Oxidative cleavage other approaches

Overall, ozone compares favorably with other approaches for oxidative alkene cleavage involving Osmium Tetroxide, Potassium Permanganate, Ruthenium(VIII) Oxide, Sodium Periodate, or chromyl carboxylates which are costly, toxic, involve metal wastes, and may require detailed workup procedures. 

In Summary Four methods of synthesizing aldehydes and ketones are oxidation of alcohols, oxidative cleavage of alkenes, hydration of alkynes, and Friedel-Crafts acylation. Many other approaches will be considered in later chapters. 

Other derivatives were prepared by modifications of the original Ellman route. Thus, a second cyclopentene precursor 18 containing the C5 6 cis double bond was carried through to give the resin-bound intermediate 19 via a Stille coupling and an oxidation. Subsequent cuprate addition, reduction, and cleavage give 20 and 21 (the F and E series) with the C56 double bond intact. This type of approach was used to synthesize 11 more compounds in this series. 

This lack of an entirely consistent pattern has not prevented the successful application of glycol-cleavage by lead tetraacetate to a wide variety of structural problems. In relating oxidation data to structure, it has been necessary only to recognize that a single approach to a chemical problem is never fully adequate and that other lines of evidence must be sought. 

The synthesis of chiral phosphines from resolved phosphonium salts or phosphine oxides is an intrinsically limited approach. The groups attached to phosphorus must be present prior to resolution and, furthermore, the preparation of phosphine oxides and phosphines from phosphonium salts by chemical or electrochemical cleavage reactions requires that one of the groups bonded to phosphorus be substantially easier to cleave than the other three. 

---