Bridged-Selective Intramolecular Diels-Alder Reactions in the Synthesis of Bicyclo[2.2.2]octanes.
Regioselectivity for intramolecular Diels-Alder (IMDA) reactions of 6-acetoxy-6-alkenylcyclohexa-2,4-dien-1-ones that were formed by oxidation of 2-alkenylphenols with lead tetraacetate in acetic acid were studied. Bridged regioselectivity was observed in the IMDA reactions of 6-acetoxy-6-alkenylcyclohexa-2,4-dien-1-ones having a dienophile part which could conjugate with an aromatic group. Bridged seven- and eight-membered rings and bicyclo[2.2.2]octane skeletons were constructed by the present IMDA reactions. Density functional theory (DFT) calculations suggested that conjugation of the dienophile with neighboring aromatic groups lowered the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap and preceded bridged [4 + 2] adducts.
['Hanashima|Mika|M|', 'Matsumura|Toshiki|T|', 'Asaji|Yuta|Y|', 'Yoshimura|Tomoyuki|T|', 'Matsuo|Jun-Ichi|JI|']
D001643:Bridged Bicyclo Compounds D061565:Cycloaddition Reaction D000077318:Density Functional Theory D015394:Molecular Structure D009795:Octanes D013237:Stereoisomerism
bicyclo[2.2.2]octane bridged regioselectivity density functional theory (DFT) calculation intramolecular Diels–Alder reaction medium ring