The enantioselective synthesis of polycyclic aromatic hydrocarbon (PAH)‐based planar chiralcyclophanes was achieved for the first time by the rhodium‐catalyzed intramolecular regio‐ and enantioselective [2+2+2] cycloaddition of tethered diyne‐benzofulvenes followed by stepwise oxidative transformations. The thus synthesized planar chiral bent cyclophanes, that possess bent p‐terphenyl‐ and 9‐fluorenone‐cores
TBDPS and Br-TBDPS Protecting Groups as Efficient Aryl Group Donors in Pd-Catalyzed Arylation of Phenols and Anilines
作者:Chunhui Huang、Vladimir Gevorgyan
DOI:10.1021/ja904791y
日期:2009.8.12
as an efficient phenyl group donor for o-bromophenols via Pd-catalyzed C-Harylation followed by a routine TBAF deprotection of the resulting silacycles. Employment of the newly designed Br-TBDPS protecting group in the same sequence allows for a facile introduction of a phenyl group at the ortho position of phenols and anilines. Alternatively, switching desilylation to oxidation in the last step allows
phenol from ortho-bromophenyl silylethers without using RLi is described. Various ortho-bromophenyl silylethers are treated with commercially available Mg turnings, which are easy to handle in air, and transfer of the silyl group to the ortho-position occurs in good to high yields. Selective mono-magnesiation of 2,6-dibromophenyl silylether is observed even in the presence of excess Mg, and ortho-bromo-6-silylphenol
描述了不使用RLi由邻-溴苯基甲硅烷基醚实际合成邻-甲硅烷基取代的苯酚的方法。各种邻-溴苯基甲硅烷基醚用市售的Mg车削剂处理,易在空气中处理,并且甲硅烷基转移至邻位的收率高至高。即使在存在过量的Mg的情况下,也观察到2,6-二溴苯基甲硅烷基醚的选择性单放大,并且获得了邻溴-6-甲硅烷基苯酚作为主要产物。将得到的邻甲硅烷基取代的苯酚用(CH 2 O)n / MgCl 2 / Et 3甲酰化。N,然后与二胺缩合以良好的收率得到甲硅烷基取代的Salen型配体。该方案适用于大规模合成带有亚胺基的甲硅烷基取代的salen型配体。
Phase-Transfer Catalyzed <i>O</i>-Silyl Ether Deprotection Mediated by a Cyclopropenium Cation
作者:Roya Mir、Travis Dudding
DOI:10.1021/acs.joc.6b02733
日期:2017.1.6
The use of a cyclopropenium cation as a phase transfer catalyst for O-silyl ether deprotection is reported. Mechanistic insight into this deprotection methodology derived by linear free-energy relationships (LFER), quantum theory of atoms in molecules (QTAIM), and density functional theory (DFT) calculations are also provided.
Modular Approach to Silicon-Bridged Biaryls: Palladium-Catalyzed Intramolecular Coupling of 2-(Arylsilyl)aryl Triflates