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STUDIES IN THE SYNTHESIS OF POLYCYCLOPENTANOIDS - SYNTHESIS, OXA-DI-PI-METHANE REARRANGEMENT OF ANNULATED BICYCLO[2.2.2]OCTENONES AND CYCLOPROPANE RING CLEAVAGE OF TETRACYCLO[6.3.0.0(2,4)O(3,7)]UNDECENONES

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Title STUDIES IN THE SYNTHESIS OF POLYCYCLOPENTANOIDS - SYNTHESIS, OXA-DI-PI-METHANE REARRANGEMENT OF ANNULATED BICYCLO[2.2.2]OCTENONES AND CYCLOPROPANE RING CLEAVAGE OF TETRACYCLO[6.3.0.0(2,4)O(3,7)]UNDECENONES
 
Creator SINGH, VK
DEOTA, PT
BEDEKAR, AV
 
Subject olefin cyclo-additions
mediated cyclization reaction
diels-alder reactions
beta,gamma-unsaturated ketone
natural-products
building-blocks
(+/-)-hirsutene
photochemistry
sesquiterpenes
 
Description A short, new and general approach for the synthesis of linear polyquinanes having the cis:anti:cis tricyclopentanoidal framework is delineated. The key element of this approach is the photochemical 1,2-acyl shift or oxa-di-pi-methane rearrangement of annulated bicyclo[2.2.2]octenones, having beta,gamma-unsaturated carbonyl chromophoric systems. An efficient method for the synthesis of a variety of annulated bicyclo[2.2.2]octenones via inverse demand pi(4s) + pi(2s) cycloaddition of cyclohexa-2,4-dienones (9-12) with olefins (18-26) is reported. The structure of the adducts has been established through the study of their high-field H-1 NMR and C-13 NMR spectra and decoupling experiments. Synthesis of tricyclo[5.2.2.0(2,6)]undecadienones (51-57) from readily available adduct 43 has been achieved. Oxa-di-pi-methane rearrangement of various chromophoric systems to polyquinanes (60-68) is described. The adduct 32 did not undergo oxa-di-pi-methane rearrangement upon sensitized irradiation, while adduct 40 rearranged inefficiently to compound 64. Studies on the cleavage of the cyclopropane ring of the tetracyclic ketones (60, 66, 67 and 73) with formic acid and acetyl methanesulfonate is also reported.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2011-08-28T19:11:00Z
2011-12-26T12:58:10Z
2011-12-27T05:47:41Z
2011-08-28T19:11:00Z
2011-12-26T12:58:10Z
2011-12-27T05:47:41Z
1992
 
Type Article
 
Identifier JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1, (7), 903-912
0300-922X
http://dx.doi.org/10.1039/p19920000903
http://dspace.library.iitb.ac.in/xmlui/handle/10054/11823
http://hdl.handle.net/10054/11823
 
Language en