Sc(OTf)3-catalyzed intramolecular aza-Prins cyclization for the synthesis of heterobicycles

The coupling of (E)- and (Z)-hex-3-ene-1,6-ditosylamide with various aldehydes in the presence of 10 mol % Sc(OTf)3 gave the corresponding trans- and cis-fused 1,5-ditosyl-octahydro-1H-pyrrolo[3,2-c]pyridines, respectively, in good yields via intramolecular aza-Prins cyclization, whereas the coupling of (E)- and (Z)-N-(6-hydroxyhex-3-enyl)-4-methylbenzenesulfonamide afforded the corresponding trans- and cis-fused octahydro-1-tosylpyrano[4,3-b]pyrroles derivatives, respectively, via intramolecular Prins-cyclization.