title: Synthesis of chiral cyclic nitrones by asymmetric addition of β-ketosulfones to nitroalkenes followed by reductive cyclization.
abstract: The first organocatalytic addition of β-ketosulfones to nitroalkenes catalyzed by thiourea cinchona alkaloids is presented. The readily obtained addition products were selectively transformed into chiral nitrones by reduction of the nitro group and in situ cyclization (up to 99:1 e.r. and >98:2 d.r.). Moreover, the utility of this method has additionally been demonstrated by the further transformation to functionalized N-hydroxypyrrolidines that possess a quaternary center by addition of trimethylsilyl cyanide (TMSCN) to the C=N bond of the cyclic nitrones in the presence of a Lewis acid.
authors.affiliation: Organisch-Chemisches Institut, Westfälischen Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster, Germany. olga.garcia@uni-muenter.de
authors.forename: Olga
authors.initials: O
authors.lastname: García Mancheño
authors.forename: Pia
authors.initials: P
authors.lastname: Tangen
authors.forename: Renate
authors.initials: R
authors.lastname: Rohlmann
authors.forename: Roland
authors.initials: R
authors.lastname: Fröhlich
authors.forename: José
authors.initials: J
authors.lastname: Alemán