"On water" cascade synthesis of benzopyranopyrazoles and their macrocycles. Issue 15 (11th April 2018)

• Record Type: Journal Article
• Authors: Muthusamy, Sengodagounder; Gangadurai, Chinnakuzhanthai
• Is Part Of: Tetrahedron letters. Volume 59:Issue 15(2018)
• Page Start: 1501
• Page End: 1505
• Publication Date: 2018-04-11
• Subjects: Benzopyranopyrazole -- Cascade reaction -- Diazo compound -- Open flask chemistry -- Water; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2018.03.013
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: Green approach to synthesize benzopyranopyrazoles in excellent yields. Water mediated intramolecular 1, 3-dipolar cycloaddition reaction. Cascade reaction under open to air atmosphere. Synthesis of pyrazole incorporated macrocycles. No catalyst as well as column purification. Abstract: Reported herein is an intramolecular 1, 3-dipolar cycloaddition strategy for rapid entry into benzopyranopyrazoles (BPP) on water medium as "open flask chemistry" approach. The in situ generation of diazo functionality in two-step sequence from the appropriate alkylated salicylaldehydes undergoes smooth [3 + 2]-cycloaddition with unactivated alkynes/alkenes furnishing benzopyranopyrazoles in good yield. This methodology was also extended for the synthesis of pyrazole incorporated macrocycles. This cascade protocol involving water medium provides an atom-economical and environment friendly approach.