Generation and Carbonyl Addition Reactions of Dibromofluoromethyllithium Derived from Tribromofluoromethane as Applied to the Stereoselective Synthesis of Fluoro Olefins and 2-Bromo-2-fluoro-1,3-alkanediols
作者:Masaki Shimizu、Nobuko Yamada、Yoko Takebe、Takeshi Hata、Manabu Kuroboshi、Tamejiro Hiyama
DOI:10.1246/bcsj.71.2903
日期:1998.12
3 was converted stereoselectively to (E)-1-bromo-1,2-difluoro olefin 5 via fluorination with Et2NSF3, followed by dehydrobromination with lithium 2,2,6,6-tetramethylpiperidide, while (E)-1-bromo-1-fluoro olefin was obtained with high selectivity by acetylation of 3, followed by reductive elimination using EtMgBr/(i-Pr)2NH. Difluoro olefin 5 underwent a cross-coupling reaction with an aryl, alkenyl,
在-130 °C 的 THF-Et2O (2:1) 中用 BuLi 处理三溴氟甲烷生成二溴氟甲基锂,使其与共存的醛或酮 (RR'C=O) 顺利反应生成氟化醇 RR'C( OH)CFBr2 (3) 收率良好。通过用 Et2NSF3 氟化,然后用 2,2,6,6-四甲基哌啶锂脱溴化氢,醇 3 立体选择性地转化为 (E)-1-溴-1,2-二氟烯烃 5,而 (E)-1-溴-通过将 3 乙酰化,然后使用 EtMgBr/(i-Pr)2NH 还原消除,以高选择性获得 1-氟烯烃。二氟烯烃 5 与芳基、烯基或炔基金属试剂发生交叉偶联反应,得到相应的具有构型保留的氟烯烃。另一方面,RCH[OCH2O(CH2)2OCH3]CFBr2 与 BuLi 在 -130 °C 下在 4-庚酮存在下处理得到相应的非对映选择性加合物。立体化学结果用锂和氧之间的螯合来解释......