STRUCTURAL CHARACTERIZATION OF DIHYDROSELENAPYRANS PREPARED BY THE REACTION OF DIARYLSELENOKETONES WITH CONJUGATED DIENES

Diarylselenoketones (ArArC)-Ar-1-C-2=Se (2b: Ar-1 = C6H5, Ar-2 = -p-C6 H4Cl; 2c: Ar-1 = Ar-2 = -p-C6H4F) were generated by treatment of the c orresponding ylides with elemental selenium (''Staudinger-Chalcogenati on'') and trapped with 2,3-dimethylbutadiene and 4-bis(methylene)-1,1- diphenyl-1-germacyclopentane, respectively, to yield the substituted 2 ,2-diaryl-3,6-dihydro-2H-selenapyrans 5b and 5c. The compounds 5b and 5c were characterized by X-ray crystal structure analyses.