ROTENONE. III. DEHYDROROTENONE¹

The Determination of the Structure of Rotenone.

“…One of the acetyl groups in dihydrorotenonic acid is therefore of the enol acetate type, whereas the other results from the acetylation of the phenol group. Tetrahydro derivatives of all the characteristic rotenone derivatives have been obtained by hydrogenation (16,24,28,29,31). All of these are phenols, soluble in alkali.…”

“…(XXXII) (31,24), the reaction being the same as that involved in the formation of derrisic acid from dehydrorotenone.7 Tetrahydroderrisic acid is methylated to the methyl ester of monomethyltetrahydroderrisic acid (XXXVI) which is alkali- By the action of acetic anhydride and anhydrous sodium acetate, tetrahydroderrisic acid (XXXV) is converted by dehydration and acetylation into the monoacetyl derivative of dehydrodihydrorotenonic acid (tetrahydrodehydrorotenone) (XXXVII) (24), from which the acetyl group is easily removed. The methyl ester of methyltetrahydroderrisic acid (XXXVI) does not undergo ring closure when treated with acetic anhydride and sodium acetate but is simply converted into the 6-acetyl derivative (24).…”

“…On oxidation of derrisic acid with hydrogen peroxide in alkaline solution, derric acid, of the formula C12H14O7, a dibasic acid containing two methoxyl groups and one unreactive oxygen atom, is obtained (29). Permanganate oxidation converts derric acid into its next lower homologue, risic acid, of the formula C11H12O7 (30).…”

“…Rotenone is oxidized by chromic acid (42) or by nitrous acid (3) to rotenonone, a yellow compound of the formula C23H18O7 (29); analogous compounds are obtained in the same manner from iso-(50), dihydro- (29), and 0-dihydro-rotenone (9), as well as from dihydrorotenonic acid (29). It is apparent that the first step of this oxidation process consists in the formation of the dehydro derivatives, because rotenonone and its analogues are also obtained from the corresponding dehydro compounds (29).…”

“…This change from a benzopyran to a benzo-a-pyrone system results in the formation of a coumarin derivative and rotenonone is, therefore, to be represented by the formula XLII (5, 50, 23). formula C23H2o08 (29). By energetic alkaline hydrolysis, rotenonone or rotenononic acid is further cleaved with the formation of derritol and oxalic acid (50, 5, 23).…”