Synthesis of 3H‐Quinazolin‐4‐ones and 4H‐3,1‐Benzoxazin‐4‐ones via Benzylic Oxidation and Oxidative Dehydrogenation using Potassium Iodide‐tert‐Butyl Hydroperoxide

Abstract

A simple and elegant method for benzylic activation was demonstrated employing the potassium iodide/tert-butyl hydrogen peroxide catalytic system. This methodology was further extended for the synthesis of biologically important heterocycles namely, 3H-quinazolin-4-ones and 4H-3,1-benzoxazin-4-ones including mecloqualone and etaqualone which are important quinazolinone-based drugs used for the treatment of insomnia in good yields.

Selective copper(II) acetate and potassium iodide catalyzed oxidation of aminals to dihydroquinazoline and quinazolinone alkaloids

“…The Cu/TEMPO/DABCO catalyst system employed by Han et al [35] for the oxidation of aminals to quinazolines provided an increased yield of 50% (Table 3, entry 9). The best yields were obtained by using the conditions developed by Reddy and co-workers [36], namely the combined use of catalytic amounts of potassium iodide (20 mol %) and excess TBHP (5 equiv), followed by the addition of piperidine. In this instance, deoxyvasicinone was isolated in 80% yield (Table 3, entry 12).…”

“…2). In addition, Reddy and co-workers have developed a catalytic system in which 2,3-substituted tetrahydroquinazoline aminals are converted to quinazolinones using tert- butylhydroperoxide (TBHP) and catalytic potassium iodide [36–37]. While these examples deal with the oxidation of bicyclic aminals, we were interested in developing methods to create dihydroquinazoline and quinazolinone alkaloids from ring-fused aminals.…”

Copper‐Catalyzed Oxidative Coupling of Carboxylic Acids with N,N‐Dialkylformamides: An Approach to the Synthesis of Amides

“…In our previous work, we used potassium iodide as a catalyst for various organic transformations,11a–11d including amide bond formation by using aldehydes and amines under oxidative conditions 11e. During these investigations, we anticipated the possible formation of the corresponding acids as one of the intermediates.…”

Enhanced Structural Variety of Nonplanar <i>N</i>-Oxyl Radical Catalysts and Their Application to the Aerobic Oxidation of Benzylic C–H Bonds

“…Aerobic Benzylic C-H Oxidation, Etherification, and Acetamidation Full spectroscopic data were described for new compounds. Compound 37b, 41) f, 42) g, 43) h, 44) i, 45) j, 46) l, 47) m, 48) and n 49) are known compounds.…”