Gloor, Christian Simon

Kavanagh, Y.

Kovalova, I.

Locher, P.

Pichowicz, M.

Renaud, Philippe

Soulard, V.

Bern Open Repository and Information System (BORIS)

Organic Chemistry, Poster OC-166Retention of Absolute Configuration in Hydrogen Atom Transfer/Cyclisation CascadeC. Gloor1, I. Kovalova1, V. Soulard1, P. Locher1, Y. Kavanagh1, M. Pichowicz1, P. Renaud1*1University of BernDue to the nature of radicals, few stereoselective reactions are known in which a radical isgenerated at a chiral center with retention of the absolute configuration. In an early report byHeiba and Dessau, the formation of an optically active lactone was observed although thereaction proceeds through a radical at the chiral center via a 1,5-H shift.[1] The level of retentionwas however unknown. Recently, Curran and coworkers published a related cyclisation processof a-amide radicals involving retention of chirality.[2, 3]Meanwhile, our group reported a radical cyclisation involving phosphonyl and thiyl radicals toaccess cyclopentane derivatives.[4] We decided to use this reaction as the starting point tostudy whether retention of chirality is possible and the factors influencing the stereochemicaloutcome.The alkynyl malonate 1 was readily synthesized in a five-step procedure strating from(S)-(–)-ethyl lactate. Treatment of 1 with diethylphosphite afforded the cyclic product 2 withpartial retention of configuration (Scheme 1)[1] El-Ahmadi I. Heiba, Ralph M. Dessau, J. Am. Chem. Soc., 1967, 89, 2238-2239[2] Aniruddha Sasmal, Tsuyoshi Taniguchi, Peter Wipf, Dennis P. Curran, Can. J. Chem., 2013,91, 1-5[3] For a review on memory of chirality see: Hongwu Zhao, Danny C. Hsu, Paul R. Carlier,Synthesis, 2005, 1-16[4] a) Florent Beaufils, Fabrice Dénès, Phillippe Renaud, Angew. Chem. Int. Ed., 2005, 44,5273-5275b) Florent Beaufils, Fabrice Dénès, Phillippe Renaud, Org. Lett., 2004, 6, 2563-2566Powered by TCPDF (www.tcpdf.org)

Retention of Absolute Configuration in Hydrogen Atom Transfer/Cyclization Cascade

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Retention of Absolute Configuration in Hydrogen Atom Transfer/Cyclization Cascade

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