Shigemasa et al. conducted a photochemical FR using UV irradiation. They found that 2-hydroxymethyl glycerol was the major product under such reaction conditions which they proposed was produced via the condensation of glyceraldehyde with FA to produce 2-formyl glycerol, followed by a cross-Cannizzaro reaction. Importantly, 2-formyl glycerol is largely inert to the major operative reactions of the FR and thus accumulates. Of the intermediates detected by Shigemasa et al. , only 2-formyl glycerol is present in Epstein's mechanism , and none of Shigemasa et al.'s suggested intermediates are present in Breslow's mechanism . It is therefore probable that there is a network of chemical reactions which propagates the FR which are not well represented by various previous minimal schemas of the FR.