Victor Florencio Santes, Elizabeth Gómez Pérez, Verónica Zárate, Rosa Luisa Santillán Baca, José Norberto Farfán García, Susana Rojas-Lima. Synthesis of new homochiral 2,3-dialkylpiperazines derived from (R)-(-)-phenylglycinol Tetrahedron: Asymmetry, 12, 241-247 (2001). DOI: http://dx.doi.org/10.1016/S0957-4166(01)00036-2
The synthesis of four new 2,3-dialkylpiperazines in yields of 7099% using (R)-(?)-phenylglycinol as a chiral inductor is described. The synthesis involved reduction of the oxazinooxazine type derivatives obtained by condensation of glyoxal and phenylglycinol to give hydroxyethylenediamine precursors which were further condensed with glyoxal, butanedione and 1-phenyl-1,2-propanedione and then reduced to provide the corresponding piperazines. The stereochemical outcome is determined by the configuration of the bisoxazolidine precursors, which is in turn dictated by steric effects exerted by the substituents on the five membered ring. The structures of five derivatives were established by X-ray analysis.