Issue 10, 2013

Conformation and reactivity in dibenzocyclooctadienes (DBCOD). A general approach to the total synthesis of fully substituted DBCOD lignansvia borostannylative cyclization of α,ω-diynes

Abstract

Dibenzocyclooctadienes (DBCOD) are a class of plant-derived natural products that exhibit a broad range of biological activities. These include cytotoxicity, anti-hepatitis-B activity, inhibition of HIV replication and of NO production and activity. None of the fully substituted DBCODs have been prepared before. 2,2′-Dipropargylbiphenyls undergo highly regio- and atropselective cyclizations mediated by a [B-Sn]-reagent, 1-trimethylstannyl-2,5-diazaborolidine (Me3Sn–B[–N(Me)CH2CH2(Me)N–], in the presence of Pd(II)-catalysts, to give highly functionalized DBCOD precursors. The configuration of the newly created, axially chiral, 1,2-bis-alkylidene moiety is controlled by the resident chirality of the starting biphenyls and the configurations of the benzylic positions. New chemistry of the bis-alkylidenes described in this paper enables the first total syntheses of a wide variety of DBCOD natural products, fully functionalized at the cyclooctadiene ring. These include ananolignans B, C, D, F, interiotherin C, kadsuralignan B, tiegusanin D and schizanrin F. Revision of the structure of a key natural product, ananolignan B, is also reported. Key steps in the syntheses exploits the conformational features of the various DBCOD intermediates as revealed by NMR spectroscopy and X-ray crystallography.

Graphical abstract: Conformation and reactivity in dibenzocyclooctadienes (DBCOD). A general approach to the total synthesis of fully substituted DBCOD lignans via borostannylative cyclization of α,ω-diynes

Supplementary files

Article information

Article type
Edge Article
Submitted
23 Jun 2013
Accepted
16 Jul 2013
First published
17 Jul 2013

Chem. Sci., 2013,4, 3979-3985

Conformation and reactivity in dibenzocyclooctadienes (DBCOD). A general approach to the total synthesis of fully substituted DBCOD lignans via borostannylative cyclization of α,ω-diynes

W. Gong and T. V. RajanBabu, Chem. Sci., 2013, 4, 3979 DOI: 10.1039/C3SC51751A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements