Expanding the Scope of Primary Amine Catalysis: Stereoselective Synthesis of Indanedione-Fused 2,6-Disubstituted <i>trans-</i>Spirocyclohexanones
作者:G. Madhusudhan Reddy、Chi-Ting Ko、Kai-Hong Hsieh、Chia-Jui Lee、Utpal Das、Wenwei Lin
DOI:10.1021/acs.joc.5b02921
日期:2016.3.18
A cinchona-alkaloid-derived chiral primary-amine-catalyzed enantioselective method for the synthesis of the thermodynamically less stable indanedione-fused 2,6-trans-disubstituted spirocyclohexanones is demonstrated. Both the enantiomeric forms of the trans isomer are obtained in excellent yields and enantioselectivities. Furthermore, one of the enantiopure trans-spiranes bearing an additional α-substitution
证实了金鸡纳生物碱衍生的手性伯胺催化的对映选择性方法,该方法用于合成热力学上较不稳定的茚满的二氮杂茚并稠合的2,6-反式-二取代的螺环己酮。反式异构体的两种对映体形式均以优异的收率和对映选择性获得。此外,在环己酮环上带有一个额外的α-取代基的对映体反式螺环烷被差向异构化成其热力学稳定的顺式对应物,几乎没有对映选择性损失,证明了这种转化的可行性。机理研究揭示了形成相应产物的两个竞争途径,一致的狄尔斯-阿尔德反应和逐步的迈克尔加成。