已经开发出一种高效的NaBAr F 4催化氧化环化反应,该反应可轻松获得1,5和1,6二炔。重要的是,这种无过渡金属的氧化催化是通过一种可能的路易斯酸催化的S N 2'途径进行的,这与相关的氧化铑和金的催化作用不同。这种方法可以轻松实用地构建各种合成有用的γ-和δ-内酰胺,且收率范围从大到优,而且底物范围广。
Regioselective Cobalt-Catalyzed Formation of Bicyclic 3- and 4-Aminopyridines
摘要:
Bimolecular cobalt-catalyzed [2 + 2 + 2] cycloadditions between yne-ynamides and nitriles afford bicyclic 3- or 4-aminopyridines in up to 100% yield. The high regioselectivity observed depends on the substitution pattern at the starting ynamide. Aminopyridines bearing TMS and Ts groups are efficiently deprotected in an orthogonal fashion.
Synthesis of Aminopyridines and Aminopyridones by Cobalt-Catalyzed [2+2+2] Cycloadditions Involving Yne-Ynamides: Scope, Limitations, and Mechanistic Insights
switched toward 3‐ or 4‐aminopyridines. Application of this synthetic methodology to the construction of the aminopyridone framework using a yne‐ynamide and an isocyanate was also briefly examined. DFT computations suggest that 3‐aminopyridines are formed by formal [4+2] cycloaddition between the nitrile and the intermediate cobaltacyclopentadiene, whereas 4‐aminopyridines arise from an insertion pathway
synthesis of a variety of N‐containing aromatic heterocycles by a formal gold‐catalyzed dehydro‐Diels–Alder reaction of ynamide derivatives has been developed. Deuterium‐labeling experiments and kinetic studies support the involvement of a dual gold catalysis mechanism in which a gold acetylide moiety adds onto an aurated keteneiminium.