Features of 3-amino-5-methylisoxazole in heterocyclizations involving pyruvic acids

Stereoselective, Multicomponent Approach to Quaternary Substituted Hydroindole Scaffolds

“…This rapid Mannich-type addition provides an intermediate capable of intramolecular lactamization to form the α-ketolactam that subsequently tautomerizes to the observed multicomponent product 4 . The mechanism is supported through the observations that preformed electron-deficient imines do not undergo this mild reaction in agreement with literature reports that require harsh reaction conditions for such reactions. − It is also possible that upon imine protonation a more concerted (albeit asynchronous) process ensues as we do not observe the amino ester in any of the reaction mixtures. Further exploration in the reaction mechanism and efforts to render it asymmetric are ongoing.…”

“…Among the various multicomponent approaches to access highly functionalized heterocycles, including pyrrolidinones, imines serve as a common intermediate. − In addition to our efforts, there has been a long history of elegant methods toward these versatile building blocks. Gein and co-workers have contributed significant efforts to the synthesis of these molecules via a similar multicomponent reaction that requires an acyl electron-withdrawing group and prolonged reaction time. − A number of other groups have used analogous strategies, all employing activated precursors and aggressive reaction conditions. − Joo and co-workers and Yavari and Souri independently synthesized related pyrrolidinones utilizing symmetrical alkynes. , …”

Ultrasonic-assisted unusual four-component synthesis of 7-azolylamino-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines

“…Thus, using nonclassical activation methods such as ultrasonication and microwave irradiation enabled us to develop highly selective procedures for obtaining triazolo-, tetrazolo-, and pyrazolopyrimidines [4,5,[16][17][18][19][20][27][28][29], as well as oxygenbridged tetrahydropyrazolopyrimidines [4,19], furanone [17,30], and pyrrolone derivatives [5,[16][17][18].…”

Crystal structure of 1H-imidazole-1-methanol

“…The title molecule is not capable of this highly interconnected hydrogen-bonding network due to the methanol substitution being at N1 of the imidazole ring, removing the possibility of a nitrogen hydrogen-bond donor. The remaining seven hits included 3-methyl-3-pyrazolin-5-one (MPYAZO10, MPYAZO11; De Camp & Stewart, 1971;Zhang et al, 2004), 3-methyl-1,2-oxazol-5-amine and 5-methyl-1,2-oxazol-3-amine (NOSZAZ and NOSZED; Morozova, et al, 2019), 3-methyl-N-hydrox-pyrazole (REHKOE; Reuther and Baus, 1995), and N-nitrosopyrroline (UCONIJ, UCONIJ01; Ohwada et al, 2001;Marsh & Clemente, 2007).…”