Concise Preparation of Optically Active Heteroaryl [alpha]-(Hydroxyamino) Esters

A practical sequence for the synthesis of optically active heteroaryl [alpha]-(hydroxyamino) esters was explored. The highly diastereoselective addition of heteroaromatics to a cyclic chiral nitrone allowed access to a series of heteroaryl hydroxylamines. The scope of this reaction was evaluated on substrates possessing a pyrrole, an indole, or a furan core. The three-step sequence afforded the [alpha]-(hydroxyamino) esters in good overall yields (36-62%) with good enantiomeric excess values (76 to ≥98%).