4-Dimethylaminopyridine-catalyzed [3 + 3] spiroannulation reactions of isatin-derived Morita-Baylis-Hillman carbonates with indoline-2-thiones

DMAP-catalyzed diastereoselective [3 + 3] spiroannulations of isatin-derived Morita-Baylis-Hillman carbonates with indoline-2-thiones were achieved. A series of bisindole-annulated thiopyran frameworks were synthesized in good yields with good diastereoselectivities. The strategy developed in this paper offered a novel way for the synthesis of valuable indole-annulated sulfur heterocycle derivatives which might be beneficial in organic synthesis and medicinal chemistry. • A novel way for the synthesis of valuable indole-annulated sulfur heterocycle derivatives. • Bisindole-annulated thiopyran derivatives were synthetized under mild conditions. • DMAP-catalyzed diastereoselective [3 + 3] spiroannulations of isatin-derived Morita-Baylis-Hillman carbonates with indoline-2-thiones. DMAP-catalyzed diastereoselective [3 + 3] spiroannulations of isatin-derived Morita-Baylis-Hillman carbonates with indoline-2-thiones were achieved. A series of bisindole-annulated thiopyran frameworks were synthesized in good yields with good diastereoselectivities. The strategy developed in this paper offered a novel way for the synthesis of valuable indole-annulated sulfur heterocycle derivatives which might be beneficial in organic synthesis and medicinal chemistry.