Y-butyro lactone

High exoselectivity in Diels-Alder addition of a-vinylidene and a-methylene-y-butyro-lactones to cyclopentadiene [98]... 

Tetrahydrofuran has been reported to exhibit an absorption maximum at 280 nm (52,56), but several workers have shown that this band is not produced by the purified solvent (30,41,57). Oxidation products from THF have been invoked in order to account for the appearance of the 280-nm band in PVC films that are solvent-cast from THF in air (57. 581. However, in some reported cases (56,59), this band was undoubtedly produced, at least in part, by a phenolic antioxidant (2.6-di-tert-butyl-p-cresol)(59) in the solvent. Since certain -alkylphenols have now been shown to be powerful photosensitizers for the dehydrochlorination of PVC (60), it is clear that antioxidant photosensitization might well have been responsible for some of the effects attributed previously (56) to THF alone. On the other hand, enhanced rates of photodegradation under air have also been observed for PVC films cast from purified THF (57), a result which has been ascribed to radical formation during the photooxidation of residual solvent (57,61). Rabek et al. (61) have shown that this photooxidation produces a-HOO-THF, a-HO-THF, and y-butyro-lactone, and they have found that the hydroperoxide product is an effective sensitizer for the photodehydrochlorination of PVC at X = 254 nm (61). 

Terpolymers of 3HB, 3HV, and 5-hydroxyvalerate (5HV) were obtained from R. eutropha grown with mixtures of 5-chloropentanoic acid and pentanoic acid [25], and PHAs containing 3HB units and 4-hydroxybutyrate (4HB) units have been produced by R. eutropha grown with mixtures of glucose and y-butyro-lactone [26]. The mole fraction of 4HB unit in these PHAs varied as a function of the concentration of carbon sources and pH of the culture. PHAs containing 5HV or 4HB were less crystalline and were biodegraded more readily than poly(3HB) or poly(3HB-co-3HV). 

Substrate Temperature rq Time [h] Conversion [%] Yield of y-butyro-lactone [%]b)... 

An allenylaldehyde can be transformed efficiently into an a-methylene-y-butyro-lactone by a ruthenium-catalyzed carbonylative cycloaddition process (Scheme 16.34) [37]. The reaction mechanism may involve a metallacyclopentene, which undergoes insertion of CO and reductive elimination leading to the product. 

Carbonylation of alkynes to give 2-substituted 4-methyl-y-butyro-lactones (Table 8.9)... 

Nair and co-workers reported the diastereoselective synthesis of spiro y-butyro-lactones from 1,2-dicarbonyls [125]. The authors studied the reaction with 1,2-cyclohexane dione 230 which produces the desired lactone 232 in good yields Eq. 22a. Isatins 233 are more reactive, but the products 235 are obtained as a 1 1 separable mixture of diastereomers Eq. 22b. The Nair research group extended this methodology to include homoenolate addition to tropanone 236 to form bicyclic 5-lactones 238 Eq. 22c [126]. 

Pyrano-fused heterocycles, namely pyrano[3,2-f]quinoline-2,5(6//)-diones, pyrano[3,2-f]benzopyran-2,5(6//)-dione, and pyrano[3,2-f]pyridine-2,5(67T)-diones, have been efficiently prepared by the condensation of 4-hydroxy-2-(l//)-quinolines, 4-hydroxycoumarin, or 4-hydroxy-(17/)-pyridone with a-acetyl-y-butyrolactone or the sodium salt of a-formyl-y-butyro-lactone in the presence of ammonium acetate <1999JHC467>. 

SYNTHESIS OF 4-(2-BROMO-2-PROPENYL)-4-METHYL-y-BUTYRO-LACTONE BY THE REACTION OF ETHYL LEVULINATE WITH (2-BROMO-ALLYL)DIISOPROPOXYBORANE PREPARED BY HALOBORATION OF ALLENE... 

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. 

Reaction of the enol ether 58 with dimethyl diazomalonate provides the spiro compound 59 in high yield. Reduction and acid catalyzed cyclopropane cleavage gives the unsaturated y-lactol 60 which can be oxidized to p-methylene y-butyro-lactone 61 20). 

