Download PDF
Synthesis 2006(16): 2784-2788  
DOI: 10.1055/s-2006-942492
PAPER
© Georg Thieme Verlag Stuttgart · New York

Indium(III) Halides as New and Highly Efficient Catalysts for N-tert-Butoxycarbonylation of Amines

Sunay V. Chankeshwara, Asit K. Chakraborti*
National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar, Punjab 160062, India
Fax: +91(172)2214692; e-Mail: akchakraborti@rediffmail.co; e-Mail: akchakraborti@niper.ac.in;
Further Information

Publication History

Received 7 April 2006
Publication Date:
13 July 2006 (online)

    Permissions and Reprints All articles of this category

Abstract

Indium(III) bromide and chloride efficiently catalysed the N-tert-butoxycarbonylation of amines with (Boc)2O at room temperature and under solvent-free conditions. Various aromatic, heteroaromatic and aliphatic amines were converted to N-tert-butylcarbamates in excellent yields in short times. Chiral amines, esters of α-amino acids and β-amino alcohols afforded optically pure N-t-Boc derivatives in high yields. The reactions were chemoselective and no competitive side reactions such as isocyanate, urea, and N,N-di-t-Boc formation were observed. Chemoselective conversion to N-tert-butylcarbamates took place with amino alcohols without any formation of oxazolidinones.

Key words

indium(III) halides - N-tert-butylcarbamates - amines - chiral α-amino acid esters - di-tert-butyl dicarbonate - chemoselectivity - solvent-free - room temperature