Heck cross-coupling of vinyl heteroaromatic compounds with aryl and heteroaryl halides using Pd(II) complex under phosphine-free conditions

Palladium-meta-Terarylphosphine Catalyst for the Mizoroki–Heck Reaction of (Hetero)Aryl Bromides and Functional Olefins

“…Following general method, the reaction of 2-vinylpyridine (140.2 μL, 1.3 mmol) and 3-bromopyridine (96.3 μL, 1 mmol) proceeded for 8 h, of which the crude product was purified by column chromatography using EtOAc to afford the title compound as a brown solid (180 mg, 99%): 1 H NMR (600 MHz, CDCl 3 ) δ = 8.79 (td, J = 1.7, 0.9 Hz, 1 H), 8.62 (ddt, J = 5.0, 2.0, 1.0 Hz, 1 H), 8.51 (ddt, J = 4.9, 1.8, 0.8 Hz, 1 H), 7.89 (ddt, J = 7.7, 3.0, 1.5 Hz, 1 H), 7.72–7.66 (m, 1 H), 7.63 (d, J = 16.1 Hz, 1 H), 7.40 (dq, J = 7.8, 1.2 Hz, 1 H), 7.33–7.28 (m, 1 H), 7.22 (dq, J = 16.2, 1.2 Hz, 1 H), 7.19 (ddp, J = 7.1, 4.8, 1.2 Hz, 1 H) ppm; 13 C­{ 1 H} NMR (151 MHz, CDCl 3 ) δ = 154.9, 149.9, 149.2, 149.1, 136.9, 133.5, 132.5, 130.0, 129.2, 123.8, 122.8, 122.6 ppm. The physical data were in full accordance with the literature value …”

“…Following general method, the reaction of 2-vinylpyridine (140.2 μL, 1.3 mmol) and 3bromopyridine (96.3 μL, 1 mmol) proceeded for 8 h, of which the crude product was purified by column chromatography using EtOAc to afford the title compound as a brown solid (180 mg, 99%): 1 H NMR (600 MHz, CDCl 3 ) δ = 8.79 (td, J = 1.7, 0.9 Hz, 1 H), 8.62 (ddt, J = 5.0, 2.0, 1.0 Hz, 1 H), 8.51 (ddt, J = 4.9, 1.8, 0.8 Hz, 1 H), 7.89 (ddt, J = 7.7, 3.0, 1. 67 1-(2-Aminopyrimidin-5-yl)pentan-3-one (3r). Following the general method, the reaction of 2-amino-5-bromopyrimidine (174 mg, 1 mmol) and 1-penten-3-ol (112 mg, 1.3 mmol) proceeded for 8 h, of which the crude product was purified by column chromatography using MeOH/EtOAc/petroleum ether (3:47:50) as the eluent to give the title compound as a white solid (160 mg, 89%): mp 123−126 °C; Methyl (E)-3-(1-tosyl-1H-indol-5-yl)acrylate (3s).…”

Fluorescent 2-(Pyridin-2-yl)vinyl Pyridine Dyes and Their Thermocontrolled Release

“…Recent data have focused on developing methods for the construction of Csp 2 –Csp 2 bonds between heterocycles (e.g., 2-vinylpyridine) and simple aryl or heteroaryl halides. However, a combination of more nitrogen-containing aromatic compounds and substituted 2,2′-vinylenedipyridines is still challenging to investigate. − In this regard, we developed an optimal reagent combination for the Heck cross-coupling formation of vinylene-heteroaromatic systems via two synthetic paths: A and B. Our investigation began with optimization of the microwave-assisted Heck cross-coupling reaction between 2,6-dibromopyridine ( 2 ) and 2-vinylpyridine ( 1 ) in the presence of a palladium catalyst to obtain ( E )-2-bromo-6-[2-(pyridin-2-yl)-vinyl]­pyridine ( 3 ).…”

Heck Reaction of N‐Heteroaryl Halides for the Concise Synthesis of Chiral α‐Heteroaryl‐substituted Heterocycles

“…Nevertheless, the asymmetric Heck reaction of N ‐heteroaryl halides and heterocyclic alkenes has been an unsolved problem and scarce examples were included in these previous reports. The key issue is the strong coordinating ability of N ‐heteroaryl substrates in particular pyridyl halides to transition metal resulting in catalyst deactivation with low or no activities, [15a] which has significantly impeded the development of robust Heck reaction protocols tolerating N ‐heteroaryl halide substrates [15b–e] . To address this challenge, we hypothesized that the employment of a sterically bulky P, P=O ligand [16] could be a solution for the Heck reaction of N ‐heteroaryl halides with the following considerations (Figure 2b): 1) The steric bulk would create coordinative unsaturation and inhibit the formation of fully coordinated inactive palladium species; 2) The hemilabile character of the P, P=O ligand enables ready release of a coordination site of Pd II complex after oxidative addition, allowing facile coordination of the alkene substrate to proceed the ensuring insertion process.…”