A Synthetic and Spectroscopic Investigation of the Asymmetric α-Lithiation-trapping of Six-Membered N-Boc Heterocycles Using Alexakis Diamines
作者:Peter O'Brien、James D. Firth、Giacomo Gelardi、Peter J. Rayner、Darren Stead
DOI:10.3987/com-18-s(t)87
日期:——
The asymmetric lithiation-trapping of six-membered N-Boc heterocycles using s-BuLi and two different Alexakis diamines is reported. These readily available ligands outperform the current 'best-in-class' sparteine-type diamines in the lithiation and benzophenone trapping of N-Boc piperazines and the lithiation-cyclisation-trapping of N-Boc-4-chloropiperidine. In situ IR spectroscopy has been used to optimise lithiation times and to discover previously unknown subtleties regarding the lithiation step.