Lipase-catalyzed kinetic resolution as key step in the synthesis of enantiomerically pure σ ligands with 2-benzopyran structure
作者:Inga Knappmann、Kirstin Lehmkuhl、Jens Köhler、Dirk Schepmann、Martin Giera、Franz Bracher、Bernhard Wünsch
DOI:10.1016/j.bmc.2017.04.042
日期:2017.7
conformationally restricted spirocyclic 2-benzopyrans 2 revealed higher σ1 affinity than the more flexible aminoethyl derivatives 3. The (R)- and (R,R)-configured enantiomers (R)-2 and (R,R)-3 represent the eutomers of this class of compounds with eudismic ratios of 4.8 (2b) and 4.5 (2c). High σ1/σ2 selectivity (>49) was found for the most potent σ1 ligands (R)-2b, (R)-2c, (R)-2d, and (S)-2d (Ki(σ1) 9–15 nM).
为了获得对映异构纯σ 1与2-苯并吡喃支架与对映体纯2-苯基乙醇衍生物(一个氧杂的Pictet-Spengler反应受体配体- [R )- 4和(小号) - 4设想。使用Amano脂肪酶PS-C II和乙酸异丙烯酯在叔丁基甲基醚中的外消旋醇(±)-4的动力学拆分导致(R)-构型醇(R)-4的产率为42%,对映体过量99.6%。(S)-配置的酒精(S)-4通过天野脂肪酶PS-C II催化水解对映体富集的乙酸(S)-5(76.9%ee)并提供(S)-4,收率26%和99.7%ee。通过双(溴代苯甲酸酯)(R)-7的激子耦合CD光谱测定醇(R)-4的绝对构型。合成2-苯并吡喃2和3的下一个重要步骤是对映体纯醇(R)-4和(S)-4的Oxa-Pictet-Spengler反应与哌啶酮缩酮8和氯丙醛缩醛12。构象限制的螺环2-苯并吡喃2显示更高的σ 1比更灵活氨基乙基衍生物亲和力3。(R)和(R,R