Aryl derivatives carbon-oxygen bond formation

Heterocyclization based on simple acetylenes requires a catalyst to be present [33, 447-449]. Haloacetylenes with alkyl or aryl substituents also undergo heterocyclization but less effectively. However, activated electron-deficient haloacetylenes readily react with nucleophiles. With binucleophiles, this reaction often leads to the formation of heterocycles. Haloacetylene often reacts in a similar manner to acetyl chloride, differing from the latter by the absence of released water. However, sometimes an unusual reaction occurs, as was shown by the reaction of dialkyl l-chloroacetylene-2-phosphonates with specific binucleophiles. l-Chloro-2-dialkoxyphorylacetylenes 4.981 react readily with diethyl acetamidomalonate in acetonitrile in the presence of potassium carbonate as a base, to form oxazoline derivatives 4.991. The reaction has two steps nucleophilic substitution of the acetylenic chlorine atom followed by attack of the amide oxygen atom on the triple bond activated by... 

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