Organocatalytic Asymmetric Transfer Hydrogenation of Nitroolefins
摘要:
We describe a highly efficient and highly enantioselective Hantzsch ester mediated conjugate transfer hydrogenation of beta,beta-disubstituted nitroolefins that is catalyzed by a Jacobsen-type thiourea catalyst.
The first primary aminocatalytic direct cross-aldol reaction of acetaldehyde is presented. Among the various vicinal diamines screened, the L-tert-leucine derivative 1c in conjunction with (H4SiW12O40)0.25 was identified as the optimal catalyst; good catalytic activity (up to 99 % yield in 4 h), and high enantioselectivities (up to 92 % ee) were achieved for a range of donors, including aromatic aldehydes
derivatives containing three stereocenters were prepared via one-step synthesis in yields ranging from 88 to 96% and in enantioselectivities (enantiomeric excess (ee)) ranging from 85 to 97%, with diastereoselectivities of approximately 14/2/1. Therefore, this method provides an efficientroute for the synthesis of a new class of opticallyactive 2-spirobenzothiophenones.
本报告描述了在金鸡纳生物碱胺存在下2-亚烷基苯并[ b ]噻吩酮衍生物与烯酮之间的有机催化级联反应。通过一步合成,制备了包含三个立体中心的螺苯并噻吩苯甲酸环己烷衍生物,其产率为88%至96%,对映选择性(对映体过量(ee))为85至97%,非对映选择性约为14/2/1。因此,该方法为合成新型的光学活性的2-螺苯并噻吩酮提供了有效的途径。
New Auxiliaries for Copper-Catalyzed Asymmetric Michael Reactions: Generation of Quaternary Stereocenters at Room Temperature
Dialkyl amides of L-valine, L-isoleucine, and L-tert-leucine (2) are excellent chiral auxiliaries for the construction of quaternary stereocenters at ambient temperature. Enaminoesters 3, prepared from these auxiliaries 2 and Michael donors 1, undergo a copper-catalyzed asymmetricMichaelreaction with methyl vinyl ketone (MVK, 4) to afford products 5 in 70-90% yield and 90-99% ee (enantiomeric excess)
Synthesis of Axially Chiral Styrenes through Pd‐Catalyzed Asymmetric C−H Olefination Enabled by an Amino Amide Transient Directing Group
作者:Hong Song、Ya Li、Qi‐Jun Yao、Liang Jin、Lei Liu、Yan‐Hua Liu、Bing‐Feng Shi
DOI:10.1002/anie.201915949
日期:2020.4.16
The atroposelective synthesis of axially chiral styrenes remains a formidable challenge due to their relatively lower rotational barriers compared to the biaryl atropoisomers. Herein, we describe the construction of axially chiral styrenes through PdII‐catalyzed atroposelective C−H olefination, using a bulky amino amide as a transient chiral auxiliary. Various axially chiral styrenes were produced with
A Transient Directing Group Strategy Enables Enantioselective Multicomponent Organofluorine Synthesis
作者:Zhonglin Liu、Lucas J. Oxtoby、Mingyu Liu、Zi-Qi Li、Van T. Tran、Yang Gao、Keary M. Engle
DOI:10.1021/jacs.1c03178
日期:2021.6.23
6-trimethylpyridinium hexafluorophosphate facilitated by a transient directing group. The synthetically enabling methodology constructs vicinal stereocenters with excellent regio-, diastereo-, and enantioselectivities, forging products that map onto bioactive compounds.