Chiral Organometallic Reagents, XX. An Enantiomerically Enriched (α‐Phenylselenoalkyl)magnesium Compound

Abstract α‐Selenoalkyl Grignard reagents 2 are chiral. On reaction with the magnesium chelate 3a of α‐benzyloxypropionaldehyde they show significant degrees of kinetic resolution, especially when the reactions are run in CH 2 Cl 2 . Under these conditions, racemic 2 was resolved by reaction with 0.59 equivalents of 3a at temperatures below –20°C. The remaining 2 had an enantiomer enrichment of 80–86% e.e. (as found by trapping). Hence, 2 has a considerably higher configurational stability than its lithium counterpart 1 .