Stereoselective Syntheses of (+)-2-<i>epi</i>-Deoxoprosopinine, (−)-Deoxoprosophylline, (+)-<i>cis</i>-195A, and 2,5-Di-<i>epi</i>-<i>cis</i>-195A from a Common Chiral Nonracemic Building Block
作者:Krishna Annadi、Andrew G. H. Wee
DOI:10.1021/acs.joc.5b00621
日期:2015.5.15
Approaches toward the syntheses of alkaloids belonging to the 2,6-disubstituted 3-hydroxypiperidine and cis-decahydroquinoline (cis-DHQ) classes of alkaloids are developed, starting from a common chiral nonracemic bicyclic lactam lactone (BLL). Two key δ-lactam intermediates, (5S,6S)-5-hydroxy-6-hydroxymethyl- and (5S,6S)-5-hydroxy-6-methylpiperidin-2-ones, are prepared; the latter δ-lactam is obtained
从常见的手性非外消旋双环内酰胺内酯(BLL)开始,开发了合成属于2,6-二取代的3-羟基哌啶和顺式-十氢喹啉(顺式-DHQ)类生物碱的生物碱的方法。制备了两个关键的δ-内酰胺中间体,(5 S,6 S)-5-羟基-6-羟甲基-和(5 S,6 S)-5-羟基-6-甲基哌啶-2-酮。后者的δ-内酰胺是通过双环内酰胺内酯直接脱羰而获得的。BLL还用于制备(4a R,5 R,8a S)-和(4a R,5 S,8a S)-5-甲基八氢喹啉-2-酮,其涉及6 - exo - trig自由基共轭加成反应。发现在自由基环化步骤中观察到的立体选择性受烯丙基1,2-菌株的影响,该烯丙基1,2-菌株是由N-(对甲氧基苄基)基团与自由基中间体的内酰胺环中的C6取代基的相互作用引起的。2- -发达方法的有效性是通过的不对称合成(+)证实外延( - ) - -deoxoprosopinine,deoxoprosophylline,(+)