Chemoselective Michael Type Addition of Aliphatic Amines to α,β-Ethylenic Compounds Using Bismuth Triflate Catalyst

Abstract

Catalytic amounts of bismuth triflate efficiently catalyse the conjugate addition of aliphatic amines to α,β-ethylenic compounds in acetonitrile under mild conditions. The reaction is chemoselective, as aromatic amines do not participate in the reaction. Further, the catalyst can be easily recovered and reused.

Key words

Michael addition - bismuth triflate - aliphatic amines - α,β-ethylenic compounds - chemoselectivity

References

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11

General procedure for the Michael addition of Methyl-(3-pyrrolidine)-propionate(1). A mixture of pyrrolidine (0.2 mL, 2.3 mmol), methyl acrylate (0.414 mL, 4.6 mmol) and bismuth triflate (2 mol%) in anhydrous acetonitrile (5 mL) was kept at ambient temperature under vigorous stirring for 30 min. After completion of the reaction as indicated by TLC, the reaction mixture was filtered and catalyst was separated out, reaction mixture was extracted with ethyl acetate and purified by using column chromatography on silica gel to obtain pure product all most in quantitative yield. Similar experimental procedures have been carried out for other substrates and their chemical yields of isolated products are summarized in Table [1] . All isolated compounds were fully characterized by comparing their physical data (¹H NMR, Mass Spectra, IR) of authentic compounds.