Direct Dehydrogenative Arylation of Benzaldehydes with Arenes Using Transient Directing Groups

Wang, Da-Yu; Guo, Shi‐Huan; Pan, Gao‐Fei; Zhu, Xue‐Qing; Gao, Ya‐Ru; Wang, Yongqiang

doi:10.1021/acs.orglett.8b00292

Cited by 72 publications

(24 citation statements)

References 50 publications

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“…[20c] In another study,W ang andc o-workers developed the first example of applying the transient strategy to thed irect oxidative dehydrogenative arylation of aldehydes with arenes by using 2-amino-2-methylpropanoic acid (L8)a satransient ligand.T he cyclometalated intermediate was isolated and then treated under standard reaction conditions to form the product in 47 %yield (Scheme 8). [21]…”

Section: Reversible Covalent Bonding For Transitionmentioning

confidence: 99%

Transient Ligand‐Enabled Transition Metal‐Catalyzed C−H Functionalization

et al. 2019

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Transition metal‐catalyzed C−H bond functionalization is among the most efficient and powerful strategies in synthetic organic chemistry to derivatize otherwise inert sites of organic molecules for the construction of C−C and C−heteroatom bonds. However, additional steps are often required to install the directing groups to realize selective C−H bond functionalization of the substrates. These tedious steps run counter to the step‐economical nature of the C−H activation. In contrast, direct functionalization of the substrate by using transient ligands avoids the unnecessary steps for the pre‐functionalization of the substrates. This Minireview provides a short overview of the major progress made in this field for C−H functionalization at sp2 and sp3 carbon centers with different transient working modes, including covalent, hydrogen, and ionic bonds.

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Section: Reversible Covalent Bonding For Transitionmentioning

confidence: 99%

Transient Ligand‐Enabled Transition Metal‐Catalyzed C−H Functionalization

et al. 2019

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“…This tendency is further illustrated by another bidentate DG, 2-(benzylideneamino)acetic acid. This imine is a transient DG (Liu et al., 2017), generally formed in situ from an aldehyde or a ketone and an amino acid (Wang et al., 2018, Xu et al., 2017). In the presence of base, both the carboxylic acid and the imine nitrogen coordinate to palladium, with a relative strength slightly weaker than the N -(quinolin-8-yl)benzamide.…”

Section: Resultsmentioning

confidence: 99%

Relative Strength of Common Directing Groups in Palladium-Catalyzed Aromatic C−H Activation

et al. 2019

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SummaryEfficient functionalization of C−H bonds can be achieved using transition metal catalysts, such as Pd(OAc)2. To better control the regioselectivity in these reactions, some functional groups on the substrate may be used as directing groups, guiding the reactivity to an ortho position. Herein, we describe a methodology to score the relative strength of such directing groups in palladium-catalyzed aromatic C−H activation. The results have been collected into a scale that serves to predict the regioselectivity on molecules with multiple competing directing groups. We demonstrate that this scale yields accurate predictions on over a hundred examples, taken from the literature. In addition to the regioselectivity prediction on complex molecules, the knowledge of the relative strengths of directing groups can also be used to work with new combinations of functionalities, exploring uncharted chemical space.

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“…In this mild process, benzaldehydes are directly reacted with arenes and TFA at 60°C in the presence of Pd(OAc) 2 and potassium persulfate as the stoichiometric oxidant promoting a Pd(II)/Pd(IV) catalytic cycle to deliver the corresponding ortho-arylated benzaldehydes in moderate to good yields (Scheme 25). [52] In their study, Wang and coworkers could demonstrate that the catalytic cycle was operating through a fused 5,5-membered palladabicycle which could be isolated as its pyridine-complex and further reacted with the arene coupling partner under their standard reaction conditions to afford the desired product in 47 % yield. The mechanism was proposed to first involve the formation of the transient imine that would then coordinate to the palladium catalyst.…”

Section: (Hetero)arylation Reactionsmentioning

confidence: 99%

Transient Directing Groups in Metal−Organic Cooperative Catalysis

Jacob

Maes

Evano

2021

Chemistry A European J

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The direct functionalization of CÀ H bonds is among the most fundamental chemical transformations in organic synthesis. However, when the innate reactivity of the substrate cannot be utilized for the functionalization of a given single CÀ H bond, this selective CÀ H bond functionalization mostly relies on the use of directing groups that allow bringing the catalyst in close proximity to the CÀ H bond to be activated and these directing groups need to be installed before and cleaved after the transformation, which involves two additional undesired synthetic operations. These additional steps dramatically reduce the overall impact and the attractiveness of CÀ H bond functionalization techniques since classical approaches based on substrate pre-functionalization are sometimes still more straightforward and appealing. During the past decade, a different approach involving both the in situ installation and removal of the directing group, which can then often be used in a catalytic manner, has emerged: the transient directing group strategy. In addition to its innovative character, this strategy has brought CÀ H bond functionalization to an unprecedented level of usefulness and has enabled the development of remarkably efficient processes for the direct and selective introduction of functional groups onto both aromatic and aliphatic substrates. The processes unlocked by the development of these transient directing groups will be comprehensively overviewed in this review article.

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Direct Dehydrogenative Arylation of Benzaldehydes with Arenes Using Transient Directing Groups

Cited by 72 publications

References 50 publications

Transient Ligand‐Enabled Transition Metal‐Catalyzed C−H Functionalization

Transient Ligand‐Enabled Transition Metal‐Catalyzed C−H Functionalization

Relative Strength of Common Directing Groups in Palladium-Catalyzed Aromatic C−H Activation

Transient Directing Groups in Metal−Organic Cooperative Catalysis

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