106. Photochemical Synthesis of Cyclic 2-(2,2,-Dimethylpropylidene)-1,3-Dicarbonyl Compounds

Article abstract of DOI:10.1002/hlca.19890720513

Photolysis (λ=254 nm) of 4-(t-Bu)-substituted -fused bi- and tricyclic pyrandiones 5 affords title compounds 4 in good yields as well a small amounts of spiroalkanediones 8.The alkyl-substitution pattern at C(4) of the pyran ring in 5 determines the relative amount of α- vs. β-cleavage products obtained from the primarly formed acyl-vinyloxy biradical.