Resolution of 2-substituted 1,4-benzodioxanes by entrainment

The methyl ester of 1,4-benzodioxane-2-carboxylic acid 1 and the mesylate of 2-hydroxymethyl-1,4-benzodioxane 2 are synthetic intermediates whose enantiomers can be advantageously used to prepare a number of enantiopure 2-substituted 1,4-benzodioxanes from readily accessible (±)-1,4-benzodioxane-2-carboxilic acid. We have previously demonstrated the conglomerate nature of the enantiomeric systems of 1 and 2. Herein, we report the resolution of their racemates by preferential crystallization according to an entrainment procedure. In particular, the entrainment resolution of 1 showed good efficiency, which makes the present method a competitive alternative to the classical resolutions of 1,4-benzodioxane-2-carboxylic acid with dehydroabietylamine and para-substituted 1-phenylethylamines that we have recently reported.