Asymmetric Alkylation of <i>N</i>-Toluenesulfonylimines with Dialkylzinc Reagents Catalyzed by Copper−Chiral Amidophosphine
作者:Takahiro Soeta、Kazushige Nagai、Hidetaka Fujihara、Masami Kuriyama、Kiyoshi Tomioka
DOI:10.1021/jo035234q
日期:2003.12.1
amidophosphine ligand 5 bearing two bulky substituents, 2,4,6-trimethylphenylmethyl or 2,4,6-triisopropylphenylmethyl groups, on the pyrrolidine ring was improved by employing the borane-THF reduction of the lactam-alcohol intermediate 8. The resulting amino alcohol was selectively acylated to give an amide-alcohol 11, which was then converted to the chloride 12 in 55-73% yields by the treatment with
通过使用内酰胺醇中间体的硼烷-THF还原反应改进了吡咯烷环上带有两个庞大的2,4,6-三甲基苯基甲基或2,4,6-三异丙基苯基甲基取代基的手性酰胺基膦配体5的合成程序8.将得到的氨基醇选择性地酰化,得到酰胺-醇11,然后通过用甲磺酰氯的可力丁处理将其转化为氯化物12,产率为55-73%。氯化物12与NaPPh(2)在二恶烷-THF中的反应以可接受的高产率82-83%得到酰胺基膦5。将二烷基锌试剂的己烷溶液加到催化量的氨基膦5,铜物质的混合物中,苯甲醛在甲苯中的N-甲苯磺酰亚胺化合物1a提供了一种溶液,该溶液以高收率和高达96%的对映选择性得到烷基化的酰胺3。对铜源和溶剂的调查得出的结论是,三氟甲磺酸铜(II)和三氟甲磺酸铜(I)-苯配合物是良好的铜源,而甲苯则是溶剂的选择。用二乙基锌成功地将芳基醛,糠醛和链烷烃的N-甲苯磺酰亚胺1a-e乙基化,得到令人满意的69-97%的产率和86-96%