Cp2TiCl-Promoted Endo-Trig Radical Cyclization to Six- and Seven-Membered Carbocycles: Synthesis of (±)-Isoclavukerin A

Begum, S and Bhattacharya, R and Paul, S and Chakraborty, TK (2023) Cp2TiCl-Promoted Endo-Trig Radical Cyclization to Six- and Seven-Membered Carbocycles: Synthesis of (±)-Isoclavukerin A. In: Journal of Organic Chemistry, 88 (17). 12677 -12697.

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Abstract

A systematic study is undertaken to investigate the less explored endo-trig radical cyclization in activated olefin-appended epoxides using Cp2TiCl. The radical generated by the Ti(III)-promoted reductive opening of the epoxy ring promptly underwent endo-trig cyclization, giving access to differently 1,3-disubstituted six- and seven-membered carbocycles in good yields and diastereoselectivity. This protocol was successfully employed in the construction of 5,7- and 6,7-fused bicyclic frameworks entailing a de novo synthesis of (±)-isoclavukerin A belonging to tri-nor-guaiane class of sesquiterpene natural products in eight simple steps from commercially available starting materials. Besides the Ti(III)-mediated reaction serving as a key step in the synthesis, a sequential 2,3-sigmatropic rearrangement/syn-elimination of an allyl sulfenate intermediate successfully rendered the highly constrained diene moiety in the hydroazulene core of the target molecule. © 2023 American Chemical Society.

Item Type:	Journal Article
Publication:	Journal of Organic Chemistry
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to the American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	04 Nov 2023 04:20
Last Modified:	04 Nov 2023 04:20
URI:	https://eprints.iisc.ac.in/id/eprint/83154

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