- Semicarbazide: A Transient Directing Group for C(sp3)?H Arylation of 2-Methylbenzaldehydes
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Semicarbazide as an effective transient directing group for C(sp3)?H arylation of 2-methylbenzaldehydes is described. Various substituted 2-benzylbenzaldehydes are efficiently synthesized by this strategy. The salient features of this protocol are the use of inexpensive transient directing group, wide scope of substrates with good functional group compatibility, up to 98% yield, and applicability to gram scale. (Figure presented.).
- Wen, Fei,Li, Zheng
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- Acetohydrazone: A Transient Directing Group for Arylation of Unactivated C(sp3)-H Bonds
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A straightforward and efficient method has been developed for the synthesis of 2-benzylbenzaldehyde derivatives from 2-methylbenzaldehyde and iodobenzene via a C(sp3)-H activation process. In the course of the activation reaction, acetohydrazon
- Ma, Fei,Lei, Min,Hu, Lihong
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- Nano palladium catalyzed C(sp3)[sbnd]H bonds arylation by a transient directing strategy
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Reported herein is the first example of heterogeneous palladium catalyzed C(sp3)-H bonds arylation by a transient-ligand-directed strategy. Using supported palladium (metallic state) nanopariticles as catalyst, a wide range of aryl iodides undergo the coupling with various o-methylbenzaldehyde derivatives to assemble a library of highly selective and functionalized o-benzylbenzaldehydes. The stability of the catalyst was easily recovered four runs without significant loss of activity. The XPS analysis of the catalyst before and after reaction indicated that the reaction might be carried out by a catalytic cycle starting with Pd0.
- Chen, Jianxia,Bai, Chaolumen,Ma, Hongpeng,Liu, Dan,Bao, Yong-Sheng
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- Regiodivergent CDC reactions of aromatic aldehydes with unactivated arenes controlled by transient directing strategy
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The regiodivergent catalytic dehydrogenative cross-coupling reactions at both sp2and sp3hybridized carbons of aromatic compounds are particularly challenging. Herein, we report the finding of transient directing group controlled regiodivergent C(sp3)-C(sp2) and C(sp2)-C(sp2) cross-coupling in theo-methyl benzaldehyde frameworks. Catalyzed by palladium, using K2S2O8or [F+] reagents as by-standing oxidants and unactivated arenes as substrates/solvents, various benzyl benzaldehydes or phenyl benzaldehydes were prepared. A mechanism study indicated that the regiospecificity is dominated by the [5,6]-fused palladacycle or [6,5]-fused palladacycle intermediates, which are generated from Pd-chelation with specified transient directing groups and further C-H activations.
- Bai, Chaolumen,Baiyin, Menghe,Bao, Agula,Bao, Yong-Sheng,Chao, Bao,Liu, Dan,Muschin, Tegshi
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supporting information
p. 11229 - 11232
(2021/11/03)
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- Palladium-catalyzed benzylic C(sp3)–H arylation of o-alkylbenzaldehydes
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The palladium-catalyzed benzylic C(sp3)–H arylation of o-alkylbenzaldehyde derivatives was achieved utilizing 2-dimethylaminoethylamine as a novel transient directing group. The γ-C(sp3)–H arylation reaction efficiently afforded a variety of arylated o-alkylbenzaldehydes and polycyclic aromatic hydrocarbons (PAHs) in one pot, exhibiting high functional group tolerance with broad substrate scope. The aliphatic diamine auxiliary represents a simple, inexpensive, readily available, and removable directing group for C–H activation. The resultant o-benzylbenzaldehyde products could be diversely transformed into potentially important synthetic intermediates under mild conditions.
- Lei, Lan,Wu, Ping,Liu, Zhuqing,Lou, Jiang
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supporting information
(2021/02/16)
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- Glycinamide hydrochloride as a transient directing group: Synthesis of 2-benzylbenzaldehydes by C(sp3)?H arylation
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Glycinamide hydrochloride as an inexpensive and commercially available transient directing group for the C(sp3)?H arylation of 2-methylbenzaldehydes is described. A series of practical 2-benzylbenzaldehydes bearing various functional groups are efficiently synthesized in satisfactory yield by this strategy. This method can also be extended to gram scale.
- Wen, Fei,Li, Zheng
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supporting information
p. 3462 - 3474
(2020/08/10)
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- Synthesis method of 2-benzylbenzaldehyde derivative
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The invention discloses a synthesis method of an important organic synthesis intermediate 2-benzyl benzaldehyde derivative for constructing bioactive molecules. The synthesis of the 2-benzyl benzaldehyde is realized in one step by taking cheap and easily
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Paragraph 0021
(2020/12/15)
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- Direct synthesis of anthracenes from o-tolualdehydes and aryl iodides through Pd(II)-Catalyzed sp3 C–H arylation and electrophilic aromatic cyclization
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The first direct synthesis of substituted anthracenes from o-tolualdehydes and aryl iodides via a Pd(II)-catalyzed C–H arylation using an alcohol-bearing transient directing group and subsequent AgOTf-assisted electrophilic aromatic cyclization is described. New transient directing groups consisting of amino acids and amino alcohols enhanced the reactivity, and the C–H arylation was complete in 12 h at 90 °C. By simply changing the silver salt to silver triflate, the one-pot synthesis of anthracene derivatives was carried out using the present reaction conditions.
- Park, Hyojin,Yoo, Kwangho,Jung, Byunghyuck,Kim, Min
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p. 2048 - 2055
(2018/03/13)
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- Organic chemistry: Functionalization of C(sp3)-H bonds using a transient directing group
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Proximity-driven metalation has been extensively exploited to achieve reactivity and selectivity in carbon-hydrogen (C-H) bond activation. Despite the substantial improvement in developing more efficient and practical directing groups, their stoichiometric installation and removal limit efficiency and, often, applicability as well. Here we report the development of an amino acid reagent that reversibly reacts with aldehydes and ketones in situ via imine formation to serve as a transient directing group for activation of inert C-H bonds. Arylation of a wide range of aldehydes and ketones at the β or γ positions proceeds in the presence of a palladium catalyst and a catalytic amount of amino acid. The feasibility of achieving enantioselective C-H activation reactions using a chiral amino acid as the transient directing group is also demonstrated.
- Zhang, Fang-Lin,Hong, Kai,Li, Tuan-Jie,Park, Hojoon,Yu, Jin-Quan
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p. 252 - 256
(2016/01/25)
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