The formation of the new C-C bond (stable b) in the Robinson mechanism101 of the Fischer indole synthesis, could be justified only after the isolation of the dienone imine intermediate during the indolization of the phenylhydrazone. Many attempts were made102-106 to isolate such an intermediate. The reported a-ketimino-/3-(o-aminophenyl)-y-butyro-lactone hydrochloride,104 107 and 3-acetylamino-2-(o-aminophenyl)-2-butene106 were proved by NMR not to be the dienone imines, but were found to have structures 20103 and 21,108 respectively. Recently, the... 

Ethyl a-(bromomethyl)acrylate has proved to be an excellent reagent for conversion of aldehydes and ketones, both acyclic and cyclic, into the corresponding a-methylene-y-butyrolactone derivatives " in a Re-formatsky type reaction. The yield was excellent in the case of several spiro a-methylene-y-butyrolactones. Synthetic a-methylene-y-butyro-lactone derivatives have been shown to possess antitumor activity. " Ethyl a-(bromomethyl)acrylate has also proven of value in the synthesis of alkylated products of enol ethers of cyclohexane-1,3-dione. ... 

The highly stereoselective synthesis of contiguously substituted y-butyro-lactones 347 takes place by the [2,3]-sigmatropic rearrangement of eight-... 

Five-membered unsubstituted lactone, y-butyro-lactone (y-BL), is not polymerized by conventional chemical catalysts. However, oligomer formation from y-BL was observed by using PPL or Pseudomonas sp. lipase as catalyst.1523 157 d-Valerolactone (<3-VL, six-membered) was polymerized by various lipases of different origin to give the polymer with Mn of several thousands.148 Another six-membered lactone, l,4-dioxan-2-one, was polymerized by Candida antarctica lipase (lipase CA) to give the polymer with Mw higher than 4 x 104.158 The resulting polymer is expected as a metal-free polymeric material for medical applications. 

Castiglioni, G.L. Fumagalli, C. Guercio, A. Lancia, R. Messori, M. Vaccari, A. Vapor-phase hydrogenation of maleic anhydride to y-butyro-lactone 2. Role of reaction parameters. Erdol Kohle-Erdgas-Petrochem. 1994, 47, 337-341. 

This zinc-promoted reaction has been used with a variety of carbonyl compounds. Thus, the Luche conditions were applied in a synthesis of (-1-)-muscarine using an aldehyde derived from ethyl lactate [109]. Allyl halide condensation onto a-ketoamides of proline benzyl ester gave good diastereoselec-tivity when performed in the presence of zinc dust and pyridinium p-toluene-sulfonate in a water/THF mixture. In this way, a-hydroxy ketones were obtained with good enantioselectivity after removal of the chiral auxiliary [110]. Reactions of allyl bromide under the Luche conditions with y-aldo esters afforded y-hydroxy esters, which were converted in a one-pot reaction to y-allyl-y-butyro-lactones (Scheme 22) [111]. 

Production of (R)-4-Chloro-3-hydroxy-butyrate (CHB) and (S)-3-Hydroxy-y-butyro-lactone (HL) by Enterobacter sp. 

Recently, catalytic hetero-[2 + 2 + 1]-cycloaddition of a carbon—carbon multiple bond, a carbon—heteroatom bond, and carbon monoxide, the so-called hetero-Pauson—Khand reaction, has been used frequently for the synthesis of functionalized y-butyro-lactones and y-butyrolactams 381 (Scheme 120). 

Asymmetric hydrogenation of 2- and 4-alkylidene-y-butyro-lactones.1 This reaction can be effected by catalysis with Ru(ll)/(S)- or (R)-BINAP in 94-98% cc regardless of the geometry of the olefinic group. This method is also applicable to 2-alkylidcnecyclopentanes. 

They also used this general method for synthesis of a-methylene-y-butyro-lactone (equation II). 

Polyurethanes (uncross-linked) Formic acid, y-butyro-lactone, dimethylformamide, m-cresol Methanol, diethyl ether, hydrocarbons... 

The Hantzsch reaction has also been incorporated in a multi-component reaction described by Rao et al. to produce 2-pyrazol 4-yl-substituted diiazole system in one step. The reaction involves a one-pot cyclization to form thiazole, pyrazolone and cyclopropane rings via the reaction of aryl bromomethylketonewith, thiosemicarbazide, and a-acetyl-y-butyro lactone in phosphorus oxychloride. 

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