Ruthenium‐Catalyzed Cycloaddition of 1,6‐Diynes and Nitriles under Mild Conditions: Role of the Coordinating Group of Nitriles

Abstract

In the presence of a catalytic amount of [Cp*RuCl(cod)] (Cp*=pentamethylcyclopentadienyl, cod=1,5-cyclooctadiene), 1,6-diynes were allowed to react chemo- and regioselectively with nitriles bearing a coordinating group, such as dicyanides or alpha-halonitriles, at ambient temperature to afford bicyclic pyridines. Careful screening of nitrile components revealed that a C[triple chemical bond]C triple bond or heteroatom substituents, such as methoxy and methylthio groups, proved to act as the coordinating groups, whereas C==C or C==O double bonds and amino groups failed to promote cycloaddition. This suggests that coordinating groups with multiple pi-bonds or lone pairs are essential for the nitrile components.

Highly Functionalized Terpyridines as Competitive Inhibitors of AKAP–PKA Interactions

“…[14] Reducing the nitrile moiety with borane-dimethyl sulfide led to amine 10 . Monobenzylated amine 10 -Bn was obtained by reductive amination followed by dibenzylation with Et 3 N as the base.…”

Bio- and air-tolerant carbon–carbon bond formations via organometallic ruthenium catalysis

“…The study was extended to include [2+2+2] cycloaddition affording pyridine derivative 6 (Scheme 2) 16a, 18,19 , and Alder-ene-type coupling of alkyne 7 with allyl alcohol (8) 16a,20,21 , to give a mixture of aldehydes 9 and 10 (Scheme 3). Of note is that aldehyde functionality is generated in this process.…”

Ruthenium-Catalyzed Cycloisomerization−6π-Cyclization: A Novel Route to Pyridines

“…Recently, the cycloisomerization of diynols of type 2 to form α,β,γ,δ-unsaturated ketones and aldehydes in the presence of [CpRu(CH 3 CN) 3 ]PF 6 (1) has been demonstrated (Eq. 2).…”

“…4 While recent catalytic methods achieve high levels of regioselectivity for certain classes of substrates (e.g., substrates with two sterically differentiable substituents), the question of regioselectivity remains ambiguous. 5,6(1)Recently, the cycloisomerization of diynols of type 2 to form α,β,γ,δ-unsaturated ketones and aldehydes in the presence of [CpRu(CH 3 CN) 3 ]PF 6 (1) has been demonstrated (Eq. 2).…”