Cyclopropanols 0- ketone

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

A carbonyl group in the P-position of a cyclopropanol tosylate fragment, as in 99, facilitates the elimination so that it occurs upon treatment of the tosylate 99 with a primary or secondary amine. An ensuing Michael addition of the amine to the a,f5-un-saturated ketone 100 then yields the P-(l-aminocydopropyl)ketone 101, the product of a formal substitution of the hydroxy group in the cyclopropanol precursor to 99 (Scheme 11.27) [123],... 

DePuy, as early as 1966 [14], reported that cw-1-methyl-2-phenylcyclopropanol gave exclusively deuterated 4-phenyl-2-butenone in 0.1 M NaOD/D20/dioxane. However, homoenolates derived from simple cyclopropanols by base-induced proton abstraction fail to react with electrophiles such as aldehydes and ketones, which would afford directly 1,4-D systems. Lack of a reasonably general preparative method was another factor which impeded the studies of homoenolate chemistry. For this reason, in the past twenty years more elaborated cyclopropanols, which might be suitable precursors of "homoenolates", have been prepared and studied. 

Further research on intramolecular photocyclization of amino enones and amino ketones based on electron transfer has been made by Kraus and Chen [228]. In analogy to the earlier results of Roth and El Raie [229], Kraus and Chen obtain the cyclopropanol derivative 286 as single stereoisomer by direct irradiation of 285. Photolysis of the amino enone 287 does not lead to a three-membered ring product, but only to pyrrolidine 288. The irradiation of the unsaturated keto ester 289 results in the even more unexpected formation of a nine-membered ring product 290. Such remote photocyclizations have rarely been described so far. 

The chemistry of cyclopropanol [7] has long been studied in the context of electrophilic reactions, and these investigations have resulted in the preparation of some 3-mercurio ketones. As such mercury compounds are quite unreactive, they have failed to attract great interest in homoenolate chemistry. Only recent studies to exploit siloxycyclopropanes as precursors to homoenolates have led to the use of 3-mercurio ketones for the transition metal-catalyzed formation of new carbon-carbon bonds [8] (vide infra). 

Cyclopropanols react with mercuric salts to give a variety of 3-mercurio ketones, and the chemistry of this ring cleavage has been thouroughly studied from the mechanistic viewpoint [7],... 

Such disjoint molecules may serve as synthetic intermediates. Thus a [3 + 2] annulation method exploits the facile ring opening of cyclopropanols and the transfer of the donor site to the p carbon of the resulting ketones, the nascent carbanions may... 

A number of new methods for the preparation of cyclopropanols from carbonyl derivatives via 1,3-bond formation between the carbonyl and carbons have been developed. 7>ons-2-alkylcyclopropanols are stereoselectively produced from 2- or 3-substituted acrolein upon exposure to chromium(II) chloride in the presence of a catalytic amount of nickel chloride in DMF (equation 56)73. 2,3-Disubstituted acroleins are, in contrast, inert to the chromium reagent. Treatment of / -stannyl carbonyls with titanium(IV) chloride affords cyclopropanols in good yields when the substrates are ketones not bearing j -alkyl... 

Alternatively, the reaction of cyclopropylethynylmagnesium bromide with cyclo-propanone hemiacetal gives l-(cyclopropylethynyl)cyclopropanol (equation 152)232. The reaction of cyclopropanone acetal with other alkynyl Grignard reagents serves as a general route to alkynylcyclopropanols. Similarly, alkynyllithium derivatives of vitamin D were coupled with cyclopropane carbonyl isoxazolidine to give the corresponding alkynyl-cyclopropyl ketones (equation 153). 

A similar reaction with a-halo ketones provides cyclopropanols. Example ... 

P,Y-Unsaturated ketones.1 The reaction of acyclic a,p-epoxy ketones with two equivalents of 1 results in the cyclopropanols 2, which are converted into p,Y-enones on treatment with BF3 etherate or HC1. 

Cyclopropanols and their derivatives Diiodomethane-Samarium, 113 Trimethylstannylmethyllithium, 331 Cyclopropyl aldehydes, ketones, esters, etc. 

Keywords czv-9-dccalyl aryl ketone, Norrish type II photochemistry, cyclopropanol, cyclobutanol, cyclopentanol... 

Irradiation of CH3CN solutions of czv-9-dccalyl p-carbomethoxyphenyl ketone 1 (145 mg) through Pyrex afforded cyclobutanols 2 (47%) and 5 (47%) along with 6% of cyclopentanone 4. In contrast, when crystals of ketone 1 were irradiated (Pyrex, -20 °C, 76 mg), a mixture of cyclobutanol 2 (81%) and cyclopropanol 3 (19%) was formed. 

Bridgehead bicyclic cyclopropanols or cyclopropyl silyl ethers 103 (R=H) cleaved to ring-expanded mixtures of cyclic (1-hydroxy ketones 105 and (1-diketones 106 in good overall yields catalyzed by 10 mol% of VO(acac)2 in the presence of oxygen (Fig. 32) [191, 192]. With 3-substituted substrates 103 (R=Me), mixtures of bicyclic endoperoxide hemiketals 104B and (1-hydroxy ketones 105 arose. In separate experiments it was shown that 105 is not oxidized to 106 under the reaction conditions, and thus the products most likely form from... 

In fact, the reaction proceeded as expected [23]. Thus, by heating the l-[o-(l-alkynyl)phenyl]cyclopropanol complexes 36-Co2(CO)6 in refluxing 2-propanol, 2,3-dihydro-1-naphthalenone derivatives 37 are obtained as a mixture of (Aland (Z)-isomers in moderate yield accompanied by a substantial amount of an ethyl ketone derivative formed by ring opening of the cyclopropanol moiety. Furthermore, when an analogous naphthyl derivative 38 was employed, the reaction proceeded cleanly and the 2,3-dihydrophenanthren-l-one derivative 39 was obtained in 83 % yield (Scheme 17). The obvious difference in reactivity between phenyl and naphthyl derivatives is probably due to the presence of hydrogen at the peri position of the latter. To avoid steric repulsion between the alkyne-Co2(CO)6 moiety and this hydrogen, the molecule adopts a conforma-... 

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