Sequential C–H Functionalization Reactions for the Enantioselective Synthesis of Highly Functionalized 2,3-Dihydrobenzofurans
作者:Hengbin Wang、Gang Li、Keary M. Engle、Jin-Quan Yu、Huw M. L. Davies
DOI:10.1021/ja401731d
日期:2013.5.8
The enantioselectivesynthesis of 2,3-dihydrobenzofurans was achieved by using two sequential C-H functionalizationreactions, a rhodium-catalyzed enantioselective intermolecular C-H insertion followed by a palladium-catalyzed C-H activation/C-O cyclization. Further diversification of the 2,3-dihydrobenzofuran structures was possible by a subsequent palladium-catalyzed intermolecular Heck-type sp(2)
We report a highly stereoselective synthesis of all‐carbon or fluorinated tetrasubstituted alkenes from diazo reagents and fluorinated enolsilylethers, using C−F bond as a synthetic handle. Cationic AuI catalysis plays a key role in this reaction. Remarkable fluorine effects on the reactivity and selectivity was also observed.
S–H bond insertionreaction was developed by cooperative catalysis of dirhodium(II) carboxylates and chiralspirophosphoricacids (SPAs) under mild and neutral reaction conditions with fast reaction rates, high yields (77–97% yields), and excellent enantioselectivities (up to 98% ee). The catalytic S–H bond insertionreaction provides a highly efficient method for the synthesis of chiral sulfur-containing
第一个高对映选择性的S–H键插入反应是通过在温和和中性的反应条件下以快速反应速率,高收率(77–97%的收率)协同催化羧酸二(II)盐和手性螺环磷酸(SPA)的催化作用而开发的,和出色的对映选择性(高达98%ee)。催化的S–H键插入反应为合成手性含硫化合物提供了一种高效的方法,并促进了手性含硫药物(S)-Eflucimibe的合成。一项系统的31 P NMR研究表明,反应中没有发生羧酸二吡啶(II)与SPA之间的配体交换。协同催化剂Rh 2的不同行为(TPA)4 /(R)-1a和通过原位FT-IR光谱观察到的制备的复合物Rh 2(R - 1a)4排除了Rh 2(R -SPA)4的可行性。是真正的催化剂。DFT计算表明,质子转移步骤中的激活势垒由于SPA的促进而显着降低。根据实验结果和计算结果,提出将SPA用作反应中质子转移的手性质子穿梭体。另外,测量了几个SPA的单晶结构,并用于合理化反
Diazo Activation with Diazonium Salts: Synthesis of Indazole and 1,2,4-Triazole
作者:Xuming Li、Xiaohan Ye、Chiyu Wei、Chuan Shan、Lukasz Wojtas、Qilin Wang、Xiaodong Shi
DOI:10.1021/acs.orglett.0c01232
日期:2020.6.5
reported. The diazenium intermediate was found to undergo cyclization to give indazoles in excellent yields. Alternatively, in the presence of nitriles, substituted 1,2,4-triazoles were obtained in good to excellent yields. This interesting diazenium route provides a new approach to achieve complex heterocycle synthesis under mild conditions.
palladium‐catalyzed asymmetric OHinsertionreaction was developed. Palladium complexes with chiral spiro bisoxazoline ligands promoted the insertion of α‐aryl‐α‐diazoacetates into the OH bond of phenols with high yield and excellent enantioselectivity under mild reaction conditions. This palladium‐catalyzed asymmetric OHinsertionreaction provided an efficient and highly enantioselective method for the preparation