From Substituted Maleic Anhydrides

A complementary procedure for the preparation of ylidenebutenolides from maleic anhydrides, which has several advantages over the Grignard-and Perkin-type approaches, employs phosphoranylides. This approach was first applied in the synthesis of alkylidenephthalides e.g. 162) by reaction between phthalic anhydride and the appropriate triphenylphos-phorane 133). Interestingly, the condensations involving phosphoranes 

Massy-Westropp and co-workers 135) have used the -ylidenebutenolide (165, R=Me) in an alternative synthesis of freelingyne (33). Thus, Reformatsky reaction between the butenolide and the furylpropargyl bromide (170) first gave the / r/-alcohol (171 a). Flash vacuum pyrolysis of the derived acetate (171 b) then led to a mixture of geometrical isomers of freelingyne, one of which was identical with the natural metabolite. 

In studies of the reactions between 2-methoxysubstituted maleic anhydrides viz 172) and the stabilized phosphoranes (161) and (164), it has been shown that the condensations are regioselective leading to those products viz 173) resulting from nucleophilic addition to the carbonyl functions nearest to the methoxy-substituent 136). 

The biosynthesis of pulvinic acids in lichens has recently been shown to proceed via enzymatic oxidative rearrangement of hydroxyterphenyl-quinones (see biosynthesis section). As early as 1928, Kogl had provided 

In an earlier section of this review (p. 148), and in another context, the novel thermal equilibration of the pulvinone carbon skeleton (60) with the l,3-6w-arylcyclopentan-2,4,5-trione system (62) was discussed briefly. The incidence of this equilibrium has inspired a useful synthesis of 

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Olefination reactions of the phosphonates (254) and (255) derived from hydantoin and 1-methylhydantoin, respectively, provide good yields of the expected C-5 unsaturated hydantoin derivatives (256), generally as mixtures of isomers. 52 Heterocyclic analogues, e.g. (257), of pulvinones and, e.g. (258), of permethylated pulvinic acids have been synthesized by Wadsworth-Emmons reactions of the phosphonates (259) and (260), themselves prepared directly from substituted maleic anhydrides. 55 The reaction of ylide (261) with aldehydes to give (262) has been used as a key... 

Substituted maleic anhydrides. The catalyzed formation of butenolides from alkynes and CO is changed to maleic anhydrides by adding carbon dioxide in the system. 

A variety of substituted maleic anhydrides (93) are available from Michael additions of imidazo[1,2-a]pyridinium salts (92) to the... 

In the second approach, a substrate incorporating an intact but-2-enolide system is employed as a pivotal intermediate. Thus, either of the procedures involving addition of carbon nucleophiles to substituted maleic anhydrides viz 91) or addition of carbanions produced from simple butenolides viz 92) to carbonyl compounds, followed by appropriate 1,2-eliminations, provide expeditious routes to the corresponding 4-ylidene systems (Scheme 3). The present discussion will be made with these broadly-based approaches in mind. Synthetic approaches which are not accommodated comfortably within this framework are collected in a miscellany. 

Hoberg [1-10] first emphasized the synthetic potential of oxametallacyclopentenones, showing that they are useful starting materials or intermediates for the synthesis of unsaturated cyclic anhydrides (for instance, substituted maleic anhydrides, which can be obtained from the oxanickelacycles by reductive carbon-ylation with CO) or unsaturated carboxylic acids, which can be released upon protonolysis. The stoichiometric coupling reaction has also proved to be useful for the synthesis of unsaturated carboxylic acids through carboxylation and... 

One of the most noted reactions of furan involves its cycloaddition with substituted maleic anhydrides in the context of the synthesis of cantharidin. Dauben et al. synthesized cantharidin (349), a natural product and potent vesicant, from 2,5-dihydothiophene-3,4-dicarboxylic anhydride (346) and furan [97]. The high-pressure induced Diels-Alder cycloaddition proceeded at 15kbar and provided an... 

