Integration of CO Reduction with Subsequent Carbonylation: Towards Extending Chemical Utilization of CO.

Currently, it still remains a challenge to amplify the spectrum of chemical fixation of CO , although enormous progress has been achieved in this field. In view of the widespread applications of CO in a myriad of industrial carbonylation processes, an alternative strategy is proposed in which CO reduction to CO is combined with carbonylation with CO generated ex situ, which affords efficiently pharmaceutically and agrochemically attractive molecules. As such, CO in this study was efficiently reduced by triphenysilane using CsF to CO in a sealed two-chamber reactor. Subsequently, palladium-catalyzed aminocarbonylation, carbonylative Sonogashira coupling of aryl iodides, and rhodium(I)-mediated Pauson-Khand-type reaction proceeded smoothly to yield amides, alkynones, and bicyclic cyclopentenones, respectively. Furthermore, the formed alkynones can further be successfully converted to a series of heterocycles, for example, pyrazoles, 3a-hydroxyisoxazolo[3,2-a]isoindol-8-(3aH)-one derivatives and pyrimidines in moderate yields. The striking features of this protocol include operational simplicity, high efficiency, and relatively broad application scope, which represents an alternative avenue for CO transformation.