Synthesis of Some Spirochroman-4-Ones by Regioselective [4+2] Cycloaddition Reactions

Synthesis of several spiro[4-aryl-5-hydroxy-2-(1-isoquinolinyl)-5-phenyl-4,5-dihydro-3H-pyrrole- 3,3'-3H-chroman-4'-ones] has been accomplished in satisfying yields by regioselective [4+2] cycloaddition reaction of a 2-benzoyl-1,2-dihydroisoquinoline-1-carbonitrile tetrafluoroborate salt across (E)-3-arylidene-4- chromanones. The spirocompounds evolve to pyrroles after acidic hydrolysis. The crystal structure of (10c) has been determined by an X-Ray study diffraction.