this led to the development of voglibose, an N-substituted valiolamine, as an anti-diabetic drug. However, it is still controversial whether either of valienamine or validamine is involved in the de novo pathway to validamycin A. Intuitively, the reductive coupling of valienamine and validone, or validamine and valienone is predicted to lead to the formation of validoxylamine A, which is them converted to validamycin A by a glucose appendage formation.