Teaching Aldehydes New Tricks Using Rhodium- and Cobalt-Hydride Catalysis

Area of Science:

• Organic Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Carbon-hydrogen (C-H) bonds are traditionally inert and difficult to functionalize.
• Transition metal catalysis has revolutionized synthesis by enabling C-H bond activation.
• Aldehyde C-H bond activation offers a promising route for novel chemical transformations.

Purpose of the Study:

• To review the laboratory's efforts in overcoming limitations in hydroacylation reactions.
• To explore the potential of aldehyde C-H bond activation for creating complex molecular architectures.
• To develop new catalytic methods for synthesizing valuable organic compounds from aldehydes.

Main Methods:

• Focus on generating acyl-metal-hydrides via oxidative addition of the formyl C-H bond.
• Development of new hydroacylation variants and related transformations (carboacylation, cycloisomerization, transfer hydroformylation).
• Utilizing Rh and Co catalysts for transformations of dienyl aldehydes and exploring enantioselective hydroacylation of carbonyls.

Main Results:

• Demonstrated the first hydroacylation of olefins and expanded asymmetric variants for medium-sized rings.
• Achieved selective intermolecular couplings and identified catalysts for diverse carbocycle synthesis.
• Reported highly enantioselective hydroacylation of carbonyls (ketoaldehydes, ketoamides) and developed transfer hydroformylation for olefin synthesis from aldehydes.

Conclusions:

• Transition metal catalysis transforms aldehydes into diverse structural motifs through C-H bond activation.
• Fine-tuning acyl-metal-hydride species promotes C-C and C-O bond formation, as well as C-C bond cleavage.
• This work expands the synthetic utility of aldehydes, offering new routes to complex molecules.