An Efficient Catalytic Stereoselective Route to a Key Intermediate for the Synthesis of the Long-Lived PGI2 Analog ZK 96480 (CicaprostTM)
作者:E.J Corey、Christopher J Helal
DOI:10.1016/s0040-4039(97)01803-0
日期:1997.10
An expeditious and stereoselective synthesis of a key chiral intermediate (2) for the synthesis of the therapeutically useful PGI(2) analog Cicaprost(TM) is described. (C) 1997 Elsevier Science Ltd.
Cuprous Chloride Accelerated Stille Reactions. A General and Effective Coupling System for Sterically Congested Substrates and for Enantioselective Synthesis
作者:Xiaojun Han、Brian M. Stoltz、E. J. Corey
DOI:10.1021/ja991500z
日期:1999.8.1
of cuprous chloride as an accelerant for coupling. Thus, using a protocol for coupling that involves the system Pd(PPh3)4/CuCl/LiCl under anaerobic conditions in dimethylsulfoxidesolution at 60 °C, a wide variety of Stille coupling reactions which otherwise fail can be effected in excellent yield (Table 1). The process has been applied to the enantioselective synthesis of the chiral 1-(arylethyl)alkylcarbinol
Stille 偶联反应的一个主要限制来自空间筛选,特别是在乙烯基锡烷组分中。例如,由于非常缓慢的反应速率和竞争性电影取代,通常观察到 1-取代的乙烯基锡烷和芳基全氟烷烃磺酸盐或卤化物可以忽略不计或低产率。通过发现和应用氯化亚铜作为偶联促进剂,这个问题在目前的工作中得到了克服。因此,使用涉及 Pd(PPh3)4/CuCl/LiCl 系统在 60 °C 的二甲基亚砜溶液中的厌氧条件下的耦合协议,可以以优异的产率实现各种各样的 Stille 耦合反应,否则这些反应会失败(表1)。该工艺已应用于手性1-(芳乙基)烷基甲醇26的对映选择性合成,天然产物尼康酮的模型。氯化亚铜对Stille偶联的加速可以通过乙烯基锡烷→乙烯基铜(I)跨金属的干预来解释。
Direct Catalytic Enantioselective Reduction of Achiral α,β-Ynones. Strong Remote Steric Effects Across the C−C Triple Bond
作者:Christopher J. Helal、Plato A. Magriotis、E. J. Corey