This chapter covers the developments in carbonyl ylide and carbonyl oxide chemistry from 1995 to 2003. The major methods of formation of carbonyl ylides are discussed: epoxide ring opening, interaction of carbenes with carbonyl compounds, cycloreversion reactions, and elimination reactions. Also included are recently developed methods for enantioselective generation and reaction of the carbonyl ylides, particularly in inter- and intramolecular cycloaddition reactions. Carbonyl oxide formation from the ozonolysis of alkenes and alkynes, and from the interaction of carbenes with molecular oxygen, is examined with reference to mechanistic studies, its importance in atmospheric chemistry, and the synthetic uses of the oxides.
