Synthesis of 2,5-substituted piperidines: transposition of 1,4-substitution pattern for the analgesic drug R6582.
作者:Nicole P. Baens、Frans Compernolle、Suzanne M. Toppet、Georges J. Hoornaert
DOI:10.1016/s0040-4020(01)89901-4
日期:1993.4
resulting cis and trans 3-chloro lactams 8a,b and 9a,b. 1H NMR analysis for the epimeric 3,6-substituted lactam compounds revealed a preferred axial orientation for the 3-chloro substituent and an equatorial orientation for the 3-(oxobenzimidazolyl) group. For the reduced compound, cis N-methyl piperidine 1a, a conformational equilibrium was observed. This was shifted to the [2ax,5eq] form for the cis
该报告描述了顺式5-(1,3-二氢-2-氧代-2H-苯并咪唑-1-基)-2-对氟苯基-1-甲基哌啶(1a)以及类似的顺式和反式1,-苄基哌啶2a,b。合成的关键步骤是内酰胺5和6(1-甲基-和1-苄基-6-对氟苯基-2-哌啶酮)的α-氯化反应,以及所得顺式和反式3-氯内酰胺的亲核取代。8a,b和9a,b。对差向异构体3,6-取代的内酰胺化合物的1 H NMR分析显示,3-氯取代基的轴向优选方向和3-(氧杂苯并咪唑基)基的赤道方向。对于还原的化合物,顺式N-甲基哌啶如图1a所示,观察到构象平衡。对于顺式N-苄基类似物2a,其转变为[2ax,5eq]形式。