Excellent Z or E selectivity is observed in the
HornerâWadsworthâEmmons reactions of methyl
bis(trifluoroethyl)phosphonoacetate 2 with aryl alkyl ketones 3aâd
or aldehydes 3f,g using Sn(OSO
2
CF
3
)
2
in
the presence of N-ethylpiperidine, which should have a different
reaction mode to those using sodium hydride.
STEREOSELECTIVE SYNTHESIS OF 3-ARYLACRYLATES BY COPPER-CATALYZED SYN HYDROARYLATION
作者:Kirai, Naohiro、Yamamoto, Yoshihiko、Wipf, Peter、Vowell, Courtney L.
DOI:10.15227/orgsyn.087.0053
日期:——
Controlling Enantioselectivity and Diastereoselectivity in Radical Cascade Cyclization for Construction of Bicyclic Structures
作者:Congzhe Zhang、Duo-Sheng Wang、Wan-Chen Cindy Lee、Alexander M. McKillop、X. Peter Zhang
DOI:10.1021/jacs.1c04719
日期:2021.7.28
controlling enantioselectivity as well as diastereoselectivity in radical cascade cyclization, we herein report the development of a Co(II)-based catalytic system for asymmetric radical bicyclization of 1,6-enynes with diazo compounds. Through the fine-tuning of D2-symmetric chiral amidoporphyrins as the supporting ligands, the Co(II)-catalyzed radical cascade process, which proceeds in a single operation under
自由基级联环化反应是有机合成中构建多环分子的极具吸引力的合成工具。虽然它已成功应用于天然产物和其他复杂化合物的非对映选择性合成,但自由基级联环化面临着控制对映选择性的重大挑战。作为金属自由基催化(MRC)在自由基级联环化中控制对映选择性和非对映选择性的首次应用,我们在此报告了一种基于Co(II)的催化系统的开发,用于1,6-烯炔与重氮化合物的不对称自由基双环化。通过对D 2 -对称手性酰胺卟啉作为支持配体的微调,Co(II)催化的自由基级联过程在温和条件下单次操作进行,能够不对称构建带有三个连续的多取代环丙烷稠合四氢呋喃。立体异构中心,包括两个全碳四元中心,产量高且具有优异的立体选择性。结合计算和实验研究揭示了这种新的基于 Co(II) 的级联双环化的潜在逐步自由基机制,该机制涉及几种 Co-支持的 C 中心自由基中间体的中继,包括 α-、β-、γ-、和ε-金属烷基自由基。所得到的对映体富
Cu-catalyzed stereoselective conjugate addition of arylboronic acids to alkynoates
作者:Yoshihiko Yamamoto、Naohiro Kirai、Yu Harada
DOI:10.1039/b802231c
日期:——
The CuOAc-catalyzed reaction of internal alkynoates with arylboronic acids proceeded under mild conditions to yield trisubstituted cinnamates stereoselectively.