The effectiveness of a primary aliphatic amino group as an internal Lewis base on the formation of a boron-oxygen-carbon linkage: a computational study

It is well known that boronic acids form covalent linkages with compounds containing 1,2- or 1,3-diols, to form 5- or 6-membered cyclic boronate esters. In this article, we present results from a computational study designed to assess the ability of a primary aliphatic amino group to function as an internal Lewis base and catalyze the construction of a boron-oxygen-carbon linkage. In particular, thermodynamic and kinetic parameters for the dehydration reaction of (3-amino-1-propenyl)-monohydroxy borane, H2N-CH2-CH=CH-B(OH)H, and methanol are reported. It is shown that when the amine group in the reactant, H2N-CH2-CH=CH-B(OH)H, is appropriately positioned, it effectively lowers the activation barrier for the formation of (3-amino-1-propenyl)-borane methyl ether, H2N-CH2-CH=CH-B(OCH3)H. (C) 2004 Elsevier B.V. All rights reserved.