Diels-Alder reaction of butadiene with maleic anhydride

Dichlorodibutyl ether, 27 Diels-Alder reaction of butadiene with maleic anhydride, 93 Diene synthesis of cis-A -tetrahydro-phthalic anhydride, 93 Diethyl benzalmalonate, 84 Diethyl carbonate, 44 Diethyl fumarate, 46 Diethyl cis-HEXAiiYDROPiiTHALATE, 29 Diethyl malonate, 70 Diethyl o-nitrobenzoylmalonatc, 71 Diethyl sodium phthalimidomalonate, 7... 

With its concerted mechanism implying little charge distribution change along the pathway, the Diels-Alder reaction has been understood to have little rate dependence on solvent choice. For example, the relative rate of cyclopentadiene dimerization increases only by a factor of 3 when carried out in ethanol. The relative rate for the Diels-Alder reaction of isoprene with maleic anhydride (Table 7.1) varies by only a factor of 13 with solvents whose dielectric constants vary by almost a factor of 10, but the rate acceleration is not a simple function of the solvent polarity. Furthermore, the dimerizations of cyclopentadiene and 1,3-butadiene proceed at essentially identical rates in the gas and solution phases. ... 

The sulfenyl phthalimides are one of the oldest groups of fungicides and are effective, safe and persistent (B-77MI10706). Captan (59) is cheaply made from the Diels-Alder adduct of butadiene and maleic anhydride, followed by conversion to the imide and reaction with trichloromethanesulfenyl chloride. Folpet (60) and captafol (61) are similar in structure. 

The simplest example of a Diels-Alder reaction is the one that takes place between 1,3-butadiene and ethene. This reaction, however, takes place much more slowly than the reaction of butadiene with maleic anhydride and also must be carried out under pressure ... 

The relative orientations of the diene and dienophile in a favorable TS for a Diels-Alder reaction is predicted by Alder s endo-rule [33]. The Alder s endo-rule states that for Diels-Alder reactions of substituted butadiene derivatives with dienophiles having an electron-withdrawing substituent, kinetically controlled endo-TS will be preferred over exo-TS because of secondary orbital interactions of the electron-withdrawing substituent with the butadiene n system. The endo-TS has lower activation energy than that of exo-TS. The product derived from endo-TS is called kinetically controlled product and the product derived from exo-TS is called thermodynamically controlled product. Frequently a mixture of both stereoisomers is formed and sometimes the thermodynamically controlled cxo-product predominates. It has been observed that reaction of butadiene with maleic anhydride using deuterium-labeled butadiene gives 85 % of the endo-pioduct 50 from endo-TS [33]. The reaction of cyclopentadiene with maleic anhydride also gives 97.5 % cnJo-product 51. The secondary orbital interactions in preferred endo-TS are shown in Fig. 3.8. 

Reaction 1 The preparation of captan begins with the Diels-Alder addition of butadiene to maleic anhydride to form the 1,2,3,6-tetrahydrophthalic anhydride. 

Diels-Alder reaction, of acrolein with -butyl cyclohexenyl ether, n-butyl vinyl ether, and ethyl iso-propenyl ether, 34,30 of butadiene with maleic anhydride, 30,93... 

Knutson et al. (280) measured the kinetics of the Diels-Alder reaction of maleic anhydride (MA) and 2,3-dimethyl-1,3-butadiene (DMB) in SCF propane solutions at 100-140°C and 46-141 bar. Reaction to the product 4,5-dimethyl-CM-l,2,3,6-tetrahydrophthalic anhydride (DMTA) was evaluated with excess DMB as a reactive cosolvent and 2,2,2-trifluoroethanol (TFE) as an unreac-tive cosolvent (Scheme 21). Near-critical effects and cosolvent effects on reaction rates were analyzed from transition state theory. Rate constants increased with increasing pressure at 140 C, but were not significantly affected at 100°C and 120 C at near-critical densities. A similar lack of pressure dependence has been reported by Reaves and Roberts (281) for the Diels-Alder reaction of MA with isoprene in subcritical propane at 80°C. This minimal pressure effect is in contrast to those noted above for Diels-Alder reactions in SCCO2 where the reactants were at approximately equal and dilute concentrations. The influence of the unreactive cosolvent, TFT, on reaction rates was found to be minimal. These results suggest that the local reactant composition, as well as pressure, temperature, and cosolvent, can be used to control the reaction rate of such reactions in the near-critical region. 

