- Visible Light Photocatalytic Synthesis of Tetrahydroquinolines Under Batch and Flow Conditions
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In this work, we describe the use of visible light and a photocatalytic system for the cyclization of iodoaryl vinyl derivatives to tetrahydroquinoline structures. The reaction proceeds under very mild conditions, tolerates different functional groups and more importantly, the method allows the synthesis of N-free tetrahydroquinolines from N-unprotected starting materials. In addition, the reaction can also be performed using flow-chemistry. Finally, a mechanistic proposal based on some mechanistic studies has been described.
- González-Mu?oz, Daniel,Nova-Fernández, José Luis,Martinelli, Ada,Pascual-Coca, Gustavo,Cabrera, Silvia,Alemán, José
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- Intramolecular Mizoroki-Heck reaction in the regioselective synthesis of 4-alkylidene-tetrahydroquinolines
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The Mizoroki-Heck reaction of N-alkenyl-substituted 2-haloanilines is an effective protocol for the synthesis of substituted 4-alkylidene- tetrahydroquinoline derivatives, avoiding isomerization and oxidation. When non-substituted alkenes are used, the regioselectivity of the reaction can be directed towards the formation of an exocyclic or endocyclic double bond by choosing an adequate catalytic system. When the double bond is substituted by an amide moiety, the exocyclic double bond of E geometry is obtained selectively. Thus, this protocol efficiently synthesizes a series of 2-substituted tetrahydroquinolines with an exo α,β-unsaturated amide moiety at the C-4 position. Optimal conditions for Mizoroki-Heck reactions of N-alkenyl-substituted 2-haloanilines have been developed to access 4-alkylidene-tetrahydroquinoline derivatives regioselectively, avoiding isomerization and oxidation. Copyright
- Martinez-Estibalez, Unai,Garcia-Calvo, Oihane,Ortiz-De-Elguea, Veronica,Sotomayor, Nuria,Lete, Esther
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p. 3013 - 3022
(2013/06/27)
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- Intramolecular Pd(0)-catalyzed reactions of (2-iodoanilino)-aldehydes: A joint experimental-computational study
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An extensive joint experimental-computational density functional theory (DFT) study has been carried out to gain insight into the factors that control the chemoselectivity (i.e., acylation vs α-arylation reaction) of palladium-catalyzed cyclizations of (2-iodoanilino)-aldehydes. To this end, the nature of the tethers joining the aniline nitrogen and the aldehyde moiety, different palladium precatalysts and reaction conditions (base and temperature), as well as different additives (mono- and bidendate ligands) has been explored. The adequate selection of these variables allows for the control of the selectivity of the process. Thus, (2-iodoanilino)-aldehydes generally lead to the formation of nucleophilic addition derived products when Cs 2CO3/Et3N is used as base. In contrast, the use of stronger bases like KtOBu (in the presence of PhOH) mainly forms α-arylation reaction products. The different reaction pathways leading to the experimentally observed reaction products have been studied by means of computational tools.
- Sole, Daniel,Mariani, Francesco,Fernandez, Israel,Sierra, Miguel A.
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p. 10272 - 10284
(2013/01/15)
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