Synthesis of substituted 1,3-oxazines using sulfamic acid as an efficient and eco-friendly catalyst

摘要

Sulfamic acid catalyzed the synthesis of substituted 1,3-oxazines by one-pot three-component reaction of aniline, alkynoates, and formaldehyde in excellent yields. The catalyst possesses distinct advantages shows ease of handling, good yields, cleaner reactions, nonhygroscopic, noncorrosive, and high activity. Sulfamic acid is a green alternative for metal-containing acidic materials, which are toxic and deleterious for human health and environmental protection.