The Knoevenagel product of indolin-2-one and ferrocene-1,1′-dicarbaldehyde

Abstract

Indolin-2-one (oxindole), (I), undergoes a Knoevenagel condensation with ferrocene-1,1'-dicarbaldehyde, (II), to afford the title complex 3,3'-[(E,E)-ferrocene-1,1'-diyldimethylidyne]diindolin-2-one dichloromethane disolvate, [Fe(C(28)H(20)N(2)O(2))]·2CH(2)Cl(2), (IV). The structure of (IV) contains two ferrocene complex molecules in the asymmetric unit and displays, as expected, intermolecular hydrogen bonding (N-H···O=C) between the indolin-2-one units. Intermolecular π-π stacking interactions are also observed.

Oxindole as starting material in organic synthesis

“…Oxindole 1 also undergoes a Knoevenagel condensation with ferrocene-1,1′-dicarbaldehyde 18 to afford the complex 3,3′-[(E,E)-ferrocene-1,1′-diyldimethylidyne]diindolin-2-one 19 (as bisdichloromethane solvate) (Scheme 8). 22 Compound 21, with antiamnesic effects, has been synthesized by the condensing of oxindole 1 and 4-aminonicotinaldehyde 20 in methanol in the presence of piperidine as catalyst (Scheme 9).…”