Cycloalkene oxides, 1-methyl

Cyclization, solvolytic, 54, 84 Cycloalkene oxides, 1-methyl, conversion to exocyclic methylene alcohols, 53, 20 Cyclobutadiene, generation in situ, 50, 23... 

Isomerization of substituted styrene oxides allows the synthesis of aldehydes in high yields726 [Eq. (5.275)]. Cycloalkene oxides do not react under these conditions, whereas 2,2,3-trimethyloxirane gives isopropyl methyl ketone (85% yield). Isomerization of oxiranes to carbonyl compounds is mechanistically similar to the pinacol rearrangement involving either the formation of an intermediate carbocation or a concerted mechanism may also be operative. Glycidic esters are transformed to a-hydroxy-/3,y-unsaturated esters in the presence of Nafion-H727 [Eq. (5.276)]. 

Cycloalkene Derivatives Cyclopropenes readily interact with nitrile oxides. Reactions of a broad series of 3,3-disubstituted cyclopropenes with 4-substituted benzonitrile, methoxycarbonyl- and cyanoformonitrile oxides (229) as well as with di(isopropoxy)phosphorylformonitrile oxide (230) give 2-oxa-3-azabicyclo[3.1.0]hexene derivatives 62. Stereoselectivity of the cycloaddition is governed by both steric and polar factors. In particular, steric factors are supposed to prevail for 3-methyl-3-phenylcyclopropene affording 62 [R1 =... 

Methyl ketones. Hydrogen peroxide in the presence of Pd(OAc)-. as catalyst converts terminal alkenes to methyl ketones in high yield and with high selectivity (equation I).1 Internal and cycloalkenes are inactive. The actual oxidant is... 

The rate constants for oxidation of a series of cycloalkenes with ozone have been determined using a relative rate method. The effect of methyl substitution on the oxidation of cycloalkenes and formation of secondary organic aerosols has been analysed.155 Butadiene, styrene, cyclohexene, allyl acetate, methyl methacrylate, and allyl alcohol were epoxidized in a gas-phase reaction with ozone in the absence of a catalyst. With the exception of allyl alcohol, the yield of the corresponding epoxide ranged from 88 to 97%.156 Kinetic control of distereoselection in ozonolytic lactonization has been (g) reported in the reaction of prochiral alkenes.157... 

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. 

RSeCJIi — ROCHi. Oxidation of an alkyl phenyl selenide with m-chloroperben-zoic acid (2-5 equiv.) in methanol affords the corresponding alkyl methyl ethers in high yield. Oxidation of selenides with a vicinal phenyl group is accompanied by rearrangement of the phenyl group. vtc-Methoxy selenides derived from cycloalkenes are oxidized under these conditions to dimethyl acetals of ring-contracted aldehydes. 

Cyclic olefins preferably undergo twofold carbonylation, even without the presence of buffer compounds such as sodium acetate. With methanol serving as the solvent and under comparable reaction conditions to those mentioned above, cycloalkenes give product mixtures consisting of methyl rrans-2-methoxy-cycloalkanecarboxylates, dimethyl cw-cycloalkane-l,2-dicarboxylates and dimethyl cw-cycloalkane-1,3-dicarboxylates (eq. (3) and Table 1). The formation of 1,3-diesters may be explained by an intermediate reaction sequence which involves an oxidative elimination and a subsequent readdition of the Pd species, thus giving rise to an isomerization [9]. 

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. ... 

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