Menthone dissolving metals

In terms of mechanism and stereochemical consequences, reductions by dissolving metals in liquid NH3 are very similar to reductions by the same metals in alcoholic media. However, reductions carried out in liquid ammonia do not suffer from the same inherent problems as those by metals in alcohols. There is no evidence for equilibration of the product alcohols, and ketones which undergo epimerization prior to reduction with metals in alcohols are reduced cleanly by metals in NH3. For example, menthone (4) on reduction with Li-NHs-ethanol gives a mixture of alcohols (6) and (7), with no trace of alcohols (8) and (9).22... 

In reductions carried out by dissolving metals in alcohols, Na in primary alcohols or K in tertiary alcohols are the most common systems. Somewhat different epimeric mixtures are occasionally obtained with these systems and it has been reported that Li-ethanol does not reduce a menthone/isomenthone mixture. ... 

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