Alkali metal ynolates

Metal ynolates are not as easy to prepare in a similar fashion as metal enolates, because the intermediates may be labile monosubstituted ketenes. Several preparative methods for alkali metal ynolates have been reported, among which some have been used as intermediate steps in one-pot organic syntheses. Silyl ynolates have been prepared from lithium ynolates. There have been few reports on the other metal ynolates. Since there is no universal method to determine the yield of metal ynolates, the efficiency of preparation is estimated from the results of some of the following reactions. 

S -Analogues of lithium or sodium ynolates (thioalkynolates or alkynethiolates) are prepared from lithium or sodium acetylide and sulfur, and are trapped as alkynyl sulfides with bromoethane (equation 77). In a synthetic approach analogous to equation 72, 5-lithio-l,2,3-thiadiazoles (198) also afford lithium alkynethiolates (199) by elimination of nitrogen (equation 78) . Alkynyl sulfides (200) are treated with lithium in ammonia to afford lithium alkynylthiolates (199) (equation 79) °. Theoretical studies on the structure of alkali metal alkynylthiolates are reported. ... 

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