Stereoselective alkylation of N-Boc-2-pyrrolidinones and N-Boc-2-piperidinones. Synthesis and characterization of disubstituted lactams
作者:Adriano O. Maldaner、Ronaldo A. Pilli
DOI:10.1016/s0040-4020(99)00835-2
日期:1999.11
Alkylation of enolates of monosubstituted N-Boc lactams 4–6 afforded trans-disubstituted lactams as the major isomer. In the pyrrolidinone series, 1,3-induction seems to be ruled by steric interactions and the diastereoselection is low for the alkylation of enolates with small substituents at C-5 (e.g., Me) and methyl iodide. The trans selectivity improves with bulkier substituents at C-2 and/or bulkier
单取代的N-Boc内酰胺4-6的烯醇化物的烷基化提供了反式-二取代的内酰胺作为主要异构体。在吡咯烷酮系列中,1,3-诱导似乎是由空间相互作用决定的,并且对于在C-5处带有小取代基的烯醇化物(例如Me)和甲基碘的烷基化反应,非对映体选择很低。的反式选择性在C-2和/或更膨松电体与笨重的取代基提高了。3,6-反式-双取代的哌啶酮的形成得益于C-2上取代基的轴向取向,这是由于具有N-Boc基团的A 1,3应变和出色的反式 即使在N-Boc-6-甲基哌啶酮的烯醇锂与甲基碘的烷基化中也观察到优选。