Catalyst-Free Chemoselective N-tert-Butyloxycarbonylation of Amines in Water

Sunay V. Chankeshwara and Asit K. Chakraborti*

*Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar 160 062, Punjab, India, Email: akchakrabortiniper.ac.in

S. V. Chankeshwara, A. K. Chakraborti, Org. Lett., 2006, 8, 3259-3262.

DOI: 10.1021/ol0611191

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Abstract

A catalyst-free N-tert-butyloxycarbonylation of amines in water gives N-t-Boc derivatives chemoselectively without any side products (such as isocyanate, urea, N,N-di-t-Boc). Chiral amines and esters of α-amino acids afforded optically pure N-t-Boc derivatives. Amino alcohols and 2-aminophenol afforded N-t-Boc protected derivatives without oxazolidinone formation.

see article for more examples

proposed mechanism

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HClO₄-SiO₂ as a new, highly efficient, inexpensive and reusable catalyst for N-tert-butoxycarbonylation of amines

A. K. Chakraborti, S. V. Chankeshwara, Org. Biomol. Chem., 2006, 4, 2769-2771.

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Key Words

tert-butyl carbamates, green chemistry

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ID: J54-Y2006-2000