Ethers acetylenic

Unsaturated esters can be prepared from the corresponding acetylenic ethers with yields in most cases of >50% (91) as in the following example ... 

The partial hydrogenation of a 17-ethynyl group over deactivated palladium occurs more readily than the saturation of any other functional group. This is also true of 17-ethynyl carbinols and 17-acetylenic ethers (52). ... 

With other acetylenes steric factors may be operative which render the selective reduction somewhat difficult. In the aldosterone intermediates (53) and (54), for instance, selective hydrogenation is obtained only with the 14 -acetylenic ether " (hydroxyl group effect). 

A number of other reagents cyclize 3-propanolamines to 5,6-dihydro-1,3-4/f-oxazines, These reagents are acetylenic ethers (which act as... 

Acetylene ethers have the same instability and dangerous reactions as acetylene compounds. 

Acetylenic ethers 7 can be hydrozirconated, and subsequent iododezirconation leads to (fc)-iodo enol ethers 8 (Scheme 4.4) [18], These species undergo efficient Sonogashira couplings to give (E)-enynes, which are ultimately converted to stereodefined dienol ethers. These dienes have proven useful in studies of diastereoselective cycloaddition reactions with singlet oxygen, where R in 8 is a nonracemic auxiliary (e. g., menthyl) (Procedure 3, p. 140). 

Zinc enolate 4, prepared from acetylene ether pyridine i-oxide, mercuric chloride, and zinc, adds to aldehydes to form a-chloro-3-hydroxy esters 5 in good yields ( ). Subsequent treatment with base gives trans-epoxyesters, one of which 6 is converted to 2-amino-2-deoxy-D-ribose stereoselectively in good yields (O. 

Acetylenic ethers react with lithium dialkylamides to give ynamines in good yields [13] (Eq. 13). Examples of this reaction are described in Table II. 

General Method for Preparation of Ynamines by Reaction of Acetylenic Ethers... 

Reaction of Acetylenic Ethers with an Equivalent Amount of Lithium Dialkyl Amides to Give Ynamines [13]... 

Carboxylic esters, thiol esters, and amides can be made, respectively, by acid-catalyzed hydration of acetylenic ethers, thioethers,162 and ynamines, without a mercuric catalyst 163... 

For a review of acetylenic ethers, sec Radchenko Petrov Russ. Chem. Rev. 1989, 58. 948-966. 

D1-tert-butoxyethyne, like other acetylenic ethers having hydrogen atoms... 

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