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Ring Construction by Palladium(0)-Catalyzed C(sp(3))-H Activation

Baudoin, Olivier. (2017) Ring Construction by Palladium(0)-Catalyzed C(sp(3))-H Activation. Accounts of Chemical Research, 50 (4). pp. 1114-1123.

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Abstract

CONSPECTUS: The catalytic activation and functionalization of unactivated C(sp(3))-H bonds of alkyl groups has undergone intense development in recent years. In particular, a variety of directing groups as well as native functional groups have been employed in combination with palladium(II) catalysis in order to perform a variety of intermolecular, and to some extent intramolecular reactions. In parallel, inspired by precedents in C(sp(2))-H arylation, our group and others have developed a different approach, which is the focus of this Account. This strategy relies on the use of oxidative addition of a carbon-leaving group bond to palladium(O) to induce intramolecular C(sp(3))-H activation and the subsequent formation of a C(sp(2))-C(sp(3)) or C(sp(3))-C(sp(3)) bond. Since our first publication in 2003, the construction of olefins and, more interestingly, of an array of valuable monocyclic and polycyclic systems has been reported according to this principle. (Hetero)aryl bromides were initially employed as reactants, but the scope was later expanded to include (hetero)aryl chlorides and triflates, alkenyl bromides, carbamoyl chlorides and alpha-chloroamides. Mechanistic studies enabled a better understanding of the C-H activation step, which was proposed to occur through ambiphilic metal-ligand activation-6 (AMLA-6), also known as concerted metalation deprotonation (CMD), and a better rationalization of the observed selectivity patterns. Moreover, the wealth of accumulated experimental data indicate that the number of atoms separating the C-H bond from Pd and the type of C-H bond are the main factors controlling the site-selectivity of the C-H bond cleavage. Recent efforts have been devoted to the development of enantioselective reactions. To this purpose, two different strategies have been employed: a chiral ancillary ligand in combination with an achiral base, and a chiral base in combination with an achiral ligand, and allowed for the achievement of high enantioselectivities in the construction of both tri- and tetrasubstituted stereocenters. On the other hand, the current C-H activation-based ring-forming method was applied to the synthesis of pharmacologically active substances and agrochemicals, as well as complex natural products such as the aeruginosins, thereby demonstrating its great potential for step-economical organic synthesis.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Synthetische Chemie (Baudoin)
UniBasel Contributors:Baudoin, Olivier
Item Type:Article, refereed
Article Subtype:Further Journal Contribution
Publisher:American Chemical Society
ISSN:0001-4842
e-ISSN:1520-4898
Note:Publication type according to Uni Basel Research Database: Journal item -- The final publication is available at ACS, see DOI link
Language:English
Identification Number:
Last Modified:17 Aug 2018 12:12
Deposited On:20 Dec 2017 08:40

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