Iodine-catalyzed stepwise [4+2] cycloaddition of phenothiazine- and ferrocene-containing Schiff bases with DHP promoted by microwave irradiation

Emese Gál, Castelia Cristea, Luminita Silaghi-Dumitrescu, Tamás Lovász, A. Csámpai

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

On simultaneous effect of iodine-catalysis and microwave irradiation Schiff bases deactivated by electron-donating C-phenothiazinyl- and ferrocenyl-substituents, respectively, underwent formal inverse electron demand aza-Diels-Alder (DA) cycloaddition with 3,4-dihydro-2H-pyrane (DHP) employed as donor component. Depending on the substitution pattern of the N-phenyl group the reactions of phenothiazine-containing imines afforded 2H-pyrano[3,2-c] quinolines or 3-(3-hydroxypropyl)quinolines. Irrespective of the electronic properties of the N-phenyl substituent the less reactive ferrocene-based imines were directly converted into quinoline products. The intermediate iodoiminium ions were analysed by B3LYP/DGZVP calculations suggesting stepwise mode for the cycloaddition process. In one case the regioselectivity of the second step of cycloaddition was also interpreted by DFT analysis of the alternative rotamers of the primarily formed DHP adduct.

Original languageEnglish
Pages (from-to)9938-9944
Number of pages7
JournalTetrahedron
Volume66
Issue number52
DOIs
Publication statusPublished - Dec 24 2010

Fingerprint

Microwave irradiation
Cycloaddition
Schiff Bases
Cycloaddition Reaction
Microwaves
Quinolines
Iodine
Imines
Electrons
Regioselectivity
Catalysis
Discrete Fourier transforms
Electronic properties
Substitution reactions
Ions
ferrocene
phenothiazine

Keywords

  • [4+2] Cycloaddition
  • DFT
  • Frontier molecular orbitals
  • Iodine-catalysis
  • Microwave-assisted reactions

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry
  • Drug Discovery

Cite this

Iodine-catalyzed stepwise [4+2] cycloaddition of phenothiazine- and ferrocene-containing Schiff bases with DHP promoted by microwave irradiation. / Gál, Emese; Cristea, Castelia; Silaghi-Dumitrescu, Luminita; Lovász, Tamás; Csámpai, A.

In: Tetrahedron, Vol. 66, No. 52, 24.12.2010, p. 9938-9944.

Research output: Contribution to journalArticle

Gál, Emese ; Cristea, Castelia ; Silaghi-Dumitrescu, Luminita ; Lovász, Tamás ; Csámpai, A. / Iodine-catalyzed stepwise [4+2] cycloaddition of phenothiazine- and ferrocene-containing Schiff bases with DHP promoted by microwave irradiation. In: Tetrahedron. 2010 ; Vol. 66, No. 52. pp. 9938-9944.
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