Diversity-Oriented Synthesis of Spiro- and 3-Methylene-hydroquinoline-Indandiones via an Organobase-Controlled Cascade Strategy

The catalyst-controlled diversity-oriented synthesis of spirohydroquinoline-indandiones and 3-methylenehydroquinoline-indandiones from ortho-sulfonamidophenyl-substituted para-quinone methides and allylidene-indandiones is reported. The strategies utilized an organobase such as DMAP or TMG to control the reaction pathway chemoselectively, furnishing the corresponding products in 40–99% yields with excellent diastereoselectivities. The mechanistic studies revealed that spirohydroquinoline-indandione was the kinetic product to afford 3-methylenehydroquinoline-indandione in the presence of TMG, which probably involved an unusual base-initiated 1,3-nitrogen rearrangement process. (Figure presented.).