Substrate Structural Effects in Yttrium(III)-Catalyzed Hydroamination/Cyclizations of 1,2-Disubstituted and 1,1,2-Trisubstituted Aminoalkenes ­Terminated by 2-(Phenyl) and 2-(2-Heteroarenyl) Groups

A series of 2-phenyl- and 2-(2-heteroarenyl)-bearing amines possessing 1,2-disubstituted and 1,1,2-trisubststuted ­alkenes have been evaluated in intramolecular hydroaminations catalyzed by Y[N(TMS) 2 ] 3 ( 1 Y ). Aminoalkenes possessing a terminal 2-(5-trimethylsilyl)thienyl group exhibited substantially enhanced reactivity compared to their 2-(phenyl)-containing counterparts. Cyclization efficiencies imparted by the 2-[(5-trimethylsilyl)furanyl] substituent were comparable or only slightly better than those obtained with the simple the 2-(phenyl) group.