Tertiary a-acetylenic alcohols

The isomerization of secondary and tertiary a-acetylenic alcohols to a,(3-unsaturated carbonyl compounds via 1,3-shift. When the acetylenic group is terminal, the products are aldehydes, whereas the internal acetylenes give ketones. 

Nesmeyanov, A. N. Anisimov, K. N. Kolobova, N. E. Magomedov, G. K. Aniono-tropic rearrangament of tertiary a-acetylene alcohols of cyclopentadienylmanganum-tricarbonile. J. Org. Chem., 1967, 1149-1153. 

Similarly, the Rupe rearrangement is the reaction of tertiary a-acetylenic alcohols to a,P-unsaturated ketones in the presence of an acid catalyst. ... 

It has been noted that the synthesis of pyrroles from ketoximes and acetylene in some case leads to tertiary a-acetylenic alcohols [4,5,7], It indicates a possibility of oxime involvement into the Favorsky alkynol synthesis. The conditions of acetylenic alcohols formation from ketoximes and acetylene have been investigated on the example of the reaction between cyclohexanone oxime and acetylene (Scheme 1.160) [175]. 

Acid-catalyzed rearrangement of tertiary a-acetylenic (terminal) alcohols, leading to the formation of a,(3-unsaturated ketones rather than the corresponding a,(3-unsaturated aldehydes. Cf. Meyer-Schuster rearrangement. 

Meyer and Schuster discovered the rearrangement that carries their names in an attempt to convert a-acetylenic alcohols such as 1 to the respective tertiary chloride in the presence of an acetyl chloride catalyst. Rather than the expected chloride products, a,p-imsaturated ketone 2 was obtained via a previously unknown acid-catalyzed rearrangement. Further research demonstrated the ability of a variety of acid catalysts (i.e., acetic acid, concentrated sulfuric acid, ether saturated with dry hydrogen chloride, and acetic anhydride) to induce the observed transformation. ... 

Economic Aspects. A number of secondary and tertiary acetylenic alcohols and glycols are manufactured by Air Products and Chemicals Co. In 1990, U.S. bulk prices of ethyloctynol, methylbutynol, and tetramethyldecynediol were about 8.35/kg, 3.95/kg, and 8.00/kg, respectively. 

This one-step procedure is a convenient and general method for the preparation of carbamates. It is substantially simpler, quicker, and safer than the multistep methods hitherto used for the preparation of carbamates of tertiary alcohols. This procedure is applicable to the preparation of carbamates of primary, secondary, and tertiary alcohols and mercaptans, polyhydric alcohols, acetylenic alcohols, phenols, and oximes. It has also been extended to the preparation of carbamyl derivatives (i.e., ureas) of inert (non-basic) amines.10... 

Regarding the first problem, the most elemental treatment consists of focusing on a few points on the gas-phase potential energy hypersurface, namely, the reactants, transition state structures and products. As an example, we will mention the work [35,36] that was done on the Meyer-Schuster reaction, an acid catalyzed rearrangement of a-acetylenic secondary and tertiary alcohols to a.p-unsaturatcd carbonyl compounds, in which the solvent plays an active role. This reaction comprises four steps. In the first, a rapid protonation takes place at the hydroxyl group. The second, which is the rate limiting step, is an apparent 1, 3-shift of the protonated hydroxyl group from carbon Ci to carbon C3. The third step is presumably a rapid allenol deprotonation, followed by a keto-enol equilibrium that leads to the final product. 

The nonfluorinated tertiary acetylenic alcohol 2-methylbut-3-yn-2-ol (13) reacts explosively to give a mixture of 3-fluoro-3-methylbut-l-yne and 2-methylbut-l-en-3-yne.56... 

When treated with a mixture of triphenylbismuth dibromide (Ph3BiBr2) and iodine, tertiary and secondary alcohols are converted to the corresponding most stable alkenes under mild conditions. Sesquiterpinic alcohol is dehydrated to cedrene by this binary system (Equation (143)).236 Irradiation of tri(/>-tolyl)bismuth diazide in benzene in the presence of acetylenes results in the transfer of one of the azido ligands to the triple bond, affording 1,2,3-triazoles in moderate yields (Equation (144)).237... 

Tertiary alcohols are resistant to oxidation. rcr -Butyl alcohol is frequently used as a solvent in oxidations. However, some tertiary alcohols are converted into tertiary hydroperoxides on treatment with hydrogen peroxide in sulfuric acid [177, 179]. Dimethylphenylcarbinol added to a mixture of 87% hydrogen peroxide and sulfuric acid at a temperature below 0 °C gives a 94% yield of cumyl hydroperoxide after 3.5 h [777]. Similarly, acetylenic alcohols with the tertiary hydroxyl group adjacent to the triple bonds are converted into the corresponding hydroperoxides in high yields [179] (equation 272). 

The acid catalyzed rearrangement of tertiary acetylenic alcohols, the Rupe reaction, is a viable procedure for the preparation of a,p-unsaturated carbonyl compounds. Under standard acidic conditions, however, the products can polymerize and various by-products can be produced. With solid acids these problems are minimized. The reaction of an acetylenic tertiary alcohol with Nafion-H gave the a,P-unsaturated ketone in good to very good yields (Eqns. 22.24—25). When this reaction was run using a vanadium pillared... 

Very similar results to those described with propyne can be obtained with a wide variety of other alkynes, e. g., acetylene, higher aliphatic and aromatic alkynes as well as other nucleophilic reagents, such as water, aliphatic (primary, secondary, and tertiary) and aromatic alcohols, thiols, and amines. 

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