[3+2] regioselective annulation reaction of 2-arylidene-1,3-indandiones towards synthesis of spirocyclopentenes: understanding the mechanism of γ-attack
vs. α-attack using DFT studies.
RSC Adv 2021;
11:38648-38653. [PMID:
35493224 PMCID:
PMC9044273 DOI:
10.1039/d1ra07165c]
[Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 11/19/2021] [Indexed: 12/18/2022] Open
Abstract
A regioselective [3+2] cyclisation reaction between 2-arylidene-1,3-indanedione and ethyl 2,3-butadienoate catalysed by triphenylphosphine has been demonstrated to synthesize functionalised spirocyclic cyclopentenes. The reaction tolerated various electron-rich and electron-deficient aryl substituted 2-arylidene-1,3-indanediones with high to excellent chemical yields (up to 99%) and moderate to good regioselectivity (up to 5 : 1). DFT studies have also been carried out to understand the regioselective nature of this reaction. The results of Frontier molecular orbital calculations and the activation energy (Ea) favour the formation of compound 3avia γ-attack compared to that of 4avia α-attack.
A [3+2] annulation protocol for the construction of functionalized spirocyclopentenes utilizing 1,3-indanedione derived benzylidene-1,3-indanedione and ethyl-2,3-butadienoate at room temperature was developed.![]()
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