Stereocontrolled lithiation/trapping of chiral 2-alkylideneaziridines: investigation into the role of the aziridine nitrogen stereodynamics.

Nitrogen dynamics and reactivity of chiral aziridines: generation of configurationally stable aziridinyllithium compounds.

Diastereomeric oxazolinylaziridines (R,R)-9 and (R,S)-9 have been regioselectively lithiated at the α-position with respect to the oxazolinyl ring. The resulting aziridinyllithium compounds proved to be chemically and configurationally stable under the experimental conditions used, thus furnishing, upon trapping with electrophiles, chiral 2,2-disubstituted aziridines, in contrast to the corresp...

Solvent- and temperature-dependent functionalisation of enantioenriched aziridines.

A highly stereo- and regioselective functionalisation of chiral non-racemic aziridines is reported. By starting from a parent enantioenriched aziridine and finely tuning the reaction conditions, it is possible to address the regio- and stereoselectivity of the lithiation/electrophile trapping sequence, thereby allowing the preparation of highly enantioenriched functionalised aziridines. From ch...

Graphical Abstract Optically active aziridine esters by nucleophilic addition of nitrogen heterocycles to a chiral 2H-azirine-2-carboxylic ester

Mechanistic interrogation of the asymmetric lithiation-trapping of N-thiopivaloyl azetidine and pyrrolidine.

A fundamental mechanistic study of the s-BuLi/chiral diamine-mediated lithiation-trapping of N-thiopivaloyl azetidine and pyrrolidine is reported. We show that lithiated thiopivalamides are configurationally unstable at -78 °C. Reaction then proceeds via a dynamic resolution of diastereomeric lithiated intermediates and this accounts for the variable sense and degree of asymmetric induction obs...

Diastereoselective Lithiation of (h6- Arene)dicarbonyltriphenylphosphane Chromium(0) Oxazoline Complexes–Direct Preparation of Enantiopure Complexes Having Planar Chiral Fragments of Either Configuration**

Planar chiral h6-arene chromium(0) complexes are finding increasing application in the synthesis of enantioenriched compounds by serving as enantiopure starting materials or ligands for catalytic asymmetric processes.[1,2] Whereas early methods of generating enantiopure 1,2-disubstituted h6-arene chromium(0) complexes relied on resolution of racemates,[3] many methods have been developed recent...