Catalytic Enantioselective Protonation of α‐Oxygenated Ester Enolates Prepared through Phospha‐Brook Rearrangement

Phosphonates go chiral: The organocatalytic enantioselective reaction of α-ketoesters with phosphites using cinchona alkaloids and Na2CO3 has afforded α-phosphonyloxy esters with high enantioselectivities (see scheme). This process allows the formation of both enantiomers of the product. A catalyst loading of as low as 2 mol % does not result in a significant decrease of the enantioselectivity.