Ketones, cyclopropyl methyl

A number of miscellaneous reactions involving diazonium ions and possible vinyl cations have been reported. Treatment of amine 138 with sodium nitrite in 20% aqueous acetic acid is reported to give methyl cyclopropyl ketone as one of four products (116). The reaction has been postulated to involve a vinyl cation, presumably by the following sequence of reactions (116) ... 

Although not formally a type I cleavage process, /1-cleavage of cyclopropyl ketones to form propenyl ketones and/or epimerized cyclopropyl groups bears such a close similarity to a-cleavage that it should be discussed in combination with the latter. The first report of a reaction thought to occur by 0-cleavage was made by Pitts in 1954 for the formation of methyl propenyl ketone from methyl cyclopropyl ketone,<72)... 

For methyl cyclopropyl ketone the question is more complex since in addition to the low-lying n and n levels, a cyclopropyl level is present also<89) ... 

The overlap populations for the ground and various excited states of methyl cyclopropyl ketone are shown in Figure 4.6. Only for the A —> it excited state would the EHT calculations suggest that cyclopropyl (/3) cleavage (C3-C4) should be important. While this has not been experimentally confirmed, it should be subjected to test with the proper compound. 

Cyclization, 2-mercaptobenzoxazole from o-aminophenol, 30, 57 methyl cyclopropyl ketone from 5-chloro-2-pentanone, 31, 74... 

Cyclopropanes. IX. Methyl Cyclopropyl Ketone. J. Amer. chem. Soc,... 

Figure 6.1 NMR Spectra of Methyl Cyclopropyl Ketone (CDCI3 Solvent, 100 MHz), (a) Spectrum with Full Broad Band Decoupling of (b) DEPT Spectrum (c) Spectrum with no Decoupling of H (d) SFORD Spectrum...

Figure 6.1 C NMR Spectra of Methyl Cyclopropyl Ketone (CDCI3 Solvent, 68...

O-Methylcaprolactim, 31, 72 Methyl cellosolve, 32, 43 Methyl chloride, 32, 22 2-Methylcyclohexanol, 31, 4 Methyl cyclopropyl ketone, 31, 74, 75... 

The useful synthetic intermediate 30, from which methyl cyclopropyl ketone can be made, comes from the 4-hydroxyketone 31, disconnected to the enolate of acetone 32 and ethylene oxide. 

Walsh orbitals6 are the MOs corresponding to the cyclopropane C-C bonds. We begin by supposing that carbon orbitals are sp2 hybrid. Indeed, many studies show that cyclopropane is more like ethylene than propane or cyclobutane. For example, it adds bromine slowly, whereas cyclobutane is inert. Hydrogenation of cyclopropane occurs at 120°and cyclobutane at 200°. Asymmetric CH2 stretching modes appear in the IR spectrum of cyclopropane at 3050 and in that of ethylene at 3080 cm-1. Methyl cyclopropyl ketone shows a carbonyl stretch at 1695 cm-1. Finally, the HCH angle is 116°6 in ethylene, and 118° in cyclopropane. 

A single product is also formed in the case of unsymmetrical ketones of the MeCOCHR R2 or RCH2COCHR R2 type, since for the Pfitzinger reaction to occur the ketone must contain either a methyl group or a methylene group next to the carbonyl group. For example, only one appropriate cyclopropyl-substituted acid 16 is formed from methyl cyclopropyl ketone 15 and isatins 9 [23, 24],... 

It is known that ketones, which are capable of aldol condensation, react with trichlorogermane in a particular way. First, an aldol condensation occurs and then trichlorogermane adds to the C=C double bond of the product of condensation74. However, in the case of methyl cyclopropyl ketone, the condensation does not occur and a single isomer derived from the ring opening reaction is formed with 65% yield (equation 28)75. 

METHYL CYCLOPROPYL KETONE (Ketone, cyclopropyl methyl)... 

B. Methyl cyclopropyl ketone. A 2-1. three-necked flask is fitted with a sweep-type stirrer made from K-in. iron rod (Note 6), a reflux condenser, and a 500-ml. dropping funnel. In the flask there is placed a solution consisting of 180 g. (4.5 moles) of sodium hydroxide pellets and 180 ml. of water. To this solution there is added over a period of 15-20 minutes 361.5 g. (342 ml., approximately 3 moles) of the crude 5-chloro-2-pentanone (Note 7). If the reaction mixture does not begin to boil during the addition, boiling is initiated by slight heating of the flask and is continued for 1 hour. Three hundred and seventy milliliters of water is then added slowly to the reaction mixture over a 20-minute period, and the mixture is heated under reflux for an additional hour. 

The condenser is arranged for distillation, and a water-ketone mixture is distilled until all the organic layer is removed from the reaction mixture. The aqueous layer of the distillate is saturated with potassium carbonate, and the upper layer of methyl cyclopropyl ketone is separated. The aqueous layer is extracted with two 150-ml. portions of ether. The ether extracts and the ketone layer are combined and dried over 25 g. of calcium chloride for 1 hour. The ether solution is decanted and dried... 

Methyl cyclopropyl ketone has been prepared from ethyl aceto-acetate and ethylene bromide,6 and by the action of methyl-magnesium bromide on cyclopropyl cyanide.6-7 The procedure described for its preparation from 5-chloro-2-pentanone is similar to that of Zelinsky and Dengin.8 5-Chloro-2-pentanone has been prepared by a number of methods.9 The procedure given is essentially that of Boon 10 and of Forman.11 A similar procedure has been used for the preparation of the corresponding bromo-and iodoketones.10... 

Pitts, IN., Ir., and Norman, I. 1954. Structure and reactivity in the vapor-phase photolysis of ketones, i. methyl cyclopropyl ketone. JAm Chem Soc 76, 4815—4819. 

Methyl y-chloropropyl ketone, CHjCO(CHj)jCl, undergoes intramolecular cyclization to methyl cyclopropyl ketone under the influence of 50% aqueous sodium hydroxide. ... 

Schoberlh and Hanack have reported a simple synthesis of cyclopropylacetylene (11) from methyl cyclopropyl ketone (9), The ketone is converted into the dichloride (10) by treatment with purified phosphorus pentachloride in carbon tetrachloride, and this is then dehydrohalogenated with potassium r-buioxide in DMSO. 

Cyclopropyl ketones. Cyclopropyl ketones can be obtained in 42-59% yields by healing esters of 3-hydroxypropylphosphonium salts with potassium -butoxide in refluxing f-butanol. For example, 3-acetoxypropyltriphenylphosphonium bromide (I is converted into methyl cyclopropyl ketone (2) in 49% yield by way of the intermediates shown in the formulation. 

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