The polyispbptylenes (PIB) having molecular weights ranging from 1000 to 2000 are substituted by maleic anhydride, and the polyisobutylene succinic anhydride (PIBSA) formed is neutralized by a polyethylene-polyamine as indicated in Figure 9.10. 

Process Technology Evolution. Maleic anhydride was first commercially produced in the early 1930s by the vapor-phase oxidation of benzene [71-43-2]. The use of benzene as a feedstock for the production of maleic anhydride was dominant in the world market well into the 1980s. Several processes have been used for the production of maleic anhydride from benzene with the most common one from Scientific Design. Small amounts of maleic acid are produced as a by-product in production of phthaHc anhydride [85-44-9]. This can be converted to either maleic anhydride or fumaric acid. Benzene, although easily oxidized to maleic anhydride with high selectivity, is an inherently inefficient feedstock since two excess carbon atoms are present in the raw material. Various compounds have been evaluated as raw material substitutes for benzene in production of maleic anhydride. Fixed- and fluid-bed processes for production of maleic anhydride from the butenes present in mixed streams have been practiced commercially. None of these... 

The original compound, maleimide (2,5-dioxo-A -pyrroline), is synthesized by the cyclo-condensation of ammonia and maleic acid. Similarly, primary amine is added to maleic anhydride, followed by cyclocondensation, to form N-substituted maleimide (Fig. 2). This reaction is applied to the preparation of bis-maleimides (BMl) [1]. At first, BMI was used as a crosslinking agent for natural rubber (NR). An o-dichlorobenzene solution of NR was crosslinked by BMI at I08-150°C in the presence of peroxides. The radicals generated from peroxides react with the double bonds of both BMI and NR [ 1 ]. 

Benz[/]isoindole (125), recently prepared from the p-toluene-sulfonyl derivative (124), proved to be too unstable for isolation, but eould be trapped in solution as the Diels-Alder adduct (127). The corresponding 1-phenyl derivative (126) was also prepared and, aecording to spectral measurements, reacts with maleic anhydride to give the product (128) derived by additive substitution. This subsequently rearranged to the adduct (129). The same behavior is observed in the reaction of (126) with V-phenylmaleimide. This provides the first clear indication that substitution products from isoindole derivatives and dienophiles can be converted into the normal addition products. 

The equilibrium between oxepin and benzene oxide created interest in performing Diels-Alder reactions trapping one or both isomeric structures.1 The reaction of maleic anhydride or maleic imide with oxepin and substituted derivatives gives products 1 derived from the addition of the dienophile to the benzene oxide structure.2-l4-126 14 9 156 158 228 231-259... 

As previously discussed, solvents that dissolve cellulose by derivatization may be employed for further functionahzation, e.g., esterification. Thus, cellulose has been dissolved in paraformaldehyde/DMSO and esterified, e.g., by acetic, butyric, and phthalic anhydride, as well as by unsaturated methacrylic and maleic anhydride, in the presence of pyridine, or an acetate catalyst. DS values from 0.2 to 2.0 were obtained, being higher, 2.5 for cellulose acetate. H and NMR spectroscopy have indicated that the hydroxyl group of the methy-lol chains are preferably esterified with the anhydrides. Treatment of celliflose with this solvent system, at 90 °C, with methylene diacetate or ethylene diacetate, in the presence of potassium acetate, led to cellulose acetate with a DS of 1.5. Interestingly, the reaction with acetyl chloride or activated acid is less convenient DMAc or DMF can be substituted for DMSO [215-219]. In another set of experiments, polymer with high o -celliflose content was esterified with trimethylacetic anhydride, 1,2,4-benzenetricarboylic anhydride, trimellitic anhydride, phthalic anhydride, and a pyridine catalyst. The esters were isolated after 8h of reaction at 80-100°C, or Ih at room temperature (trimellitic anhydride). These are versatile compounds with interesting elastomeric and thermoplastic properties, and can be cast as films and membranes [220]. 

