Reduction of ozonides

The Adams platinum oxide catalyst gives satisfactory results in the reduction of ozonides. 

Halide synthesis reduction of ozonides isomerization reactions Staudinger reaction (heterogeneous)... 

Reduction of ozonides is very useful, especially when aldehydes are the desired products. Ozonides are easily hydrogenolyzed over palladium [670], or reduced by zinc in acetic acid [671], usually in good yields. Ozonolysis of methyl oleate followed by hydrogenation over 10% palladium on charcoal... 

An elegant one-pot reduction of ozonides consisting of the treatment of a crude product of ozonization of an alkene in methanol with dimethyl sulfide (36% molar excess) gives 62-97% yields of very pure aldehydes [244. ... 

Notes 1. Use as other hydroborating reagents. Its value is in the increased reagent stability and solvent solubility. Like other hydroborating agents, it is stable to an array of functional groups. It is useful for the reduction of ozonides. 

Acetic acid, CH3CO2H Used as a solvent for the reduction of ozonides with zinc (Section 7.9) and the a-bromination of ketones and aldehydes with Br2 (Section 22.3). 

The reduction of ozonides with triphenylphosphine,113 on the other hand, proceeds quantitatively with both ketozonides and aldozonides. Lorenz102,112 used this reaction as the basis of a method for the determination of ozonides. The reaction mechanism is probably as shown in Eq. (8).102... 

Ozonides are rarely isolated [75, 76, 77, 78, 79], These substances tend to decompose, sometimes violently, on heating and must, therefore, be handled with utmost safety precautions (safety goggles or face shield, protective shield, and work in the hood). In most instances, ozonides are worked up in the same solutions in which they have been prepared. Depending on the desired final products, ozonide cleavage is done by reductive or oxidative methods. Reductions of ozonides to aldehydes are performed by catalytic hydrogenation over palladium on carbon or other supports [80, 81, 82, S3], platinum oxide [84], or Raney nickel [S5] and often by reduction with zinc in acetic acid [72, 81, 86, 87], Other reducing agents are tri-phenylphosphine [SS], trimethyl phosphite [89], dimethyl sulfide (DMS) [90, 91, 92], and sodium iodide [93], Lithium aluminum hydride [94, 95] and sodium borohydride [95, 96] convert ozonides into alcohols. 

Reduction of ozonides [1, 1244, after citation of ref. 23]. Pappas et al.2Sa found triphenylphosphine the most satisfactory reducing agent for ozonides derived from nephthalenic compounds. 

White, R.W. King, S.W. O Brien, J.L. Catalytic reduction of ozonides. 11. Synthesis of amines from olefins. Tetrahedron Lett. 1971,12, 3591-3593. 

Unfortunately, the mechanism of hydride reduction of ozonides is not known. However, we can consider the most reasonable possibilities, all of which place the greatest portion of the label in the peroxide bridge at oxygen-3. 

Figure 3. Methyllithium reduction of ozonide hy proton removal...

Methyllithium reduction of ozonides appears to follow a course similar to that of Grignard reduction. Greenwood treated diethyl ozonide with isopropyl Grignard and obtained 2-methyl-3-pentanol, isopropyl alcohol, and propane in good yield (9). 

Reduction of ozonides with EtCHO JACS C197l 93 3042... 

Reduction of Ozonides. In the synthesis of ecdysone from ergosterol, the ozonide product produced from (5) was reduced with (Mc2N)3P under mild conditions to the aldehyde (6) without isomerization (eq 18). The scope of this method has not been investigated. 

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