Valorization of carbon oxides by sequential catalysis: Combining the reverse water gas shift reaction with catalytic carbonylation for the synthesis of high value added compounds (COXSECAT)

The COXSECAT (Carbon OXides SEquenatial CATalysis) project is aimed at developing innovative catalytic systems (homogeneous
and heterogeneous) and conditions for realizing an efficient indirect chemical valorization of carbon dioxide, through the catalytic
reduction of CO2 with hydrogen to give carbon monoxide (reverse water gas shift reaction, RWGSR) followed by in situ sequential
catalytic carbonylation of readily available organic substrates by CO fixation to give high value added carbonylated scaffolds.
The rapid industrialization of society and population expansion has led, during the past half century, to a huge consumption of fossil
fuels, with a significant over-release of carbon dioxide in the atmosphere. This, in turn, has led to sensible global warming, with
serious environmental consequences. Accordingly, huge efforts are currently devoted to CO2 capture and storage (CCS). Very
attractive ways for “environmental decarbonization” can be based on CO2 conversion into more reactive carbon species (such as CO
or fuels) or on coupling of CCS with the chemical incorporation of CO2 into organic substrates to give fine chemicals (“artificial
carbon fixation”). An important approach for the chemical reduction of CO2 to CO is based on the catalytic RWGSR (CO2 + H2 = CO
+ H2O), usually carried out at high temperatures under catalytic heterogeneous conditions. Considering the importance and
versatility of catalytic carbonylations that employ CO gas as carbonylating agent for the production of high value added scaffolds,
the possibility to combine the RWGSR with carbonylation in a single catalytic procedure is of evident conceptual as well as practical
interest. The development and implementation of an approach like this, however, is still in its infancy, as only a limited number of
examples have appeared in the literature, mostly related to the use of alkenes as substrates. COXSECAT is aimed at achieving a
major advancement in this important field that encompasses organic synthesis and catalysis with evident environmental and
socioeconomic benefits. In fact, COXSECAT will develop novel catalytic processes, also based on cooperative catalysis, for the
incorporation into several different organic substrates of the CO produced in situ from the RWGSR. More specifically, the innovative
catalytic systems, able to promote this sequential process, will be based on transition metals (palladium, in particular, for in situ
carbonylation) in conjunction with rhodium-, ruthenium-, or less expensive first row transition metals (for RWGSR) under either homogeneous or heterogeneous conditions. These systems will be applied to functionalized olefins as well as aryl halides and
acetylenic substrates (which have not been employed so far in this approach), for the synthesis of particularly important classes of
carbonylated compounds (such as esters, thioesters, amides, and functionalized heterocycles).