Over the past decade, several metalloenzymes have been characterized which catalyze dioxygenase-type aliphatic carbon–carbon bond cleavage reactions. The substrates for these enzymes vary from species that are stable with respect to O 2 under ambient conditions, to examples that in anionic form exhibit O 2 reactivity in the absence of enzyme. Described herein are advances from studies of the enzymes themselves and model systems. These combined investigations provide insight into novel mechanistic pathways leading to aliphatic carbon–carbon bond cleavage and/or the factors that influence regioselectivity in the oxidative carbon–carbon bond cleavage reactions.