Figure 3.

The simplest hypothetical autocatalytic formose reaction cycle. In each turn of the cycle, a glycolaldehyde molecule facilitates the synthesis of a second glycolaldehyde molecule from two formaldehyde molecules. The direct formation of glycolaldehyde from formaldehyde does not occur. The stereochemistry of the asymmetric carbon atoms (marked with an asterisk in the diagram) is not specified. The side reaction leading to a branched-chain aldehyde is one of the many reactions that tend to complicate the cycle or divert molecules from it.