Santonic acid

The photorearrangement of a dienone was noted<4) as early as 1830 in a study of the sesquiterpene a-santonin (1). However, the structure and stereochemistry of the various photoproducts were not conclusively established until 1965.(6) Upon irradiation in neutral media, a-santonin (1) undergoes rapid rearrangement to the cyclopropyl ketone, lumisantonin (2). However, if the irradiation is not terminated after a short period of time the lumisantonin itself rearranges into a linearly conjugated dienone (3). The dienone (3) can be isolated from the photolysis of either (1) or (2) in benzene or ether. In nucleophilic solvents (alcohol or water) the dienone (3) is also photo-chemically active and is further converted into an ester or an acid (photo-santonic acid) (4). 

That concentration is the number of moles per kilogram of benzene, but the solution used only 300 grams of the solvent. The moles of santonic acid is found as follows ... 

The boiling point of a solution was used to determine that santonic acid has a molecular weight of approximately 246. You can also find this value by using the freezing point of the solution. 

In the two previous examples, the sucrose and santonic acid existed in solution as molecules, instead of dissociating to ions. The latter case requires the total molality of all ionic species. Calculate the total ionic molality of a solution of 50.0 grams of aluminum bromide (AlBr3) in 700 grams of water. Because the gram formula weight of AlBt3 is... 

Santonin—Santonic acid——Santoninum U. S., /Jr.)—24G.— A glucoside having distinct acid properties obtained from various species of Artemisia It crystallizes in colorless, rectangular prisms, which turn yellow on exposure to light odorless and tasteless insoluble in cold water, sparingly soluble in hot water, alcohol, and ether its solutions are faintly acid in reaction. Santonin, in solution, gives a chamois-colored precipitate with the fen ic salts, and a white precipitate with silver, zinc, and mercurous salts no precipitate with mercuric salts. 

Santonic Acid. Octahydro-a,3a,S-trimethyl-6,8-dioxo-l,4-methano-lH-indene-l-acetic acid hexahydro- x,3a,5-trimethyl-6,8-dioxo-l,4-methanoindan-I-acetic add. 

The first synthesis, that of Corey, Ohno, Vatakencherry, and Mitra (27), is schematically shown in Chart 1. The key-feature in the synthesis is the internal Michael addition (7 -> 8), which had precedence in the reported (25) conversion of santonin (10) into santonic acid (11) under the influence of hot aqueous potassium hydroxide. However, in the present case Michael cyclization proved quite difficult and was finally achieved in a yield of 10—20%, by prolonged exposure of (7) to triethylamine in ethylene glycol at 225°. After methylation of the resulting diketone (8), the less hindered carbonyl function was removed as shown to yield (i)-longicamphenilone (9) which could be readily transformed into ( )-... 

Problem 1L7. Using the curved arrow formalism, write a suitable pathway from a-santonin to santonic acid and then to santonide (Woodward, 1950). Answered. (Note the details of the mechanism are suggestions )... 

Birladeanu L (2003) The stories of santonin and santonic acid. Angew Chem Int Ed 42 1202-1208... 

Santonous acid d ( C,5HooOi, ) + Desmotoposantonous acid 1 ( C15H20O1, )... 

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