Palladium(II)-Catalyzed 1,4-Oxidation of 2-Aryl-1,3-cyclohexadienes. Application to the Synthesis of (±)-Epibatidine and Analogues
作者:Andreas Palmgren、Anna L. E. Larsson、Jan-E. Bäckvall、Paul Helquist
DOI:10.1021/jo981668n
日期:1999.2.1
Palladium(II)-catalyzed 1,4-chloroacetoxylation of 2-aryl-1,3-cyclohexadienes 2a and 2b resulted in a highly regio- and stereoselective reaction to give cis-1-acetoxy-3-aryl-4-chloro-2-cyclohexenes 7a and 7b, respectively. The phenyl adduct 7a was subjected to the synthesis of exo- and endo-2-phenyl-7-azabicyclo[2.2.1]heptanes (exo-1a and endo-1a). Stereoselective allylic nucleophilic substitution
钯(II)催化的2-芳基-1,3-环己二烯2a和2b的1,4-氯乙酰氧基化反应导致高度的区域选择性和立体选择性反应,从而产生顺式1-乙酰氧基-3-芳基-4-氯-2 -环己烯7a和7b。使苯基加合物7a进行外-和内--2-苯基-7-氮杂双环[2.2.1]庚烷(exo-1a和endo-1a)的合成。用甲苯磺酰胺对7a中的氯进行立体选择性的烯丙基亲核取代,并保留或转化并水解,分别得到9a和14a,然后进行氢化,环化和脱保护,得到目标分子。有趣的是,中间体9a和14a的立体选择性氢化分别在氮和苯基之间提供了所需的1,2-顺式和1,2-反式关系。以类似的方式,将7b转化为exo-12b,