2- butyrolactones

Butyrolactones. - A variety of ruthenium3 4 and rhodium hydride30 complexes have been tested for their suitability as dehydrogenation catalysts for the oxidation of 1,4-diols into butyrolactones. with 2-substituted and 2,2-disubstituted diols, the regioselectivity can be almost complete and the accompanying excellent yields make the overall transformation ((336) - (337) ] a genuinely viable proposition. 

5-Pentanediols can similarly be transformed into valerolactones. An alternative approach to lactones (337) is by oxidation of the corresponding tetrahydrofurans this can be achieved using mixtures of sodium bromate, NaBrC, and 47% hydrobromic acid.306 No regioselectivity studies have yet been reported with this method. A 

A key feature of this reagent is its inability to oxidise primary and secondary alcohols, which allows the preparation of mono- and bicyclic 

Reagents i, MnlOAc), RSSR, TFA, CH C Basic hydrolysis iii, CoCt2, H20 

Some new carbonylation procedures have been reported in this area. A variety of 1-alkynes (340) are regiospecifically 

Substituted butyrolactones are formed in moderate yields by the photoalkylation of alcohols to 5,6-dihydro-2-pyrone.  

Activated zinc has been found to promote the reaction of dimethyl maleate with carbonyl compounds to give y-butyrolactone derivatives in yields between 

DeKimpe, L. DeBuyck, and N. Schamp, Synth. Commun., 1981,11, 35. 

23 and 86% Benzoyl peroxide-catalysed addition of bromo-acids to olefins,  

Reagents i. LDA-HMPA-R X ii, LDA-HMPA-R X iii, HCl-MeOH iv, LAH v, NaI04-H20 vi, Jones oxidation 

The potent biological action of many natural products isolated from plants and their ability to inactivate certain selected enzymes have been attributed to the 

To address the remarkable ot-substituted effects, the Pd-catalyzed allylation of benzaldehyde with a,p- and p,y-disubstituted allylic benzoates has been investigated. Using MBH adducts as substrates, a-methylene-8-butyrolactones (cis-lVt) were obtained exclusively via Pd-catalyzed allylation and spontaneous 

Ayalon-Chass, E. Ehlinger, and P. Magnus, J.C.S. Chem. Comm., 1977, 772. 

Enolates of succinic and methylsuccinic anhydride can be generated using the highly hindered base (33), previously reported to be capable of reacting specifically with esters and methyl ketones while aldehydes are ur aflfected. Coupling of such enolates with aldehydes leads to 3-methoxycarbonyl-4-substituted butyrolactones (34) in yields generally above 70%. 

Kasahara, T. Izumi, K. Sato, M. Maemura, and T. Hayasaka, Bull. Chem. Soc. Japan, 1977, 50, 1899. 

An alternative method to halolactonization of unsaturated acids consists of reaction with triethylamine followed by benzenesulphenyl chloride to give phenyl-thio-lactones (e.g. 42). Elimination of the sulphur group by standard methods gives saturated or unsaturated fused lactones. Essentially the same method, but using phenylselenenyl chloride, has also been reported. Vinyloxirans undergo carbonyl insertion when treated with iron pentacarbonyl oxidation of the resulting complexes (e.g. 43) with cerium(iv) gives (44) as the only lactone isolated.  

Michael fashion to but-2-en-4-olide to give largely one diastereoisomer (267) accompanied only by the C-1 ( ) epimer. 

Presumably, therefore, optically active -substituted butyrolactones could be obtained by starting with a chiral sulphoxide. Related conjugate additions to 

5-Alkenylbutenolides (271) can be readily obtained from the corresponding but-2-en-4-olides by kinetic enolization and 

Systematic studies have shown that intramolecular [2+2] cycloadditions of unsaturated ketenes or ketiminium salts (278) constitute a simple and reasonably general approach to cyclobutanones (279), which are useful as precursors to butyrolactones following Baeyer-Villiger oxidation. The potential of this method is clearly shown by the efficient formation of the bicyclo[5.2.0]nonane (280) and of the 

B-hydroxy-acid using monomethyl malonate followed by enolization 

Peroxydisulphuryl difluoride [(FS03)2l, which is generated electrochemically from fluorosulphonic acid and potassium fluorosulphate, oxidizes carboxylic acids to give single lactones as major products, usually y- or 8-isomers, depending on the acid chain length.  

A convenient method of converting alkyl amides into 4-alkylbutyrolactones in moderate yields has appeared. Acid-catalysed condensations between arylpyruvic acids and aromatic aldehydes give access to ketolactones of type (41) in good 

An asymmetric approach to the aldehyde lactone (44), an intermediate in 12-methylprostaglandin synthesis, has been outlined. Incubation of diacetate (45) with Bacillus subtillus affords monoacetate (46) which may be converted into the fused lactone (47) of 35 % optical purity. Conditions have been found for the efficient cyclization of methyl 6,7-epoxycitronellate to the puleganolides (48). 

