Efficient synthesis of functionalized 3H-pyrrolo[1,2-a]indoles

Abstract

Dialkyl 9-chloro-3H-pyrrolo[1,2-a]indole-2,3-dicarboxylates are obtained in excellent yields from the 1 : 1 : 1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates and 3-chloroindole-2-carbaldehyde; dimethyl 9-chloro-3H-pyrrolo[1,2-a]indole-2,3-dicarboxylate is converted to dimethyl 9-oxo-9H-pyrrolo-[1,2-a]indole-2,3-dicarboxylate.

Asymmetric Isocyanide‐Based MCRs

“…The reaction between an isocyanide, a dialkyl acetylene- dicarboxylate and cyclopentanetrione 107, allowed the preparation in excellent yields of a series of enaminoesters of general formula 108, as single diastereoisomers [92]. The reaction most likely proceeds through the formation of zwitterionic intermediate 106, followed by the nucleophilic attack of the enolate of 107 and a final Claisen rearrangement and cyclization, as depicted in Scheme 1.37.…”

Augmented indoles

“…[8][9][10] Similar reactions can be achieved from indole-7-carbaldehydes, and a six-membered ring is fused between C7 and N1, to give pyrroloquinolines. In the case of a 6-hydroxy-7-formylindole, there is a choice of reaction between the indole nitrogen and the phenolic oxygen atoms.…”

Reactivity of β‐Carbolines and Cyclopenta[b]indolones Prepared from the Intramolecular Cyclization of 5(4H)‐Oxazolones Derived from L‐Tryptophan

“…Using an approach that has recently been described for the construction of various heterocycles, [28Ϫ30] the aldehydes 20 and 21 were each treated with dimethyl acetylenedicarboxylate (DMAD) in the presence of triphenylphosphane to give the substituted unsaturated canthine derivatives 28 and 29, respectively (Scheme 9). Presumably, [28,29] a 1:1 adduct is formed between triphenylphosphane and DMAD. This deprotonates the β-carboline, and the soformed species subsequently attacks the 1:1 adduct to form phosphorane 26 or 27.…”