Synthesis 2024; 56(02): 346-356
DOI: 10.1055/a-2186-7034
paper

Examination of Diels–Alder/Tsuji–Trost Route towards Kopsia Alkaloids

Ekaterina A. Zhigileva
a   Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 16/10 Miklukho-Maklaya St., Moscow 117997, Russian Federation
b   Lomonosov Moscow State University, Leninskie Gory 1 (3), Moscow 119991, Russian Federation
,
Marina V. Molchanova
a   Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 16/10 Miklukho-Maklaya St., Moscow 117997, Russian Federation
b   Lomonosov Moscow State University, Leninskie Gory 1 (3), Moscow 119991, Russian Federation
,
c   Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, 32 Vavilova St., Moscow 119991, Russian Federation
,
Alexander A. Korlyukov
d   Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow 119334, Russian Federation
e   Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russian Federation
,
a   Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 16/10 Miklukho-Maklaya St., Moscow 117997, Russian Federation
e   Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russian Federation
,
a   Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 16/10 Miklukho-Maklaya St., Moscow 117997, Russian Federation
› Author Affiliations
The authors gratefully acknowledge support from the Russian Science Foundation, grant No. 21-73-00165.


Abstract

A reaction sequence of Diels–Alder cycloaddition and Tsuji–Trost allylation was examined in terms of its application to the synthesis of kopsinine and the related Kopsia alkaloids. Results of the studies in two synthetic directions are presented herein: 1) synthesis of the properly substituted diene, required for the Diels–Alder step; and 2) model studies and optimization of the key reaction sequence in the absence of side-chain. Details on the challenging introduction of the side-chain into tetrahydrocarboline ketone and its silylation, resulting in rare but unproductive vinylogous Claisen cyclization, and the successful Mannich/Mukaiyama aldol sequence are disclosed in the first direction. In the second direction, the endo-selective Diels–Alder reaction with allyl acrylate and Tsuji–Trost allylation providing incorrect stereochemistry are disclosed. Interaction of both dienes with an alkyne provides carbazoles via Alder–Rickert reaction.

Supporting Information



Publication History

Received: 04 September 2023

Accepted after revision: 05 October 2023

Accepted Manuscript online:
05 October 2023

Article published online:
06 November 2023

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