7-Butyrolactone, preparation

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],... 

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. 

With Friedel-Crafts catalysts, butyrolactone reacts with aromatic hydrocarbons. With ben2ene, depending on experimental conditions, either phenylbutyric acid or 1-tetralone can be prepared (162). 

The lowest members of the series of perfluoroalkanedicarboxyhc acids have been prepared and are stable compounds. They have been synthesized by oxidation of the appropriate chlorofluoroolefin as well as by electrochemical fluorination and direct fluorination. Perfluoromalonic acid is an oxidation product of CH2=CHCE2CH=CH2 (21). Perfluorosuccinic acid has been produced by oxidation of the appropriate olefin (see eq. 7) (5) or by electrochemical fluorination of succinyl chloride or butyrolactone (41) and subsequent hydrolysis. 

Much more important is the hydrogenation product of butynediol, 1,4-butanediol [110-63-4]. The intermediate 2-butene-l,4-diol is also commercially available but has found few uses. 1,4-Butanediol, however, is used widely in polyurethanes and is of increasing interest for the preparation of thermoplastic polyesters, especially the terephthalate. Butanediol is also used as the starting material for a further series of chemicals including tetrahydrofuran, y-butyrolactone, 2-pyrrohdinone, A/-methylpyrrohdinone, and A/-vinylpyrrohdinone (see Acetylene-DERIVED chemicals). The 1,4-butanediol market essentially represents the only growing demand for acetylene as a feedstock. This demand is reported (34) as growing from 54,000 metric tons of acetylene in 1989 to a projected level of 88,000 metric tons in 1994. 

Fig. 7. Preparation of Alpine-borane (93) and use in the synthesis of homochiral butyrolactones and arylhydroxytetronic acids. Rg and denote small and...

Methyl-2-Pyrrolidinone. N-Meth5l-2-pyrrohdinone [872-50-4] (44) (NMP or methyl-2-pyrrohdone, M-Pyrol) was fkst reported in 1907 as prepared by alkylation of 2-pyrrohdinone with methyl iodide (81). The present commercial route, ie, condensation of butyrolactone with methylamine, was first described in 1936 (50). 

A number of other N-substituted 2-pyrroHdinones have been offered commercially or promoted as developmental products. These materials offer different and sometimes unique solvency properties. AH are prepared by reaction of butyrolactone with suitable primary amines. Principal examples are Hsted in Table 4. 

The monomer is prepared from acetylene, formaldehyde and ammonia via but-2-yne-1,4-diol, butane-1,4-diol, y-butyrolactone and y-pyrrolidone (Figure 17.8). 

Fig. 2.4. Preparative chromatographic resolution of 5 g of )/-phenyl-)>-butyrolactone on 480 g of CTA I (column 5 cm x 60 cm). [Reproduced from Helv. Chim. Acta 70 1569 (1987) by permission of Verlag Helvetica Chimica Acta, A.G.]...

Perfluoro-y-butyrolactone can be prepared from 1,4 diiodoperfluorobutane by reaction with turning sulfuric acid (oleum) [7S] (equation 19) The yield depends on the concentration of sulfur trioxide One of the by-products, 4-iodoperfluo-robutyryl fluoride, can be recycled to increase the overall yield of the lactone Pure sulfur trioxide generates only perfluorotetrahydrofuran, the lodo acyl fluoride, and perfluorosuccmyl fluoride... 

Hydrazoic acid reaction with cyclobu-tanecarboxyhc acid, 47, 28 Hydrogenation of t butylazidoacetate to glycme ( butyl ester, 46,47 Hydrogen bromide 46, 43 reaction with y butyrolactone, 46, 43 Hydrogen fluoride anhydrous, precautions in use of, 46, 3 in preparation of mtromum tetra-fluoroborate 47, 57 reaction with benzoyl chloride, 46,4 with boron tnfluonde in conversion of p cymene to m cymene, 47, 40 in bromofluorination of 1 heptene, 46, 11... 

The conversion of vicinal azido selenides into tetrahydrofiirans by PhSeOTf in MeCN at room temperature is reported <96JOC7085>. 3-Butadienyl tetrahydrofiirans and a-butadienyl y-butyrolactones can be prepared by radical cyclization of P-bromopent-4-en-2-ynyl ethers and mixed acetals <96SL391>. The total synthesis of trilobacin was reported <96JOC7642>. 

Homoenolate Reactivity The ability to generate homoenolates from enals and its application to the preparation of y-butyrolactones 30, through reaction with an aldehyde or aryl trifluoromethyl ketone, was reported independently by Glorius [8], and Bode and Burstein [9] (Scheme 12.4). A sterically demanding NHC catalyst is required to promote reactivity at the d terminus and to prevent competitive benzoin dimerisation. Nair and co-workers have reported a similar spiro-y-lactone formation reaction using cyclic 1,2-diones, including cyclohexane-1,2-dione and substituted isatin derivatives [10]. 

As noted in Section 12.2.2, homoenolates can be accessed from enals. Glorias and co-workers have nsed pre-catalyst 159 to prepare y-butyrolactones from enals enanti-oselectively, thongh ees of up to only 25% were obtained (Scheme 12.34) [8],... 

The preparation of ketenes has been discussed by Hanford and Sauer in Organic Reactions Dimethylketene has been prepared by the treatment of a-bromoisobutyryl bromide with zinc,3 and by the pyrolysis of isobutyrylphthalimide,4 dimethylmalonic anhydride,6 or a-carbomethoxy-a,j3-dimethyl- -butyrolactone. Dimethylketene dimer has been prepared by heating isobutyryl chloride with a tertiary amine. Pyrolysis of the dimer yields dimethylketene.7... 

