Enantiomerically enriched alpha,alpha-disubstituted phenylacetonitriles have been readily prepared by stereoselective quaternization of 2-alkyl-2-[2-(p-tolylsulfinyl)phenyl]acetonitriles with different alkylating electrophiles in the presence of bases. The use of potassium hexamethyldisilazane (KHMDS)/[18]crown-6 ether and NHMDS with alkyl halides afforded S,S(S) and R,S(S) diastereoisomers, respectively, in high enantiomeric purities, thus providing stereodivergent processes for synthesizing both isomers. The dependence of the stereochemical course of the reactions on the experimental conditions (mainly on the counterion) has been rationalized by assuming a planar or pyramidal structure for the benzylic carbanions. This hypothesis has been supported by NMR spectroscopic studies, which permit one to assign a chelated pyramidal structure to the sodium benzylic carbanions and an almost planar naked carbanionic structure to the potassium benzylic carbanions generated in the presence of [18]crown-6 ether.

A range of C 2 -symmetric, chiral Cu II ·bisoxazoline complexes were tested as catalysts for the asymmetric Diels−Alder cycloaddition between cyclopentadiene and a range of α-sulfenylacrylates. The optimum acrylate was ethyl α-phenylthioacrylate and the optimum catalyst was the bisoxazoline derived from phenylalanine which, upon complexation with Cu(SbF 6 ) 2 , gave the cycloadducts in 92% yield, 88% de and

Enantiomerically enriched α-aryl α-cyanoacetates and α-aryl α-acylacetonitriles bearing a benzylic quaternary stereocenter have been readily synthesized by stereoselective reaction of 2-alkyl-2-[2-(p-tolylsulfinyl)phenyl]acetonitriles with different acylating and alkoxycarbonylating reagents under basic conditions. The stereoselectivity of the reactions proved closely dependent on the nature of the intermediate carbanionic species, the evolution of which was effectively controlled by a sulfinyl group as a remote chiral auxiliary.

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