86724-63-2Relevant academic research and scientific papers
Heterodiene Cycloadditions of 3-Acylchromones with Enol Ethers
Saengchantara, Suthiweth T.,Wallace, Timothy W.
, p. 789 - 794 (2007/10/02)
3-Formylchromones behave as heterodienes in stereoselective (4?+2?) cycloadditions with enol ethers at 20 deg C, the formal endo-addition product predominating.An electron-donor substituent (OH, OMe) in the aromatic ring retards the reaction and slightly increases endo selectivity, while an electron-withdrawing group (NO2) has the reverse effect. 3-Acetyl- and 3-benzoyl-chromone react much more slowly but with similar stereoselectivity.The reaction of 3-formylchromone (3a) with t-butoxyethene is almost non-selective, while with dihydropyran it forms novel isomeric pyranopyranobenzopyranones (23) and (24) in which the enol ether geometry is retained.Reaction rates and stereoselectivity vary slightly with solvent and temperature, and the results indicate a concerted cycloaddition mechanism with kinetically controlled stereoselection.
Heterodiene Cycloadditions of 3-Acylchromones with Ethoxyethene
Wallace, Timothy W.
, p. 228 - 229 (2007/10/02)
3-Acylchromones behave as heterodienes in stereoselective (4? + 2?) cycloadditions with ethoxyethene, the formal endo-addition product predominating.
