A new asymmetric approach towards 2-pyrrolidinones and pyrrolidines: Simple versus double stereodifferentiation

Article abstract of DOI:10.1016/0040-4039(95)01788-J

The condensation of a chiral 2-silyloxypyrrole derivative with achiral and chiral formyl cation equivalents has been studied for the first time. The methodology allows to build-up pyroglutammic aldehydes and prolinal systems with a stereocontrol from good to excellent. Whereas the chiral auxiliary residing on the pyrrole system shows an intrinsic good level of diastereoface discrimination at C-5, the combined use of a 2-methoxy-3-tosyl-oxazolidine as a chiral formylating agent allows a total stereocontrol of the condensation. A rationale for the observed stereochemical outcome is presented.