Synthesis of Tricyclic Fused 3-Aminopyridines Through Intramolecular CoI-Catalyzed [2 + 2 + 2] Cycloaddition Between Ynamides, Nitriles, and Alkynes.

摘要: Three-ring circus: An expedient route to tricyclic fused 2-trimethylsilyl-3-aminopyridines exhibiting unprecedented skeletons is described. The key step a very efficient cobalt-catalyzed [2+2+2] cycloaddition of polyunsaturated compound displaying an ynamide, alkyne, and nitrile functionality (see picture). first cocyclizations between ynamides, nitriles, alkynes are reported. They open new access nitrogen-containing heterocycles type 2-trimethylsilyl-3-aminopyridines. Such frameworks, which can be found in various compounds biological interest, difficult prepare by conventional methods. However, using [CpCo(C(2)H(4))(2)] (Cp=cyclopentadienyl) as catalyst, the intramolecular cyclizations could achieved up 100 % yield. presence trimethylsilyl group allowed rare Hiyama cross-coupling: one silylated pyridines coupled with p-iodoanisole give biaryl system.