Dcm. Kong et M. Vonitzstein, THE FIRST SYNTHESIS OF A C-7 NITROGEN-CONTAINING SIALIC-ACID ANALOG, 7-TRIDEOXY-D-GLYCERO-D-GALACTO-2-NONULOPYRANOSONIC ACID (7-AZIDO-7-DEOXY-NEU5AC), Tetrahedron letters, 36(6), 1995, pp. 957-960
2-Acetamido-4-azido-2,4-dideoxy-D-mannopyranose and sodium pyruvate un
dergoes an enzymatically-catalysed aldol condensation to afford 7-trid
eoxy-D-glycero-D-galacto-2-nonulopyranosonic acid.