Quaternary stereocenters: Chiral α-magnesiated nitriles can be formed by deprotonation and are configurationally stable at low temperature, even for acyclic examples. These can be trapped with electrophiles to give enantiomerically enriched quaternary substituted products (see scheme; TMP = 2,2,6,6-tetramethylpiperidine).

Quartäre Stereozentren: Chirale α‐magnesierte Nitrile – sogar acyclische – können durch Deprotonierung erhalten werden und sind bei tiefen Temperaturen konfigurativ stabil. Sie lassen sich mit Elektrophilen in Form enantiomerenangereicherter Produkte mit quartärem Stereozentrum abfangen (siehe Schema, TMP=2,2,6,6‐Tetramethylpiperidin).

No abstract

An efficient synthetic approach to the core structure of the manzamine alkaloids is reported, particularly in relation to incorporating a one-carbon unit in ring B from which the aldehyde in ircinal A or the betacarboline unit in manzamine A could potentially be generated. The key steps involve a JohnsonÐClaisen rearrangement, enolate alkylation, dithiane alkylation and a stereoselective intramolecular dipolar cycloaddition of an azomethine ylide, which provided the desired tricyclic ABC core structure.

Remarkable Configurational Stability of Magnesiated Nitriles. -This method gives α-substituted nitriles with high enantioselectivities from enantioenriched substrates using a magnesium base. The best results are obtained by in situ generation of the electrophile. -(BARKER, G.; ALSHAWISH, M. R.; SKILBECK, M. C.; COLDHAM*, I.; Angew. Chem., Int. Ed. 52 (2013) 30, 7700-7703, http://dx.