The catalytic hydrogenation of carbon dioxide and bicarbonate to formate has been explored extensively. The vast majority of the known active catalyst systems are based on precious metals. Herein, we describe an effective, phosphine-free, air- and moisture-tolerant catalyst system based on Knölker's iron complex for the hydrogenation of bicarbonate and carbon dioxide to formate. The catalyst system can hydrogenate bicarbonate at remarkably low hydrogen pressures (1-5 bar).

Carbonylation reactions are a most powerful method for the synthesis of carbonyl-containing compounds. However, most known carbonylation procedures still require noble-metal catalysts and the use of activated compounds and good nucleophiles as substrates. Herein, we developed a copper-catalyzed carbonylative transformation of cycloalkanes and amides. Imides were prepared in good yields by carbonylation of a C(sp(3) )-H bond of the cycloalkane with the amides acting as weak nucleophiles. Notably, this is the first report of copper-catalyzed carbonylative C-H activation.

Amides are important intermediates and building blocks in organic synthesis. Among the known preparation procedures, aminocarbonylation is an interesting and powerful tool. However, most of the studies were focused on noble metal-catalyzed synthesis of aromatic amides. Herein, we describe an attractive copper-catalyzed synthesis of aliphatic amides from alkanes and amines. A variety of amides were prepared in good yields by carbonylation of the C(sp3)–H bond of alkanes with different amines. Good functional groups tolerance can be observed.

A novel procedure on the carbonylative synthesis of chromenones has been developed. With simple phenols and internal alkynes as the substrates, various chromenones were isolated in moderate to good yields with excellent regioselectivity and functional-group tolerance by using iridium as the catalyst and copper as the promotor at atmospheric pressure. Notably, this is the first example on carbonylative annulation of simple phenols and alkynes.

A highly efficient and selective Pd/C-catalyzed carbonylation reaction for the synthesis of flavones has been developed. Various flavone derivatives were isolated in excellent yields with excellent functional group tolerances. The catalyst is reusable, and no phosphine ligand or inert gas protection is needed.