An effective one-pot access to polynuclear dispiroheterocyclic structures comprising pyrrolidinyloxindole and imidazothiazolotriazine moieties via a 1,3-dipolar cycloaddition strategy

An effective and highly regio- and diastereoselective one-pot method for the synthesis of new polynuclear dispiroheterocyclic systems with five stereo g enic centers (dispiro [imidazo [4,5-e]thiazolo [3,2-b]- 1,2,4-triazine-6, 3 '-pyrro lidine-2 ', 3 - indo le s]) comprising pyrrolidinyloxindole and imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine moieties has been developed. The method relies on a 1,3-dipolar cycloaddition of azomethine ylides generated in situ from isatin derivatives and sarcosine to 6-benzylideneimidazo [4,5-e] thiazolo [3,2-b]- 1,2,4-triazine-2,7-diones.