Transition metal-catalysed carbene- and nitrene transfer to carbon monoxide and isocyanides.

Transition metal-catalysed carbene- and nitrene transfer to the C1-building blocks carbon monoxide and isocyanides provides heteroallenes ( i.e. ketenes, isocyanates, ketenimines and carbodiimides). These are versatile and reactive compounds allowing in situ transformation towards numerous functional groups and organic compounds, including heterocycles. Both one-pot and tandem processes have been developed providing valuable synthetic methods for the organic chemistry toolbox. This review discusses all known transition metal-catalysed carbene- and nitrene transfer reactions towards carbon monoxide and isocyanides and in situ transformation of the heteroallenes hereby obtained, with a special focus on the general mechanistic considerations.