5-Valerolactone, hydrolysis

The synthesis of 4-alkyl-y-butyrolactones 13 and 5-alkyl-<5-valerolactones 14 can be achieved in high enantiomeric excess by alkylation of ethyl 4-oxobutanoate and ethyl 5-oxopentanoate (11, n = 2, 3). The addition of diethylzinc, as well as dimethylzinc, leads to hydroxy esters 12 in high optical purity. When methyl esters instead of ethyl esters are used as substrates, the enantioselectivity of the addition reaction is somewhat lower. Alkaline hydrolysis of the hydroxy esters 12, followed by spontaneous cyclization upon acidification, leads to the corresponding y-butyro- and -valerolactones32. 

Levulinic acid is obtained by hydrolysis of cellulose-containing biomass. R D is actively conducted at DuPont Co. to employ levulinic acid for the synthesis of pyr-rolidones (solvents and surfactants), a-methylene-y-valerolactone [monomer for the preparation of polymers similar to poly(methyl methacrylate)], and levulinic acid esters (fuel additives) [26]. 

Lipases are enzymes of the hydrolase family and, in nature, hydrolyze fatty acid esters in aqueous environment. It is worth recalling that the hydrolysis of esters is a reversible reaction. Chemists thus often use lipases to catalyze the reverse reaction, i.e., the esterification and the ROP of lactones. In 1993, the groups of Kobayashi [91] and Knani [92] reported independently the hpase-catalyzed ROP of sCL and 8-valerolactone. The aliphatic polyesters were functionalized by a carboxylic group at one chain-end and a hydroxyl group at the other chain-end. Accordingly, the polymerization was initiated and terminated by water present in the reaction media. 

This compound on bromination, followed by hydrolysis of the ester group with hydrobromic acid and removal of carbon dioxide, gave a-brom-S-chlor-y-valerolactone, from which by treatment with ammonia 7-oxyproline was obtained —... 

Imidate salts having a syn conformation were also studied (33). Imidate salt 128 which has a syn conformation due to its cyclic structure, gave on basic hydrolysis a mixture of amidoalcohol 129 (66%), s-valerolactone (130, 33%) and dimethyl amine (33%). Likewise, the hydrolysis of imidate salt 131 gave a one to one mixture of the corresponding amidoalcohol 132 and y-butyro-lactone 133 plus dimethyl amine. 

Poly(e-caprolactone) (PCL) is synthesized by anionic, cationic or coordination polymerization of e-caprolactone. Degradable block copolymers with polyethylene glycol, diglycolide, substituted caprolactones and /-valerolactone can also be synthesized. Like the lactide polymers, PCL and its copolymers degrade both in vitro and in vivo by bulk hydrolysis, with the degradation rate affected by the size and shape of the device and additives. 

More advantageous is the use of solids acids and especially bifunctional catalysts, exhibiting acid sites for hydrolysis in combination with a metal (Rh, Pt, Ru, and Ni) for hydrogenation, which can be used, in appropriate solvents, for the direct conversion of cellulose into value-added chemicals (e.g. sorbitol, mannitol, ethylene glycol, hydroxymethylfurfural, 2,5-dimethyltetrahydrofuran, levulinic acid, valerolactone, and isosorbide) [33 36]. 

Ethyl-/3-methylglutaric acid has been prepared by the acid hydrolysis of a,a -dicyano- S-ethyl-fl-methylglutarimide, 3-cy-ano-4-ethyl-6-imino-2-keto-4-methylpiperidine-5-carboxamide or the diimide of 8-ethyl- 9-methylpropane-a,a,a, a -tetracarboxylic acid by the oxidation of jS-ethyl-fl-methyl-5-valerolactone with chromic acid and by the reaction of sodium hypobromite on l,4-dimethyl-l-ethyl-3,S-cyclohexanedione. ... 

The oxidation of tetrahydrofuran, tetrahydropyran and dihydropyran produced y-butyrolactone and 5-valerolactone in fairly good yields. Linear ethers, conversely, produced exclusively the corresponding acids, presumably through the in situ hydrolysis of intermediate esters [116]. 

The absolute configuration at C-2 of C was elucidated by identifying the (-f- )-/3-methyl-y-carboxy-y-valerolactone (CVII) with one of the two possible forms (threo or erythro). The cyanhydrin of ( )-j3-methyllevu-linic acid (CXVI) gave on hydrolysis two lactones (+ )-lactone A, CXVI (mp 151°-152° p-bromophenacyl ester, mp 86°-88°) and lactone B, CXVII (mp 65°-67° p-bromophenacyl ester, mp 105°-106°). Lactone B... 

Metalation of chiral oxazolines, derived from (15,25)-l-phenyl-2-amino-1,3-propanediol, followed by alkylation and hydrolysis, leads to optically active dialkylacetic acids, e.g. eq 22, 2-substituted butyrolactones and valerolactones, p-hydroxy and -methoxy acids, 2-hydroxy carboxylic acids, and 3-substituted alkanoic acids (eq 23). ... 

