Phosphine-catalyzed synthesis of highly functionalized coumarins.
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.
Henry
Christopher E
CE
Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, USA.
Kwon
Ohyun
O
D002384:Catalysis; D003374:Coumarins / Q000138:chemical synthesis*; D015394:Molecular Structure; D010720:Phosphines / Q000737:chemistry*; D013237:Stereoisomerism
D003374:Coumarins; D010720:Phosphines; C044646:phosphine