- Biocatalytic Desymmetrization of Prochiral 3-Aryl and 3-Arylmethyl Glutaramides: Different Remote Substituent Effect on Catalytic Efficiency and Enantioselectivity
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Catalyzed by an amidase-containing Rhodococcus erythropolis AJ270 microbial whole cell catalyst in neutral phosphate buffer at 30 °C, desymmetric hydrolysis of a series of prochiral 3-aryl and 3-arylmethylglutaramides efficiently afforded 3-substituted glutaric acid monoamides in up to 95% yield and >99.5% ee. Even far away from the reaction site, the substituents on the aryl still have a significant effect on the catalytic activity and enantioselectivity and different remote substituent effect was observed for the two types of substrates. The synthetic application of biocatalytic desymmetrization was demonstrated by the facile transformation of the obtained enantiopure (R)-3-substituted 4-carbamoylbutanoic acid products to chiral dihydroquinolinone and δ-lactone compounds. (Figure presented.).
- Ao, Yu-Fei,Zhang, Li-Bin,Wang, Qi-Qiang,Wang, De-Xian,Wang, Mei-Xiang
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supporting information
p. 4594 - 4603
(2018/10/31)
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- Synthesis and insecticidal activity of mesoionic pyrido[1,2-α]pyrimidinone derivatives containing a neonicotinoid moiety
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Mesoionic pyrido[1,2-α]pyrimidinone derivatives containing a neonicotinoid moiety were designed, synthesized, and evaluated for their insecticidal activity. Some of the title compounds showed remarkable insecticidal properties against Aphis craccivora. Compound I13 exhibited satisfactory insecticidal activity against A. craccivora. Meanwhile, label-free proteomics analysis of compound I13 treatment identified a total of 821 proteins. Of these, 35 proteins were up-regulated, whereas 108 proteins were down-regulated. Differential expressions of these proteins reflected a change in cellular structure and metabolism.
- Pan, Jianke,Yu, Lu,Liu, Dengyue,Hu, Deyu
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- Palladium-Catalyzed, Ring-Forming Aromatic C-H Alkylations with Unactivated Alkyl Halides
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A catalytic C-H alkylation using unactivated alkyl halides and a variety of arenes and heteroarenes is described. This ring-forming process is successful with a variety of unactivated primary and secondary alkyl halides, including those with β-hydrogens. In contrast to standard polar or radical cyclizations of aromatic systems, electronic activation of the substrate is not required. The mild, catalytic reaction conditions are highly functional group tolerant and facilitate access to a diverse range of synthetically and medicinally important carbocyclic and heterocyclic systems.
- Venning, Alexander R. O.,Bohan, Patrick T.,Alexanian, Erik J.
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p. 3731 - 3734
(2015/04/14)
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- Tuning the lewis acidity of boranes in frustrated lewis pair chemistry: Implications for the hydrogenation of electron-poor alkenes
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An analysis of the metal-free reduction of electron deficient olefins by frustrated Lewis pairs indicates that the rate-determining step might be either the heterolytic cleavage of H2 to form an -onium borohydride salt, or the subsequent transfer of the hydride moiety to the substrate following a Michael-type addition reaction. While the use of strong Lewis acids such as B(C6F5)3 facilitates the first of these processes, hydride transfer to the olefin should be contrarily favoured by the use of weak Lewis acids which, for this very same reason, might be unable to promote the prior H2 split. After systematic testing of several boranes of different Lewis acidity (assessed by using the Childs' method) and steric demand, an optimal situation that employs tris(2,4,6-trifluorophenyl) borane was reached. Mixtures of this borane with 1,4-diazabicyclo[2.2.2]octane (DABCO) exhibited excellent catalytic activity for the hydrogenation of alkylidene malonates. In fact, this transformation could be achieved under milder conditions than those we reported previously. Moreover, the reaction scope could be expanded to other electron deficient olefins containing esters, sulfones or nitro functionalities as electron-withdrawing substituents.
- Nicasio, Juan A.,Steinberg, Sebastian,Ines, Blanca,Alcarazo, Manuel
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p. 11016 - 11020
(2013/09/02)
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- Metal-free hydrogenation of electron-poor allenes and alkenes
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The poorer, the better: A metal-free catalytic procedure for the reduction of electron-poor allenes and alkenes has been developed. The method employs a frustrated Lewis pair based catalyst. 1,4-Diazabicyclo[2.2.2]octane (DABCO)/B(C6F5)3 was shown to be the best combination in optimization studies. Copyright
- Ines, Blanca,Palomas, David,Holle, Sigrid,Steinberg, Sebastian,Nicasio, Juan A.,Alcarazo, Manuel
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supporting information
p. 12367 - 12369
(2013/02/22)
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- A facile experimental method to determine the hydride affinity of polarized olefins in acetonitrile
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(Chemical Equation Presented) Choosing a suitable hydride reducing agent and thermodynamic analysis of reduction mechanisms is facilitated by experimental hydride affinities ΔHH-A, which are reported herein for 28 polarized olefins 1 in acetonitrile (see scheme). The method should also be applicable to ketones, aldehydes, and imines.
- Zhu, Xiao-Qing,Zhang, Min,Liu, Qiao-Yun,Wang, Xiao-Xiao,Zhang, Jian-Yu,Cheng, Jin-Pei
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p. 3954 - 3957
(2007/10/03)
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