Synthetic ventures into the furanocembranes: bielschowskysin and beyond

Lear, Martin (2016) Synthetic ventures into the furanocembranes: bielschowskysin and beyond. In: Lecture Tour, January 2016, Tokyo University, Tohoku University, Kyushu University, 5-22 January 2016, Japan.

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Abstract

The cembrane natural products hold such promise in both biological and chemical senses. They are a diverse class of macrocyclic diterpenes found in both plants and animals.[1] In particular, the furanocembranoids are highly oxidized cembranes, which have been discovered to exist in significant abundance and structural complexity, particularly in the Pseudopterogorgia sea whips from the Carribean, as well as from corals of the genus Sinularia, Plumarella, and Leptogorgia.[1c] Beyond their presumed antifeedant role in marine coral reefs, these biosynthetically-linked secondary metabolites display a wide range of biological activities; for example, derivatives and extracts of the pseudopterosins are not only being used medically as anti-inflammatory and analgesic agents, but are also being investigated as antimicrobial (TB, malaria) and as antitumour agents.

Bielschowskysin (1) belongs to this diverse class of cembranoid diterpenes.[1b] In 2006, the Rodríguez group characterized 1 to be a tricyclo[9.3.0.02,10]tetradecane derived from the self-closure of a regular furanocembrane macro-skeleton (about the C6/C12 and C7/C11 carbon-carbon bonds).[2] Amid several strategies from other groups, we have been striving to develop [2+2]-transannulation tactics to construct the multicyclic skeleton of 1 via macrocyclic allenes like 2 (Figure 1).[3] Previously, we secured the tricyclic cyclobutane core (C5-to-C12) of 1 by employing a stereocontrolled photochemical [2+2] cyclization of an allene-tethered gamma-butenolide[3a] and have recently gained conformational insights into forming macrocyclic alkyne precursors to 2.[3b]

In this talk, we summarise our progress to this family of natural products.[3c] In particular, we cover our macrocyclisation and transannulation strategies to the bielschowskyane framework (cf. 1).

Selected References
1. (a) Rodríguez, A. D. Tetrahedron 1995, 51, 4571–4618; (b) Roethle, P. A.; Trauner, D. Nat. Prod. Rep. 2008, 25, 298–317; (c) Li, Y.; Pattenden, G. Nat. Prod. Rep. 2011, 28, 1269–1310.
2. Marrero, J.; Rodríguez, A. D.; Baran, P.; Raptis, R. G.; Sánchez, J. A.; Ortega-Barria, E.; Capson, T. L. Org. Lett. 2004, 6, 1661–1664.
3. (a) Miao, R.; Gramani, S. G.; Lear, M. J. Tetrahedron Lett. 2009, 50, 1731–1733; (b) Yang, E. G.; Karthik, S.; Lear, M. J. Tetrahedron Lett. 2013, 4406–4409; (c) Lear, M. J.; Liang, J.; Boudhar, A.; Sriramula, R. K.; Sekar K.; Yang, E. G.; Gramani, S. G.; Battu, P.; Dymock, B. W., papers in preparation.

Keywords:Total synthesis studies, Diterpenes, Organic synthesis
Subjects:F Physical Sciences > F160 Organic Chemistry
F Physical Sciences > F100 Chemistry
Divisions:College of Science > School of Chemistry
ID Code:20136
Deposited On:27 Jan 2016 11:43

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