Solvent- and catalyst-free synthesis of new hydroxylated trisubstituted pyridines under microwave irradiation

Abstract

A facile solvent-and catalyst-free method for the synthesis of a series of new hydroxylated 2,4,6trisubstituted pyridines under microwave irradiation was developed. The expected products were obtained through a simplified purification process without protection of the hydroxyl group. UV-Vis and fluorescence spectra of these conjugated multi-hydroxyl compounds were also investigated.

Exploring the C^N^C theme: Synthesis and biological properties of tridentate cyclometalated gold(III) complexes

“…A previously described procedure reports on the use of a conventional microwave with unfocused irradiation at 400 Watts. 23 We found this high power in our focussed reactor to cause pressure build up within in the system, leading to the termination of the microwave through triggering of the inbuilt safety features. A basis set (100 W, 120 °C, 30 minutes) was chosen, from which on the single parameters were optimized.…”

“…In detail, microwave irradiated synthesis of the [C^N R^C ] ligands was carried out adapting a previously reported procedure for hydroxylated tri-substituted pyridines. 23 Optimization of the reaction conditions was performed with respect to temperature, power and reaction time of the irradiation. A major benefit of the microwave synthesis is the circumvention of otherwise needed catalyst, such as previously reported Bi(OTf)3, 24 and solvents, thus enabling a metal and solvent free synthesis.…”

Optimising a vortex fluidic device for controlling chemical reactivity and selectivity

“…2,4,6-Triarylpyridines are accessible using SDP but the short residence time necessitates several passes through the microfluidic device, with less control over the product distribution9. They are also accessible in a one step process in the presence of NH 4 OAc using microwave irradiation33, but this is not immediately scalable processing, and the energy usage using microwave heating is questionable34.…”

Clean and efficient assembly of functionalized benzofuro[2,3-c]pyridines via metal-free one-pot domino reactions

“…11 In addition, we have found a threecomponent reaction of aromatic aldehydes, acetophenone derivatives and ammonium acetate for the direct synthesis of hydroxylated triarylpyridines under microwave irradiation. 12 In continuation of our efforts to develop new synthetic protocols for constructing heterocyclic frameworks, we herein describe a one-pot domino reaction for the synthesis of substituted benzofuro[2,3-c]pyridines from easily accessible 2-hydroxychalcones, α-bromo ketones and ammonium acetate. that they can be prepared starting from 1,5-diketone (5) bearing the 2,3-disubstituted dihydrobenzofuran moiety and ammonium acetate by a modified Kröhnke reaction.…”