The network also includes many examples of multi-step reaction pathways with three-and four-membered rings as intermediates with significantly reduced overall barriers compared with the analogous single-step conversion. For example, 3-hexulose (7-6 in Fig. ) and HEH (5-5) are important intermediates of many major products from glucose pyrolysis. The commonly acknowledged lowest overall barrier reaction pathways of the formation of 3-hexulose and HEH are either from D-Gluclose or from D-Psicose with overall barriers between 40-45 kcal/mol, respectively. These pathways were also discovered here, along with several unreported lower barrier reaction pathways (Fig. ). When only considering D-Glucose and D-Psicose, the overall barriers of 3hexulose and HEH formation are 37.01 and 36.07 kcal/mol, respectively (Fig. ). However, more relevant reactions were explored that further reduced the overall barrier. The formation pathway of HEH with β-D-Psicofuranos (4-1 in Fig. ) as an intermediate reduced the overall barrier to 35.55 kcal/mol. More interestingly, a series of low barrier ring transformations connected both 3-hexulose and HEH with an overall barrier of 30.98 kcal/mol. The discovery of these reaction pathways challenged previous computational studies in which the barrier to glucose conversion was supposed to be more than 45 kcal/mol or even 60 kcal/mol and provides new insights into the possible existence of intermediates and reaction mechanisms. date. This network also includes complete reaction pathways to two of the major experimental pyrolysis products (in terms of mass percent), hydroxyacetaldehyde (HAA) and dihydroxyacetone (DHA). Nevertheless, we still wished to provide pathways to remaining products, even if they were not spontaneously discovered by the forward exploration.