Highly Efficient One‐Pot Synthesis of 2‐Substituted Quinazolines and 4H‐Benzo[d][1,3]oxazines via Cross Dehydrogenative Coupling using Sodium Hypochlorite

Abstract

This communication describes a catalystfree synthesis of 2-substituted quinazolines and 4H-]oxazines using commericially available sodium hypochlorite as oxidant. Operational simplicity, mild reaction conditions and the ability to construct structurally diverse 2-quinazolines and 2- ,3]oxazines by this method render it to be a practical alternative for the synthesis of these heterocycles.

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

“…The above strategy was further applied for the synthesis of 2-phenylbenzo (11a) by our earlier reported method [18] which, on further treatment with KI/TBHP at room temperature, resulted in the desired product 12a along with the cleaved product 13a (Scheme 5).…”

“…[18] Herein, we wish to report a new strategy for the synthesis of 3H-quinazolin-4-ones and 4H-3,1-benzoxazin-4-ones via benzylic oxidation using potassium iodide/tertbutyl hydrogen peroxide (KI-TBHP).…”

Laccase‐Based Oxidative Catalytic Systems for the Aerobic Aromatization of Tetrahydroquinazolines and Related N‐Heterocyclic Compounds under Mild Conditions

“…One strategy for the synthesis of these valuable compounds is through the oxidative cyclization of 2‐aminobenzylamines with aldehydes mediated by stoichiometric amounts of strong oxidant such as DDQ, MnO 2 , NaClO and etc . However, these reagents are often toxic and show poor atomic efficiency.…”

Experimental and theoretical investigations into the stability of cyclic aminals

“…These methods allow the synthesis of the partially unsaturated alkaloids vasicine or deoxyvasicine in good yields [22,28] (Scheme 2). Furthermore, copper-catalysed reactions or oxidation with sodium hypochlorite were also described to yield the aromatic quinazoline core [26,29–30] (Scheme 2). Besides all the oxidation reactions described, also reductive conditions applying NaBH 4 onto the tetrahydroquinazoline-based aminal systems were investigated, thereby providing the possibility to “open” the rigid aminal core gaining access to sterically more flexible compounds [31–33] (Scheme 2).…”