Several other complexes, M(CNBu )jL (L = an activated olefin), have also been reported recently (110). This group of complexes, with the ligands (L) including maleic anhydride, fumaronitrile, and tetracyano-ethylene, arises from isocyanide ligand substitution by the olefin. Less active olefins such as ethylene and diphenylacetylene, and azobenzene did not react. 

Ethoxy)-allylidenecyclopropane (136a) readily underwent Diels-Alder reaction with activated dienophiles under mild conditions (Table 14) [33]. Only one regioisomer was formed with unsymmetrically substituted dienophiles such as methyl maleic anhydride (137), and quinones 138-141 (entries 2 and 3-6). AH the cycloadducts 143-147 derive from an endo approach between the two reagents. Two site-isomers were obtained in 96 4 ratio with 3-isopropyl-6-methyl-p-quinone (141) (entry 6) and the high site-selectivity observed in this... 

Cycloadducts have been successively obtained by reaction of MCP with maleic anhydride (116) and a number of related electron-deficient alkenes (137,486,487) under photolytic conditions in the presence of a sensitizer (Table 38, entries 5-8) [132b]. Analogous cycloadditions in mild conditions with high yields have also been performed with electron-donor substituted alkenes, such as vinylene carbonates 483 and 484 and the imidazolinone 485 (entries 2-4) [132], In the case of the unsymmetrical anhydride 137 (entry 6), an almost equimolar mixture of both the possible regioisomers has been obtained [132b]. In all these cases the reaction has also been proposed to occur via diradical intermediates formed from the reaction of 1 with the alkene in its excited triplet state [132]. 

The allene 149 gave by reaction with maleic anhydride (entry 1) and N-phenylmaleimide (entry 2) the [2 + 2] adducts 155a, b as mixtures of two diastereoisomers [36], Nevertheless, their chemical yield was very low and competitive reactions, mostly [4 + 2] cycloadditions on a rearranged al-lylidenecyclopropane and on a primary 1 1 adduct derived from an ene reaction (see Sect. 2.1.2), prevailed. Allenes 149 and 563 cycloadded to tetracyano- and l,l-bistrifluoromethyl-2,2-dicyanoethylene (Table 45, entries 3-6) also selectively at the cyclopropyl substituted double bond in order to remove most of the ring strain [149a],... 

The equivalent weight increased from 210 for UPE A to 316 for UPE E with one third of the maleic anhydride was replaced with succinic anhydride and 634 for UPE F with two thirds of the maleic anhydride is replaced with succinic anhydride. This change will effectively decrease the crosslink density of the final cured film. The Brookfield viscosities of the two new polyesters (E and F) are less than those from the first series. Since the molecular weights should be about the same (1760), it is not surprising that the Brookfield viscosities were relatively constant for all three unsaturated polyesters. The slight decreasing trend in viscosity with increasing succinic anhydride in the unsaturated polyester may be due to the increased free volume obtained when succinic anhydride is substituted for maleic anhydride. 

Aniline virtually quantitatively reacts with the corresponding anhydride in refluxing toluene in the presence of triethanolamine to form N-phenylmaleimide 189, whose oxidation with m-CPBA affords imsymme-trical sulfone in 67% yield (08CC3281). N-Substituted compounds were synthesized in a similar way starting from (2-methylbenzo[b]thiophen-3-yl)maleic anhydride and /J-alanine 190a or 5-amino-l,10-phenanthroline... 

The reaction of maleic anhydride with trimethylsilyl azide was reported to provide l,3-oxazine-2,6-dione in good yield. Control of the temperature proved essential in order to avoid a violent, exothermic reaction this could readily be accomplished by running the reaction in methylene chloride at 0°C <19950PP651>. Similar transformations of 3-substituted phthalic anhydrides 546 resulted in formation of 8- 547 or 5-substituted 548 isatoic anhydrides (Equation 66). The ratio of the regioisomeric products was strongly influenced by the substituent X while nitro and acetylamino derivatives 546 (X = NO2, NHAc) gave exclusively the 8-substituted isomers, only the 5-substituted product was formed from 3-aminophthalic anhydride 546 (X = NH2) <1998JOC6797>. 

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