1,5-Pentanediol synthesis

The by-products of these reactions are sulfides. The sulfide formed in the synthesis of 2-mercaptoethanol, 3-thia-l,5-pentanediol (thiodiglycol), has a variety of uses ranging from lubricant additive intermediates to textile finishing. 

Chiral acetals/ketals derived from either (R,R)- or (5,5 )-pentanediol have been shown to offer considerable advantages in the synthesis of secondary alcohols with high enantiomeric purity. The reaction of these acetals with a wide variety of carbon nucleophiles in the presence of a Lewis acid results in a highly diastereoselective cleavage of the acetal C-0 bond to give a /1-hydroxy ether, and the desired alcohols can then be obtained by subsequent degradation through simple oxidation elimination. Scheme 2-39 is an example in which H is used as a nucleophile.97... 

The synthesis of 5 lan thick Ti02 Si02 layers on a porous support can be performed using the procedure given below. First a mixed Ti[(OMe)3]4 alkoxide is synthesized by reacting partially hydrolyzed Si(OMe)4 with Ti-isopropoxide. This inorganic polymer is hydrolyzed at pH 11.0 and treated with 2-methyl-2-4-pentanediol and a binder. This solution is then slip-cast onto a porous support, dried and calcined at 700°C. The membrane can be useful in reverse osmosis applications. 

The same group also demonstrated an efficient, two-step asymmetric synthesis of (S)-2-phenylpiperidine as an extension of the N-heterocycUzation of primary amines with diols the results are illustrated in Scheme 5.25. First, the reaction of enantiomerically pure (R)-l-phenylethylamine and 1-phenyl-1,5-pentanediol was conducted to produce a diastereomeric mixture of the corresponding N-(l-phenyl-ethyl)-2-phenylpiperidines 32 and 33 with 92% diastereomeric excess (de). Hydrogenation of this diastereomeric mixture of 32 and 33 with Pd/C catalyst then gave (S)-2-phenylpiperidine in 96% yield (78% ee). 

The use of tartrate esters was an obvious place to start, especially since both enantiomers are readily available commercially and had already found widespread application in asymmetric synthesis (Figure 11) (e.g.. Sharpless asymmetric epoxidation).23.24 Reagents 36-38 are easily prepared and are reasonably enantioselective in reactions with achiral, unhindered aliphatic aldehydes (82-86% ee) typical results are given in Figure 12.3c,h Aromatic and a,p-unsaturated aldehydes, unfortunately, give lower levels of enantioselection (55-70% e.e.). It is also interesting to note that all other C2 symmetric diols that we have examined (2,3-butanediol, 2,4-pentanediol, 1,2-diisopropylethanediol, hydrobenzoin, and mannitol diacetonide, among others) are relatively ineffective in comparison to the tartrate esters (see Table ll).25... 

ANTI-SELECTIVE BORON-MEDIATED ASYMMETRIC ALDOL REACTION OF CARBOXYLIC ESTERS SYNTHESIS OF (2S, 3R)-2,4-DIMETHYL-1,3-PENTANEDIOL... 

Pentanediol (PDO) holds promise for being used in the synthesis of polyesters. It has been synthesized from GVL in the presence of a copper chromite catalyst. At 150 °C and 20.3-30.4 MPa hydrogen pressure, 78.5% PDO was produced together with 8.1% 1-pentanol. ... 

Glycols such as neopentyl glycol, 2,2,4-trimethyl-l,3-pentanediol, 1,4-cyclohexanedimethanol, and hydroxypivalyl hydroxypivalate are used in the synthesis of polyesters (qv) and urethane foams (see Foamed PLASTICS). Their physical properties are shown in Table 1 (1—6). 

In general, ethers are low on the scale of chemical reactivity because the carbon-oxygen bond is not cleaved readily. For this reason ethers frequently are employed as inert solvents in organic synthesis. Particularly important in this connection are diethyl ether, diisopropyl ether, tetrahydrofuran, and 1,4-dioxane. The mono- and dialkyl ethers of 1,2-ethanediol, 3-oxa-l,5-pentanediol, and related substances are useful high-boiling solvents. Unfortunately, their trade names are not very rational. Abbreviated names are in... 

Gu and Soucek reported the synthesis of ceria nanoparticle in hydrocarbon solvents. Cerium-oleate complex was refluxed in high boiling point organic solvents such as octyl ether, 1-tetradecene, decalin, dipropylene glycol monomethyl ether, dipropylene glycol n-butyl ether, and 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate, to decompose and form ceria nanocrystals. The sizes of the nanocrystals are uniform and could be... 

