Recent Advances in Transition-Metal-Free Oxygenation of Alkene C=C Double Bonds for Carbonyl Generation.

Carbonyl-forming reactions are a class of fundamental transformations in organic chemistry. Guided by the current importance of environmentally benign metal-free catalysis and synthesis, herein we review recent advances in carbonyl-generation reactions based on alkene C=C double oxygenation as well as related cascade reactions in the synthesis of diverse organic products. The content of this focus review consists of two important but different reaction models: oxygenation based on full C=C double-bond cleavage and oxygenation based on partial C=C double-bond cleavage.