α-​D-​Galactopyranoside, (1aS,​1bS,​2S,​5aR,​6R,​6aS)​-​2-​(β-​D-​glucopyranosyloxy)​-​1a,​1b,​2,​5a,​6,​6a-​hexahydro-​1a-​(hydroxymethyl)​oxireno[4,​5]​cyclopenta[1,​2-​c]​pyran-​6-​yl