Diols, vicinal with lead tetraacetate

The oxidative cleavage of the central carbon-carbon bond in a vicinal diol 1, by reaction with lead tetraacetate or periodic acid, yields two carbonyl compounds 2 and 3 as products. 

Acyl esters of vicinal diols are obtained by the reaction of alkenes with metal carboxylates [436]. Lead tetraacetate in acetic acid at 70 °C converts 1,2-dihydronaphthalene to rranj-l,2-diacetoxy-l,2,3,4-tetrahy-dronaphthalene in 72% yield [436]. The reaction is not always stereospecific. Cyclohexene treated with thallium triacetate gives a mixture of diastereomers in varying ratios, depending on reaction conditions, and byproducts as a result of rearrangements (equation 89) [411],... 

Two oxidants essentially dominate these oxidations lead tetraacetate in organic solvents and periodic acid in aqueous media. On occasion, other oxidation reagents cause the cleavage of vicinal diols ceric ammonium nitrate [424], sodium bismuthate [482, 483], chromium trioxide [482, 555], potassium dichromate with perchloric acid [949], manganese dioxide [817], and trivalent [779, 789] or pentavalent [798] iodine compounds. 

Lead tetraacetate-2,7-dichlorofluorescein (A) lead tetraacetate (saturated solution) in glacial acetic acid (B) 2,7-dichlorofluorescein in water (1%, m/v, or lower, down to 0.2%, if background interferes with detection) A and B are mixed 1 1 (v/v), then toluene (19 1, v/v) is added Plate is dipped in reagent for 10s, then heated at 100°C for 3 min All carbohydrates with vicinal diol groups, oxidized by lead tetraacetate, are detected fluorimetric scanning (excitation 313nm, emission 366 nm) 50-100pmol... 

Moving forward from 59, six steps were required to convert this compound to 60. Vicinal dihydroxylation of the olefin was followed by oxidative cleavage of the intermediate diol using lead tetraacetate. Reductive amina-tion of the resulting aldehyde with methylamine, followed by acylation of the intermediate secondary amine gave the desired carbamate. Swern oxidation of the secondary alcohol, followed by enol ether formation gave 60. Elimination of -toluenesulfinic acid from 60 provided 61. Oxidation of this dienol ether to dienone 62 was followed by release of the secondary amine, followed by a conjugate addition reaction to establish the critical C-N bond. The remainder of the synthesis followed known chemistry. The mixture of enones 63 was converted to codeinone (35), codeine (3) and then morphine (1). 

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