Organolithiums by reductive lithiation: the catalytic aromatic method versus the use of preformed aromatic radical-anions. Naphthalene can behave as a catalyst or an inhibitor
作者:Ao Yang、Heather Butela、Kai Deng、Mary Dosch Doubleday、Theodore Cohen
DOI:10.1016/j.tet.2006.03.056
日期:2006.7
using aromatic radical-anions for reductive lithiation, the replacement of a C–heteroatom bond with a C–Li bond, have been compared with regard to yield and the mildness of reaction conditions required. It was found that the use of preformed radical-anions generally resulted in higher yields and milder reaction conditions than the ‘catalytic’ method in which catalytic amounts of the aromatic compound
在收率和所需反应条件的温和性方面,已经比较了两种常见的模式,即使用芳族自由基阴离子进行还原锂化,以及将C-杂原子键替换为C-Li键。已经发现,与“催化”方法相比,使用预制的自由基阴离子通常可产生更高的产率和更温和的反应条件,在“催化”方法中,催化量的芳族化合物被使用,自由基阴离子被生成并就地使用。一个明显的例外是N-苯基氮丙啶,但事实表明,在这种情况下,芳族化合物萘实际上是抑制剂而不是催化剂。给出了合理的机械解释。