Rearrangements alcohols

MEYER - SCHUSTER Propargyl alcohol rearrangement Add catalyzed rearrangement of acetylenic alcohols into o, -unsaturated carbonyl derivatives... 

The corresponding monofluoroallylic alcohol rearranges more slowly and resists dehydrofluorination to the dienal.206... 

Morgans, D. J. Sharpless, K. B. Traynor, S. G. Epoxy alcohol rearrangements hydroxyl-mediated delivery of Lewis add promoters./. Am. 

Furfuryl alcohols rearrange to 4-hydroxycyclopentenones by acid treatment, and the latter isomerize to 4-hydroxycyclopentenones (02SL1451). 

Dehydration works best with tertiary alcohols and almost as well with secondary alcohols. Rearrangements and poor yields are common with primary alcohols. 

The leaving group need not be tosylate in the following example, part of a synthesis of berg-amotene (a component of valerian root oil and the aroma of Earl Grey tea), a 2-iodo alcohol rearranges. 

The next example makes more involved use of these [2,3]-sigmatropic allylic sulfoxide-allylic alcohol rearrangements. It comes from the work of Evans (he of the chiral auxiliary) who, in the early 1970s, first demonstrated the synthetic utility of allylic sulfoxides. Here he is using this chemistry to make precursors of the prostaglandins, a family of compounds that modulate hormone activity within the body. 

Deuterium-labelling studies revealed that no more than a few percent cyclo-propylcarbinyl-cyclopropylcarbinyl cation rearrangement takes place in the parent 2-bicyclo[4.1.0]heptyl system. However, acid-catalyzed alcohol rearrangement and... 

Solvent % Yield of benzoate ester % Ester rearranged % Alcohol rearranged... 

The possibility of vinyl alcohol rearrangement to acetaldehyde was recognized but not stressed. This rearrangement would make possible the oxidation of acetaldehyde to glycollic acid followed by decomposition and further oxidation of the decomposition products to water and carbon dioxide. 

Phenylurethanes of ailyiic alcohols rearrange on heating to 200 240 °C in the presence of a catalytic amount of sodium hydride with expulsion of carbon dioxide. Rearrangement of optically active 2-cyclohexenylphenyiurethane, to give 2, is accompanied by 65% retention of configuration and 35% racemization. Small amounts of imidazolidones are found as byproducts436. 

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