Catalytic Asymmetric Ring-Opening/Cyclopropanation of Cyclic Sulfur Ylides: Construction of Sulfur-Containing Spirocyclopropyloxindoles with Three Vicinal Stereocenters

A highly efficient asymmetric ring-opening/cyclopropanation reaction of (E)-3-(oxyethylidene)-2-oxoindolines with 1-alkyl-3-oxotetrahydro-1H-thiophen-1-ium salts as cyclic sulfur ylides was realized by using a chiral N,N′-dioxide/Mg­(OTf)2 complex as catalyst. A range of sulfur-containing syn,anti spirocyclopropyloxindoles with three contiguous stereocenters were obtained in excellent yields with excellent dr and good ee values under mild reaction conditions. The origin of stereoselectivity was discussed

Catalytic Asymmetric Henry Reaction of Nitroalkanes and Aldehydes Catalyzed by a Chiral <i>N</i>,<i>N</i>′<i>-</i>Dioxide/Cu(I) Complex

An easily available <i>N</i>,<i>N</i>′-dioxide/Cu­(I) complex has been developed for the catalytic asymmetric nitroaldol (Henry) reaction of aldehydes with nitroethane. Under mild reaction conditions, a series of substituted aromatic, heteroaromatic and α,β-unsaturated aldehydes are transformed to the corresponding <i>anti</i>-β-nitroalcohols in good to excellent yields (up to 99%) with moderate to good <i>dr</i> (up to 16.7:1 <i>anti</i>/<i>syn</i>) and high <i>ee</i> values (up to 97%). Besides nitroethane, nitromethane and 1-nitropropane were also employed as nucleophiles, and good enantioselectivities were obtained