Synthesis of 2-Amino-2-methyl-4-phosphonobutanoic Acids by Conjugate Addition of Lithiated Bislactim Ether Derived from Cyclo[Ala-d-Val] to Vinylphosphonates - Ruiz, María; Fernández, M Carmen; Conde, Susana; Díaz, Aniana; Quintela, José M (Synlett, 1999)