Regio- and Enantioselective Synthesis of Novel Functionalized Pyranopyrrolidines by 1,3-Dipolar Cycloaddition of Carbohydrates

A new methodology is described for the rapid enantiomeric synthesis of a novel series of pyranopyrrolidines from readily available and inexpensive carbohydrate compounds. The major feature of the method is a highly selective [3+2] cycloaddition reaction of different azomethine ylides with a chiral carbohydrate-derived enone. The reaction proved to be extremely regio- and stereoselective, giving rise to single enantiomeric compounds in all cases. Moreover, the method is totally atom-efficient and amenable to diversity, since structural diversity of the new compounds is dictated by the choice of the starting materials employed.