Dialkylacetylenes, oxidation

T1(N03)3 is a versatile oxidant since it converts diarylacetylenes to 1,2-diketones and dialkylacetylenes to a-hydroxy ketones 716... 

Dialkylacetylenes usually cannot be reduced electrochemically up to —3.0 V which is the limit in most solvents suitable for these experiments. However, the three seven-membered cyeloalkynes, (31) and its corresponding S-oxide and S,S-dioxide, exhibit irreversible reduction waves at —2.93, —2.78 and —2.83 V vs. saturated calomel electrode, although the corresponding cyclooctynes are not reduced up to —3.0 V182). 

With dialkylacetylenes, the products of hydrolysis and oxidation are cis-alkenes and ketones, respectively. 

Franzen170 observed that when dialkylacetylenes are oxidized by peracetic acid a rearrangement to give dialkylacetic acids accompanies cleavage of the triple bonds, e.g ... 

The versatile thallium(ni) nitrate (TTN) oxidizes acetylenes to different types of product, depending on the acetylene. Terminal acetylenes are converted into the carboxylic acid with the loss of a carbon atom, diaryl-acetylenes ve benzils, dialkylacetylenes give acyloins, and alkylarylacetyl-enes are oxidized in methanol to alkylaryl acetates (Scheme 3). ... 

The same ruthenium(II) catalytic system with 1 equiv. of Cu(0Ac)2-H20 oxidant was used to generate 2-pyridones directly firom acrylamides by C-H and N-H bond functionalization and annulation with alkynes. This reaction offers improved substrate scope with respect to the similar reaction reported with rhodium catalyst [(Eq. 88)] [177]. The reaction is applicable to dialkylacetylenes. Alkylphenyla-cetylenes lead to regioselective annulation with an (aryl)C-N linkage formation, consistent with the coupling of the electron-deficient alkyne carbon with the electron-rich carbon of the Ru-C bond. 

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