Olefin cleavage

The periodate olefin cleavage generated large amounts of colloidal MnO2 waste and sodium iodate (NalOj). The process therefore involved multiple unit operations and suffered from poor volume productivity and oxidation efficiency (three out of four available oxygens in NalO4 are wasted). 

We therefore employed a similar combination of catalytic Ru , with NaOCl as oxidizing agent, to the intermediate 38 to effect endocylic olefin cleavage affording dioic acid 39 (or corresponding monomethyl ester) in comparable yield, as shown in Scheme 14.12. 

Figure 14.3 Process flow chart for periodate olefin cleavage to obtain 39.

Similarly to oxidative olefin cleavage with periodate, the first intermediate formed is ester 35, here a perruthenate at the oxidation level +VI1 A -elimination releases ketone 6 and the mthenium(V) acid 36 /V-Methylmorpholine-N-oxide (NMO) serves in this case to regenerate the perruthenate(VII) speck s, and must therefore be introduced in stoichiometric quantity. 

The second step consists of an oxidative olefin cleavage. 

Statistically, the rate of formation of new olefins for Type II reactions, except in some cases involving branched olefins, is twice the rate for Type I reactions both alignments of the double-bond isomers to form the transition state will result in products different from the reactants. For Type III reactions three situations can exist depending on the reactants, both, only one, or neither alignment of the olefins will form a four-center transition state that dissociates into new olefins. Cleavage of 2-butene with propylene will not form new olefines however, cleavage of 2-butene with ethylene will form propylene. 

Use of the chiral carbon pool for cyclopentenone preparation is also known. The fungal metabolite terrein [88] was selectively monoacetylated and then reduced with chromous chloride to enone [89]. Acetylation and olefin cleavage with ruthenium tetroxide aiwi sodium periodate led to aldehyde [90], which was readily decarbonylated to [65] (51). An alternative route (52) began with the less common S,S-tartaric acid [91], converted in four steps to diiodide [92]. Dialkylation of methyl methylthiomethyl sulfoxide with [92] gave the cyclopentane derivative [93]. Treatment of [93]... 

Intermediate (61) has also been taken forward by a new procedure whereby the ethylene ketal, by olefin cleavage, esterification, Baeyer—Villiger oxidation and lactonisation, afforded (66a), of which the formyl derivative (66b) on ozonolysis and acetylation gave (67). PGEi then followed via olefin cleavage and Wittig elaboration [65]. 

Trost BM, Ochiai M, McDougal PG. Hydroxysulfenylation of olefins. An olefin cleavage with functional group differentiation. J. Am. Chem. Soc. 1978 100 7103-7106. 

Rxn. with HCl in aq. MeOH - kinetic and thermodynamic data for olefin cleavage, isotope effect (I367). 

Synth. By rxn. of Et3SnCl with CH2 CHCH2MgCl in Et20, in 76% yield (I367). Prop. Anal. detn. by GLC (I376), by iodometric titration (I619)-Rxn. with HCl in aq. MeOH kinetic and thermodynamic data on olefin cleavage rxn. (1367). 

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