Asymmetrized tris(hydroxymethyl)methane as precursor of iminosugars: application to the synthesis of isofagomine

A new synthetic application of asymmetrized tris(hydroxymethyl)methane (THYM*), readily obtained in both enantiomeric forms through a chemoenzymatic procedure, is reported. In this case THYM* precursor 3 was elaborated by ring closing metathesis into some enantiopure branched tetrahydropyridines, that have been used as precursors of the potent glycosidase inhibitor isofagomine28.