Cycloalkanone oxidative ring

Oxidative Cleavage of Ketones. Aldehydes, and Alcohols Cycloalkanone oxidative ring opening... 

Cycloalkanones of ring size from four to six oxidize with ring contraction to give the cycloalkanecar-boxylic acid of the next smaller ring size with thallium(III), as shown in equation (44). This reaction... 

Ballini, R., Curini, M., Epifano, F., Marcotullio, M. C., Rosati, O. A new, modulated, oxidative ring-cleavage of a-nitro cycloalkanones by Oxone. Synthesis of a,co-dicarboxylic acids and a,to-dicarboxylic monomethyl esters. Syn/eff 1998, 1049-1050. 

Greater preparative importance attaches to oxidative ring opening of cycloalkanols and cycloalkanones, which then afford alkanedioic acids containing an unchanged number of carbon atoms. Thus, for instance, adipic acid is obtained in up to 90% yield from cyclohexanol or cyclohexanone by means of about 60% nitric acid containing vanadium and copper salts as catalyst 125... 

Oxidative ring cleavage. Trost and Hiroi have developed a method for cleavage of cycloalkanones that involves essentially two steps selective sulfenyla-tion with diphenyl disulfide (5, 276-277 this volume) and oxidation with lead tetraacetate. The method is illustrated for estrone methyl ether as the substrate. Thus this five-membered ring ketone can be converted in high overall yield into... 

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-... 

Reduction, carboxyl groups, 56,83 Reduction of a,0-unsaturated p-toluene-sulfonyl-hydrazones to alkenes, 59,42 Reductive alkylation, 56,52 Reductive cleavage, 56, 101 Resolution of amines, 55,80, 83 Rexyn 201,55,4 Rhodium(III) oxide, 57, 1 Ring contraction, 56, 107 Ring expansion of cycloalkanones to cycloalkenones, 59, 113... 

The procedure described is a simple, rapid, and convenient method for conversion of n-sized cycloalkenones into n+4 alkenolides. Significant but limited progress has been reported in the recent literature toward the preparation of medium and large ring lactones via ring-expansion reactions. One of the most notable and useful developments in this area involves conversion of a cycloalkanone into a bicyclic vinylic ether which is oxidatively cleaved to form a ring-enlarged keto lactone.3... 

Hydroxymercuration and thallium(III) oxidation of cycloalkenes, 1-methylcycloalkenes and methylenecycloalkanes have been reported to yield ring-contracted aldehydes, ring-contracted ketones and ring-expanded cycloalkanones, respectively. 

Ring cleavage. Several oxidants can cleave lactols at the Ca—C 3 bond, and the PhI(OAc)2-l2 pair is useful for attaching an iodine atom to C(3 in the process. From bicychc lactols such as those prepared from alkylation of cycloalkanones with epoxides as substrates iodolactones are obtained. ... 

More complex products are obtained from cyclizations in which the oxidizable functionality and the alkene are present in the same molecule. y9-Keto esters have been used extensively for Mn(III)-based oxidative cyclizations and react with Mn(OAc)3 at room temperature or slightly above [4, 10, 11, 15], They may be cyclic or acyclic and may be a-unsubstituted or may contain an a-alkyl or chloro substituent. Cycloalkanones are formed if the unsaturated chain is attached to the ketone. y-Lactones are formed from allylic acetoacetates [10, 11]. Less acidic /3-keto amides have recently been used for the formation of lactams or cycloalkanones [37]. Malonic esters have also been widely used and form radicals at 60-80 °C. Cycloalkanes are formed if an unsaturated chain is attached to the a-position. y-Lactones are formed from allylic malonates [10, 11]. yff-Diketones have been used with some success for cyclizations to both alkenes and aromatic rings [10, 11]. Other acidic carbonyl compounds such as fi-keto acids, /3-keto sulfoxides, j8-keto sulfones, and P-nitro ketones have seen limited use [10, 11]. We have recently found that oxidative cyclizations of unsaturated ketones can be carried out in high yield in acetic acid at 80 °C if the ketone selectively enolizes to one side and the product cannot enolize... 

Cyclizations that form a single carbon-carbon bond can be accomplished by oxidative cyclization of unsaturated -diketones, y9-keto esters, or f3-keto amides 55 that lead to cycloalkanone radicals 56 and 57, unsaturated )ff-diketones, )ff-keto esters, or malonate esters 58 that lead to cycloalkanes 59 and 60, and unsaturated esters or amides 61 that lead to lactams or lactones 62 and 63 (Scheme 19) [10, 37], Cyclizations of radicals stabilized by two carbonyl groups will only occur with electron-rich aromatic rings as in the conversion of 64 to 65 (Scheme 20) [39] the initial cyclization product is acetoxylated under the reaction conditions. The addi-... 

---