Ketone-alkenes, from keto acids

The oxidative cleavage of unsaturated ketones takes place under the same conditions as that of alkenes or other unsaturated derivatives. The fate of the primary fission product depends on the position of the double bond with respect to the carbonyl group and on the subsequent reactions. Ozonization of A -cholestenone in acetic acid and ethyl acetate, followed by treatment with 30% hydrogen peroxide, gives a keto acid, evidently resulting from the decomposition of the primarily formed diketo acid (equation 444) [1176]. 

More complex products are obtained from cyclizations in which the oxidizable functionality and the alkene are present in the same molecule. y9-Keto esters have been used extensively for Mn(III)-based oxidative cyclizations and react with Mn(OAc)3 at room temperature or slightly above [4, 10, 11, 15], They may be cyclic or acyclic and may be a-unsubstituted or may contain an a-alkyl or chloro substituent. Cycloalkanones are formed if the unsaturated chain is attached to the ketone. y-Lactones are formed from allylic acetoacetates [10, 11]. Less acidic /3-keto amides have recently been used for the formation of lactams or cycloalkanones [37]. Malonic esters have also been widely used and form radicals at 60-80 °C. Cycloalkanes are formed if an unsaturated chain is attached to the a-position. y-Lactones are formed from allylic malonates [10, 11]. yff-Diketones have been used with some success for cyclizations to both alkenes and aromatic rings [10, 11]. Other acidic carbonyl compounds such as fi-keto acids, /3-keto sulfoxides, j8-keto sulfones, and P-nitro ketones have seen limited use [10, 11]. We have recently found that oxidative cyclizations of unsaturated ketones can be carried out in high yield in acetic acid at 80 °C if the ketone selectively enolizes to one side and the product cannot enolize... 

P-keto-acids, and the saponification of only one cyano-function in the reaction with malononitrile is difficult to rationalise. Treatment of compounds containing active methylene groups with cupric acetate in the presence of an alkene can lead to a cyclopropane (8—66%) by a radical route.1,3-Debromination, by sodium, of suitable precursors has led to a series of new spirans, and a new synthesis of cyclopropane from 3-bromopropyne and allylic zinc bromides has been claimed. Miscellaneous Methods.—Pyrolysis of (144) leads to carbonylcyclopropane, which undergoes ready dimerization on warming to ambient temperatures. The ketone... 

The synthesis of bicyclo[3.2.2]non-6-en-3-one (192) and the spiro-substituted derivatives (195) can be achieved via similar methodology. Thus, thermolysis of the enol silyl ether (190), which is readily derived from the ketone (189), gives the bicyclic substance (191). Mild acid hydrolysis of (191) affords (192 Scheme 27). In a similar fashion the exo-ketones (193) have been converted, via the enol silyl ethers (194), into the tricyclic keto alkenes (195). ... 

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