88046-53-1Relevant articles and documents
New Synthetic Approaches to Fused-ring Carbocycles based on Intramolecular Photocycloadditions of 1,3-Dione Enol Esters
Begley, Michael J.,Mellor, Michael,Pattenden, Gerald
, p. 1905 - 1912 (2007/10/02)
Irradiation of 3-acetoxy-2-pent-4-enylcyclohex-2-enone (12) leads to the tricyclic adduct (18), in high yield (>95percent), which on hydrolytic cleavage in ethanolic potassium hydroxide gives rise to bicycloundecane-2,6-dione (20).In contrast, irradiation of the isomeric enol acetate, 3-acetoxy-4-pent-4-enylcyclohex-2-enone (17) led to the two photoadducts (25) and (26) resulting from intramolecular photocycloaddition, and to the trione (24) produced via photo-Fries rearrangement of (17); the formation of (25) and (26) followed from the structures (29) and (27) produced after saponification-retroaldolisation of mixtures containing (25) and (26).Irradiation of the 6-phenyl substituted enol ester (16) gave rise to only the photo-Fries rearrangement product (24).Irradiation of 1-acetoxy-2-pent-4-enylcyclopentene (39) led (93percent) to a 2:3 mixture of the photoadducts (41) and (42) whose structures followed from X-ray measurements.The corresponding cyclohexene (45), instead produced the product (46) of photo-Fries rearrangement on irradiation.Hydrolytic cleavage of (41) in KOH-EtOH leads to the bicyclodecanone (47), whereas similar treatment of (42) instead gave directly the aldol (49) by way of the transient retro-aldol intermediate (48).
