Transition‐Metal‐Free Multiple Functionalization of Piperidines to 4‐Substituted and 3,4‐Disubstituted 2‐Piperidinones
作者:Delfino Chamorro‐Arenas、Alejandro A. Nolasco‐Hernández、Lilia Fuentes、Leticia Quintero、Fernando Sartillo‐Piscil
DOI:10.1002/chem.201905262
日期:2020.4.9
2-piperidones was developed. Second, the intrinsic low reactivity of the unsaturated piperidones toward conjugated Grignard additions was overcome by using trimethylsilyl chloride (TMSCl) as Lewis acid. Subsequently, conjugated Grignard addition/electrophilic trapping protocol provided substituted 2-piperidone intermediates, some of which were then transformed into pharmaceutical alkaloids.
在不使用过渡金属催化剂和精细的导向基团的情况下,哌啶的远程和多重官能化是有机合成的主要挑战之一。本文报道了史无前例的两步方案,该方案能够使哌啶多功能化为4-取代的或反式的3,4-二取代的2-哌啶酮。首先,通过利用TEMPO反应性的对偶性(在氧化和热条件下在阳离子和持久自由基形式之间波动),开发了新颖的哌啶多C(sp3)-H氧化为α,β-不饱和2-哌啶酮的化合物。其次,通过使用三甲基甲硅烷基氯(TMSCl)作为路易斯酸,可以克服不饱和哌啶酮对共轭格氏试剂的固有的低反应性。随后,