The chiral base n-BuLi/(-)-sparteine or n-BuLi/(+)-sparteine surrogate promotes kinetic resolution of N-Boc-2-arylpiperidines by asymmetric deprotonation. The enantioenriched starting material was recovered with yields 39-48% and ers up to 97 : 3. On lithiation then electrophilic quench, 2,2-disubstituted piperidines were obtained with excellent yields and enantioselectivities.

A systematically varied series of conformationally restricted ketones, readily prepared from N-acetyl-D-glucosamine, were tested against representative olefins as asymmetric epoxidation catalysts showing useful selectivities against terminal olefins and, in particular, typically difficult 2,2-disubstituted terminal olefins.

Regio- and stereoselective hydrostannation of allenes by using di-n-butyliodotin hydride (Bu2SnIH) was accomplished to give alpha,beta-disubstituted vinyltins, which induced the synthesis of multi-substituted alkenes in a one-pot procedure.

A facile method for the preparation of highly active and enantioselective yttrium precatalysts for asymmetric hydroamination of gem-disubstituted aminoalkenes, from the combination of YCl(3) or YCl(3)(THF)(3.5) with ligand (R)- and n-BuLi is described.

Abstract We report the application of Pd(II)-catalyzed, directing-group-aided C–H arylation/alkylation tactics to functionalize pyrene core, especially, relatively inaccessible C2 and K-region C10 positions core augmentation library derivatives with C1,C2- C1,C10-disubstituted motifs. The Pd(II)-catalyzed β-C–H C2-position pyrene-1-carboxamide possessing an 8-aminoquinoline directing group yiel...

Recent results in the chemistry of disubstituted carbenium ions (vinyl cations and phenyl cations) are described separately under three different sections: From kinetic and solvolytic data of several 1—cyclobutenyl nonaflates, the intermediacy of a non-classical vinyl cation, namely the 1-cyclobutenyl cation 2 is established. Cycloaddition reactions of solvolytically generated vinyl cations wit...

A method is described which provides for the direct asymmetric catalytic synthesis of trisubstituted aziridines from imines and diazo compounds. While unactivated imines were not reactive to α-diazo carbonyl compounds in which the diazo carbon was disubstituted, N-Boc imines react with both α-diazo esters and α-diazo-N-acyloxazolidinones to give trisubstituted aziridines with excellent diastere...

The asymmetric synthesis of substituted pyrrolidines has been accomplished using a novel organocatalytic cyclization reaction promoted by a Cinchona alkaloid based primary amine. The reaction proceeds smoothly yielding pyrrolidine-2,2-dicarboxylates after in situ diastereoselective reduction with high levels of enantioselection. Furthermore, these adducts could be easily transformed into N-prot...