A number of reactions do not seem to belong to any of the above mechanistic types. Such processes are referred to as multicenter reactions. The Diels-Alder cycloaddition reaction of 1,3-butadiene with maleic anhydride is an example (Scheme 5). No charged or odd election intermediates seemingly are involved in this reaction. 

Diels-Alder reactions of the type shown in Table 12.1, that is, Diels-Alder reactions between electron-poor dienophiles and electron-rich dienes, are referred to as Diels-Alder reactions with normal electron demand. The overwhelming majority of known Diels-Alder reactions exhibit such a normal electron demand. Typical dienophiles include acrolein, methyl vinyl ketone, acrylic acid esters, acrylonitrile, fumaric acid esters (fnms-butenedioic acid esters), maleic anhydride, and tetra-cyanoethene—all of which are acceptor-substituted alkenes. Typical dienes are cy-clopentadiene and acyclic 1,3-butadienes with alkyl-, aryl-, alkoxy-, and/or trimethyl-silyloxy substituents—all of which are dienes with a donor substituent. 

Although the Diels-Alder reaction of a conjugated diene, such as butadiene or isoprene, with maleic anhydride, has been known to yield tetrahydrophthalic anhydride, it has recently been shown (81, 85) that alternating copolymers are prepared under the influence of ionizing radiation (81) or free radical initiators (81, 85). The participation of the charge transfer complex as a common intermediate in both adduct... 

A report of Backer and Blaas6 is responsible for evolution of the present procedure these workers were first to conduct a Diels-Alder synthesis utilizing a 3-sulfolene in place of the free diene (by heating the cyclic adduct of sulfur dioxide and 2-methyl-3-thiomethyl-1,3-butadiene with maleic anhydride). The generality of the method as a variant of the conventional diene synthesis is limited largely by the availability of the appropriate 3-sulfolene its greatest utility, perhaps, will be presently realized in those diene reactions normally requiring 1,3-butadiene, since 3-sulfolene itself is now the least expensive and most widely available diene cyclic sulfone. 

Craig and coworkers have reported rate constants for the reaction of 2-substituted 1,3-butadienes with maleic anhydride in benzene at 25 °C their values are X, k Cl, 0,019 H, 0.19 Me, 0,57 Et, l.l5 /-Pr, 2.2 t-Bu, 5.6 OMe, 1.9. As the Diels-Alder reaction proceeds through the s-cis conformation of the diene, and substituents in the 2-and 3-positions can affect the fraction of the diene in this conformation, steric effects must be considered. The data set was correlated therefore with the CRS equation ... 

When catalyst 333 was applied in the cycloaddition reaction of 2-methoxy-l,3-butadiene (334) with /-(o-tolyl)maleimide (335), the conesponding cycloadduct 337a was obtained with only 58% ee. However, an ee of 95% was observed when catalyst 338 and N-(o-t-butylphenyl)maleimide (336) were employed (equation 94). The meta methyl substituents on the phenyl groups of catalyst 338 proved crucial for producing 337 with high enantioselectivity. In contrast, the Diels-Alder reaction of maleic anhydride with 2-methoxy-1,3-butadiene using catalyst 338 afforded a racemic adduct. These results were considered to result from a different complexation behavior of the catalyst in the case of maleic anhydride in comparison with, V-arylmaleimides-, ... 

The catalyst clearly makes methyl acrylate more electrophilic, however not much more electrophilic than maleic anhydride. This fact, together with the A5 value in the range typical of common Diels-Alder reactions, and with the stereochemical and orientational features mentioned, suggests that the catalysed reaction is similar in mechanism to the uncatalysed one . The electronic interactions that govern the course of the addition seem to be only strengthened. The stereochemistry of the AICI3 catalysed reaction of butadiene with 2-phenyl-2-cyclohexen-1-one favours, however, the existence of a dipolar intermediate. 

There are many examples of the Diels-Alder reaction (a [4+2] cycloaddition). In the reaction of 1,3-butadiene (1) with ethene, high temperatures are required for the reaction to generate cyclohexene. If 1-methoxyethene (5) is heated with 1,3-butadiene, the reaction requires heating to >200°C in a reaction bomb for several hours however, the yield of product (6) is lower than the yield of cyclohexene observed in the reaction with ethene. This result suggests that 5 is even less reactive than ethene. As shown in Section 24.1, the reaction of 1 and maleic anhydride (2) occurs in benzene at 100°C to give 3 (see the experiment from Section 24.1). 

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