Asymmetric Mannich-Type Addition of Ketene Silyl Acetals and Thioacetals to N,N-Dialkylhydrazones - Díez, Elena; Prieto, Auxiliadora; Simon, Monika; Vázquez, Juan; Álvarez, Eleuterio; Fernández, Rosario; Lassaletta, José María (Synthesis, 2006)