Lithium ethoxyacetylide

Lithium ethoxyacetylide appears superior to the magnesium reagent for avoiding further transformations of particularly sensitive alcohols produced in this reaction. 

Homologues of ethoxyacetylene can be obtained by reaction of the metallated ethynyl ether in liquid ammonia with primary alkyl bromides and iodides 167]. Because of their better solubiliiy, the lithium compounds are preferred over their sodium and potassium analogues, lithium ethoxyacetylide is generated from the readily accessible 2-bromovinyl ethyl ether and two equivalents of lithium amide. This starting compound is obtained as a mixture of the E-and Z-isomer. When this mixture is heated with powdered KOH, only the Z-isomer is converted into ethoxyethyne. Alkali amides are able to conven both isomers into ethoxyethyne and its alkali compounds. A possible explanation for this violation of the "rule of... 

Synthetic methods for 2(5jF/)-furanones have been developed in the preparation of cardenolides (65MI31200). The ketone (171) when reacted with lithium ethoxyacetylide gives the carbinol (172) which undergoes acid catalyzed rearrangement to the a,/3-unsaturated ester (173). Allylic oxidation of (173) with selenium dioxide under mild conditions gives digitoxigenin acetate (174) (Scheme 38). 

In the laboratory of S.C. Welch, the Meyer-Schuster rearrangement was the key step in the stereoselective total synthesis of the antifungal mold metabolite (+)-LL-Z1271a. A tricyclic enone acetal was treated with lithium ethoxyacetylide, and the crude product was exposed to H2SO4 in anhydrous methanol, which brought about the rearrangement and afforded the desired product in 30% yield along with 12% of an epimer. 

Hydrogenation Copper chromite (Lazier catalyst). Copper chromium oxide (Adkins catalyst). Lindlar catalyst (see also Lithium ethoxyacetylide, Malealdehyde, Nickel boride). Nickel catalysts. Palladium catalysts. Palladium hydroxide on carbon. Perchloric acid (promoter). Platinum catalysts. Raney catalysts, Rhenium catalysts. Rhodium catalysts. Stannous chloride. Tributylborane. Trifluoroicetic acid, Tris (triphenylphosphine)chlororhodium. 

For ell ecling addition of the ethoxyethynyl group to the carbonyl group of cro-tonaldehyde. Stork and Tomasz added ethoxyacetylene in ether to an ethereal solution of phenylUthium and added the aldehyde to the resulting suspension of lithium ethoxyacetylide (1). The resulting carbinol is rearranged readily under acid catalysis to ethyl sorbate (4). 

The synthesis of fused butenolides via the reaction of a-ketols with lithium ethoxyacetylide had been previously developed in connection with the synthesis of Securinega alkaloids.22 This synthesis has now been generalized... 

The two-step preparation of fused butenolides used in the synthesis of securinine (Scheme 29) was generalized and further applied to the partial synthesis of dihydrosecurinine (70). The a-ketol 17a (Scheme 10) obtained from degradation of dihydrosecurinine was treated with lithium ethoxyacetylide and the resulting crude product refluxed with sulfuric acid to give, in 25% overall yield, dihydrosecm-inine (70) shown to be identical with the natural product (Section II, B) by IE spectral and GLO comparison. 

Treatment of 1,1-dichloroalkanes 231 with -butyllithium (3.0 eq.) produces the lithium acetylides. The chloroacetaldehyde diethyl acetal affords with excess lithium diethylamide lithium ethoxyacetylide via intermediate 232 (Scheme 1-178). ... 

Dicaesium acetylide Copper(ll) acetylide Dicopper(l) acetylide Silver acetylide Caesium acetylide Potassium acetylide Lithium acetylide Sodium acetylide Rubidium acetylide Lithium acetylide-ammonia Dipotassium acetylide Dilithium acetylide Disodium acetylide Dirubidium acetylide Strontium acetylide Silver trifluoromethylacetylide Sodium methoxyacetylide Sodium ethoxyacetylide... 

Formation and Reaction of Alkynylaluminum Reagents. Lithium acetylides react with Me2AlCl to give dimethylaluminum acetylides that react analogously to the more commonly used diethylaluminum acetylides (see Diethylalu-minum Ethoxyacetylide). Addition of the aluminum acetylide to propiolactone results in an Sn2 reaction to give an alkynic acid (eq 1) ... 

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