Tags

Type your tag names separated by a space and hit enter

Substrate activation strategies in rhodium(III)-catalyzed selective functionalization of arenes.
Acc Chem Res. 2015 Apr 21; 48(4):1007-20.AC

Abstract

The possibility of developing new methods for the efficient construction of organic molecules via disconnections other than traditional functional group transformations has driven the interest in direct functionalization of C-H bonds. The ubiquity of C-H bonds makes such transformations attractive, but they also pose several challenges. The first is the reactivity and selectivity of C-H bonds. To achieve this, directing groups (DGs) are often installed that can enhance the effective concentration of the catalyst, leading to thermodynamically stable metallacyclic intermediates. However, the presence of a pendant directing group in the product is often undesirable and unnecessary. This may account for the limitation of applications of C-H functionalization reactions in more common and general uses. Thus, the development of removable or functionalizable directing groups is desirable. Another key problem is that the reactivity of the resulting M-C bond can be low, which may limit the scope of the coupling partners and hence limit the reaction patterns of C-H activation reactions. While the first Cp*Rh(III)-catalyzed C-H activation of arenes was reported only 7 years ago, significant progress has been made in this area in the past few years. We began our studies in this area in 2010, and we and others have demonstrated that diversified catalytic functionalization of arenes can be realized using Cp*Rh(III) complexes with high reactivity, stability, and functional group compatibility. This Account describes our efforts to solve some of these challenges using Rh(III) catalysis. We fulfilled our design and activation of the arene substrates by taking advantage of the nucleophilicity, electrophilicity, oxidizing potential, and properties of a participating ligand of the directing groups when the arenes are coupled with relatively reactive unsaturated partners such as alkenes and alkynes. These in situ funtionalizable roles of the DG allowed extensive chemical manipulation of the initial coupled product, especially in the construction of a diverse array of heterocycles. In the coupling of arenes with polar coupling partners, the polar Rh(III)-C(aryl) bond showed higher reactivity as both an organometallic reagent and a nucleophilic aryl source. The polar coupling partners were accordingly activated by virtue of umpolung, ring strain, and rearomatization. All of these transformations have been made possible by integration of the higher reactivity, stability, and compatibility of Rh(III)-C bonds into catalytic systems. We have demonstrated that to date some of these transformations can be achieved only under rhodium catalysis. In addition, by means of stoichiometric reactions, we have gained mechanistic insights into the interactions between the Rh-C bond and the other coupling partners, which have opened new avenues in future direct C-H functionalization reactions.

Authors+Show Affiliations

†Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.†Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

25844661

Citation

Song, Guoyong, and Xingwei Li. "Substrate Activation Strategies in rhodium(III)-catalyzed Selective Functionalization of Arenes." Accounts of Chemical Research, vol. 48, no. 4, 2015, pp. 1007-20.
Song G, Li X. Substrate activation strategies in rhodium(III)-catalyzed selective functionalization of arenes. Acc Chem Res. 2015;48(4):1007-20.
Song, G., & Li, X. (2015). Substrate activation strategies in rhodium(III)-catalyzed selective functionalization of arenes. Accounts of Chemical Research, 48(4), 1007-20. https://doi.org/10.1021/acs.accounts.5b00077
Song G, Li X. Substrate Activation Strategies in rhodium(III)-catalyzed Selective Functionalization of Arenes. Acc Chem Res. 2015 Apr 21;48(4):1007-20. PubMed PMID: 25844661.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Substrate activation strategies in rhodium(III)-catalyzed selective functionalization of arenes. AU - Song,Guoyong, AU - Li,Xingwei, Y1 - 2015/04/06/ PY - 2015/4/7/entrez PY - 2015/4/7/pubmed PY - 2015/4/7/medline SP - 1007 EP - 20 JF - Accounts of chemical research JO - Acc Chem Res VL - 48 IS - 4 N2 - The possibility of developing new methods for the efficient construction of organic molecules via disconnections other than traditional functional group transformations has driven the interest in direct functionalization of C-H bonds. The ubiquity of C-H bonds makes such transformations attractive, but they also pose several challenges. The first is the reactivity and selectivity of C-H bonds. To achieve this, directing groups (DGs) are often installed that can enhance the effective concentration of the catalyst, leading to thermodynamically stable metallacyclic intermediates. However, the presence of a pendant directing group in the product is often undesirable and unnecessary. This may account for the limitation of applications of C-H functionalization reactions in more common and general uses. Thus, the development of removable or functionalizable directing groups is desirable. Another key problem is that the reactivity of the resulting M-C bond can be low, which may limit the scope of the coupling partners and hence limit the reaction patterns of C-H activation reactions. While the first Cp*Rh(III)-catalyzed C-H activation of arenes was reported only 7 years ago, significant progress has been made in this area in the past few years. We began our studies in this area in 2010, and we and others have demonstrated that diversified catalytic functionalization of arenes can be realized using Cp*Rh(III) complexes with high reactivity, stability, and functional group compatibility. This Account describes our efforts to solve some of these challenges using Rh(III) catalysis. We fulfilled our design and activation of the arene substrates by taking advantage of the nucleophilicity, electrophilicity, oxidizing potential, and properties of a participating ligand of the directing groups when the arenes are coupled with relatively reactive unsaturated partners such as alkenes and alkynes. These in situ funtionalizable roles of the DG allowed extensive chemical manipulation of the initial coupled product, especially in the construction of a diverse array of heterocycles. In the coupling of arenes with polar coupling partners, the polar Rh(III)-C(aryl) bond showed higher reactivity as both an organometallic reagent and a nucleophilic aryl source. The polar coupling partners were accordingly activated by virtue of umpolung, ring strain, and rearomatization. All of these transformations have been made possible by integration of the higher reactivity, stability, and compatibility of Rh(III)-C bonds into catalytic systems. We have demonstrated that to date some of these transformations can be achieved only under rhodium catalysis. In addition, by means of stoichiometric reactions, we have gained mechanistic insights into the interactions between the Rh-C bond and the other coupling partners, which have opened new avenues in future direct C-H functionalization reactions. SN - 1520-4898 UR - https://www.unboundmedicine.com/medline/citation/25844661/Substrate_activation_strategies_in_rhodium_III__catalyzed_selective_functionalization_of_arenes_ L2 - https://doi.org/10.1021/acs.accounts.5b00077 DB - PRIME DP - Unbound Medicine ER -
Try the Free App:
Prime PubMed app for iOS iPhone iPad
Prime PubMed app for Android
Prime PubMed is provided
free to individuals by:
Unbound Medicine.