Efficient One Pot and Chemoselective Synthesis of Polysubstituted Dihydro-6H-chromeno4,3-dpyrazolo1,5- αpyrimidin-6-ones via a Four-Component Reaction

摘要

In this research, a simple and chemoselective synthesis of highly fluorescent polysubstituted dihydro-6H-chromeno[4,3- d]pyrazolo[1,5-α]pyrimidin-6-ones containing one chiral stereocenter is presented by a sequential four-component reaction of 4-chloro-3-formylcoumarin, 1-phenyl-2-(1,1,1-triphenyl-λ~5- phosphanylidene)ethan-1-ones (Wittig reagent), benzoylacetonitriles and hydrazine hydrate as readily available starting materials, which includes base-mediated 1,4-addition/aza-Michael addition/formation of two C-N bonds. The desired products were obtained with short reaction times, easy purification (products can be purified by washing with EtOH), and medium to high yields (up to 92%) under relatively mild reaction conditions. Molecular structures were determined by IR spectrophotometry, mass spectrometry, NMR spectroscopy, and single-crystal X-ray analysis.