The effect of catalyst loading and donor ligands in the Mn(III) salen catalysed chiral epoxidation of chromenes: Synthesis of BRL 55834

Article abstract of DOI:10.1016/0040-4039(96)00683-1

In the absence of a donor ligand both the reaction rate and product e.e. of the manganese (III) salen catalysed epoxidation of 2,2-dimethyl-6- pentafluoroethylchromene were dependent on the catalyst loading. Isoquinoline N-oxide was the most effective donor ligand, affording highly efficient epoxidations with catalyst loadings of 0.1-0.4 mol%. These findings allowed the realisation of a concise, inexpensive synthesis of BRL 55834.