Enantioselective cyclopropanation with TADDOL-derived phosphate ligands

The synthesis of new chiral TADDOL-derived phosphate ligands is described. The ligands were efficiently synthesized on a multi-gram scale in three steps starting from the readily available corresponding TADDOL and were fully characterized. An X-ray structure was obtained and compared to known BINOL-phosphates. Their use in the asymmetric Simmons-Smith cyclopropanation of both functionalized and unfunctionalized olefins gave the desired cyclopropanes in good yields and good to moderate enantioselectivities.