54345-23-2Relevant academic research and scientific papers
A SYNTHESIS OF γ-ALKYLIDENEBUTENOLIDES PHOTOCHEMICAL REARRANGEMENT OF 2,3-EPOXY-1,4-CYCLOHEXANEDIONES
Kitamura, Tohru,Kawakami, Yosihide,Imagawa, Takeshi,Kawanssi, Mituyosi
, p. 1183 - 1190 (1980)
Photo-induced rearrangement of 2,3-epoxy-1,4-cyclohexanediones was investigated for a synthesis of γ-alkylidene-γ-butirolactones and γ-alkylidenebutenolides.Irradiation of epoxy diketones 1 and 4 in acetone gave γ-lactones, 2 and 5, and triketones, 3 and 6.On the other hand, in CH2Cl2, EtOAc, or PhH solution epoxy diketones 1 and 4 gave only triketones, 3 and 6.Retro-Diels-Alder reaction of γ-lactones 5aE or 5aZ at 230 deg C (20 mmHg) afforded γ-alkylidenebutenolides 7aE and 7aZ in addition to anthracene.According to the procedure, butelonide 7bZ, a key intermediate for the synthesis of freelingyne, was prepared.The dramatic solvent effect in the photochemical rearrangement was also discussed.
