Transition-Metal-Catalyzed C–C Bond Formation from C–C Activation

• Published in: Accounts of chemical research 2023-11, Vol.56 (21), p.2867-2886
• Main Authors: Song, Feijie, Wang, Biqin, Shi, Zhang-Jie
• Format: Article
• Language: English
• ISSN: 0001-4842; 1520-4898
• DOI: 10.1021/acs.accounts.3c00230

Conspectus C–C single bonds are ubiquitous in organic compounds. The activation and subsequent functionalization of C–C single bonds provide a unique opportunity to synthesize conventionally inaccessible molecules through the rearrangement of carbon skeletons, often with a favorable atom and step economy. However, the C–C bonds are thermodynamically and kinetically inert. Consequently, the activation of C–C bonds is particularly attractive yet challenging in the field of organic chemistry. In the past decade, we sought to develop efficient strategies to carry out transition-metal-catalyzed diverse C–C cleavage/C–C forming reactions and to obtain some insights into the intrinsic reactivities of different C–C bonds. With our efforts, readily available alcohols, carboxylic acids, and ketones served as suitable substrates for the catalytic C–C coupling reactions, which are reviewed in this Account. In 2009, we observed a Ni-catalyzed cross coupling of aryl nitriles with arylboronic esters through C–CN cleavage. Encouraged by these results, we are interested in transition-metal-catalyzed C–C bond activation. Due to their broad availability, we then turned our attention to C–C cleavage of carboxylic acids. Rhodium-catalyzed decarbonylative coupling of carboxylic acids with (hetero)­arenes was then achieved through oxidative addition of in situ formed, more reactive mixed anhydrides to Rh­(I) without the need for oxidants that are commonly required for the decarboxylative coupling of carboxylic acids. Subsequently, the decarbonylation of more challenging unstrained aryl ketones was realized under Rh catalysis assisted by N-containing directing groups. Following this work, a group exchange of aryl ketones with carboxylic acids was achieved through 2-fold C–C bond cleavage. By employing the chelation strategy, Rh-catalyzed C–C bond activation of secondary benzyl alcohols was also accomplished through β-carbon elimination of the rhodium alcoholate intermediates. The competing oxidation of secondary alcohols to ketones via β-hydrogen elimination of the same intermediates was suppressed as thermodynamically favorable five-membered rhodacycles are formed after β-carbon elimination. Different types of transformations of alcohols, including the Heck-type reaction with alkenes, cross coupling with arylsilanes, and Grignard-type addition with aldehydes or imines, have been achieved, showing the great potential of secondary alcohols in the formation of C–C bonds. These C–C