Synthesis 2017; 49(18): 4357-4371
DOI: 10.1055/s-0036-1588467
paper
© Georg Thieme Verlag Stuttgart · New York

Palladium-Catalyzed Synthesis of Diarylamines and 1- and 2-Oxygenated Carbazoles: Total Syntheses of Natural Alkaloids Clauraila A, Clausenal, Clausine P, and 7-Methoxy-O-methylmukonal

R. Israel Hernández-Benitez
Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala, 11340 Mexico City, Mexico   eMail: jtamarizm@gmail.com
,
Daniel Zárate-Zárate
Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala, 11340 Mexico City, Mexico   eMail: jtamarizm@gmail.com
,
Francisco Delgado
Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala, 11340 Mexico City, Mexico   eMail: jtamarizm@gmail.com
,
Joaquín Tamariz*
Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala, 11340 Mexico City, Mexico   eMail: jtamarizm@gmail.com
› Institutsangaben
J.T. acknowledges SIP/IPN (Grants 20150917, 20161791 and 20170902) and CONACYT (Grant 178219) for financial support. R.I.H.-B. and D.Z.-Z. thank CONACYT for graduate scholarships awarded, and SIP/IPN (BEIFI) for scholarship complements. F.D. and J.T. are fellows of the EDI-IPN and COFAA-IPN programs.
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Publikationsverlauf

Received: 07. April 2017

Accepted after revision: 22. Mai 2017

Publikationsdatum:
05. Juli 2017 (online)


Abstract

The scope and limitations of the strategy for the conversion of 2-anilinocyclohexenones and N-arylcyclohexane enaminones into the 1- and 2-oxygenated carbazole scaffolds, respectively, were evaluated. The one-pot palladium(0)-catalyzed aromatization/methylation process of the aforementioned substrates provided a diversity of the corresponding diarylamines. A subsequent palladium(II)-catalyzed cyclization of the latter delivered the desired 1- and 2-oxygenated carbazoles in good overall yields. Special attention was given to the synthesis of the uncommon 1,8-disubstituted carbazoles. This methodology was employed for the total synthesis of the naturally occurring clauraila A, clausenal, clausine P, and 7-methoxy-O-methylmukonal.

Supporting Information