Cycloalkenes oxidative cleavage

Phase transfer oxidative cleavage of cycloalkenes Ru04/NaI04 in h2o/co2 Morgenstern et al. (1996)... 

Oxidative cleavage of cycloalkenes is an important reaction, usually affording co,a/-dicarboxylic acids e.g., adipic acid is formed on oxidation of cyclo-hexene by permanganate.114 If there is no hydrogen on one of the doubly bonded carbon atoms, the product is an oxo carboxylic acid, e.g., a>pinonic acid from a-pinene 115... 

Better yields are often obtained when ozone is used for oxidative cleavage of olefins to carboxylic acids or of cycloalkenes to dicarboxylic acids. Olefinic double bonds are very much more easily attacked by ozone than are aromatic systems, so that arylethylene derivatives can be successfully treated with ozone without appreciable effect on the ring. If the ozonide which is formed initially is decomposed with water, the aldehyde is obtained together with hydrogen peroxide and other products ... 

An oxidative cleavage of cycloalkanones to unsaturated aldehyde-esters has been developed. Thus, for example, cyclononanone was converted into 2,2-dithio-trimethylenecyclononanone, which was cleaved using lead(iv) acetate (66 %), and the product so obtained treated with methanol and sodium periodate to give (208 in = 5). Cyclododecanone was similarly converted into (208 n = 8). 1,2-Bis(trimethyl-silyloxy)cycloalkenes, prepared by acyloin condensations, have been converted into 2-alkyl-2-hydroxycycloalkanones by treatment with methyl-lithium and an alkyl halide, and the oximes of these a-hydroxyketones cleaved to give open-chain co-cyanoketones using mesyl chloride-pyridine. ... 

The stereochemistry of ring-opening polymerizations has been studied for epoxides, episul-fides, lactones, cycloalkenes (Sec. 8-6a), and other cyclic monomers [Pasquon et al., 1989 Tsuruta and Kawakami, 1989]. Epoxides have been studied more than any other type of monomer. A chiral cyclic monomer such as propylene oxide is capable of yielding stereoregular polymers. Polymerization of either of the two pure enantiomers yields the isotactic polymer when the reaction proceeds in a regioselective manner with bond cleavage at bond 1. 

Cleavage of epoxides. As with simpler haloboranes, these reagents cleave epoxides of cycloalkenes to give, after nonoxidative workup, halohydrins in 65-90% yield. When carried out at -78 to -100°, the cleavage can show high en-antioselectivity. Thus the halodiisopinocampheylboranes derived from (+ )-pinene react with the oxide of cyclohexene or of cyclopentene to furnish (1R,2R) halo-... 

A practical synthesis of 1,3-OX AZEPINES VIA PHOTOISOMERIZATION OF HETERO AROMATIC V-OXIDES is illustrated for 3,1-BENZOXAZEPINE. A hydroboration procedure for the synthesis of PERHYDRO-9b-BORAPHENALENE AND PERHYDRO-9b-PHEN-ALENOL illustrates beautifully the power of this methodology in the construction of polycyclic substances. The conversion of LIMONENE TO p-MENTH-8-EN-YL METHYL ETHER demonstrates a regio-and chemoselective method for the PHOTOPROTONATION OF CYCLOALKENES. An efficient method for the conversion of a ketone to an olefin involves REDUCTIVE CLEAVAGE OF VINYL PHOSPHATES. A mild method for the conversion of a ketone into the corresponding trimethylsiloxy enol ether using trimethylsilyl acetate is shownforthe synthesis of (Z)-3-TRIMETHYLSILOXY-2-PENTENE. 

One of the most popular ways of using the double bond cleavage sequence envisages its utilization for the preparation of l, -dicarbonyl compounds via oxidation of the respective cycloalkene derivatives. Thus oxidation of cyclohexene represents the easiest way to prepare the 1,6-dialdehyde 460. Intramolecular aldol condensation of460 proceeds with ease to give the respective cyclopentene derivatives 461 or 462 (Scheme 2.149). 

A much more frequently used reaction is the cleavage of unsaturated compounds to aldehydes (equations 98 and 99). Alkenes and cycloalkenes that possess one or two hydrogens at the double bonds are oxidized by ozone to ozonides, which have to be reduced to prevent a subsequent oxidation to acids by the excess oxygen atom. Reductions are carried out, usually without isolation of the ozonides, by catalytic hydrogenation over palladium catalyst [80, 81,1106] or Raney nickel [55] or by treatment with... 

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