Pentane diol

H-pyran synthesis from, 3, 757 tetrahydropyranone synthesis from, 3, 845 Pentane-1,5-diol, 1,5-diphenylring closure, 3, 774 Pentane-1,5-diols... 

Acryloyl chloride (0.2 mol) in dry benzene (60 ml) was added over 0.5 hour with mechanical stirring to pentane-1,5-diol (0.1 mol), triethylamine (0.2 mol) and pyrogallol (0.1 g) in dry benzene (100 ml). Further dry benzene (ca 100 ml) was added followed by triethylamine (10 ml), and the mixture stirred at 50°C for 0.5 hour. The triethylamine hydrochloride was fii-tered off and the solvent removed In vacuo to leave a yellow oil which was distilled in the presence of a trace of p-methoxyphenol, excluding light, to give 1,5-pen tarn ethylene diacrylate (12.9g 61% BP90°to95°C/0,01 mm Hg),... 

The production of alcohols by the catalytic hydrogenation of carboxylic acids in gas-liquid-particle operation has been described. The process may be based on fixed-bed or on slurry-bed operation. It may be used, for example, for the production of hexane-1,6-diol by the reduction of an aqueous solution of adipic acid, and for the production of a mixture of hexane-1,6-diol, pentane-1,5-diol, and butane-1,4-diol by the reduction of a reaction mixture resulting from cyclohexane oxidation (CIO). 

The result of the retrosynthetic analysis of rac-lO is 2-hydroxyphenazine (9) and the terpenoid unit rac-23, which may be linked by ether formation [29]. The rac-23 component can be dissected into the alkyl halide rac-24 and the (E)-vinyl halide 25. A Pd(0)-catalyzed sp -sp coupling reaction is meant to ensure both the reaction of rac-24 and 25 and the ( )-geometry of the C-6, C-7 double bond. Following Negishi, 25 is accessible via carboalumination from alkyne 27, which might be traced back to (E,E)-farnesyl acetone (28). The idea was to produce 9 in accordance with one of the methods reported in the literature, and to obtain rac-24 in a few steps from symmetrical 3-methyl-pentane-1,5-diol (26) by selective functionalization of either of the two hydroxyl groups. 

The preparation of vinyl iodide 39 first required the transformation of (E,E)-farnesyl acetone (28), performed according to Negishi, to the terminal alkyne 27 with 75% yield [35]. The latter then gave (E)-vinyl iodide 39 in dia-stereomerically pure form and 74% yield by Zr-catalyzed carboalumination with trimethylaluminum and trapping of the intermediate vinylaluminum species with iodine [36]. The alkyl iodide rac-29 necessary to ensure the coupling with 39 was obtained by selective monofunctionalization of 3-methyl-pentane-1,5-diol (26) in a few steps [37]. 

As mentioned above, the advantage of the prochiral 3-methyl-pentane-1,5-diol (26) is that we should be able to derive the two enantiomers (R)-29 and (S)-29 necessary for the synthesis of methanophenazine (10) in enantiomerically pure form by differentiating its enantiotopic (CH2)20H groups [40]. 

Cognate preparations. 1,5-Diiodopentane (from pentane-1,5-diol). Proceed as for 1,4-diiodobutane but use 26 g (26.5 ml, 0.25 mol) of redistilled pentane-... 

The reactions of butane-2,3-diol by HCF in alkaline medium using Ru(III) and Ru(VI) compounds as catalysts leads to similar experimental rate equations for both the reactions. The mechanism involves the formation of a catalyst-substrate complex that yields a carbocation for Ru( VI) or a radical for Ru(III) oxidation. The role of HCF is in catalyst regeneration. The rate constants of complex decomposition and catalyst regeneration have been determined.89 A probable mechanism invoving formation of an intermediate complex has been proposed for the iridium(III)-catalysed oxidation of propane- 1,2-diol and of pentane-1,5-diol, butane-2,3-diol, and 2-methylpentane-2,4-diol with HCF.90-92 The Ru(VIII)-catalyzed oxidation some a-hydroxy acids with HCF proceeds with the formation of an intermediate complex between the hydroxy acid and Ru(VIII), which then decomposes in the rate-determining step. HCF regenerates the spent catalyst.93... 

Acryloyl chloride Pentane-1,5-diol Oxalic acid... 

Many examples of the synthesis of tetrahydropyrans are based on the cyclization of 1,5-diols and related compounds which can provide an electrophilic site for ring closure . Thus, pentane-1,5-diols can be quantitatively cyclized to the pyran in the presence of BuSnCl3 <1988G483> or via an intramolecular Mitsunobu condensation with cyanomethylenetributylphosphorane <1996TL2463>. Tetrahydrothiopyrans are prepared similarly by cyclizations of suitably substituted thiols . 

Acetonization of the dialcohol 337 led to 338a in 73% yield. Less efficient was the cyclization of 337 with carbonyldiimidazole therefore, dioxocinone 338b, even under rather forcing conditions, was obtained in only 29% yield (Equation 43) <2005CEJ6629>. Another example of cyclization of dialcohols, with insertion of a carbon unit, to 1,3-dioxocins, although in poor yield, was furnished by pentane-1,5-diol and (5, (l-difluoro-a-phenylvinyl sulfide <1995H(41)641>. 

It was known that HLADH oxidizes glycerol into L-glyceraldehyde stereospecifically (Hadorn et al. 1963, Bally and Leuthardt 1970). Since the stereospecific oxidation of a primary diol will afford a lactone, the synthetic utility of this oxidation is quite high. Indeed, six-membered lactones were obtained in high optical yields on oxidations of 3-substituted pentan-1,5-diol as shown in Scheme 33 (Irwin and Jones 1977a). Oxidations of diols mediated by HLADH have been further studied extensively by Jones and his collaborators. A part of a group of results is listed in Table 33 (Irwin and Jones 1977b, Jakovac et al. 1982, Ng et al. 1984, Jones and Francis 1984). 

Dehydration and Cydization. Amberlyst 15 has been used in the cyclodehydration of pentane 1,5 diol to tetrahydropyran and in the synthesis of a library of substituted benzofurans (eq 7)... 

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