Ketones, cyclopropyl dissolving metals

There have been numerous reports on the reduction of activated cyclopropanes with alkali metals either dissolved in liquid ammonia or used in suspension. Most of these reactions were carried out with lithium as reducing agent. In an early study, various substituted cyclopropyl ketones were treated with lithium in liquid ammonia. rranj-l-Acetyl-2-methylcyclopropane (1, R = Me = H R = Me) gave 3,4,4-trimethyl-2-pentanone (3) as the result of... 

Aldehydes or ketones containing a cyclopropyl group adjacent to the carbonyl group can be converted to ring-opened carbonyl compounds by several different types of two-electron reduction processes. The most widely used method employs lithium metal in liquid ammonia as the reductant. The cyclopropyl ketone is usually dissolved in anhydrous diethyl ether and added to the blue metal-ammonia solution. Occasionally, the order of addition is reversed, and the lithium is added to a solution of the ketone in ammonia and diethyl ether. After a timed interval, the reduction is quenched by adding solid ammonium chloride to give a mixture of alcohols and ketones. This mixture is generally oxidized before isolation, with chromium(VI) oxide/pyridine or with sodium dichromate/sulfuric acid, to solely afford the ketone. 

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