5-Substituted Derivatives of the Tricyclic (+)-Sparteine Surrogate in the Enantioselective Lithiation/Stannylation of an<i>O</i>-Alkyl Carbamate
作者:Matthias Breuning、David Hein
DOI:10.1002/ejoc.201300987
日期:2013.11
5-Mono- and 5,5-disubstituted tricyclic bispidines, derivatives of the known (+)-sparteine surrogate, have been synthesized in four-to-six steps from the natural alkaloid (–)-cytisine and evaluated as chiral ligands in the enantioselective lithiation/stannylation of an O-alkyl carbamate. Structure–selectivity studies revealed that a small 5-endo substituent is tolerated, whereas larger 5-endo substituents
5-单和 5,5-二取代的三环双吡啶是已知 (+)-sparteine 替代物的衍生物,已从天然生物碱 (-)-cytisine 以四到六个步骤合成,并被评估为手性配体O-烷基氨基甲酸酯的对映选择性锂化/甲锡烷基化。结构选择性研究表明,可以耐受较小的 5-endo 取代基,而较大的 5-endo 取代基甚至较小的 5-exo 取代基会导致手性转移水平显着降低。