Substituted 2,4,4,6-tetraphenyl-4H-selenopyrans: preparation, photocolouration and 4H-selenopyran ring geometry; an X-ray and DFT calculation study

摘要: 1,5-Diaryl-3,3-diphenylpentane-1,5-diones 3a–d react with Al2Se3–HCl–AcOH reagent to give the 2,6-diaryl-4,4-diphenyl-4H-selenopyrans 4a–d in satisfactory yields while same procedure starting from 1,5-diketone 5 affords small amounts of spiroheterocycle 6. 2,4,4,6-Tetraphenyl-4H-selenopyran 4a can be brominated or nitrated at positions 3 and substituted derivatives 7–9. Dibromo 4c 7 were converted copper(I) cyanide dicyano 4e 10,11, respectively. Similarly 4H-pyrans 1 4H-thiopyrans 2, 1-selena analogues 8 exhibit solid state photocolouration which was investigated terms dispersive first-order reaction kinetics. The influence selenium heteroatom on geometry heterocyclic ring molecules 4a,c 6 is discussed basis X-ray structure determinations, quantum DFT semiempirical PM3 calculations.