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  • Expedient synthesis of tetrasubstituted pyrroles via a copper-catalyzed cascade inter-/intramolecular cyclization of 1,3-enynes carry a nitro group with amines.

Expedient synthesis of tetrasubstituted pyrroles via a copper-catalyzed cascade inter-/intramolecular cyclization of 1,3-enynes carry a nitro group with amines.

Organic & biomolecular chemistry (2015-01-22)
Ganesan Bharathiraja, Mani Sengoden, Masanam Kannan, Tharmalingam Punniyamurthy
ABSTRACT

Various tetrasubstituted pyrroles/pyrazoles have been prepared from nitro-substituted 1,3-enynes with aromatic amines/hydrazines via a copper-catalyzed cascade aza-Michael addition, cyclization and aromatization at room temperature. This protocol is also effective for the synthesis of tetrasubstituted pyrazoles in high yields.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Copper(I) chloride, reagent grade, 97%
Sigma-Aldrich
Bis(triphenylphosphine)palladium(II) dichloride
Sigma-Aldrich
Copper(I) iodide, anhydrous, 99.995% trace metals basis
Sigma-Aldrich
Triphenylphosphine, polymer-bound, 100-200 mesh, extent of labeling: ~1-1.5 mmol/g Capacity (Phosphor)
Sigma-Aldrich
Copper(I) iodide, purum, ≥99.5%
Sigma-Aldrich
Bis(triphenylphosphine)palladium(II) dichloride, 98%
Sigma-Aldrich
Bis(triphenylphosphine)palladium(II) dichloride
Sigma-Aldrich
Copper(I) iodide, 99.999% trace metals basis
Sigma-Aldrich
Copper(I) chloride, ≥99.995% trace metals basis
Sigma-Aldrich
Copper(I) iodide, 98%
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Copper(I) chloride, ReagentPlus®, purified, ≥99%
Sigma-Aldrich
Copper(I) chloride, AnhydroBeads, ≥99.99% trace metals basis
Sigma-Aldrich
Triphenylphosphine, ≥95.0% (GC)
Sigma-Aldrich
Triphenylphosphine, ReagentPlus®, 99%
Copper(I) iodide ChemBeads