Ultrasound irradiation promotes the synthesis of new 1,2,4-triazolo[1,5-a]pyrimidine

Abstract

Ultrasonic irradiation was used in the synthesis of a series of novel 1,2,4-triazolo[1,5-a]pyrimidines. The products were synthetized from the cyclocondensation reaction of 1,1,1-trifluoro-4-metoxy-3-alken-2-one [CF3C(O)CHC(R)OMe, where R=Ph, 4-F-C6H4, 4-Br-C6H4, 4-I-C6H4, 4-CH3-C6H4, 4-CH3O-C6H4, Thien-2-yl, Biphen-4-yl] or β-enaminones [RC(O)CHCHNMe2, where R=Ph, 4-F-C6H4, 4-Br-C6H4, 4-I-C6H4, 4-CH3-C6H4, 4-CH3O-C6H4, 4-NO2-C6H4, Thien-2-yl, Biphen-4-yl, Naphth-2-yl, Pyrrol-2-yl, CCl3] with 5-amino-1,2,4-triazole in acetic acid at 99°C with 5-17 min of ultrasound irradiation. This methodology has shown several advantages, such as shorter reaction times, mild conditions, high regioselectivity, and excellent yields, when compared with conventional thermal heating (oil bath).

Bis(enaminones) as Versatile Precursors for Novel Bis([1,2,4]triazolo[1,5‐a]pyrimidines) and Bis(2‐thioxo‐2,3‐dihydropyrido[2,3‐d]pyrimidin‐4(1H)‐ones)

“…The reactions led to the regioselective formation of 4 rather than 3 based on NMR spectroscopy and coupling constant measurements, which indicated that the coupling constant for protons at 5 and 6 positions of 7‐substituted [1,2,4]triazolo[1,5‐ a ]pyrimidine 4 was 4.5 Hz, while that for protons at 6 and 7 positions of 5‐substituted [1,2,4]triazolo[1,5‐ a ]pyrimidines 3 had much greater value ( J = 6.8–7.0 Hz) . Further evidence based on X‐ray diffraction for similar compounds was also reported .…”

The Wonderful World of β‐Enamino Diketones Chemistry

“…The chemistry of β‐dimethylaminovinyl ketones – commonly known as β‐enaminones – has been widely explored for nearly 60 years, and the vast majority of heterocycles have been synthesized using them as starting materials. [ 1 ] Among these, azoles – such as triazolo/tetrazolo[1,5‐ a ]pyrimidines, [ 2–5 ] 1,2,3‐triazoles, [ 6 ] benzimidazoles, [ 7 ] pyrazoles, [ 8–10 ] pyrroles, [ 11,12 ] isoxazoles, [ 13,14 ] thiazoles [ 15 ] – and furans, [ 16 ] and other six‐membered heterocycles – such as quinolines, [ 17–19 ] pyridines, [ 20,21 ] chromones, [ 22 ] and oxathiines [ 23 ] – have been prepared by using β‐enaminones through formal [3+2] or [3+3] cyclocondensation or cycloaddition reactions, with a variety of reagents ( N,N‐ or N,O ‐dinucleophiles, NCN ‐dinucleophiles, etc. ), catalysts, and specific reaction conditions.…”

Facile Synthesis of Novel Pyrano‐Pyrido‐Carbazole Scaffolds Using Magnetic Fe3O4 Nanoparticles as a Heterogeneous Green and Reusable Catalyst

“…[29] To date, a huge number of useful organic compounds have been generated by using the ultrasound method. [30] Developments in these particular regions involving greener reaction media like water by applications of nanocatalysts in conjunction with the use of ultrasonic irradiation as alternative energy input are the sustainable pathways for the production of organic complex derivatives in synthetic organic chemistry.…”