Moreover, Kim and coworkers have shown that a-amino-butyrolactones can be synthesized by a related process employing the amino acid homoserine with an unprotected hydroxy functionality [31]. In a more recent publication by the same research group, morpholin-2-one derivatives of type 9-37 have been prepared (Scheme 9.6) [32]. Herein, glycolaldehyde dimer 9-32 acts as a bifunctional compound, which first reacts with the a-amino acids 9-33 to give the iminium ions 9-34,... 

Analogous alkoxides, phenoxides, and carboxylates will also initiate the ROP of epoxides, all forming propagating alkoxide species.779 Block copolymers of epoxides with /3-butyrolactone have been prepared via the addition of EO or PO to living poly(ester) chains.782 The oxygen-bound enolate of living PMMA will also react with epoxides to yield diblocks such as PEO-b-PMMA and PPO-b-PMMA (Mn= 12,800, Mw/Mn = 1.16) 787... 

The hydrocarboxylation of suitably substituted hydroxyalkylacetylenes and alkenes has been widely used to prepare a variety of butenolides and butyrolactones (see Scheme 63101,102 and Refs. 8 and 10a for reviews of earlier literature) a closely related reaction is shown in Scheme 64.103,104... 

In a 500-ml. three-necked flask fitted with a sealed mechanical stirrer and a reflux condenser are placed 86 g. (1 mole) of 7-butyrolactone (Note 1) and 72 g. (1.1 moles) of potassium cyanide (Note 2). As the contents of the flask are stirred, the mixture is heated in an oil bath for 2 hours at a temperature of 190-195° (Note 3). There is an initial vigorous reaction which soon subsides. After the completion of the heating period the mixture is cooled to about 100°, and the potassium salt of the cyano acid is dissolved in about 200 ml. of hot water. The warm solution is cautiously acidified to Congo Red by the addition of about 90 ml. of concentrated hydrochloric acid. The resultant solution, which contains glutaric acid monoamide and potassium chloride, is used to prepare glutaric acid or glutarimide. 

Mitsubishi have reported several processes based on Ru-catalyzed hydrogenation of anhydrides and acids. Succinic anhydride can be converted into mixtures of 1,4-butane-diol and y-butyrolactone using [Ru(acac)3]/trioctylphosphine and an activator (often a phosphonic acid) [97]. Relatively high temperatures are required ( 200°C) for this reaction. The lactone can be prepared selectively under the appropriate reaction conditions, and a process has been developed for isolating the products and recycling the ruthenium catalyst [98-100]. 

Hydroxy-y-butyrolactone, 46, 24 4-Hydroxycrotononitrile, by-product in preparation of 3-hydroxyglutaro-nitrile, 46, 49... 

Allenyl ethers are useful key building blocks for the synthesis of a-methylene-y-butyrolactones [129, 130], The synthesis of the antileukemic botryodiplodin was accomplished with the crucial steps briefly presented in Scheme 8.56. Bromoallenyl ethers 225 were easily prepared by base-induced isomerization from the corresponding /3-bromoalkyl alkynyl ether compounds and then subjected to electrophilic bro-mination with NBS. The resulting acetals 226 were converted into 2-alkoxy-3-methy-lenetetrahydrofurans 227 by dehydrohalogenation of the alkenyl bromide unit to an alkyne and subsequent radical cyclization employing tributyltin hydride [130],... 

Synthetic methods. / / -Dimethylglutaric acid (prepared from mesityl oxide) was converted into the di-silver salt, which, by an improvement of the method of Windaus and Klanhardt, was converted into / / -dimethyl-y-butyrolactone. The latter on treatment with constant-boiling hydrobromic and sulphuric acid gave y bromo /i/ dimethylbutyric acid which readily gave its ethyl ester. The pure fluoro ester was obtained from this by heating with silver fluoride, although the yield was low. 

An obvious way to target chiral compounds is to start with a compound in which the chiral center is already present. Here natural products and derivatives offer a rich pool of generally inexpensive starting materials. Examples include L-hydroxy and amino adds. Sometimes, just one out of many chiral centers is predestined to remain, as in the synthesis of vitamin C from D-glucose, or in the preparation of (S)-3-hydroxy-y-butyrolactone from ladose. 

Similarly, 5-lactols and 5-lactones are obtainable from the corresponding homo allylic alcohols. With dehydration, the corresponding dihydropyrans are prepared. Spirocyclic y-butyrolactones of this type and the corresponding 5-lactones are widespread in nature and play a key role as synthetic intermediates. 

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

Polymers containing pendant carbamate functional groups can be prepared by the reaction of phenyl isocyanate with poly(vinyl alcohol) in homogeneous dimethylsulfoxide solutions using a tri-ethylamine catalyst. These modified polymers are soluble in dimethyl sulfoxide, dimethylacetamide, dimethylformamide and formic acid but are insoluble in water, methanol and xylene. Above about 50% degree of substitution, the polymers are also soluble in acetic acid and butyrolactone. The modified polymers contain aromatic, C = 0, NH and CN bands in the infrared and show a diminished OH absorption. Similar results were noted in the NMR spectroscopy. These modified polymers show a lower specific and intrinsic viscosity in DMSO solutions than does the unmodified poly(vinyl alcohol) and this viscosity decreases as the degree of substitution increases. 

Cyclic carbonates have been prepared in the regiospecific ring-opening of oxiranes by butyrolactones catalysed by the quaternary ammonium salt (Scheme 3.6)... 

Synthesis of 4-(2-Bromo-2-Propenyl)-4-Methyl-Y-Butyrolactone by the Reaction of Ethyl Levulinate with (2-Bromoailyl)diisopropoxyborane Prepared by Haloboration of Allene. 

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