Highly regioselective synthesis of glycospiro heterocycles through 1,3-dipolar cycloaddition reaction

A highly regio-selective synthesis of novel glycospiropyrrolidines has been accomplished by 1,3-dipolar cycloaddition (1,3-DC) reaction. A unique dipolarophile derived from galactose has been reacted with azomethine ylide generated from 1,2-diketones and secondary aminoacids to give the corresponding spiro glycoheterocycles in good yields. The structures were assigned by 2D NMR spectra and the regio- and stereochemical outcome of the cycloadducts was established by a single crystal X-ray analysis.