The free-radical three-component carbocyanation of electron-rich olefins was investigated with p-tosyl cyanide as cyanide source. The scope and limitations of the process were established by varying the nature of the alkene and radical precursor. Carbocyanation of chiral allylsilanes was shown to occur with high diastereocontrol, leading to syn β-silyl nitriles. The origin of the stereocontrol was rationalized by a Felkin-Anh-type transition-state model. Finally, a tin-free carbocyanation process was also devised, based on the use of a new alkylsulfonyl cyanide incorporating both carbon fragments to be added across the olefinic π system.
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http://dx.doi.org/10.1002/chem.201605946 | DOI Listing |
Chemistry
March 2022
Institute of Molecular Sciences (ISM), Univ. Bordeaux, CNRS, UMR-5255, 351 Cours de la Libération, 33400, Talence, France.
The total enantioselective synthesis of (+)-eucophylline 1 was achieved using as a key-structural motif a chiral piperidinone bearing the natural product all-carbon quaternary stereocenter. The elaboration of the latter is based on two strategies relying on the free-radical carbo-cyanation and sulfonyl-cyanation respectively of enantiopure substituted cyclopropenes and cyclobutenes. Co- or Ni-boride reduction of the nitrile functional group along with the cyclopropane and cyclobutane ring-opening then led to the formation of the chiral piperidinone ring.
View Article and Find Full Text PDFChemistry
April 2017
Institute of Molecular Sciences, UMR-CNRS 5255, University of Bordeaux, 351, Cours de la libération, 33405, Talence cedex, France.
The free-radical three-component carbocyanation of electron-rich olefins was investigated with p-tosyl cyanide as cyanide source. The scope and limitations of the process were established by varying the nature of the alkene and radical precursor. Carbocyanation of chiral allylsilanes was shown to occur with high diastereocontrol, leading to syn β-silyl nitriles.
View Article and Find Full Text PDFOrg Lett
December 2016
University of Bordeaux , Institute of Molecular Sciences, UMR-CNRS 5255, 351 cours de la libération, 33405 Talence, France.
Free-radical carbocyanation of cyclopropenes offers straightforward access to tetrasubstituted cyclopropanes in satisfying yields with moderate diastereoselectivity. The incorporation of various functional groups on the cyclopropane ring allows a subsequent base-mediated ring-opening reaction leading to functionalized acyclic systems having an all-carbon quaternary stereocenter.
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