Bertrand, J. P. Dulcere, G. Gil, J. Grimaldi, and P. Sylvestre-Panthet, Tetrahedron Letters, 1976, 3305. 

Cyclization of an acyclic terpene has also been utilized to prepare the actinidiolide derivatives (49) and (50) from the phenyl sulphone of geraniol following carboxy-lation, acid catalysed cyclization and desulphurization. 

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C. Manufactured from butyrolactone and ammonia. Easily hydrolysed to 4-amino-butanoic acid, its most important use is for the formation of N-vinylpyrrolidone by reaction with elhyne. 

The procedure (with ethylene dibromide replacing trimethyleiie dibromide) described for cycZobutanecarboxylic acid (previous Section) does not give satisfactory results when applied to the cyclopropane analogue the yield of the cyclopropane-1 1 dicarboxylic acid is considerably lower and, furthermore, the decarboxylation of the latter gives a considerable proportion (about 30 per cent.) of butyrolactone ... 

Supplement (combined with Volumes XVIII and XIX) XVII, 2nd 1934 2359-3031 Hydroxy compounds Furfuryl alcohol, 112. Carbonyl compounds Butyrolactone, 234. Furfural, 272. 2-Aoetyl-thio-phene, 287. Xanfhone, 366. Succinic anhydride, 404. Phthalio anhydride, 469. 

The conversion of primary alcohols and aldehydes into carboxylic acids is generally possible with all strong oxidants. Silver(II) oxide in THF/water is particularly useful as a neutral oxidant (E.J. Corey, 1968 A). The direct conversion of primary alcohols into carboxylic esters is achieved with MnOj in the presence of hydrogen cyanide and alcohols (E.J. Corey, 1968 A,D). The remarkably smooth oxidation of ethers to esters by ruthenium tetroxide has been employed quite often (D.G. Lee, 1973). Dibutyl ether affords butyl butanoate, and tetra-hydrofuran yields butyrolactone almost quantitatively. More complex educts also give acceptable yields (M.E. Wolff, 1963). 

The 4-hydroxy-1-alkene (homoallylic alcohol) 81 is oxidized to the hetni-acetal 82 of the aldehyde by the participation of the OH group when there is a substituent at C3. In the absence of the substituent, a ketone is obtained. The hemiacetal is converted into butyrolactone 83[117], When Pd nitro complex is used as a catalyst in /-BuOH under oxygen, acetals are obtained from homoallylic alcohols even in the absence of a substituent at C-3[l 18], /-Allylamine is oxidized to the acetal 84 of the aldehyde selectively by participation of the amino group[l 19],... 

As an application of maleate formation, the carbonylation of silylated 3-butyn-l-ol affords the 7-butyrolactone 539[482], Oxidative carbonylation is possible via mercuration of alkynes and subsequent Lransmetallation with Pd(II) under a CO atmosphere. For example, chloromercuration of propargyl alcohol and treatment with PdCF (1 equiv.) under 1 atm of CO in THF produced the /3-chlorobutenolide 540 in 96% yield[483]. Dimethyl phenylinale-ate is obtained by the reaction of phenylacetylene, CO, PdCU, and HgCl2 in MeOH[484,485]. 

The reaction of a halide with 2-butene-1,4-diol (104) affords the aldehyde 105, which is converted into the 4-substituted 2-hydroxytetrahydrofuran 106, and oxidized to the 3-aryl-7-butyrolactone 107[94], Asymmetric arylation of the cyclic acetal 108 with phenyl triflate[95] using Pd-BINAP afforded 109, which was converted into the 3-phenyllactone 110 in 72% ee[96]. Addition of a molecular sieve (MS3A) shows a favorable effect on this arylation. The reaction of the 3-siloxycyclopentene 111 with an alkenyl iodide affords the. silyl... 

The acylpalladium complex formed from acyl halides undergoes intramolecular alkene insertion. 2,5-Hexadienoyl chloride (894) is converted into phenol in its attempted Rosenmund reduction[759]. The reaction is explained by the oxidative addition, intramolecular alkene insertion to generate 895, and / -elimination. Chloroformate will be a useful compound for the preparation of a, /3-unsaturated esters if its oxidative addition and alkene insertion are possible. An intramolecular version is known, namely homoallylic chloroformates are converted into a-methylene-7-butyrolactones in moderate yields[760]. As another example, the homoallylic chloroformamide 896 is converted into the q-methylene- -butyrolactams 897 and 898[761]. An intermolecular version of alkene insertion into acyl chlorides is known only with bridgehead acid chlorides. Adamantanecarbonyl chloride (899) reacts with acrylonitrile to give the unsaturated ketone 900[762],... 

The a-bromo-7-lactone 901 undergoes smooth coupling with the acetonyltin reagent 902 to afford the o-acetonyl-7-butyrolactone 903[763j. The o-chloro ether 904, which has no possibility of //-elimination after oxidative addition, reacts with vinylstannane to give the allyl ether 905, The o -bromo ether 906 is also used for the intramolecular alkyne insertion and transmetallation with allylstannane to give 907[764],... 

