Alkenes, oxidative cleavage

With trisubstituted steroid alkenes, oxidative cleavage of the C—C bond was the predominant reaction97 10 . The reaction with steroidal conjugated dienes afforded mixtures of products in which diazides usually predominate102, whereas 6/J,7a-diazido-4-en-3-ones, 4-6 together with minor amounts of 7a-azido-4-en-3,6-diones were obtained from the corresponding 4,6-dien-3-onesl03. 

For recent developments in alkene oxidative cleavage, see Griffith, W. P, Kwong, E. Synth. Commun. 2003, 17, 2945, and references therein. 

Miller s hydroxamate method [41], widely used for the preparation of mono-bactams, surprisingly scores a single application useful for penem synthesis [42]. Chiral 0-butyl hydroxamate 91 was prepared by aldol reaction of crotonalde-hyde with synthon 90a (Sn(OTf )2/iV-ethylmorpholine), followed by temporary 0-TBDMS protection of obtained 90b and displacement with butoxyamine. Lactamization of 91 under Mitsunobu conditions (PPh3/DEAD) afforded 92, an equivalent (by alkene oxidative cleavage and deprotection) of enantiomerically pure 4-acetoxyazetidinone. 

The oxidation reactions of either permanganate or osmium tetroxide with an alkene lead to a vicinal diol. The functional group exchange for this process is that shown. In other words, a diol is obtained by dihydro lation of an alkene. Oxidative cleavage reactions such as ozonolysis eventually lead to an aldehyde, ketone, or carboxylic acid, depending on the substituents attached to the unit... 

DJERASSI RYLANDER Oxidation Ru04 in oxidative cleavage ot phenols or alkenes oxidation ol aromatics to quinones oxidation ol alkyl amides to irmdes or ol ethers lo esters... 

Show the structures of alkenes that give the following products on oxidative cleavage with KMn04 in acidic solution ... 

We ve already discussed two methods of aldehyde synthesis oxidation of primary alcohols and oxidative cleavage of alkenes. 

Alkenes with at least one vinjdic hydrogen undergo oxidative cleavage when treated with ozone, yielding aldehydes (Section 7.9). If the ozonolysis reaction is carried out on a cyclic alkene, a dicarbonyl compound results. 

Oxidative cleavage of an alkene with Klvln04 gives a carboxylic acid if the alkene has at least one vinylic hydrogen (Section 7.9). 

Methods of synthesis for carboxylic acids include (1) oxidation of alkyl-benzenes, (2) oxidative cleavage of alkenes, (3) oxidation of primary alcohols or aldehydes, (4) hydrolysis of nitriles, and (5) reaction of Grignard reagents with CO2 (carboxylation). General reactions of carboxylic acids include (1) loss of the acidic proton, (2) nucleophilic acyl substitution at the carbonyl group, (3) substitution on the a carbon, and (4) reduction. 

Oxidative cleavage of alkenes, terminal alkynes, or aromatic rings... 

The obvious Vfittig disconnection gives stabilised ylid (5fi) and keto-aldehyde (57). We have used many such long-chain dicarbonyl compounds in this Chapter and they are mostly produced from available alkenes by oxidative cleavage (e.g. ozonolysis). In this case, cyclic alkene (58) is the right starting material, and this can be made from alcohol (59) by elimination,... 

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