Studies on the terpenoids and related alicyclic compounds. XXVIII. Chemical transformations of .ALPHA.-santonin into C-8 lactonized eudesmanolides: Yomogin and diastereoisomers of dihydrograveolide.
The chemical transformations of α-santonin (1), a C-6 lactonized eudesmanolide, into C-8 lactonized eudesmanolides, i.e., yomogin (2) and four diastereoisomers of dihydrograveolide (36-39), are described. Transposition of 6, 13-olide into 8, 13-olide in eudesmanolides was investigated. Allylic oxidation of the trienone (12) with tert-butyl chromate gave 3, 8-dioxotriene (20) and 3, 6-dioxotriene (22). Reductive lactonization of 20 gave 11α- and 11β-methyl cis-lactones (30 and 31). Yomogin (2) was synthesized from the cis-lactones (32 and 33) by phenylselenenylation and deselenoxylation procedures. Catalytic reduction of 30 and 31 gave diastereoisomers of dihydrograveolide (36-39).
The chemistry of santonene. Part I. Keto–enol tautomerism in santonene and dihydrosantonene
作者:T. B. H. McMurry、R. C. Mollan
DOI:10.1039/j39670001813
日期:——
In the solid state, santonene exists in the keto-form, whereas dihydrosantonene exists as the enol. Physical measurements on santonene favour the structure containing 5,6- and 7,11-double bonds, rather than that of the 4,5: 6,7-unsaturated isomer suggested by Nishikawa et al. In solution, a tautomeric equilibrium is set up between keto and enol forms in both compounds. The position of equilibrium was