title: Phosphine-catalyzed synthesis of highly functionalized coumarins.
abstract: 2-Styrenyl allenoates are converted into cyclopentene-fused dihydrocoumarins through phosphine-catalyzed regio- and diastereoselective [3 + 2] cycloadditions. Remarkably, changing the solvent from THF to benzene promotes the conversion of the 2-(2-nitrostyrenyl) allenoate into a tricyclic nitronate through a previously undocumented mode of phosphine catalysis. This nitronate was subjected to efficient face-, regio-, and exo-selective 1,3-dipolar cycloadditions to provide tetracyclic coumarin derivatives.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, USA.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Henry
authors.forename: Ohyun
authors.initials: O
authors.lastname: Kwon
mesh_terms: D002384:Catalysis; D003374:Coumarins / Q000138:chemical synthesis*; D015394:Molecular Structure; D010720:Phosphines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D003374:Coumarins; D010720:Phosphines; C044646:phosphine