Transition metal-free ketene formation from carbon monoxide through isolable ketenyl anions

The capacity of transition metals to bind and transform carbon monoxide (CO) is critical to its use in many chemical processes as a sustainable, inexpensive C1 building block. By contrast, only few s-and p-block element compounds bind and activate CO, and conversion of CO into useful carbonyl -containing organic compounds in such cases remains elusive. We report that metalated phosphorus ylides provide facile access to ketenyl anions ([RC=C=O]-) by phosphine displacement with CO. These anions are very stable and storable reagents with a distinctive electronic structure between that of the prototypical ketene (H2C=C=O) and that of ethynol (HC equivalent to C-OH). Nonetheless, the ketenyl anions selectively react with a range of electrophiles at the carbon atom, thus offering high-yielding and versatile access to ketenes and related compounds.

Automated summary

The ability of transition metals to convert carbon monoxide into useful compounds is crucial for many chemical processes. However, only a few s- and p-block elements can bind and activate CO. This study reports a new method using metalated phosphorus ylides to generate stable ketenyl anions, offering a new pathway for the synthesis of ketenes and related compounds.