The second zone also contains carbohydrate opportunities, exemplified by, e.g., glycolic [73,104], pyruvic [105], lactic [74], and acrylic acids as well as glyoxal, glycolaldehyde [72, 106], acetic acid [71], erythritol [70], and y-valerolactone [47, 77]. A petrochemical route to these chemicals could be derived (e.g., the route to lactic acid via hydrolysis of acrylonitrile [107]), but in general, the carbohydrate route is likely to be cost-competitive. Glyoxal, acetic acid, and... 

Levulinic acid (4-oxopentanoic acid) obtained from cellulose and hemicellulose materials by acid-catalysed hydrolysis can be hydrogenated to y-valerolactone (5-methyldihydrofuran-2(3H)-one) which is a useful platform chemical precursor to liquid fuels, polymers and fine chemicals. Carbon-supported tin-ruthenium catalysts were active and selective in the hydrogenation of levulinic acid (Scheme 21.4). ... 

Valerolactones.— The unstable dihydropyran anion (73) may be useful for the preparation of a-substituted valerolactones the intermediate dihydropyrans are converted into the latter by acid hydrolysis and Collins oxidation. A new route to the c/s-fused valerolactone portion of vemolepin has been developed which could have other applications. It has been briefly noted that benzene-seleninic anhydride can be used to dehydrogenate fused valerolactones to the a,j8-unsaturated derivatives the conditions, however, are somewhat drastic (120 °C, 42 h). Unsaturated valerolactones can also be obtained from vinyl-oxirans by a light-induced reaction with pentacarbonyliron followed by carbonyl-ation. ... 

Previous reports of supramolecular catalysts focused on hydrolysis and coupling reactions to yield low-molecular-weight molecules. However, supramolecular catalysts for the preparation of polymers reminiscent of DNA polymerases were not reported. Harada and coworkers reported that CDs selectively form inclusion complexes with some lactones that act as starting materials of the polyesters. The hydrolysis of -caprolactone (e-CL) in the presence of aCD is suppressed in preference to e-CL alone but is promoted in the presence of pCD. Conversely, the hydrolyses of 8-valerolactone (8-VL) in the presence of aCD, pCD, and yCD, respectively, are suppressed, indicating that the hydrolysis of lactones depends on the sizes of the CDs and lactones (Figure 12.12). ... 

Several noteworthy routes to chiral butyrolactones have been reported this year. Chiral (i )-a-substituted butyrolactones (58) can be obtained from the oxazoline (56) with enrichments of 60—86% by condensation with ethylene oxide followed by O-silylation and alkylation (LDA-RX) to give (57), and finally hydrolysis. By reversing the condensation and alkylation steps, (5)-butyrolactones (58) can be obtained. Valerolactones can be similarly prepared but with slightly lower enrichments. 

The well known valerolactone (115), commonly described as the Prelog-Djerassi lactone, has attracted the attention of many synthetic chemists over the years and another synthesis of this important macrolide antibiotic intermediate has appeared (Scheme 13). The synthesis involves the Hg -induced cycliz-ation of the aldehyde (114) to control the stereochemistry at C(2) and C(3). This was followed by demercuration with sodium trithiocarbonate in methanol at -60 C, hydrolysis, and oxidation to give the lactone (115) and its epimer in a 3.5 1 ratio. Demercuration with sodium borohydride followed by hydrolysis and oxidation gave almost complete inversion. 

Synthesis of Valerolactones.—The remote chiral centres in the lactone (222) are produced in a controlled manner by conjugate addition to the macrolide (220) followed by hydrolysis of (221) and iodolactonization (Scheme 116). ... 

Dumesic and collaborators developed a process for the catalytic upgrading of levulinic acid to 5-nonanone, with the intermediate formation of y-valerolactone (Fig. 13.3). Levulinic acid can be obtained inexpensively and in high yields via acid hydrolysis of waste cellulosic materials. The process starts with the deconstruction of solid cellulose in an aqueous solution of sulfuric acid yielding an equimolar mixture of levulinic acid and formic acid. The formic... 

An integrated catalytic process for the efficient production of y-valerolactone (GVL) from furfural (Fur) through sequential transfer hydrogenation and hydrolysis reactions catalyzed by zeolites with Bronsted and Lewis acid sites is presented in Fig. 8.12. 

The culture Pseudomonas sp. NCIB 9872 was isolated from soil using cyclopentanol as the sole carbon source [9]. Cell-free extracts of the organism displayed alcohol dehydrogenase activity and BVase activity. To obtain energy from this carbon source, the pivotal step is ling fragmentation, made possible by oxidation of the alcohol to the cyclopentanone, followed by insertion of oxygen atom to S-valerolactone, and subsequent enzymatic hydrolysis to aliphatic hydroxy acids which are then converted to metabolites. The purified enzyme consists of four subunits (M 200,000), binds two to four molecules of FAD, and requires NADH as reductant. 

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