Advancements in the synthesis of naphthoxazine-3-one derivatives over the last two decades: a brief review

Abstract

Multicomponent reactions (MCRs) play a significant role in organic synthesis, medicinal chemistry and in material science, as they permit the formation of a single product from the strategic combination of more than two starting materials. Multicomponent reactions (MCRs) represent an attractive area of research for the efficient synthesis of highly functionalized, biological active and structurally diverse heterocyclic organic compounds. Synthesis of naphthoxazine-3-one derivatives is an important multicomponent reaction. Such derivatives are typically prepared in a one-pot from β-naphthol, aromatic aldehydes and urea in the presence of suitable catalyst thereby providing most efficient route for the synthesis of structurally diverse naphthoxazinone derivatives. Aromatic condensed naphthoxazinone derivatives represent an important class of functionalized building blocks. Naphthoxazinone derivatives are well-known by their significant biological activities such as anti-inflammatory, anti-ulcer, antibacterial, antipyretic, antifungal, antihypertensive, etc. These compounds also exhibit a wide range of industrial, clinical and pharmacological applications. Several researcher groups have made notable contributions in the field of synthesis of naphthoxazine-3-one derivatives using various catalytic systems. This review highlights the advances made over the past two decades in catalytic approaches, including nanocatalysis, for the synthesis of biologically active naphthoxazine-3-one derivatives. Especially, it emphases on methodologies reported by various researchers involving multicomponent cyclocondensation reactions of β-naphthol, aromatic aldehydes, and urea under specific reaction conditions. Most of the reported protocols have significant advantages like use of non-toxic and inexpensive catalyst, shorter reaction time, solvent-free conditions, easy work-up and purification of compounds, good to excellent yields of the desired naphthoxazine-3-one derivatives, recyclability of the catalysts, making green and environmentally benign protocols. This review will be definitely beneficial for researchers engaged in designing more efficient, novel and environmentally friendly synthetic protocols for the synthesis of naphthoxazine-3-one derivatives as well as for developing new biologically active heterocyclic molecules.