Quiroga D, Becerra LD, Coy-Barrera E. Solvent Free Three-Component Synthesis of 2,4,5-trisubstituted-1
H-pyrrol-3-ol-type Compounds from
L-tryptophan: DFT-B3LYP Calculations for the Reaction Mechanism and 3
H-pyrrol-3-one↔1
H-pyrrol-3-ol Tautomeric Equilibrium.
Molecules 2020;
25:molecules25194402. [PMID:
32992704 PMCID:
PMC7582317 DOI:
10.3390/molecules25194402]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/19/2020] [Accepted: 09/24/2020] [Indexed: 11/16/2022] Open
Abstract
In this paper, we describe the solvent-free three-component synthesis of 2,4,5-trisubstituted-1H-pyrrol-3-ol-type compounds from L-tryptophan. The first step of the synthetic methodology involved the esterification of L-tryptophan in excellent yields (93-98%). Equimolar mixtures of alkyl 2-aminoesters, 1,3-dicarbonyl compounds, and potassium hydroxide (0.1 eq.) were heated under solvent-free conditions. The title compounds were obtained in moderate to good yields (45%-81%). Density functional theory using "Becke, 3-parameter, Lee-Yang-Parr" correlational functional (DFT-B3LYP) calculations were performed to understand the molecular stability of the synthesized compounds and the tautomeric equilibrium from 3H-pyrrol-3-one type intermediates to 1H-pyrrol-3-ol type aromatized rings.
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