Bronsted Acid Mediated Annulation of alpha-Hydroxy Amides with Cycloalkanones: Access to Double Spirocyclic Oxazolidin-4-ones

摘要

A Bronsted acid mediated annulation of cyclic alpha-hydroxy amides with cycloalkanones provide access to unusual double spirocyclic oxazolidin-4-one derivatives. This spirocyclization occurs in one-pot and the overall process is highly efficient. The annulation reaction does not need metal-catalyst. No self-condensation of cycloalkanone occurs under acidic conditions. The synthetic technique is operationally simple and chemoselective. The transformation exhibits broad scope constructing a large array of highly functionalized complex double spirocyclic oxazolidin-4-one derivatives in good yields. Notably, all the reactions have been carried out in gram scale.