Studies of the dehydrodimerization of 2-butanone and 3-pentanone by lead dioxide

International audienceThe dehydrodimerization of 2-butanone or 3-pentanone by lead dioxide leads to 3,4-dimethyl-2,5-hexanedione or 4,5-dimethyl-3,6-octanedione in nearly quantitative yield. This very clean and efficient reaction has been studied from mechanistic and stereochemical points of view. Dehydrodimerization of a 1:1 molar mixture of 2-butanone and 3-pentanone leads to 3,4-dimethyl-2,4-heptanedione in similar to 50% yield. From these gamma-diketones, 2,3,4-trimethylcyclopentenone, 3,4,5-trimethylcyclopentenone, 2,3,4,5-tetramethylcyclopentenone or 3-ethyl-2,4,5-trimethylcyclopentenone were obtained. (C) 2016 Elsevier Ltd. All rights reserved