Cycloheptanone pinacol

The rate of oxidation of diols with lead tetraacetate depends strongly on their configurations cis diols react 200-3000 times faster than trans diols [1154], and the racemates of certain diols react about 15 times faster than the meso forms [1154]. The rates of oxidation of pinacols prepared from cyclopentanone, cyclohexanone, and cycloheptanone are in the ratio... 

The symmetrical diols derived from cyclopentanone and cyclohexanone can similarly be converted to ring-expanded ketones in good yield. The diols from reductive coupling of cycloheptanone and cy-clooctanone give mainly the corresponding dienes in aqueous acid, especially when heated, but Chris-tol found that pinacol rearrangement is strongly favored even for these materials when cold concentrated sulfuric acid is used as the solvent. 

A variation of the pinacol reaction has been applied to esters for the preparation of hydroxyketones (acyloins). A simple example is the reaction of 257 with sodium metal (Na°) in refluxing xylene, which gave a good yield of 2-hydroxy cycloheptanone (258) after hydrolysis.203 The condensation of an a,(o-diester to an... 

More work has been reported on the inter- and intra-molecular pinacolic coupling of aldehydes and ketones, e.g. cycloheptanone and acetone gave (220) on treatment with a magnesium-mercury-titanium(iv) chloride reagent. ... 

Codeposition of magnesium atoms and cycloheptanone has been studied. Of the magnesium vapourized, 13 % led to the formation of l,T-dihydroxybicycloheptyl and 13% led to volatile hydrocarbon products, consisting of cycloheptene (91 %), nor-carane (5 %), and cycloheptane (4 %). Aldol condensation products were also found. The mechanisms proposed involved the pinacol intermediate (239). ... 

We have observed that the irradiation of cycloalkanones (cyclohexanone le, cycloheptanone 4e, cyclooctanone 5e, cyclodecanone 5 e, cyclododecanone 6e, 2-methylcyclohexanone 31e, 2-phenylcyclo-hexanone 32e, a-tetralone 17e, 5a-cholestan-3-one 1 le, and 5P-cholestan-3-one 12e) in methanol under a nitrogen atmosphere with a high-pressure mercury lamp (X > 300nm) at room temperature yields the corresponding pinacol 1,2-diols. The irradiation of cyclododecanone 6e in methanol at room temperature under nitrogen atmosphere with a 400-W mercury lamp for 4 hr gave 1,1-bicyclododecanol 61 (84%) and cyclododecanol 6k (8%). These results are summarized in Table 56.13, where it can be seen that the... 

In conclusion, the present method, while not widely appHcable, has a notable characteristic that was not observed previously. " This reaction affords a new simple synthetic method for the pinacols of cycloheptanone, cyclooctanone, and cyclododecanone. It is particularly noteworthy that this reaction is a new, clean method. 

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