Lithium alkoxyacetylides

Numerous examples of such reactions (equation 34) have been reported in earlier reviews ". In the well-known standard synthesis of alkoxyalkynes f reaction of acetals of chloroacetaldehyde 52 with sodium amide in liquid ammonia has been used to generate sodium alkoxyacetylide 54. Recently, this elimination procedure has been further improved by using lithium diethylamide in THE solution (equation 35)". In this work" in situ generated lithium alkoxyacetylide 56 was subsequently converted to either ethoxyacetylene 57 by quenching with saturated aqueous sodium diioride, or ethoxyethynyl carbinols 58 by subsequent reaction with ketones or aldehydes. 

Recently, the dehalogenation method was further modified by using 1,2-dichlorovinyl ethers 62 as starting compounds" ". Loffler and Himbert applied the reaction of 1,2-dichlorovinyl ethers 62 with butyllithium to generate lithium alkoxyacetylides 61, which were subsequently quenched with ketones or arylated by the palladium-catalyzed crosscoupling with aryl halides to yield alkoxyarylacetylenes 63 (equation 37)". ... 

Several examples of such reactions have already been shown in Section III.A.l of the present review. Recently, this method has been widely used for the preparation of various element-containing alkoxyacetylenes. For example, Lukashev and Kazankova synthesized a number of useful phosphorylated alkoxyacetylenes by the reaction of lithium alkoxyacetylides with phosphinehalides (equation 43). 

Lithium alkoxyacetylides 233 represent synthetic equivalents of ester enolates. They can also be generated by the treatment of trichloroethene with n-butyllithium in the presence of the appropriate potassium alkoxide or directly from l-bromo-2-... 

Scheme 1-179. Lithium alkoxyacetylides (233) from trichloroethene or 1 -bromo-2-alkoxyethenes.

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