Abstract
A series of directly linked 4-3′ bicoumarins have been synthesized by both Knoevenagel and Perkin reactions. This single-step transformation was accomplished by the reaction of coumarin-4-acetates with substituted salicylaldehydes in presence of piperidine using ethanol as solvent and by the reaction of coumarin-4-acetic acids with substituted salicylaldehydes in the presence of sodium hydride in acetic anhydride. Greater yields have been obtained in the sodium hydride and acetic anhydride condition. An intermediate chalcone with an ortho-hydroxyl group, which is a precursor for lactone formation, has been isolated and its structure has been confirmed by x-ray analysis. The nonplanar S-cis arrangement of two C4-C3’ double bonds has been confirmed by nuclear Overhauser spectroscopy (NOE) and x-ray studies. The UV-fluorescence studies support the formation of a conjugated bicoumarin system.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
