Ethynyl methyl ketone

A 1,6-silyl migration from N to O was postulated in the reaction of N,N -bis(trimethyl-silyl)aminophosphine 333 with ethynyl methyl ketone 334 (equation 204)471. 

To the ketene silyl (thio)acetal (1 equiv.) was added at room temperature neat ethyl propynoate, dimethyl acetylenedicarboxylate or ethynyl methyl ketone (1 equiv.). The mixture was stirred for 5 h at room temperature. The volatile products were removed at room temperature in vacuo (0.1 Torr) for 30 min. Purification of the crude reaction mixture by silica gel column chromatography (ethyl acetate-hexane, 5 95) afforded cycloadducts. 

In the reactions between diethyl hydrogenphosphonate and indantrione or 2-benzyli-deneindan-1,3-dione, the former substrate yields phosphate adducts,but in the latter case, addition affords the phosphonate 203 The additions of hydrogenphosphonic diesters to propynal and ethynyl methyl ketone and to the ketones RC=CCOMe (R = Me or Ph) ", give 1,2-adducts. 

Ethyl nitroacetate methyl nitronate and ethynyl methyl ketone mixed with icecooling, and stored 2 days aziridine derivative. Y 82.1%. F. e. s. V. A. Tarta-kovskii, O. A. Lukoyanov, and S.S. Novikov, Dokl. Akad. Nauk SSSR 178 (h) 123 (1968) C. A. 69, 18948. 

Ethyl linoleate 5178 Ethynyl methyl ketone 1686 2-Furfuryl methyl ketone 5496... 

With an activated C—C triple bond two successive additions can occur if the intermediate alkene is reactive enough. DMAD and 3,5-dimethylpyrazole give an initiaj fumarate (255) which reacts further at the other end to form regioselectively the succinates (256). On the other hand, methyl ethynyl ketone reacts twice at the same carbon atom with pyrazole to form 1,1-pyrazolylbutanone (258) (68ZC458). The probable intermediate, a pyrazolide vinylogue (257), can be prepared from methyl chlorovinyl ketone and pyrazole, in a reaction which is similar to acetylation (Section 4.04.2.1.3(x)). 

A ( )-Enol-l 1-acetates are formed by distillation of acetic anhydride in the presence of / -toluenesulphonic acid. Another procedure employed for the synthesis of enol benzoates involves treatment with benzoic anhydride and triphenyl methyl sodium or ethynyl sodium. Suitable procedures utilizing a diluent have been developed for the enol esterification of a 20-ketone without affecting an 11-ketone. 

Ethynylation of the totally synthetic racemic 18-methyl-17-ketone (63) with acetylene and potassium t-butoxide in t-butanol-toluene or with alkali metal acetylide in liquid ammonia gives a low yield of rac-18-methyl-17a-ethynyl-3-methoxyestra-l,3,5(10)-trien-17/ -ol (64). 

The 13-ethyl-17-ketones, i.e., (63), have been found to be considerably less reactive than their 13-methyl counterparts towards acetylenic nucleophiles. The difference is attributed to the additional steric hindrance provided by the ethyl group. An attempt to introduce an ethynyl group into mc- 2>-isopropyl-3-methoxygona-l,3,5(10)-trien-17-one was unsuccessful even in ethylenediamine at 50°. However ethynylation of rac-13-isopropyl-3-methoxygona-1,3,5(10),8(14)-tetraen-17-one proceeded smoothly at room temperature to afford the 17a-ethynyl compound in 60% yield. ... 

The largest industrial use of LiC2H is in the production of vitamin A, where it effects ethynyl-ation of methyl vinyl ketone to produce a key tertiary carbinol intermediate. The acetylides and dicarbides of the other alkali metals are prepared similarly. It is not always necessary to prepare this type of compound in liquid ammonia and, indeed, further substitution to give the bright red perlithiopropyne Li4C3 can be effected in hexane under reflux ... 

The retrosynthesis involves the following transformations i) isomerisation of the endocyclic doble bond to the exo position ii) substitution of the terminal methylene group by a more stable carbonyl group (retro-Wittig reaction) iii) nucleophilic retro-Michael addition iv) reductive allylic rearrangement v) dealkylation of tertiary alcohol vi) homolytic cleavage and functionalisation vii) dehydroiodination viii) conversion of ethynyl ketone to carboxylic acid derivative ix) homolytic cleavage and functionalisation x) 3-bromo-debutylation xi) conversion of vinyl trimethylstannane to methyl 2-oxocyclopentanecarboxylate (67). 

The fact that allyltributyltin and styrene which are electroneutral were successfully added to PCTFE led us to the question "Can electron-rich or electron-poor trapping agents be used ". The electron-rich agents that we examined were ethyl ethynyl ether and ethyl vinyl ether. On the side of the electron-poor alkenes, eight were investigated ethyl acrylate, methyl methacrylate, methyl vinyl ketone, acrylonitrile, methacrylonitrile, vinyl bromide, chloromethyl styrene, and 4-vinylpyridine. The details of each reaction are summarized. 

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