title: Synthesis of tricyclic fused 3-aminopyridines through intramolecular Co(I)-catalyzed [2+2+2] cycloaddition between ynamides, nitriles, and alkynes.
abstract: Three-ring circus: An expedient route to tricyclic fused 2-trimethylsilyl-3-aminopyridines exhibiting unprecedented skeletons is described. The key step is a very efficient cobalt-catalyzed [2+2+2] cycloaddition of a polyunsaturated compound displaying an ynamide, an alkyne, and a nitrile functionality (see picture). The first [2+2+2] cocyclizations between ynamides, nitriles, and alkynes are reported. They open a new access to unprecedented nitrogen-containing heterocycles of type 2-trimethylsilyl-3-aminopyridines. Such frameworks, which can be found in various compounds of biological interest, are very difficult to prepare by conventional methods. However, using [CpCo(C(2)H(4))(2)] (Cp=cyclopentadienyl) as catalyst, the intramolecular cyclizations could be achieved in up to 100 % yield. The presence of the trimethylsilyl group allowed a rare type of Hiyama cross-coupling: one of the silylated pyridines could be coupled with p-iodoanisole to give a new type of biaryl system.
authors.affiliation: Laboratoire de Chimie Organique UMR 7611, Institut de Chimie Moléculaire FR2769, Université Pierre et Marie Curie Paris 6, Tour 44-54, 4 place Jussieu 75252 Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Garcia
authors.forename: Solenne
authors.initials: S
authors.lastname: Moulin
authors.forename: Yves
authors.initials: Y
authors.lastname: Miclo
authors.forename: David
authors.initials: D
authors.lastname: Leboeuf
authors.forename: Vincent
authors.initials: V
authors.lastname: Gandon
authors.forename: Corinne
authors.initials: C
authors.lastname: Aubert
authors.forename: Max
authors.initials: M
authors.lastname: Malacria
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D000577:Amides / Q000737:chemistry*; D000631:Aminopyridines / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D003500:Cyclization; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D017655:Silicon Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000480:Alkynes; D000577:Amides; D000631:Aminopyridines; D009570:Nitriles; D017655:Silicon Compounds; D003035:Cobalt