Cobalt, (η⁵-2,4-Cyclopentadien-1-yl)bis(η²-ethene)-(9CI)

Synthesis of Aminopyridines and Aminopyridones by Cobalt‐Catalyzed [2+2+2] Cycloadditions Involving Yne‐Ynamides: Scope, Limitations, and Mechanistic Insights

“…To this end, a short comparative study was carried out (Table 3). With the classical air-sensitive complex [CpCoA C H T U N G T R E N N U N G (C 2 H 4 ) 2 ], [14] both ynamide 1 a and diyne 1 d gave rise to pyridines in low yields ( Table 3, entries 1 and 2). In sharp contrast, with [CpCo(CO)A C H T U N G T R E N N U N G (dmfu)], the products were obtained in 59 and 60 % yield in each case ( Table 3, entries 3 and 4).…”

Co(I)- versus Ru(II)-Catalyzed [2+2+2] cycloadditions involving alkynyl halides

“…With cobalt, homocoupling ensued to give tetrayne 18 in 38% yield (Entry 30), whereas 17 was isolated quantitatively with ruthenium (Entry 32). In order to verify whether the compatibility of 1 toward alkynyl bromides was inherent in its structure, some reactions of 4c were carried out using the typical precatalysts CpCo(CO) 2 and CpCo(C 2 H 4 ) 2 [12]. In each case, 4c could be recovered in part, and no trace of cycloadduct could be detected among the degradation products.…”

Synthesis, Reactivity, and Theoretical Insights of Co-Sb2 and Co-Bi2 Rings

“…The choice fell on Jonas' complex CpCo(C 2 H 4 ) 2 , 34,35 renowned over the past four decades as the most active "CpCo" reagent. 36 Remarkably, it has facilitated numerous [2 + 2 + 2]cocyclization reactions, 37−39 including the formation of hexamethylbenzene, 34 and has actively participated as a catalyst in multiple Si−H and N−H bond activations. 36,40−42 Thus, we envisaged that this reagent might be a key for the activation of dipnictenes.…”