Synthesis of Diarylamines and Methylcarbazoles and Formal Total Synthesis of Alkaloids Ellipticine and Olivacine

En este documento se describe la síntesis química, vía microondas, de derivados de alcaloides elipticina y olivacina, así como su identificación espectroscópica inequívocas.New and efficient strategies for the conversion of 4-oxazolin-2-ones into 1-methyl and 1,4-dimethyl 3-formylcarbazoles are herein described. Highly convergent cascade and one-pot processes afforded the corresponding diarylamines, as in situ formed synthetic intermediates or final products in high overall yields. Special attention was given to the synthesis of methylated carbazoles by reacting 4,5-dimethyl-4-oxazolin-2-ones with enones under microwave irradiation. The carbazole scaffold was provided by the palladium(II)-catalyzed double C−H activation to generate oxidative cyclization of diarylamines. This methodology allowed for formal total syntheses of four naturally occurring pyrido[4,3-b]carbazole alkaloids ellipticine, 9-methoxyellipticine, olivacine, and 9-methoxyolivacine.Secretaría de Investigación y Estudios Avanzados de la UAEMex. CONACYT Ludwig K. Hellweg Foundation Secretaría de Investigación y Posgrado, del IP

Synthesis of 4,5,6,7-tetrahydrobenzoxazol-2-ones by a highly regioselective Diels-Alder cycloaddition of exo-oxazolidin-2-one dienes with chalcones

En este trabajo se describe la reactividad química de derivados de chalconas y dienos exo heterocíclicos, obteniéndose una serie de compuestos los cuales fueron caracterizados y rigurosamente identificados, demostrando de esta manera la conducta de estas moléculas en ambientes controlados.The synthesis of novel of 4,5,6,7-tetrahydrobenzoxazol-2-ones is herein reported. They were obtained in moderate to good yields by a highly regio- and stereoselective Diels-Alder cycloaddition of N-substituted exo-oxazolidin-2-one dienes with chalcones or bis-chalcones as dienophilesSecretaría de Investigación y Estudios Avanzados de la Universidad Autónoma del Estado de Méxic

Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

En este trabajo se describe la reactividad de las oxazolidin-2-onas en un ambiente quiral obteniéndose resultados novedosos, los cuales se describen extensamente.Enantiopure 3‐((R)‐ and 3‐((S)‐1‐phenylethyl)‐4‐oxazoline‐2‐ones were evaluated as chiral building blocks for the divergent construction of heterocycles with stereogenic quaternary centers. The N‐(R)‐ or N‐(S)‐1‐phenylethyl group of these compounds proved to be an efficient chiral auxiliary for the asymmetric induction of the 4‐ and 5‐positions of the 4‐oxazolin‐2‐one ring through thermal and MW‐promoted nucleophilic conjugated addition to Michael acceptors and alkyl halides. The resulting adducts were transformed via a cascade process into fused six‐membered carbo‐ and heterocycles. The structure of the reaction products depended on the electrophiles and reaction conditions used. Alternative isomeric 4‐methylene‐2‐oxazolidinones served as chiral precursors for a versatile and divergent approach to highly substituted cyclic carbamates. DFT quantum calculations showed that the formation of bicyclic pyranyl compounds was generated by a diastereoselective concerted hetero‐Diels‐Alder cycloaddition.Instituto Politécnico Nacional, Secretaria de Investigación y Estudios Avanzados de la Universidad Autónoma del Estado de México, Universidad de Guanajuato y CONACYT

Tres resguardos otorgados a Joaquin Gorospe por tres pagos, recibidos a favor del Convento de San Antonio, de la Archicofradia de Nuestra Señora del Rosario y de la testamentaria del Canonigo Manuel Alday

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Palladium-Catalyzed Synthesis of Natural and Unnatural 2-, 5-, and 7-Oxygenated Carbazole Alkaloids from N-Arylcyclohexane Enaminones

A palladium-catalyzed synthesis of the carbazole framework is described, including the preparation of 2-, 5-, and 7-oxygenated natural and unnatural carbazole alkaloids. A series of N-arylcyclohexane enaminones, generated by condensation of cyclohexane-1,3-dione with diverse anilines, were aromatized by a Pd(0)-catalyzed thermal treatment to afford the corresponding diarylamines. The latter were submitted to a Pd(II)-catalyzed cyclization and methylation processes to provide the desired carbazoles, including clausine V. Following an inverse strategy, a new and short total synthesis of glycoborine is also reported

Regioselective Mercury(I)/Palladium(II)-Catalyzed Single-Step Approach for the Synthesis of Imines and 2-Substituted Indoles

An efficient synthesis of ketimines was achieved through a regioselective Hg(I)-catalyzed hydroamination of terminal acetylenes in the presence of anilines. The Pd(II)-catalyzed cyclization of these imines into the 2-substituted indoles was satisfactorily carried out by a C-H activation. In a single-step approach, a variety of 2-substituted indoles were also generated via a Hg(I)/Pd(II)-catalyzed, one-pot, two-step process, starting from anilines and terminal acetylenes. The arylacetylenes proved to be more effective than the alkyl derivatives