Octyne-3-one

For example, oxidation of4-octyne (0.015 mole) with Cr03-Py2 (0.225 mole) in methylene chloride at room temperature for 24 hr. (N2) gives 4-octyne-3-one in 42 % yield. Anhydrous sodium chromate (Na2Ct04) can also be used, but yields are lower. Considerable amounts of starting alkyne are recovered.2... 

Octene-l-al, 38,62 2-Octenes, 303 2-Octylamine, 554 4-Octyne, 96 2-Octyne-l-ol, 62 4-Octyne-3-one, 96 Olefin inversion, 303-304 Olefin methathesis, 570 Orcinol dimethyl ether, 465 Orcinol monomethyl ether, 465 Osmium tetroxide, 31,575,576 Osmium tetroxide-Potassium chlorate, 361... 

Octyne stirred 24 hrs. at room temp, under Ng with CrOg-pyridine complex in methylene diloride 4-octyn-3-one. Y 42%. F. e. s. J. E. Shaw and J. J. Sherry, Tetrah. Let. 1971, 4379. 

Is a waxy solid which does not lend itself to recrystallization. Attempts to form crystalline salts of the phthalate derivative with achiral alkyl amines only lead to waxy solids or thick oils. The phthalic amine salt made with racemic l-octyn-3-ol requires 3-4 recrystal 1 Izations from methylene chloride to resolve enantiomers. The first recrystallization may take several days, with successive recrystal 1Izations becoming easier. If the 86% ee l-octyn-3-ol is used to make the phthalic amine salt only one facile recrystalHzation is needed to provide optically-pure alcohol. The pure amine salt melts at 132-134°C. The enantiomeric purity of the salt may be determined by NMR by observing the ethynyl hydrogen doublets at 6 2.48 (minor) and 2.52 (major) (CDClj solvent). 

This catalyst (1) is a selective catalyst for hydrogenation of 4-octyne to cw-4-octene (90% yield). If the product is left in contact with 1, it isomerizes to the trans-isomer. Since monoalkenes are hydrogenated slowly with this catalyst, cyclo-octene can be obtained from either 1,3- or 1,5-cyclooctadiene. Of more interest, benzene can be hydrogenated to cyclohexane (83% yield). One drawback is that the catalyst loses about 90% of its activity after one cycle. 

The exceedingly bulky aluminum reagent aluminum tris(2,6-di-rert-butyl-4-methyl-phenoxide) (ATD) [140] was found to be superior to ATPH or MAD as a carbonyl protector in the alkylation of ynones [141]. Initial complexation of 3-octyn-2-one (13S) in toluene with ATD and subsequent addition of a hexane solution of BuLi at -78 °C generated 1,4 adduct 136 in 93 % yield together with a small amount of the 1,2 adduct (Sch. 103). 

Alkynes [e.g., 2-octyne (14 in Chart 3.4)], which are sterically not very crowded, polymerize using Mo catalysts to give polymers with molecular weights over one million. For these monomers, W and Nb catalysts are less active, and Ta catalysts yield only cyclotrimers. Symmetrical dialkylacetylenes (e.g., 4-octyne) are slightly more crowded, and consequently, Nb, Ta, and W catalysts exert high activity, while Mo catalysts are inactive. 

N-Annulation of a,(3-enone with internal alkyne To a MeOH solution (0.2 mL) of 2-methyl-5-methylenenonan-4-one (33.7 mg, 0.20 mmol) and 4-octyne (44.1 mg, 0.40 mmol) were added [Cp RhCl2]2 (3.1 mg, 0.005 mmol) and Cu(OAc)2 H2O (79.9 mg, 0.40 mmol), NH4OAC (30.8 mg, 0.40 mmol), and the reaction mixture was stirred at 130°C under a nitrogen atmosphere for 6h. After cooling to room temperature, the solvent was removed in vacuo, and the resulting erude mixture was subject to flash column chromatography (n-hexane ethyl acetate = 90 1) to afford 3-butyl-2-isobutyl-5,6-dipropylpyridine (51.8 mg, 0.188 mmol) in 94% yield. 

Obtained by [Cp RuCl2]2-catalyzed cocyclisation of T 4-octyne (1,2-dipropylacetylene), 3-buten-2-one... 

Now let us consider a second, fundamentally different ketone synthesis—hydration of an alkyne (Section 13-7). Either of two precursors, 2,7-dimethyl-3-octyne and 2,7-dimethyl-4-octyne, will lead to the target molecule. As shown here, however, only the latter, symmetric alkyne undergoes hydration to give just one ketone, regardless of the initial direction of addition. 

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