2,6 Hexadiene-4,5-diol

Conventional synthetic chemistry needs a multi-step synthesis to give the cyclo-hexadiene diol in the tram-form, which is difficult to polymerize 251). A most ingenious feature of the work of Ballard et al. was the use of a bacterial fermentation route to prepare the diol in the m-form. A detailed account of the preparation, properties and transformation of the polymer has recently been published 252). In practice, the favoured esters are those of methylcarbonic acid, since the eliminated acid decomposes at transformation temperatures to yield methanol and C02. The main... 

Reiner AM, GD Hegeman (1971) Metabolism of benzoic acid by bacteria. Accumulation of (-)-3,5-cyclo-hexadiene-l,2-diol-l-carboxylic acid by a mutant strain of Alcaligenes eutrophus. Biochemistry 10 2530-2536. 

The effect of an ally lie hydroxy group was first observed in divinylglycol (1,5-hexadiene-cA-3,4-diol and 1.5-hexadiene-/raw.v-3,4-diol). It was shown that the hydroxy substitutions directed the addition of the osmium tetraoxide to syn addition, so that the cA-diol yielded allitol (all cA-hexaol) and the iraws-diol yielded mannitol42. The oxidation of the dienol 35 yielded a lactone ring 36 by cA-dihydroxylation and transesterification... 

Oxidation of 1,5-dienes to c -tetiahydrofurandiols was accomplished with RuO /aq. Na(10 )/acetone-EtOAc thus 2,5-dimethyl-1,5-hexadiene gave tetrahydrofurandiol, geranyl acetate yielded cw-tetrahydrofurandiol, and trans, tra 5-2,6-dimethyl-2,6-octadiene-l,8-diol diacetate (1) gave tetrahydrofuran ketol diacetate (2) (Fig. 3.12 cf. mech. Ch. 1) [174],... 

Sharpless epoxidation of the meso-diol l,5-hexadiene-3.4-diol (3) could, in principle, yield four stereoisomers. In the event, 4 was the main product (see Section 43.3.2.3.3., p 420). Both relative and absolute configuration had to be determined. The relative configuration was established independently (not reported by the authors), and the absolute configuration could then be assigned by destroying all but one chiral unit, thus relating 4 with (S)-5 (vide supra)136. 

Yttrocene complexes catalyze the cascade cyclization/hydrosilylation of trienes to form saturated silylated bicyclic compounds.For example, reaction of the 4-silyloxy-4-vinyl-l,6-hexadiene 69 and phenylsilane catalyzed by Gp 2YMe(THF) at room temperature for 1 h followed by oxidation of crude 70a gave [3.3.0]bicyclic diol 70b in 73% yield over two steps as a single diastereomer (Scheme 18). Selective conversion of 69 to 70a presumably requires initial 1,2-hydrometallation of one of the less-hindered G=G bonds to form alkylyttrium alkene complex II (Scheme 18). Selective S-exo carbometallation of II in preference to -exo carbometallation would form cyclopentyl-methylyttrium complex III (Scheme 18). Gyclization of III via a chairlike transition state would form the strained /r< /75 -fused alkylyttrium complex IIIl, which could undergo silylation to form 70a. 

The synthesis of isomeric DL-allitol succeeded when the hydroxyl groups in cts,cis-2,4-hexadiene-l,6-diol were protected with benzoyl or mesyl groups. Epoxidation gave the appropriate derivatives of 2,3 4,5-dianhydro-DL-allitol (16%), which were then reduced with lithium aluminum hydride to DL-crt/f/iro-2,5-hexanediol. 

Oxidation of conjugated dienes in CH3CN-NaC104 in the presence of 1,3-dimethylurea gives a mixture of the possible 4,5-disubstituted 1,3-di-methylimidazolidin-2-ones in about 40% yield.103 Anodic oxidation of 2,4-hexadiene, 1,3-butadiene, and 1,3-cyclohexadiene in CH3CN-H20-NaC104 yields diols, 2-oxazolines, and 3-pyrrolines.104 The product distribution is influenced by the supporting electrolyte. 

Polycarbophil. Polycarbophil [73038-24-1] (copolymer of acrylic acid and divinyl glycol (l,5-hexadiene-3,4-diol [1069-23-4])) consists of white-to-creamy white granules having a slight ester-like odor. It swells to contain a maximum of 1.5% water, but is insoluble in water and most organic solvents. It is prepared by copolymerization of acrylic acid and divinyl glycerol in a hot salt slurry using azobisisobutyronitrile as the initiator. 

A triple RCM reaction cascade has been reported that allows for the construction of dihydrofurans with two adjacent dihydropyran or dihydrofuran rings from a common enantiomerically enriched acyclic precursor (Equation 55) <20010L1989>. Ring-size-selective metathesis reactions and the synthetic utility of enantiomerically pure l,5-hexadiene-3,4-diol, derived from D-mannitol, have been discussed in detail <2007ASC215>. 

The oxidation of 5-methyl-l,2-dihydro-3/7-pyrazol-3-one with lead tetraacetate produces in situ the corresponding pyrazolone which is trapped by ( , )-2,4-hexadiene-l,6-diol to give the c/.v-cycloadduct 1330. The cis configuration was assigned since hydrogenation affords the same compound which can be prepared alternatively from the cyclohexadiene adduct. 

BMB is superior to diborane for dihydroboration of terminal dienes to give, after oxidation, a.w-diols.- Thus 1,5-hexadiene is converted into 1,6-hexanediol in 93% yield, whereas with diborane the yield is 69% and the remainder is a mixture of isomeric diols. With disiamylborane, Zweifel, Nagase, and Brown were able to eifect monohydroboration of cyclic dienes in reasonable yield. This finding was used to advantage by a Merck group for selective conversion of the diene (I) to the primary alcohol (2). 

The first synthesis of racemic LTA4 methyl ester, as a mixture with its cis isomer, was reported by Corey et al. as outlined in Scheme 3.19. Alcohol 45 was used as the synthon for the C-12 portion of the target structure and ( , )-2,4-hexadien-l,6-diol became C-6 to C-11. The functionality in the diol was differentiated by its transformation to 47, which then underwent a Wittig reaction with 46 to yield the 15-carbon alcohol 48. The formation of the mesylate of 48 and the reaction of sulfonium salt 49 with methyl 4-formylbutyrate using LDA as a base is also a difficult step and only modest yields of the target compounds are obtained. ... 

IUPAC Nomenclature of Unsaturated Alcohols Section 9.1A (a) 3-buten-2-ol (b) 4-ethyl-2-hexyn-1-ol (c) 2,4-hexadien-1,6-diol ... 

On elaboration of l,5-hexadiene-3,4-diol through a 1,3-dioxolane derivative, the RCM delivers a precursor of either exo-brevicomin or endo-brevicomin. A route to (+)-malyngolide also exploits the RCM process. A successful cyclization-fragmentation approach to medium-sized rings is based on the RCM reaction of 2-hydroxycycloalkanones that are substituted with proper alkenyl groups at both a- and a -positions.- ... 

Allylic compounds containing other leaving groups are also reactive toward substitution. Thus alkoxycarbonylation of allylic phosphates is a method of homologation, on which an interesting /3-lactam synthesis is based. Using PhjSiOH as nucleophile in the displacement, 2,4-hexadiene-l,6-diols are synthesizedfrom buta-dienyloxiranes. Desilylation of the products is achieved with KF. 

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