Dehydration of Diols

Sulfurane reagent lor conversion of trans diols to epoxides, generally for dehydration of diols to olefins or cyclic ethers, and as an oxidizing agent... 

Dehydration of diols pinacol rearrangement. Preparation of pinacolone... 

Dehydration of diols to cyclic ethers. The reagent dehydrates a variety of diols to cyclic ethers with formation of triphenylphosphine oxide as the co-product. Yields of cyclic ethers are high from 1,2-, 1,4- and 1,5-diols. Although (Z)-2-butene-1,4-diol is converted into 2,5-dihydrofuran in 95% yield, the (E)-isomer is converted in 35-40% yield into 3,4-epoxy-l-butene.1... 

Enantiomerically pure [3]oxaferrocenophanes (405) are available as well, from tosyl chloride-induced dehydration of diols (equation 88). Tilt angles for these complexes as... 

Preparation of dienes is accomplished by dehydration of diols or ole-finic alcohols. Pinacol, (CHjljCOHCOHfCHjlj, is converted to 2,3-di-methyl-1,3-butadiene by heating with 48% hydrobromic acid or by passing the vapors over activated alumina at 420-470°, Yields of the diene are 60% and 86%, respectively. Aniline hydrobroniide is used as a catalyst in the dehydration of 3-methyl-2,4-pentanediol to 3 methyl-l,3-penta-diene (42%). An excellent laboratory preparation of isoprene from acetone in 65% over-all yield has been described. The last step involves catalytic dehydration of dimethylvinylcatbinol over aluminum oxide at 300° to give isoprene in 88% yield. ... 

M. Bart<5k, A. Molndr. The Chemistry of Ethers, Crown Ethers, Hydroxyl Groups and their Sulphur Analogues, Suppl. E, Chapter 16. Dehydration of diols. Ed. S. Patai, J. Wiley Sons New York, 1980, p. 721. 

SUMMARY OF DIENE CHEMISTRY PREPARATION 1. Dehydration of Diols... 

Ether compounds are also formed as a result of an intramolecular dehydration of diols, which are catalyzed by the H-phosphonate diesters [39]. 

Polymer-bound reagents have become popular lately, and diethoxy-diphenylpolystyrylphosphorane has been used for the cyclic dehydration of diols. An unbound version of this reagent is also available. 

Of AdoCbl-dependent reactions, the most important are (a) isomerizations leading to a rearrangement of the amino acid skeleton (of glutamate, a-methyleneglutarate, D-a-lysine, L-P-lysine, ornithine) and of methyl-malonyl-CoA, b) dehydration reactions, including dehydration of diols and glycerol, (c) deamination of aminoalcohols, and (d) reduction of ribonucleotide triphosphate to 2-deoxyribonucleotide triphosphate. Reactions a-c can be schematically represented as shown in Fig. 5.1. 

The formation of polyethers by dehydration of diols is one of the relatively few examples of RA2 step polymerization... 

When the dehydration of diol monoacetate (395) was carried out in deuterioacetic acid, all rearrangement products were formed free of deuterium, indicating that no elimination-reprotonation takes place under the reaction conditions (487). The backbone rearrangement of cholesterol (396) in the presence of hydrofluoric acid is combined with expansion of the D ring and 1,5-hydrogen transfer from the side-chain to give the shionane-like product (397) (488). 

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