Asymmetric organocatalytic synthesis of quaternary α-hydroxy phosphonates: en route to α-aryl phosphaisoserines.

The dual activation of acyl phosphonates and formaldehyde tert-butyl hydrazone by a BINAM-derived bis-urea catalyst is the key to achieve high reactivities and enantioselectivities in the synthesis of densely functionalized quaternary α-hydroxy phosphonates. Subsequent high-yielding transformations in a 'one-pot' fashion provide direct access to valuable azoxy compounds and quaternary α-aryl-phosphaisoserines.