Eosin Y as a direct HAT photocatalyst for the synthesis of tetrahydrodipyrazolopyridines under white LED irradiation. (6th March 2023)

• Record Type: Journal Article
• Authors: Nagasundaram, Nagarajan; Peroli, Udhayakumar; Venkatesh, Ramakrishnan; Vinoth, Nangagoundan; Lalitha, Appaswami
• Is Part Of: Tetrahedron letters. Volume 117(2023)
• Publication Date: 2023-03-06
• Subjects: Visible light -- Eosin Y -- HAT -- Multicomponent reaction -- Dipyrazolopyridines -- Multi-gram scale; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2023.154366
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: Visible light promoted eosin Y catalyzed synthesis of tetrahydrodipyrazolopyridines. Eosin Y as direct hydrogen atom transfer photocatalyst. Ambient temperature under open air atmosphere. Green, efficient, metal-free, operationally simple, rapid and high yields. Broad substrate scope and multi-gram scale synthesis. Abstract: A facile and efficient synthetic protocol has been developed for the synthesis of biologically privileged tetrahydrodipyrazolopyridines via visible light mediated one pot pseudo-six component reaction of ethyl acetoacetate, hydrazine hydrate, multifarious aldehydes and ammonium acetate (Knoevenagel condensation-Michael addition) by using metal-free, inexpensive eosin Y organic dye as a direct hydrogen atom transfer (HAT) catalyst at room temperature in open air condition. Mild condition, good yields, environment-friendly, high atom economy and good functional group tolerance of an extensive range of both electron-withdrawing and electron-donating groups are extra features of this approach. Additionally, this methodology is also appropriate for multi-gram scale, which enlighten the potentiality of using this reaction for industrial purposes.