An alternative synthesis of pyrimido[4,5-b]quinoline-4-ones via metal-free amination in water and Vilsmeier-Haack cyclization

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• 作者：Radhey M. Singh ; ^{rmohan@bhu.ac.in} ; Neha Sharma ; Ritush Kumar ; Mrityunjaya Asthana ; Shraddha Upadhyay
• 关键词：2-Chloroquinoline-3-carbonitrile ; Amination ; Aqueous media ; Vilsmeier&ndash ; Haack reaction ; Pyrimido[4 ; 5-b]quinoline-4-one
• 刊名：Tetrahedron
• 出版年：2012
• 出版时间：16 December, 2012
• 年：2012
• 卷：68
• 期：50
• 页码：10318-10325
• 全文大小：1442 K

文摘

Two-step synthesis of pyrimido[4,5-b]quinoline-4-ones is described from 2-chloroquinoline-3-carbonitries via amination and cyclization reactions, respectively. The amination reactions proceeded much faster in water via simple S_NAr displacement reactions of chlorine. The cyclization reactions using Vilsmeier reagent at 60 ¡ãC gave the best yield of the products. The isolation of starting compound from the reaction of cyclized product with I₂/K₂CO₃ provided further chemical proof of the structure of the cyclized product. Plausible mechanism for cyclization is proposed.