Stereoselective total syntheses of (−)-desoxoprosopinine and (−)-desoxoprosophylline : palladium(O)-catalyzed intramolecular N-alkylation for the key piperidine ring formation
Intramolecular N-alkylation of D-glucose-derived substrate 21E proceeded in an SN2′ mode smoothly in the presence of a Pd(O)catalyst and n-Bu4NI. The major cyclization product, a 2,6-dialkylated piperidine 22t, was effectively converted into the title alkaloids.
D-葡萄糖衍生的底物21 E的分子内N-烷基化在Pd(O)催化剂和n -Bu 4 NI的存在下以S N 2'模式顺利进行。主要的环化产物2,6-二烷基化哌啶22 t有效地转化为标题生物碱。