Synthesis of propellanes via the intramolecular vinyl radical cyclisation
TL;DR: The Michael type addition of vinyl radicals on to the enone double bond was realized in Wieland-Miescher ketone derivatives leading to the formation of functionalised propellanes as mentioned in this paper.
About: This article is published in Tetrahedron Letters.The article was published on 1993-11-05. It has received 3 citations till now. The article focuses on the topics: Enone & Ketone.
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TL;DR: In this paper, 2-cyclohexenone rings that form part of a larger structural assembly are amenable to peracid oxidation with formation of an epoxy lactone.
Abstract: 2-Cyclohexenone rings that form part of a larger structural assembly are amenable to peracid oxidation with formation of an epoxy lactone. These intermediates are readily transformed under acidic, basic, or neutral conditions to ring-contracted aldehydo lactones, which are then subjected to condensation with a slight excess of Tebbe reagent. These conditions result in methylenation of carbonyl groups and set the stage for operation of a Claisen rearrangement. When the latter is catalyzed by Tribal, the sigmatropic process occurs at room temperature. With systems typified by 17 and 24, the isomerization is complete within 15 min. The presence of a proximate angular methyl group as in 9b, 29, and 37 exerts a retarding kinetic effect. In such examples, a period of 6 h is required to achieve completion. Swern oxidation completes the conversion to the 4-cyclooctenones, where the two carbons stemming from the Tebbe reagent are inserted between the original carbonyl and α-olefinic carbons. The overall process is...
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TL;DR: Carboncentered radicals can form bonds with electron-rich or electron-deficient alkenes, allenes, and acetylenes, as well as construct hindered carbon-carbon bonds, which contribute to the importance of such reactions in organic synthesis.
Abstract: Organic chemists have begun to use intra- and intermolecular free-radical addition reactions to develop useful synthetic transformations. Carboncentered radicals can form bonds with electron-rich or electron-deficient alkenes, allenes, and acetylenes. Radical addition reactions can also be used to construct hindered carbon-carbon bonds. These characteristics, as well as the large number of functional groups that tolerate free-radical conditions contribute to the importance of such reactions in organic synthesis.
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TL;DR: In this paper, a new method for the synthesis of fused and bridged ring systems based on intramolecular addition of a vinyl radical to α,β-unsaturated carbonyls is described.
66 citations