feedstock compounds into molecular skeletons that are of use in organic synthesis.
- Chatterjee, Anamitra,K?nig, Burkhard
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p. 14289 - 14294
(2019/08/30)
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- AMINOACYLINDAZOLE IMMUNOMODULATORS FOR TREATMENT OF AUTOIMMUNE DISEASES
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2-Acylindazole compounds of formula I or formula II are disclosed. These compounds inhibit Coagulation Factor XIIa. They are useful to treat autoimmune diseases.
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- Diastereoselective synthesis of substituted tetrahydroquinoline-4-carboxylic esters by a tandem reduction-reductive amination reaction
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A diastereoselective synthesis of 1-methyl-2-alkyl- and 2-alkyl-1,2,3,4-tetrahydroquinoline-4-carboxylic esters has been developed from methyl (2-nitrophenyl)acetate (1). The method involves alkylation of 1 with an allylic halide, ozonolysis of the double bond, and catalytic hydrogenation. The final hydrogenation initiates a tandem sequence involving (1) reduction of the aromatic nitro group, (2) condensation of the aniline or hydroxylamine8 nitrogen with the side chain carbonyl, (3) reduction of the resulting nitrogen intermediate, and (4) reductive amination of the tetrahydroquinoline with formaldehyde produced in the ozonolysis to give a methyl (±)-1-methyl-2-alkyl-1,2,3,4-tetrahydroquinoline-4-carboxylate. Removal of the formaldehyde prior to hydrogenation gives the simple (±)-2-alkyl derivatives. The products are isolated in high yield as single diastereomers having the C-2 alkyl group cis to the C-4 carboxylic ester. The reaction has been extended to the synthesis of tricyclic structures with similar high diastereoselection.
- Bunce,Herron,Johnson,Kotturi
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p. 2822 - 2827
(2007/10/03)
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