Additive-Free Chemoselective Acylation of Amines

Abstract

Aliphatic and aromatic amines are efficiently acylated by acetic, pivalic, benzoic, phthalic, or maleic anhydrides in ethyl acetate at room temperature. Under the same experimental conditions, amino alcohols are chemoselectively acylated at the amino group.

Keywords:

• Acylation
• amides
• amines
• amino alcohols
• chemoselectivity

ACKNOWLEDGMENTS

Financial support from MIUR, National Projects PRIN2005, Consorzio CINMPIS (National Interuniversity Consortium for Innovative Methodologies and Synthetic Process), Bari, and University of Perugia is gratefully acknowledged.

Notes

^a All the products were characterized by ¹H and ¹³C NMR and mass spectroscopy.

^b Yields of the isolated products; ≥97% pure material by ¹H-NMR.

^c Anhydrous K₂CO₃ (2.2 mmol) was added with acetic anhydride.

^d 20% of the N, S diacetylated product was also obtained after column chromatography separation.

^e Based on monoacetylated product after column chromatography separation.

^f The reaction was performed in 4:1 mixture of EtOAc/ MeOH.

^a All the products were characterized by ¹H and ¹³C NMR and mass spectroscopy.

^b Piv = t-buCO; Bz = PhCO; Pht = COC₆H₄CO₂H; Mal = COCH˭CHCO₂H.

^c Yields of the isolated products; ≥97% pure material by ¹H-NMR.