Synthetic 2-, 3-, 4- and 6-monophosphate derivs. of Me a-D-mannopyranosides, the 4-, 6- and 7-monophosphate derivs. of Me L-glycero-a-D-manno-heptopyranosides and the corresponding phosphoethanolamine derivs. and a 6,7-cyclic phosphate analog of Me L-glycero-a-D-manno-heptopyranoside were used to study phosphate migration and hydrolysis when subjected to strong alk. conditions (4 M KOH, 120 DegC, 18 h). The resulting products were analyzed by 1H NMR spectroscopy and electrospray mass spectrometry. It was found that phosphate substituents were stable under these conditions and neither migration nor hydrolysis was obsd. except for the heptose 7-phosphate, which gave a substantial amt. of phosphate hydrolysis. In phosphoethanolamine-substituted compds. migration to adjacent positions with concomitant loss of ethanolamine was found together with hydrolysis. [on SciFinder (R)]