Lactones butyro

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). 

Scheme 2.77. Iodine-induced domino cyclization affording the pyrrolidino-butyro-lactone...

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. 

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

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

The growing market for birch control devices is driving the demand for tetrahydrofiirane while mothers milk substitutes create the gamma-butyro-lactone demand. Not really. Just checking to see if you re reading all this. Poly butylene terephthalate is an engineering thermoplastic being used in automobile and electrical components. Other minor uses include solvents, humectant, plasticizer, and pharmaceuticals. 

Oxazine derivatives are formed from unsaturated AAs. Vinylglycine, after epoxidation at the double bond, yielded methyl l,3-oxazin-2-one-4-carboxylate after treatment with sodium methoxide or p-chlorophenol (90TL2291). Similarly, some alkenes react with methyl a-methoxyhippurate and cyclization occurs with BF3-Et20 (75TL3737). In sulfuric acid butyro-lactones are formed. 

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>. 

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. 

Kricheldorf et al. reported an anionic polymerization of y-D,L-butyro-lactone or D,L-lactide with cyclic dibutyltin initiators, such as 2,2-dibutyl-2-stanna-l,3-dioxepane, to give cyclic polymers [ 138-140]. Figure 41 shows the ring expansion polymerization of lactone for synthesizing a cyclic polymer as an example. They also synthesized the cyclic polymer with a living mechanism in the polymerization of e-caprolactone [141]. 

The monomers that have been used for the synthesis include glycolide, lactide, (3-propiolactone, (3-butyro lactone, y-butyrolactone, 6-valerolactone, e-caprol-actone, l,5-dioxepan-2-one, pivalolactone, l,4-dioxane-2-one, 2-methylene-1, 3-dioxolane, 2-methylene-l, 3-dioxepane, etc. The structures of some of these monomers are given in Table 1. 

The structures of isotactic and syndiotactic stereoisomers of poly(/i-butyro-lactone) are presented in Figure 9.2. 

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). 

A solution of sodium methoxide is prepared from 50 g. (2.17 g. atoms) of freshly cut sodium and 600 ml. of absolute methanol (Note 1) in a 3-1. three-necked flask placed on a steam bath and equipped with a sealed stirrer (Note 2), dropping funnel, and a condenser set downward for distillation (Note 3). To the stirred solution is added in one portion 344 g. (4.0 moles) of 7-butyro-lactone (Note 4), and the flask is heated until methanol distils at a rapid rate. After 475 ml. of methanol is collected, a filter flask or other suitable device equipped with a side arm is connected to the condenser. This receiver is surrounded by an ice bath, and reduced pressure from an aspirator is applied cautiously (frothing) with continuous stirring. An additional 50-70 ml. of methanol is collected in this way. The residue presumably is dibutyrolactone (Note 5). 

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... 

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