The cyclization in Step B is an improvement of Butler s procedure for the synthesis of which employs less convenient reagents, KNH and l-bromo-3-chloroacetone acetal. Beside the acetals derived from neopentyl glycol, those derived from ethanol, 1,3-propanediol and 2,4-pentanediol have been synthesized by the present method. The second part of Step B involves the formation and the electrophilic trapping of cyclopropenyl anion 2, which is the key element of the present preparations. Step B provides a simple route to substituted cyclopropenones, but the reaction is limited to alkylation with alkyl halides. The use of lithiated and zincated cyclopropenone acetal, on the other hand, is more general and permits the reaction with a variety of electrophiles alkyl, aryl and vinyl halides, Me3SiCl, Bu3SnCl, aldehydes, ketones, and epoxides. Repetition of the lithiation/alkylation sequence provides disubstituted cyclopropenone acetals. 

The use of a tert-butyldimethylsilyl ether as a protecting group makes possible the synthesis of 4-methyl-1,4-pentanediol by a three-step sequence. 

Kinetic resolution of chiral acetals has been effected by use of some organoaluminum reagents [84], On treating a chiral acetal 88, derived from (2, 4/ )-(-)-pentanediol, with -Bu3A1 at room temperature, one diastereomer was found to react much faster than the other, and the residu enol ether is transformed into optically pure ketone. The efficiency of this method is demonstrated by a concise synthesis of (5)-(-)-5-hexadecan-l,5-lactone (89), the pheromone of Vespa orientalis, as shown in Sch. 56. 

Problem 21.17 The insect repellent 6-12 (2-ethyl-l,3-hexanediol) is produced by the same chemical company that produces n-butyl alcohol and 2-ethyl-l-hexanol aiissest a method for its synthesis. How could you synthesize 2-methyl-2,4-pentanediol ... 

CATALYTIC ASYMMETRIC SYNTHESIS OF NITROALDOLS USING A LANTHANUM-LITHIUM-BJNOL COMPLEX (2S,3S)-2-NITRO-5-PHENYL-1,3-PENTANEDIOL... 

This volume begins with two procedures in the area of catalytic asymmetric synthesis. The first procedure describes the synthesis of (R)-2-Dl PH ENYLPHOSPHI NO-2 -METHOXY-1,1 -BINAPHTHYL (MOP), a chiral ligand that has proven very useful in palladium-catalyzed hydrosilylation of olefins and palladium-catalyzed reduction of allylic esters by formic acid. The next procedure describes the catalytic asymmetric synthesis of nitroaldols using a chiral LANTHANUM-LITHIUM-BINOL COMPLEX, illustrated by the synthesis of (2S,3S)-2-NITRO-5-PHENYL-1,3-PENTANEDIOL. 

Synthesis and Modification. A series of polyurethanes and polyurethane-ureas of varying degress of hydrophilicity and hydrophobicity and mechanical property were synthesized. The polymers were prepared by a solution polymerization method and consisted of three components a polyether, a diisocyanate, and a chain extender. In our studies, polyurethanes (Table I) were based on a carbowax (polyoxyethylene glycol), MDI (methylene bis-4-phenyl isocyanate) and 1,5-pentanediol. Polyurethane-ureas (Table II) were obtained by substituting the chain extender from a diol to a diamine. The polyurethane-ureas (Table II) were obtained by changing the chain extender from a diol to a more reactive diamine. The polyurea-urethanes (Table III) were obtained by using a diamine terminated polyether instead of the carbowax. 

Aside from the type III cyclizations described above, acetals have seen limited use in intermolecular Prins reactionsand extensive use as initiators for cation-alkene cyclizations.Only limited success has been achieved in Lewis acid catalyzed addition of acetals to alkenes. Better success has been achieved in the synthesis of C-glycosides by Lewis acid catalyzed addition of glycosyl acetates or glycals to alkenes. Johnson has extensively developed the use of acetals as initiators for cation-alkene cyclizations. Recent studies have shown that excellent asymmetric induction can be obtained using chiral acetals derived from optically active 2,3-butanediol or 2,4-pentanediol. - ... 

Johnson and his co-workers developed two routes for the diol 95 corresponding to the carbonate 82 of Bartlett s synthesis. In their first approach (Scheme 11) (21), they coupled the acetal 89, derived from (/ ,/ )-2,4-pentanediol and 4-pemenal, with a-trimethylsilylacetone or the trimethylsilyl enol ether of acetone in the presence of titanium tetrachloride. The reaction took place... 

Treatment of a diol with chlorodiphenylphosphine in the presence of triethylainine or pyridine leads to diphosphinites. By this easy method, (S,S)-1,2-bis(diphenylphosphinoxy)cyclohexane (CHDPPO, 59) was obtained from (S,S)-l,2-cyclohexanediol (Section 4.1.2)23 58 and (5,S)-2,4-bis(diphenylphosphinoxy)pentane [(S,S)-BDPOP, (S.SV60] from (S,S)-2,4-pentanediol (Section 4.I.2.)59. In ref 59, the synthesis is described in detail from the beginning, i.e., the asymmetric synthesis of the diol by catalytic reduction of the diketone with Raney nickel modified with tartaric acid/sodium bromide. 

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