Matrix isolation and photorearrangement of cis - and trans -1,2-ethenediol to glycolaldehyde.

1,2-Ethenediols are deemed key intermediates in prebiotic and interstellar syntheses of carbohydrates. Here we present the gas-phase synthesis of these enediols, the high-energy tautomers of glycolaldehyde, trapped in cryogenic argon matrices. Importantly, upon photolysis at = 180-254 nm, the enols rearrange to the simplest sugar glycolaldehyde.