Cyclohexanone with sodium acetylide

In order to explain the selectivity observed in cyclohexanones bearing polar substituents at position 4, Cieplak cited the reactions of 5-phenyl-2-adamantanone with sodium acetylide in liquid NH3 shown in Eq. 15 and 5-carbomethoxy-2-adamantanone with LiAl(0 Bu)3H in THF shown in Eq. 16. These reactions proceed with 66 34 and 83 17 selectivity in favor of axial attack. While the example in Eq. 15 may conform to the —> a overlap as indicated... 

To a flask containing a mixture of 5.1 moles of sodium acetylide, prepared during a period of 3 hr from 117 gm of sodium and acetylene in 3 liters of liquid ammonia at -50°C, is added dropwise 5.1 moles (500 gm) of cyclohexanone. The mixture is stirred overnight while a slow stream of dry acetylene is passed through the solution. The ammonia is then evaporated, the residue acidified with 200 gm of tartaric acid in 500 ml of water, and the mixture extracted with ether. The ether layer is dried and evaporated. The residue is fractionated to yield 518 gm (82%) of 1-ethynyl-l-cyclohexanol, bp 74 -77°C (15 mm), 1.4823 and mp 31°-32 C. 

Sodium enolates of ketones have been prepared by reaction of these ketones with NaNH2. For example, the alkylation of the sodium enolate of cyclohexanone by allylbromide (Fig. 2) leads to 2-allylcyclohexanone accompanied by a little of the dialkylated product (ref. 14). Dimethyl ethynyl carbinol was obtained by reaction of the enolate of acetone (prepared by reaction of solid NaNH2 in ether) with acetylene. Although a prepared ketone enolate is used, this reaction can also be considered as an aldolisation reaction of the acetylide with acetone (ref. 15). Hauser and coll, react sodioenolates of ketones prepared in ether (ref. 16) with acid chlorides (Fig. 2). 

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