Synthesis and Reactions of Some New Spiro {Indeno[1,2-b]pyran-4,3’-indolines}

Abstract

Indan-1,3-dione (1) reacted with 3-dicyanomethylidene-2-oxoindolines (2a-c) in refluxed ethanol to afford 2-amino-3-cyanospiro{5H-indeno[1,2-b] pyrane-4,3'-(1'-substitutedindoline)}-2',5-diones (3a-c) which underwent different reactions to afford new spiro{indeno[2',1':5,6] pyrano[2,3-d]pyrimidine-5,3'-(1'-substitutedindoline)} (4a,b)-(12a,b) which are analogues of some reported biologically active spiropolycyclic compounds.Several authors [1][2][3][4][5][6][7][8][9][10][11] reported the synthesis and application of spiroheterocyclic derivatives.From this point of view and in continuation to our previous work [12][13][14][15][16][17][18][19][20] we report herein the synthesis of some new spiroheterocycles of pyrans and pyranopyrimidines containing indoline moiety.Our syntheses started with the reaction of indan-2,3-dione (1) with 3-dicyanomethylidene-2-oxoindolines (2a-c) in absolute ethanol and catalytic amount of triethyl amine to give 2-amino-3-cyanospiro{5H-indeno [1,2-b]pyran-4,3'-indoline} derivatives (3a-c) via a type of Michael addition shown in (Scheme 1).The structures of the prepared compounds (3a-c) were established from their elemental analyses and spectral data.The IR spectrum of compound (3a) showed characteristic absorption bands at ύ 3350-3300 for NH 2 , 3200 for NH, 2200, for CN, 1725, and 1700 cm -1 corresponding to C=O in indene and indoline rings respectively.The 1 H-NMR spectrum of (3b) showed multiplet signal at δ 7.81-6.38for aromatic protons and singlet signals at 4.80, 3.20, for NH 2 , and methyl protons, respectively.Compounds (3a,b) were subject to further reactions to give fused spiroheterocyclic systems incorporate pyrimidine nucleus in addition to indeno[1,2-b]pyran and indoline moieties.Thus the reaction of (3a,b) with formic acid gave spiro{6H-indeno[2',1':5,6]pyrano[2,3-d]pyrimidine-5,3'-indoline} derivatives (4a,b).Reaction of (3b) with acetic anhydride/pyridine mixture (2/1, v/v) afforded 1',2-dimethylspiro-