Lithium Bromide, an Inexpensive and Efficient Catalyst for Opening of Epoxide Rings by Amines at Room Temperature under Solvent-Free Condition

Authors

  • Asit K. Chakraborti,

    1. Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar, Punjab 160 062, India, Fax: (internat.) + 91-172-2214692
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  • Santosh Rudrawar,

    1. Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar, Punjab 160 062, India, Fax: (internat.) + 91-172-2214692
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  • Atul Kondaskar

    1. Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar, Punjab 160 062, India, Fax: (internat.) + 91-172-2214692
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Abstract

Lithium bromide has been found to be an inexpensive and efficient catalyst for the opening of epoxide rings by amines, and this provides an environmentally friendly method for the synthesis of β-amino alcohols. Aromatic and aliphatic amines react with cycloalkene oxides to exclusively form trans-2-(aryl/alkylamino)cycloalkanols in high yields. A 98−100% selectivity in favour of nucleophilic attack at the benzylic carbon atom of styrene oxide is observed with aromatic amines. However, aliphatic amines exhibit a marginal preference for the reaction at the terminal carbon atom of the epoxide ring in styrene oxide. Non-styrenoidal, unsymmetrical alkene oxides undergo selective nucleophilic attack at the sterically less hindered carbon atom by aniline. The chelation effect of the Li+ ion enables selective opening of the epoxide ring in 3-phenoxypropylene oxide in the presence of styrene oxide. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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