Spiro[4H‐2,3‐dihydropyran‐3,3′‐oxindoles] derived from 1,2,3,4‐tetrahydroquinoline

Abstract

Knoevenagel condensation of 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione 3 with aryl cyanomethyl ketones 9 generates 3‐(aroyl(cyano)methylidene)oxindoles 10 that react with cyclic 1,3‐diketones 11 to generate polycyclic hemiacetal spiro[4H‐2,3‐dihydropyran‐3,3′‐oxindoles] 13.

Progress in the Chemistry of Tetrahydroquinolines

“…Tricyclic isatin derivatives 1590 underwent Knoevenagel condensation with aryl cyanomethyl ketones 1591 in the presence of TsOH in refluxing EtOH to yield 3-(aroyl­(cyano)­methylidene)­oxindoles 1592 (Scheme ). These highly electrophilic alkenes undergo cyclization with the anion of cyclic 1,3-diketones, generated by treatment with DMAP at room temperature, to produce spirocyclic hemiacetals 1593 – 1595 in good yields.…”

“…648 The observed product 1588 is obtained through C 8 −Ir insertion of this unit onto a C-2 imino group formed from the starting 1,8-naphthyridines 1587 via hydrogen transfer followed by protodemetalation. Compounds 1588 were then employed as starting materials for the synthesis of 649 These highly electrophilic alkenes undergo cyclization with the anion of cyclic 1,3-diketones, generated by treatment with DMAP at room temperature, to produce spirocyclic hemiacetals 1593−1595 in good yields.…”

Synthesis of Hexahydrospiro[pyrazolo[3,4‐b]quinoline‐4,1′‐pyrrolo[3,2,1‐ij]quinoline‐2′,5(1H,4′H)‐diones] from 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione Using Fe3O4@Cu(OH)x as a Nanocatalyst

“…We have previously described the synthesis of spiro[3,3′‐oxindoles] beginning from 5,6‐dihydro‐4 H ‐pyrrolo[3,2,1‐ ij ]quinoline‐1,2‐dione ( 1 ) , which is a tricyclic analogue of isatin (1 H ‐indole‐2,3‐dione). The synthetic strategy relies on the high reactivity of the ketone carbonyl group of the isatin.…”