Novel Synthesis of Furo[2,3-b]indole Derivatives

Abstract

Isatin reacted with diethyl 3-amino-2-cyano-2-pentenedioate in ethanol and in presence of Et3N to give 3-(1-amino-2-cyano-2-ethoxycarbonylethenyl-2H-furo[2,3-b]indol-2-one. The reaction of (2-oxo-3-indolinylidene)malononitrile (3a) with the diethyl ester gave a mixture of diethyl 3-amino-4-(2-amino-3-cyano-4-quinolylcarbonyl)-2-cyano-2-pentenedioate (80%) and diethyl 3-amino-4-(2-amino-3-cyano-3aH-furo[2,3-b]indol-3a-yl)-2-cyano-2-pentanedioate (20%). Treatment of 3a and 3-[cyano(ethoxycarbonyl)]methylene-2-indolinone (3b) with 2-(ethoxycarbonylmethyl)-2-thiazolin-4-one gave the corresponding two pyrano[4′,5′-c] and furo[2″,3″-b]indole compounds, respectively. When 3a and 3b also reacted, with 3-methyl-2-pyrazolin-5-one or 3-methyl-1-phenyl-2-pyrazolin-5-one, the corresponding four spiro indoline-3,4′-(1′H)-pyrano[2,3-c]pyrazol products were obtained. The reaction of 3b with benzoylacetonitrile gave ethyl 2-amino-3a-[benzoyl(cyano)methyl]-3aH-furo[2,3-b]indole-3-carboxylate.

Multicomponent One‐pot Diastereoselective Synthesis of Biologically Important Scaffold under Microwaves

“…The present reaction was found to be interesting because of the contrary formation of spiro-derivative 4 to earlier report, 12,13 where the condensed derivatives 5 were formed in the reaction of 6 derivative with other heterocycles, e.g. 2-(ethoxycarbonylmethyl)-2-thiazolin-4-one/1-phenyl-2-thiohydantoin, which is possible by intermolecular cycloaddition of less acidic indole OH on the ester group of the spiro compound (Scheme 2).…”

“…However, the signals of aromatic and NH protons of the two diastereomers could not be resolved while exhibited complex multiplets. In the 13 C NMR spectrum of 4a characteristic sharp signals were observed at 12.6 (CH 3 ), 39.9 (CH 2 ), 59.1 (CH), 77.4 (spiro carbon), 158.3 (C＝N), 167.3, 177.1 and 179.2 (three C＝O). Other signals were observed at 102.…”

“…Spiro product 4 was formed exclusively instead of other possible product 5 as observed in analogous reaction with 2-(ethoxycarbonylmethyl)-2-thiazolin-4-one/1-phenyl-2-thiohydantoin. 12,13 Encouraged by the recent focus on the green chemical theme of eliminating the use of solvents, we extended our studies to neat reactions, since the reaction with solid support required an appreciable amount of solvent for adsorption of reactants and elution of products. However, no reaction occurred, but it could be made successful by addition of a few drops of DMF.…”

Solvent-Free One-Pot Synthesis of Spiro[indoline-3,4′(1H′)-pyrano[2,3-c]pyrazol]-2-one Derivatives by Grinding

“…Mp 219-220 C, lit. mp 220 C. [7] 1 H NMR (500 MHz, DMSO) d 1.54 (s, 3H, CH 3 ), 6.93-6.95 (m,1H,1H,1H, ( …”

Dicyanomethylene compounds and heterocyclization of acylthiosemicarbazides

“…Closely analogous 3-(dicyanomethylene)-2-indolone (2) [14] which is a ylidenemalononitrile like 1 reacted with ketene S,S-and N,S-acetals [15], active methylene compounds [16][17][18][19][20] and cyclohexanedione [21] to give spiro heterocyclic compounds. The reaction of N,N'diarylacetamidines with 1 afforded indenoazepine-6-ones [22].…”