Pelletier Guillaume, Constantineau-Forget Léa, Charette André B
FRQNT Centre in Green Chemistry and Catalysis, Faculty of Arts and Sciences, Department of Chemistry, Université de Montréal, PO Box 6128, Station Downtown, Montréal, Québec, Canada H3C 3J7.
Chem Commun (Camb). 2014 Jul 4;50(52):6883-5. doi: 10.1039/c4cc02220c.
A practical and highly stereoselective approach to access 2,6-disubstituted piperidines using an amidine auxiliary is reported. Following the diastereoselective addition of Grignard reagents at the 2-position of an activated pyridinium salt, the amidine group directs a regioselective metalation at the 6-position, enabling further functionalization. A subsequent electrophilic quench or a Negishi cross-coupling could be performed, resulting in 2,6-disubstituted dihydropyridines. These were reduced to the saturated piperidine rings with high diastereoselectivity.
报道了一种使用脒辅助剂制备2,6-二取代哌啶的实用且高度立体选择性的方法。在格氏试剂非对映选择性加成到活化吡啶鎓盐的2-位后，脒基引导6-位的区域选择性金属化，从而实现进一步官能化。随后可以进行亲电淬灭或根岸交叉偶联，得到2,6-二取代二氢吡啶。这些化合物以高非对映选择性还原为饱和哌啶环。
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