Catalytic Asymmetric Transformations of Ketenes

Ketenes are indispensable building blocks in organic synthesis due to their unique physical properties as cumulenes and distinctive spectrum of reactivity profile. Thanks to the development of versatile asymmetric catalysis models, numerous breakthroughs have been achieved in enantioselective ketene transformations. This comprehensive review has examined diverse catalytic protocols in asymmetric ketene transformations, including: hydrofunctionalization, difunctionalization, and various [2+n]‐cycloaddition reactions. In each section, critical selection has been made by focusing on the original asymmetric catalytic models, significant breakthroughs, and advances in recent 15 years. This comprehensive review aims to expansion of ketene chemistry in terms of methodology development and asymmetric catalysis, and inspire novel applications in synthetic chemistry, material science, medical chemistry, etc.