Conversion of Furostanol Glycosides into Steroidal Alkaloid Glycosides. I. : From Methyl Protodioscin to Kryptogenin 3-O-β-Chacotrioside

A furostanol glycoside, methyl protodioscin (1), was converted to kryptogenin 3-O-β-chacotrioside (4), which is a key intermediate in the chemical transformation to the solanidane glycoside.