Synthesis and Cytokinin Activity of New Zeatin Derivatives
摘要:
The analogue of zeatin bearing a vinylic fluorine atom and its geometrical isomer were synthesized. The fluorine atom exerts a favorable influence on cytokinin activity in the fluoro analogue of cis-zeatin, but not in the fluoro analogue of zeatin itself. Another series of zeatin derivatives in which the methyl group was replaced by alkyl (ethyl, propyl, and isopropyl), phenyl, and benzyl groups were also obtained. The ethyl analogue was found to be more active than zeatin, while the others were inactive or slightly active.
Enantioselective Preparation of Arenes with β‐Stereogenic Centers: Confronting the 1,1‐Disubstituted Olefin Problem Using CuH/Pd Cooperative Catalysis
作者:Zhaohong Lu、Stephen L. Buchwald
DOI:10.1002/anie.202004414
日期:2020.9.7
Arenes with β‐stereogenic centers are important substructures in pharmaceuticals and natural products. We have developed an asymmetric anti‐Markovnikov hydroarylation of 1,1‐disubstituted olefins by dual palladium and copper hydride catalysis as a convenient and general approach to access these substructures. This efficient one‐step process addresses several limitations of the traditional stepwise
Design and Application of Hybrid Phosphorus Ligands for Enantioselective Rh-Catalyzed Anti-Markovnikov Hydroformylation of Unfunctionalized 1,1-Disubstituted Alkenes
作者:Cai You、Shuailong Li、Xiuxiu Li、Jialing Lan、Yuhong Yang、Lung Wa Chung、Hui Lv、Xumu Zhang
DOI:10.1021/jacs.8b00275
日期:2018.4.18
series of novel hybrid phosphorus ligands were designed and applied to the Rh-catalyzed enantioselective anti-Markovnikov hydroformylation of unfunctionalized 1,1-disubstituted alkenes. By employing the new catalyst, linear aldehydes with β-chirality can be prepared with high yields and enantioselectivities under mild conditions. Furthermore, catalyst loading as low as 0.05 mol % furnished the desired
Application of Trimethylgermanyl-Substituted Bisphosphine Ligands with Enhanced Dispersion Interactions to Copper-Catalyzed Hydroboration of Disubstituted Alkenes
作者:Yumeng Xi、Bo Su、Xiaotian Qi、Shayun Pedram、Peng Liu、John F. Hartwig
DOI:10.1021/jacs.0c08746
日期:2020.10.21
report the incorporation of large substituents based on heavy maingroupelements that are atypical in ligand architectures to enhance dispersion interactions and, thereby, enhance enantioselectivity. Specifically, we prepared the chiral biaryl bisphosphine ligand (TMG-SYNPHOS) containing 3,5-bis(trimethylgermanyl)phenyl groups on phosphorus and applied this ligand to the challenging problem of enantioselective
report here a general method for the regio- and enantioselective Cu-catalyzed anti-Markovnikov hydroaminocarbonylation of unactivatedalkenes under mild conditions. The reaction tolerates a wild range of functional groups and applicable to different classes of alkenes. Alkynes are also compatible under this catalytic system with the cascade hydrogenation-hydroaminocarbonylation process to alkyl amides