Fig. 12. Aldol condensation between DHA and GA as reverse glycolysis. Fischer et al [1] demonstrated that only fructose and sorbose having trans-configurations as regards 3-OH and 4-OH are generated as a result of aldol condensation between DHA and GA. Importantly, fructose can be converted into stable aldohexoses, glucose or mannose by Lobry de Bruyn rearrangement, whereas sorbose cannot yield such stable aldohexoses. If any, gulose or idose, neither of them naturally occurr.