Synthesis, spectral characterization, and single crystal structure studies of biologically relevant bis-indoline heteroc
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TRUCTURE OF ORGANIC COMPOUNDS
Synthesis, Spectral Characterization, and Single Crystal Structure Studies of Biologically Relevant Bis-indoline Heterocyclic Scaffold1 Sakshi Sharmaa, Goutam Brahmacharib, Bubun Banerjeeb, and Vivek K. Guptaa,* aX-ray
Crystallography Laboratory, Post-Graduate Department of Physics and Electronics, University, Jammu Tawi, India b Laboratory of Natural Products and Organic Synthesis, Department of Chemistry, Visva-Bharati (a Central University), Santiniketan, West Bengal, India * e-mail: [email protected] Received April 5, 2016
Abstract—The new biologically relevant compound, 5,5''-methoxy-1'-methyl-1H,1''H-[3,3':3',3''-terindol]2'(1'H)-one was synthesized, in 89% yield, by the one-pot reaction between 5-methoxyindole and 1-methylisatin in the presence of a low-cost and environmentally benign commercially available sulfamic acid as an organocatalyst and have been characterized by elemental analyses, IR spectra, and single crystal X-ray analysis. The crystals are orthorhombic, sp. gr. Pbca, Z = 8. The structure is stabilized by N–H···O and C–H···O interactions. DOI: 10.1134/S1063774517060219
INTRODUCTION Bis-indole derivatives as an important class of heterocyclic compounds have become known. Bisindoles are regarded as scaffolds of pharmaceutical promise due to their several biological efficacies including potent anticancer activity [1–7], and this framework is widely found in bioactive natural products [8–11]. In addition, oxindole (indolin-2-one) framework is also a privileged heterocyclic motif found in numerous bioactive natural products such as donaxaridine [12], arundaphine [13], maremycins [14], paratunamide [15], and convolutamydine [16], and in a series of pharmaceutically active compounds [17–21]. Multicomponent reaction with environmen-
tally benign solvents and catalytic systems is one of the most suitable strategies, which meets the requirements of green aspects of chemistry for developing libraries of medicinal scaffolds. Also, the synthetic versatility of isatin (indol-2,3-dione) has led to its extensive use in organic synthesis and has stemmed from the interest in the biological and pharmacological properties. Under this purview, we have been motivated to synthesize a novel compound bearing these two motifs in the same structural unit of 3,3-bis(indol-3-yl)indolin-2-one, and herein report on the one-pot facile synthesis via a green route and crystal structure of 5,5''-dimethoxy1'-methyl-1H,1''H-[3,3':3',3''-terindol]-2'(1'H)-one (3) at ambient conditions: CH3 N
CH3 N O
+ H3CO
N H
5-Methoxyindole (1, 1 mmol)
O 1-Methylisatin (2, 0.5 mmol)
Sulfamic acid (NH2SOH3) (10 mol %) EtOH-H2O (1 : 1 v/v) (4 mL) Stirring at room temperature for 2 h, no column chromatographic purification
1 The article is published in the original.
889
H3CO
O
OCH3
N N H H 3,3-Bis(indol-3-yl)indolin-2-one 3 (white solid, m.p. 238‒240oC, 89%)
890
SAKSHI SHARMA et al.
Table 1. Crystallographic characteristics, X-ray-data collection and structure-refinement parameters for C28H27F
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