One-pot synthesis of C₂-symmetric N,N′-diaryl bis(oxazolidin-2-ones) as precursors for N,N′-diaryl 2,3-diamino-1,4-butanediols

A new and general one-pot synthetic method for C₂-symmetric N,N′-aryl-disubstituted bis(oxazolidin-2-ones) has been developed. Highly regioselective intramolecular cyclization reactions of 2,3-di(methanesulfonyloxy)-1,4-dihydroxybutane with arylisocyanates in the presence of sodium hydride afforded the corresponding C₂-symmetric N,N′-aryl-disubstituted bis(oxazolidin-2-ones) in 82-92% yields. Hydrolytic ring opening of the bis(oxazolidin-2-ones) provided a convenient synthetic route for optically pure C₂-symmetric N,N′-aryl-disubstituted 2,3-diamino-1,4-butanediols (58-86% yields).