Synthesis of Naphtho[2,3-d]oxazoles via Ag(I) Acid-Mediated Oxazole-Benzannulation of ortho-Alkynylamidoarylketones

Abstract

A cascade oxazole-benzannulation for the synthesis of naphtho [2,3-d]oxazoles has been developed employing orthoalkynylamidoarylketones as substrates. This procedure provides the advantage of preparing a wide variety of substituents on naphtho[2,3-d]oxazole structures. In addition, o-alkynylamidoarylketones could be prepared from easily accessible and a wide variety of commercially available starting materials. Therefore, this method is a judicious choice of strategy to synthesize naphtho [2,3d]oxazoles with a great variety of substituents. In this work, 27 examples were demonstrated to provide the desired products in moderate to good yields.

Theoretical Investigation of Ag(I) Acid-catalysed Cascade Benz Annulation of N-(3-(2-(4-Methoxybenzoyl)phenyl)prop-2-yn-1-yl)benzamide for Synthesis of Naphthooxazole

“…Based on the experimental research previously [23][24][25] of TSs and intermediates in scheme 2 are listed by figure 1 and Supplementary Figure S1, respectively. Table 1 and Supplementary Table S1 show the activation energy of all reactions and the relative energies of all stationary points.…”

“…Among efficient ways leading to core structure [21,22], of special interest to us is the protocol of Ag(I) acid-catalyzed oxazole benz annulation for the synthesis of substituted naphthooxazole [23]. Although the silver catalyst was taken as the best activator for benz annulation of ortho-alkynylarylketones in previous methods [24,25], there is no report about detailed mechanistic study for this catalyzed Sonogashira coupling between orthoiodoarylketone and N-propargylamide.…”