Heterocyclization of 2-indolinone derivatives (A review)

Abstract

At present, only a few summarizing papers devoted to the synthesis of varions heterocycles on the basis of oxindole (2indolinone) are available in the literature. The well-known monograph [ I] considered the synthesis of condensed indoles based on the 2-indolinone derivatives. Unfortunately, a recent review [2] paid little attention to the problem of heteroeyclization in these systems. We believed that it would be importaat to fill the gap, thus stimulating investigations in this direction. This review summarizes data published doting the past two decades on the annelation of various heterocycles at different "edges" of the indole cycle using substituted indoles as the initial compounds. In addition, Section IV concerns some problems related to the possible expansions of the fivemembered oxindole ring.

Synthesis and Some Biological Properties of Pyrrolo[1,2‐a]indoles

“…Despite the fact that there are many articles dedicated to methods of synthesis and properties of pyrrolo[1,2‐ a ]indoles, there is only old three summary reviews partially devoted to this issue .…”

“…Despite the fact that there are many articles dedicated to methods of synthesis and properties of pyrrolo [1,2-a]indoles, there is only old three summary reviews partially devoted to this issue [3][4][5]. A convenient method for the synthesis of 2,3-dihydro-1Н-pyrrolo [1,2-a]indoles is based on the closure of the pyrrole cycle of indole N-alkyl derivatives with a leaving group in γ-position.…”

“…Numerous research dedicated to the synthesis of dihydropyrrolo [1,2-a]indoles are associated with radical reactions [6][7][8][9][10][11][12][14][15][16][17][18], for instance, the radical cyclization of bromoalkylindole 5 into 6 under the action of ruthenic catalyst (Ru(bpy) 3 Cl 3 ) (bpy = bipyridine) and light [14,15]. The authors studied the mechanism of this process and demonstrated that the catalyst that participates in the formation of radical 7 is activated under exposure to light.…”

“…An interesting method applied to the synthesis of 2,3dihydro-1H-pyrrolo[1,2-a]indoles 14 is described in [20][21][22]. It is based on intramolecular cyclization of N-allyl-3-benzylimino-methylindone 15 with the participation of the С 2 of indole and double bonds of the N-allyl substituent by means of Wilkinson's catalyst -(PPh 3 ) 3 RhCl [20] or the rhodium and chiral phosphoramide ligand complex [21] (Scheme 6).…”

Highly Efficient Synthesis of Thieno[2,3‐b]indole Derivatives

“…For instance, thienodolin (¼ 6-chloro-8H-thieno[2,3-b]indole-2-carboxamide), which was extracted from the fermentation mixture of a streptomycete strain, specified as Streptomyces albogriseolus, has shown both growth-promoting and -inhibiting activities in rice seedlings [1]. Thienoindoles are also widely used in medicinal chemistry with applications in drug discovery and development [2], and in organic electronics as novel electroluminescence materials for designing light-emitting devices [3]. Therefore, development of an efficient procedure for the synthesis of substituted thienoindoles is still an urgent need.…”