Radical cyclisation strategies to bridged systems. Regioselective construction of chiral bicyclo [2.2.2] and [3.2.1] octanes via 6-exo trig and 5-exo trig radical cyclisation reactions

Srikrishna, A and Hemmalini, P (1992) Radical cyclisation strategies to bridged systems. Regioselective construction of chiral bicyclo [2.2.2] and [3.2.1] octanes via 6-exo trig and 5-exo trig radical cyclisation reactions. In: Tetrahedron, 48 (42). pp. 9337-9354.

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Abstract

Radical cyclisation reaction of the bromoenones $6 $and $7$, obtained from (R)-phenyl carvone $3$, gave a mixture of bicyclo [2.2.2] and [3.2.1] octanones via competitive 6-exo trig and 5-exo trig modes. On the other hand, radical cyclisation reaction of the alcohol $12$ furnished the bicyclo[3.2.1]-octanol $15$ as the major cyclised product, where as the alcohol 13 furnished the bicyclo[2.2.2]octanol $18$ as the major cyclised product. An explanation based on conformational rigidity due to the intramolecular hydrogen bonding between the hydroxy and methoxy groups is proposed, and proved by the formation of bicyclo[2.2.2]octanes as major cyclised products with the corresponding acetates $19$ and $20$.

Item Type:	Journal Article
Publication:	Tetrahedron
Publisher:	Elsevier Science Ltd.
Additional Information:	Copyright of this article belongs to Elsevier Science Ltd.
Keywords:	Radical cyclisations;Bicyclo[3.2.1]octane;Bicyclo[2.2.2]octane;5-exo trig and 6-exo trig cyclisations
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	23 Feb 2008
Last Modified:	19 Sep 2010 04:42
URI:	http://eprints.iisc.ac.in/id/eprint/12879

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