providing the corresponding 4-oxopiperidines in high yields (80–89%). Stereoselective reduction of the 2,6-cis-disubstituted 4-oxopiperidines then gave the 2,4,6-cis,cis-trisubstituted 4-hydroxypiperidines in high diastereoselectivity. The general nature of this approach was demonstrated with the synthesis of the natural products, spruce alkaloid and (+)-241D.
所述的合成途径的顺-
2-甲基-4-
氧代-6-烷基
哌啶已经使用6-开发内切- trig的环化(ë)-enones。发现碱介导的分子内环化对于烷基和芳基取代的
烯酮都是普遍的,以高收率(80-89%)提供相应的4-
氧代
哌啶。2,6-的立体选择性还原顺式二取代的4-
氧代
哌啶然后,得到
2,4,6-顺式,顺式在高非对映选择性-三取代4- hydroxypiperidines。
天然产物云杉
生物碱和(+)-241D的合成证明了这种方法的一般性质。