Enantioselective Synthesis and Chiroptical Properties of Optically Active Isoflavone Epoxides.

Abstract Enantioselective epoxidation of isoflavones 1a-f has been performed by using Mn(III)salen complexes (R,R)- 3 and (S,S)- 3 as catalysts and dimethyldioxirane (DMD) or NaOCl together with 4-phenylpyridine N-oxide (PPNO) axial ligand as oxygen donors to obtain nonracemic isoflavone epoxides 2a-f. With the help of circular dichroism (CD) spectra of three enantiomeric pairs, and Snatzke's inverse octant rule, the absolute configurations of these optically active isoflavone epoxides have been determined.