Synthesis of novel halopyridinylboronic acids and esters. Part 1: 6-Halopyridin-3-yl-boronic acids and esters

This paper describes a general method for the synthesis and isolation of novel 6-halo-pyridin-3-yl-boronic acids and esters . These compounds are prepared taking in account a regioselective halogen–metal exchange with a trialkylborate starting from 2,5-dihalopyridines. All substrates studied to date provided a single regioisomeric boronic acid or ester product. Additionally, these compounds have been found to undergo Pd-catalysed coupling with a range of arylhalides and authorise a strategy to produce new pyridines libraries.