- Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids**
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A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99 % yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state.
- Deng, Ruohan,Engle, Keary M.,Fu, Yue,Gao, Yang,Li, Zi-Qi,Liu, Peng,Tran, Van T.
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supporting information
p. 23306 - 23312
(2020/10/19)
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- Carbonylative Transformation of Allylarenes with CO Surrogates: Tunable Synthesis of 4-Arylbutanoic Acids, 2-Arylbutanoic Acids, and 4-Arylbutanals
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In this Communication, procedures for the selective synthesis of 4-arylbutanoic acids, 2-arylbutanoic acids, and 4-arylbutanals from the same allylbenzenes have been developed. With formic acid or TFBen as the CO surrogate, reactions proceed selectively and effectively under carbon monoxide gas-free conditions.
- Wu, Fu-Peng,Li, Da,Peng, Jin-Bao,Wu, Xiao-Feng
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supporting information
p. 5699 - 5703
(2019/08/01)
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- Synthesis of Novel Pterocarpen Analogues via [3?+?2] Coupling-Elimination Cascade of α,α-Dicyanoolefins with Quinone Monoimines
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By employing triethylamine as a catalyst, [3?+?2] coupling-elimination cascade of α,α-dicyanoolefins with quinone monoimines was realized. The reactions afforded various novel pterocarpen analogues with generally moderate yields (up to 75%). In addition, a plausible reaction mechanism was proposed.
- Chen, Hui,Zhao, Sihan,Cheng, Shaobing,Dai, Xingjie,Xu, Xiaoying,Yuan, Weicheng,Zhang, Xiaomei
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p. 1672 - 1683
(2019/04/08)
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- Highly enantioselective [3+2] coupling of cyclic enamides with quinone monoimines promoted by a chiral phosphoric acid
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Enantioselective [3+2] coupling of cyclic enamides with quinone monoimines was realised using a chiral phosphoric acid as a catalyst. This transformation allowed for the synthesis of highly enantioenriched polycyclic 2,3-dihydrobenzofurans (up to 99.9% ee). The absolute configuration of one product was determined by an X-ray crystal structural analysis. We also found a possible mechanism for this reaction.
- Zhang, Minmin,Yu, Shuowen,Hu, Fangzhi,Liao, Yijun,Liao, Lihua,Xu, Xiaoying,Yuan, Weicheng,Zhang, Xiaomei
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supporting information
p. 8757 - 8760
(2016/07/15)
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- 4,5-DIHYDRONAPHTHO [1,2-b] THIOPHENE DERIVATIVE
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A 4,5-dihydronaphtho[1,2-b]thiophene derivative expressed by the formula: (wherein R1 is a C1 to C10 1-hydroxyalkyl group or a C1 to C10 acyl group, and R2 and R3 separately substitute in the 6-, 7-, 8-, or 9-positions, and are each independently a hydrogen atom, a halogen atom, a C1 to C10 alkyl group, a hydroxy group, a C1 to C10 alkoxy group, a C1 to C5 alkenyloxy group, a C1 to C5 alkynyloxy group, a benzyloxy group, or the like, provided that when R1 is an acyl group and R2 is a hydrogen atom, then R3 is neither a hydrogen atom nor an acetyl group), or a pharmaceutically acceptable salt thereof. This is a novel compound that is effective in reducing triglyceride levels in the liver and reducing blood glucose levels.
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Page/Page column 10-11
(2010/11/08)
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- Integrated chemical process: One-pot aromatization of cyclic enones by the double elimination methodology
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A variety of aromatic hydrocarbons bearing multiple alkyl substituents are accessible with perfect regiocontrol in a one-pot reaction starting from cyclo-hexenones and their aromatic analogues [Eq. (1)]. The present methodology can be further extended to the synthesis of polycyclic aromatic hydrocarbons. The drawbacks encountered in the Friedel-Crafts reaction are resolved since the reaction proceeds under basic conditions.
- Orita, Akihiro,Yaruva, Jayamma,Otera, Junzo
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p. 2267 - 2270
(2007/10/03)
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- Acid-Catalyzed Rearrangement of Propella-ε-lactones
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The acid-catalyzed rearrangement of - and propella-ε-lactones 9 and 10 in boiling acetic acid takes place readily to afford the 1,2-disubstituted cyclopentene 21 and cyclohexene 26 as the major products, respectively, while such lactone ring cleavage of the - and propella-δ-lactones 1 and 2 does not occur at all under similar conditions.The remarcable distinction in reactivity in the acid-catalyzed rearrangement between the ε-lactones and the δ-lactones is attributed to the effect of lactone ring size.
- Kakiuchi, Kiyomi,Tsugaru, Toshinori,Tobe, Yoshito,Odaira, Yoshinobu
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p. 4204 - 4208
(2007/10/02)
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- Occupational medicine in Belgium
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In 1965 occupational medicine was extended to all Belgian industries. In view of the economical structure of the country, most of them became affiliated to occupational medical services. The supervision of workers' health and of the problems of industrial hygiene are the two main objectives of such a service.
- Brouwers
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p. 189 - 194
(2007/10/05)
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