- SYNTHESIS OF CEDRANOID SESQUITERPENES. III. FUNCTIONALIZATION AT CARBON 4
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Dimethyl 6,6-dimethyl-5,7-dioxobicyclooct-2-ene-2,3-dicarboxylate (8) on irradiation in acetophenone gives dimethyl 6,6-dimethyl-4,7-dioxotricyclo2,8>octane-1,8-dicarboxylate (13), which on treatment with lithium dimethyl cuprate followed by monodecarbomethoxylation gives methyl 4,4-endo-8-trimethyl-3,6-dioxo-cis-bicyclooctane-1-carboxylate (17).Similar irradiation of dimethyl 4,6,6-trimethyl-5,7-dioxobicyclooct-2-ene-2,3-dicarboxylate (24) and its 7,7-ethylenedioxy derivative (25) followed by treatment with DBU and concentrated H2SO4, respectively, gives dimethyl 3-hydroxy-4,4,8-trimethyl-6-oxo-cis-bicyclo-octa-2,7-diene-1,2-dicarboxylate (30).This, on acetylation, reduction with NaBH4/CeCl3, methanolysis, monodecarbomethoxylation, and hydrogenation, gives methyl endo-6-hydroxy-4,4-endo-8-trimethyl-3-oxo-cis-bicyclooctane-1-carboxylate (38), while on reduction with Li/NH3 followed by monodecarbomethoxylation it gives a methyl 6-hydroxy-4,4-exo-8-trimethyl-3-oxo-cis-bicyclooctane-1-carboxylate (33).
- Yates, Peter,Burnell, D. Jean,Freer, Vernon J.,Sawyer, Jeffery F.
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- THE OXIDATION OF 2-CYCLOHEXEN-1-ONES TO 2-CYCLOHEXENE-1,4-DIONES
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Treatment of 5,5-dimethyl-2-cyclohexen-1-one and isophorone with phosphomolybdic acid, potassium dichromate, cupric sulfate, and air gives 5,5-dimethyl- and 3,5,5-trimethyl-2-cyclohexene-1,4-dione, respectively.In the latter reaction treatment of the crude product with aqueous base leads to the formation of 2,3,6,6-tetramethylanthracene-1,4,5,8-tetrone.
- Freer, Vernon, J.,Yates, Peter
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p. 2031 - 2032
(2007/10/02)
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