Cyclopentanone 2-chloro

Reaction of the morpholine or piperidine enamine of cyclopentanone, however, gives an unstable adduct which rearranges under the reaction conditions and an aqueous work-up to give the ring expanded ketone 2-chloro-2-cyclohexen-l-one (203) (138,139). 

The reactions of dichlorocarbene with morpholine and piperidine enamines derived from cyclopentanone and cyclohexanone have been reported to lead to ring expanded and a-chloromethylene ketone products (355,356). Similarly a-chloro-a, -unsaturated aldehydes were obtained from aldehyde derived enamines (357). Synthesis of aminocyclopropanes (353,359) could be realized by the addition of diphenyldiazomethane (360) and the methylene iodide-zinc reagent to enamines (367). 

The results of the olefin oxidation catalyzed by 19, 57, and 59-62 are summarized in Tables VI-VIII. Table VI shows that linear terminal olefins are selectively oxidized to 2-ketones, whereas cyclic olefins (cyclohexene and norbomene) are selectively oxidized to epoxides. Cyclopentene shows exceptional behavior, it is oxidized exclusively to cyclopentanone without any production of epoxypentane. This exception would be brought about by the more restrained and planar pen-tene ring, compared with other larger cyclic nonplanar olefins in Table VI, but the exact reason is not yet known. Linear inner olefin, 2-octene, is oxidized to both 2- and 3-octanones. 2-Methyl-2-butene is oxidized to 3-methyl-2-butanone, while ethyl vinyl ether is oxidized to acetaldehyde and ethyl alcohol. These products were identified by NMR, but could not be quantitatively determined because of the existence of overlapping small peaks in the GC chart. The last reaction corresponds to oxidative hydrolysis of ethyl vinyl ether. Those olefins having bulky (a-methylstyrene, j8-methylstyrene, and allylbenzene) or electon-withdrawing substituents (1-bromo-l-propene, 1-chloro-l-pro-pene, fumalonitrile, acrylonitrile, and methylacrylate) are not oxidized. 

Dimethyl 5 methyl carboxylic acid cyclopentanone metconazole Dimethyl chloro methyl acetyl chloride dimethazone... 

Below is an example the alkylation of cyclopentanone with 2-chloro-2-methylbutane. The ketone was converted to the trimethylsilyl enol ether with triethylamine and trimethylsilylchloride we discussed this step on p. 538 (Chapter 21). Titanium tetrachloride in dry dichloromethane promotes the alkylation step. 

A number of methods may be used for self-condensation of ketones to give a, -unsaturated ketones. Cyclic ketones are especially prone to aldol condensation, and the product from cyclopentanone (equation 29) is frequently encountered as a by-product in reactions that involve exposure of cyclopentanone to acid or base. In the example shown in equation (29), the aldol addition reaction is carried out with gaseous HCl, leading to an intermediate 0-chloro ketone that is dehydrochlorinated by treatment with base. It has recently been shown that basic alumina is an effective catalyst for the aldol condensation of ketones. ... 

The interaction between the sodium salt of phenylacetic acid and isopropyl magnesium bromide results into a doubly charged species known as the Ivanov reagent. This product on treatment with cyclopentanone affords aldol condensation to yield the corresponding hydroxy acid. The resulting product on being subjected to alkylation with N-(2-chloro-ethyl)-dimethylamine gives the desired official compound. 

The 11-deoxyprostaglandins, a group not found in nature, have been synthesised by workers at the Ayerst Laboratories [115, 148-151]. 11-Deoxy-PGFy (LXXI) has been prepared starting from the enone (LXXII), obtained by the action of sulphuric acid on the monobromo derivative of the condensation product of ethyl 2-cyclopentanone carboxylate and (o-bromoethylheptanoate [115, 148, 149]. Reaction of (LXXII) with acetone cyanohydrin, hydrolysis of the ester-nitrile to the dicarboxylic acid and reaction with methanol and />-toluenesulphonic acid gave the mono ester (LXXIII) of which the acid chloride was converted with heptyne and aluminium chloride into the chlorovinylketone (LXXIV). The sequence was then completed by replacement of chloro with methoxyl, ester hydrolysis and borohydride reduction to the unsaturated ketone (LXXV) followed by borohydride reduction of the side chain carbonyl group. 

The parent compound of this series, 2-chloro-3,4,5,6-tetrahydro-pyridine (XXXIX), was obtained as an intermediate in the Beckmann rearrangement of cyclopentanone oxime ( ). Thus, heating of cyclo-pentanone oxime with thionyl chloride affords about equal amounts of the lactam hydrochloride XL and the imidoyl chloride XXXIX ( ). 

The best alkylating agents for silyl enol ethers are tertiary alkyl halides they form stable carbocations in the presence of Lewis acids such as TiCl4 or SnCl4. Most fortunately, this is just the type of compound that is unsuitable for reaction with lithium enolates or enamines, as elimination results rather than alkylation a nice piece of complementary selectivity. Below is an example the alkylation of cyclopentanone with 2-chloro-2-methylbutane. The ketone was converted to the trimethylsilyl enol ether with triethylamine and trimethylsilylchloride we discussed this step on p. 466 (Chapter 20). Titanium tetrachloride in dry dichloromethane promotes the alkylation step. 

Hexamethylenelmlne Methoxy PEG-10 intermediate. Insect repellents Hexahydrophthallc anhydride intermediate. Insecticides Allyl chloride Arsenic trichloride Benzophenone n-Butylamine t-Butylamine Cashew nut shell oil m-Chloroaniline 4-Chloro-3-nitrobenzotrifluoride 4-Chlorophenol Cumyl phenol Cyclopentanone 2,3-Dibromo-1 -propanol Dibutylamine Dicyclopentadiene Dinonyl phenol... 

Chloro-l,2-diones (110) undergo a domino Michael/aldol with enals (111) to give highly functionalized cyclopentanones (112), using diaryl prolinol TMS ethers as organocatalysts. The best de/ee/yidd results were 90/94/97%. A fluoro-substrate gives a cyclopentenone product, that is, the dehydration equivalent of (112). 

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