Postsynthetic Modification of a Metal-Organic Framework (MOF) Structure for Enantioselective Catalytic Epoxidation

Postsynthetic modification of [Cu2(mand)2(hmt)] (mand=mandelic acid, hmt=hexamethylenetetramine) with a chiral, dimeric chromium(III)salen complex led to a robust structure. Characterization of this new material showed that it perfectly preserved the textural and structural properties of the parent metalorganic framework (MOF). Although epoxidation of trans-methyl cinnamate with hydrogen peroxide led to copper leaching of 23%, experiments performed with N-methylmorpholine-N-oxide indicated no leaching, even after 72h of exposure. The obtained chiral MOF is an effective catalyst for the enantioselective epoxidation of trans-methyl cinnamate and leads to (2R,3S)-phenylglycidate with a high enantiomeric excess at room temperature.