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Enantioselective Friedel-Crafts alkylation of pyrrole with chalcones catalyzed by a dinuclear zinc catalyst.
- Source :
-
The Journal of organic chemistry [J Org Chem] 2014 Dec 05; Vol. 79 (23), pp. 11690-9. Date of Electronic Publication: 2014 Nov 20. - Publication Year :
- 2014
-
Abstract
- A highly enantioselective Friedel-Crafts (F-C) alkylation of pyrrole with a wide range of simple nonchelating chalcone derivatives catalyzed by a chiral (Zn2EtL)n (L = (S,S)-1) complex has been developed. The catalyst (Zn2EtL)n complex was prepared in situ by reacting the chiral ligand (S,S)-1 with 2 equiv of diethylzinc. A series of β-pyrrole-substituted dihydrochalcones were usually formed mostly in excellent yields (up to 99%) and excellent enantioselectivity [up to 99% enantiomeric excess (ee)] by using 15 mol % catalyst loading under mild conditions. The absolute stereochemistry of the products was determined to be the S-configuration by X-ray crystallographic analysis of 13g. Meanwhile, a weak negative nonlinear effect was observed. On the basis of the experimental results and previous reports, a possible mechanism was proposed to explain the origin of the asymmetric induction.
Details
- Language :
- English
- ISSN :
- 1520-6904
- Volume :
- 79
- Issue :
- 23
- Database :
- MEDLINE
- Journal :
- The Journal of organic chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 25392948
- Full Text :
- https://doi.org/10.1021/jo5023712