Multi-component reactions indole synthesis

Heravi MM, Baghemejad B, Oskooie HA, Hekmatshoar R (2008) A novel and facile synthesis of 2-(cyclohexylamino)-6,7-dihydro-3-aryl-lH-indole (5H)-ones via a one-pot multi-component reaction. Tetrahedron Lett 49 6101-6103... 

Carboline stmcture was constructed by one-pot reaction, which involves the three-component indole formation and nucleophilic cycUzation by the addition of t-BuOK or MsOH. This is the first example of multi-component synthesis of carbolines, except for those using the Pictet-Spengler type reaction. Utilizing the three-component indole formation, indole-fused 1,4-diazepines were also synthesized through deprotection/iV-arylation at nitrogen atom of indole by one-pot addition of MeONa after the formation of indole. These reactions form four bonds in a single reaction vessel, which involves two C-C bonds/two C—N bonds or one C-C bond/three C-N bonds. 

An efficient three-component domino strategy for the synthesis of multi-functionahzed tetracyclic indeno[l,2-h]indole derivatives has again been reported by Tu, li, and coworkers [62]. The domino reaction between enaminones 57 and 2,2-dihydroxyindene-l,3-dione 105 in acid anhydride generated the fused pyrazoles 106 (tetracyclic 6-5-S-6 skeleton), which involved a nucleophilic substitu-tion/cychzation/methyl migration/aromatization/esterification. On the other hand,... 

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