Synthesis 2020; 52(02): 246-252
DOI: 10.1055/s-0039-1690208
paper
© Georg Thieme Verlag Stuttgart · New York

A Photoredox Catalysis Approach for the Synthesis of Both the ABDE and the ABCD Cores of Tronocarpine

a   Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, 04510, México   Email: lmiranda@unam.mx
b   Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Ciudad de México, 09230, Mexico
,
Mario Castañón-García
a   Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, 04510, México   Email: lmiranda@unam.mx
,
Enrique Becerril-Rodríguez
a   Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, 04510, México   Email: lmiranda@unam.mx
,
Luis D. Miranda
a   Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, 04510, México   Email: lmiranda@unam.mx
› Author Affiliations
D.A.C. thanks the Consejo Nacional de Ciencia y Tecnología (CONACYT) for a Ph.D. scholarship (Grant No. 271165). Financial support from Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México (DGAPA-UNAM) (PAPIIT Nos. IN210516 and IN208719) is gratefully acknowledged.
Further Information

Publication History

Received: 09 August 2019

Accepted after revision: 12 September 2019

Publication Date:
08 October 2019 (online)


Dedicated to Dr. Joseph M. Muchowski on the occasion of his 82nd birthday

Abstract

A general strategy for the facile construction of both the ABDE and ABCD cores of tronocarpine, chippiine and dippinine alkaloids through the retrosynthetic disconnection of the polycyclic motifs into an indole or tryptamine fragment and a suitably functionalized alkyl chain is presented. The approach is enabled by an efficient Ir(III)-catalyzed, photoredox-mediated radical addition of tetramethyl 1-bromopentane-1,1,3,5-tetracarboxylate and dimethyl 2-bromopentanedioate selectively at C-2 of the indole. Subsequent intramolecular cyclization events furnish the desired ABDE and ABCD polycyclic cores in good preparative yields.

Supporting Information