From cycloalkenes

In this reaction, bicyclic compound 66b is formed from cycloalkene-yne 65b. 

Further variations make ozonolysis a versatile tool in organic synthesis. Equations (9.116)—(9.118) illustrate the possibility of preparing terminally differentiated products from cycloalkenes 629 630... 

There is no need to isolate this compound in order to effect addition of diphenyl disulphide (and dimethyl disulphide) to alkenes in this way tran. -l,2-bis-phe-nylthio (and methylthio) adducts were formed from cycloalkenes and 1-hexene. 

When 2-methoxycycloalkyl phenyl telluriums, prepared from cycloalkenes and phenyl tellurium trichloride in methanol, are treated with 3-chloroperoxybenzoic acid, the elimination of the phenyltelluro group is accompanied by ring-contraction and formation of the dimethyl acetals of formylcycloalkanes2 3. 

By ring-opening polymerization, polymers can formed from cycloalkenes, but mostly from simple and more complicated heterocycles containing heteroatoms such as O, N, S, P and Si. Ring-opening polymerizations are mostly initiated by the ionic mechanism. 

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. 

Acid-catalyzed epoxide cleavage takes place by back-aide attack nucleophile on the protonated toxide in a manner analogous to the step of alkene bromtnation, in ndiich a cyclic brentORtunt ion is opened nucleophilic attack (Section 7.2l. When an opoxycycloalkane is opened aqueous acid, a frona-t -diol results just as a traR5 l,2-dibroiiiide from cycloalkene hrominaUun. 

Oxidation of organohoranes. This oxidant is superior to chromic acid for oxidation of organoboranes derived from cycloalkenes to the corresponding ketones. For example, cyclohexanone is obtained in 81% yield from cyclohexene. 

Cyclic a-nitro ketones can be obtained from cycloalkenes using /1-nitroso nitro compounds (Section 7.2.1.5.) or /i-hydroxy nitro compounds (Section 7.2.1.7.)152. 

In 1,2-epoxyoctane and its unsaturated derivatives the effects of the double bonds and various Lewis acids on the rearrangement have been examined. The effects of Lewis acids on the regioselectivity have also been considered for oxiranes prepared from cycloalkenes. Equation 125 (where R = Ph and = 6) illustrates isomerization processes in which ketone is formed on the action of ZnCl2 and mainly aldehyde on the action of AlCU." ... 

Acid-catalyzed epoxide cleavage takes place by back-side attack of] nucleophile on the protonated epoxide in a manner analogous to the fn step of alkene bromination, in which a cyclic bromonium ion is opened 1 nucleophilic attack (Section 7.2). When an epoxycycloalkane is opened 1 aqueous acid, a rans-1,2-diol results, just as a [Pg.720]

Table 7. n-Chloro-n-fluorobicyclo[n —3.1.0]alkanes from Cycloalkenes, Methyl Dichlorofluoroacetate and in situ Generated Sodium Methoxide... 

Additional terminal functionalization can be accomplished by several methods. Schreiber has developed general ozonolysis and workup procedures which enable a variety of products to be prepared from cycloalkenes (eq 3). Also, iron or copper salts can be... 

Cyclic 1,2-diols can be produced stereoselectively from cycloalkenes. For example, a racemic mixture of the enantiomeric frflns-l,2-cyclohexanediols 7 and 8 is produced by reaction of a peracid with cyclohexene and hydrolysis of the intermediate epoxide 13 (Eq. 7.1). Oxidation of this alkene by permanganate, on the other hand, gives ds-l,2-cyclohexanediol (6), as shown in Equation 7.2. The intermediate in this process is presumably the cyclic manganese-containing species 14, which is not isolated. 

The sulphur and nitrogen heterocycles (80) and (81) have been prepared by hydroboration-carbonylation of bis-olefinic precursors, and the latter case is reported to be the first example of such a synthesis in the presence of a reducible functional group. Another hydroboration-carbonylation sequence has been used in the preparation of methylene cycloalkanes from cycloalkenes, and is shown in Scheme 11. ... 

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