Butyrolactones are prepared by intramolecular reaction of haloallylic 2-alkynoates. The a-chloromethylenebutyrolactone 301 is prepared by the intramolecular reaction of300[150,151]. 4 -Hydroxy-2 -alkenyl 2-alkynoates can be used instead of haloallylic 2-alkynoates, and in this reaction, Pd(II) is regenerated by elimination of the hydroxy group[152]. As a related reaction, the q-(chloromethylene)-7-butyrolactone 304 is obtained from the cinnamyl 2-alkynoate 302 in the presence of LiCl and CuCbflSS]. Isohinokinin (305) has been synthesized by this reaction[l 54]. The reaction is explained by chloro-palladation of the triple bond, followed by intramolecular alkene insertion to generate the alkylpalladium chloride 303. Then PdCb is regenerated by attack of CuCb on the alkylpalladium bond as a key step in the catalytic reaction. 

Indoles can also be alkylated by lactones[l4]. Base-catalysed reactions have been reported for (3-propiolactone[15], y-butyrolactone[10] and 5-valerolac-tone[10]. These reactions probably reflect the thermodynamic instability of the N -acylindole intermediate which would be formed by attack at the carbonyl group relative to reclosure to the lactone. The reversibility of the JV-acylation would permit the thermodynamically favourable N-alkylation to occur. 

These trivial names are permitted -y-butyrolactone, -y-valerolactone, and 5-valerolactone. Names based on heterocycles may be used for all lactones. Thus, -y-butyrolactone is also tetrahydro-2-furanone or dihydro-2(3/f)-furanone. 

PORONCOMPOUNDS - BORIC ACID ESTERS] (Vol 4) a,g,g-Trimethyl-g-butyrolactone [2610-96-0]... 

Because of its relatively high, price, there have been continuing efforts to replace acetylene in its major appHcations with cheaper raw materials. Such efforts have been successful, particularly in the United States, where ethylene has displaced acetylene as raw material for acetaldehyde, acetic acid, vinyl acetate, and chlorinated solvents. Only a few percent of U.S. vinyl chloride production is still based on acetylene. Propjiene has replaced acetylene as feed for acrylates and acrylonitrile. Even some recent production of traditional Reppe acetylene chemicals, such as butanediol and butyrolactone, is based on new raw materials. 

With various catalysts, butanediol adds carbon monoxide to form adipic acid. Heating with acidic catalysts dehydrates butanediol to tetrahydrofuran [109-99-9] C HgO (see Euran derivatives). With dehydrogenation catalysts, such as copper chromite, butanediol forms butyrolactone (133). With certain cobalt catalysts both dehydration and dehydrogenation occur, giving 2,3-dihydrofuran (134). 

Uses. The largest uses of butanediol are internal consumption in manufacture of tetrahydrofuran and butyrolactone (145). The largest merchant uses are for poly(butylene terephthalate) resins (see Polyesters,thermoplastic) and in polyurethanes, both as a chain extender and as an ingredient in a hydroxyl-terminated polyester used as a macroglycol. Butanediol is also used as a solvent, as a monomer for vadous condensation polymers, and as an intermediate in the manufacture of other chemicals. 

Butyrolactone. y-Butyrolactone [96-48-0] dihydro-2(3H)-furanone, was fkst synthesized in 1884 via internal esterification of 4-hydroxybutyric acid (146). In 1991 the principal commercial source of this material is dehydrogenation of butanediol. Manufacture by hydrogenation of maleic anhydride (147) was discontinued in the early 1980s and resumed in the late 1980s. Physical properties are Hsted in Table 4. 

Butyrolactone is completely miscible with water and most organic solvents. It is only slightly soluble in aUphatic hydrocarbons. It is a good solvent for many gases, for most organic compounds, and for a wide variety of polymers. 

Rea.ctlons, Butyrolactone undergoes the reactions typical of y-lactones. Particularly characteristic are ring openings and reactions in which ring oxygen is replaced by another heteroatom. There is also marked reactivity of the hydrogen atoms alpha to the carbonyl group. 

With acid catalysts, butyrolactone reacts with alcohols rapidly even at room temperature, giving equiUbtium mixtures consisting of esters of 4-hydroxybutyric acid [591-81-1] with unchanged butyrolactone as the main component. Attempts to distill such mixtures ordinarily result in complete reversal to butyrolactone and alcohol. The esters can be separated by a quick flash distillation at high vacuum (149). 

When butyrolactone and alcohols are heated for long times and at high temperatures in the presence of acidic catalysts, 4-alkoxybutytic esters are formed. With sodium alkoxides, sodium 4-alkoxybutyrates are formed (150). 

Butyrolactone and hydrogen sulfide heated over an alumina catalyst result in replacement of ring oxygen by sulfur (151). 

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