Rapid and Efficient Synthesis of 3,3-Di(1H-indol-3-yl)indolin-2-ones and 2,2-Di(1H-indol-3-yl)-2H-acenaphthen-1-ones Catalyzed by p-TSA

Abstract

An efficient synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones and 2,2-di(1H-indol-3-yl)-2H-acenaphthen-1-ones via a reaction of various isatins or acenaphthenequinone with indoles in the presence of p-methylbenzene sulfonic acid (p-TSA) in CH₂Cl₂ at room temperature is described. The advantages of this method include good reaction yield, simple workup procedure, and mild reaction condition.

GRAPHICAL ABSTRACT

Keywords:

• Acenaphthenequinone
• 2,2-di(1H-indol-3-yl)-2H-acenaphthen-1-ones
• 3,3-di(1H-indol-3-yl)indolin-2-ones
• indole
• isatin
• p-TSA

Notes

^a Reaction conditions: isatin 1a (1 mmol), indole 2a (2 mmol), solvent (5 mL).

^b r.t. = room temperature.

^c Isolated yields.

^a Reaction conditions: isatin 1 (1 mmol), indole 2 (2 mmol), p-TSA (10 mol %), CH₂Cl₂ (5 mL), rt.

^b Isolated yields.

^{c, d, e, f} Yields of reported literature.^{[ 26 , 13 , 16 , 27 ]}

^a Reaction conditions: acenaphthenequinone 4 (1 mmol), indole 2 (2 mmol), p-TSA (10 mol %), CH₂Cl₂ (5 mL), rt.

^b Isolated yields.

^c Yields of reported literature.^{[ 31 ]}