Regio- and stereoselective synthesis of new spiro-isoxazolidines via 1,3-dipolar cycloaddition

Abstract New spiro-isoquinolinediones were prepared by regio- and stereoselective 1,3-dipolar cycloaddition of ( E )-4-arylidene- N -methyl-isoquinoline-1,3-dione derivatives 1a – d with C -aryl- N -phenylnitrones 2e – g . NMR studies confirmed that only one regioisomer was formed selectively in the majority of cases. Regioselectivity of the reaction was established by 1 H and 13 C NMR assignments. The stereochemistry of spirannic compounds 3a – l and 4a – c has been corroborated by means of DFT calculations. The structures of all the products were characterized thoroughly by NMR and elemental analyses.