Asymmetric [4 + 3] Annulations for Constructing Divergent Oxepane Frameworks via Cooperative Tertiary Amine/Transition Metal Catalysis
作者:Zhi Chen、Zhi-Chao Chen、Wei Du、Ying-Chun Chen
DOI:10.1021/acs.orglett.1c03279
日期:2021.11.5
We report asymmetric [4 + 3] annulations between isatin-derived Morita–Baylis–Hillman carbonates and two types of vinyl carbonates synergistically catalyzed by tertiary amines and transition metals, through chemoselective assemblies of in situ formed allylic ylides and metal-containing 1,4-dipoles. A range of oxepane frameworks are generally constructed in moderate to good yields with high stereocontrol
The investigation of a Lewis base catalyzed asymmetric allylicamination of Morita-Baylis-Hillmancarbonates derived from isatins afforded an electrophilic pathway to access multifunctional oxindoles bearing a C3-quaternary stereocenter, provided with good to excellent enantioselectivity (up to 94% ee) and in high yields (up to 97%).
An α-regio-, diastereo-, and enantioselective [3 + 2] annulation reaction of Morita–Baylis–Hillman carbonates of isatins and activated alkenes with a bulky electron-withdrawing 1,2-benzoisothiazole 1,1-dioxide or 1,2,3-benzoxathiazine 2,2-dioxide motif is reported, furnishing an array of spirooxindoles (>19:1 dr, up to >99% ee) catalyzed by cinchona-derived tertiary amines. Density functional theory
A Double Deprotonation Strategy for Cascade Annulations of Palladium–Trimethylenemethanes and Morita–Baylis–Hillman Carbonates to Construct Bicyclo[3.1.0]hexane Frameworks
species having an activated alkene moiety through a second deprotonation process, which then undergo cascade [1+2]/[3+2] annulations to furnish complex bicyclic [3.1.0]hexane frameworks having three contiguous quaternary stereogenic centers with good to excellent enantioselectivity. Moreover, by using benzoyl aldehyde-derived substrates, a [1+4]/[3+2] annulation sequence is similarly developed to produce
在这里,我们报告说,在 Morita-Baylis-Hillman 碳酸盐的存在下,可以实现通过去质子化策略对 Tsuji 的 2-(氰甲基)烯丙基碳酸酯进行化学选择性活化以生成钯-三亚甲基甲烷 1,3-偶极子。以下 S N 2'-加成能够通过第二次去质子化过程形成具有活化烯烃部分的新 1,3-偶极物质,然后进行级联 [1+2]/[3+2] 环化以提供复杂的双环[3.1.0] 己烷骨架具有三个连续的四元立体中心,具有良好到出色的对映选择性。此外,通过使用苯甲醛衍生的底物,类似地开发了 [1+4]/[3+2] 环化序列以产生稠合的环戊二烯 [b] 呋喃结构。
Construction of polycyclic spirooxindoles through [3+2] annulations of Morita–Baylis–Hillman carbonates and 3-nitro-7-azaindoles
作者:Kai-Kai Wang、Wei Du、Jin Zhu、Ying-Chun Chen
DOI:10.1016/j.cclet.2016.11.003
日期:2017.3
A mild and efficient dearomatic [3+2] annulation reaction of 3-nitro-7-azaindoles and Morita−Baylis−Hillmancarbonates from isatins was developed catalyzed by DMAP, affording the corresponding polycyclic spirooxindoles containing fused azaindoline architectures and vicinal quaternary centers in excellent yields (up to 96%) with high regio- and diastereoselectivity (dr > 19:1). Moderate enantioselectivity