N- -phenyl -maleimide

Various o-quinodimethanes, generated in situ from o-alkenylbenzyltributyl-stannane precursors, have been used to synthesize functionalized polycycles by Diels Alder reaction with maleic anhydride, methylacrylate, dimethylfumarate and N-phenyl maleimide in the presence of electrophiles [37] (Scheme 2.16). 

Figure 20-2. N-(2-Chloropropyl) maleimide, N-ethyl maleimide, N-cyclohexyl maleimide, and N-phenyl maleimide.

Sulfonated styrene-maleimide copolymers are similarly active [1073], Examples of maleimide monomers are maleimide, N-phenyl maleimide, N-ethyl maleimide, N-(2-chloropropyl) maleimide, and N-cyclohexyl maleimide. N-aryl and substituted aryl maleimide monomers are preferred. The polymers are obtained by free radical polymerization in solution, in bulk, or by suspension. 

The first phase of our efforts was the unambiguous synthesis of each model substrate. PN and PX were already well characterized materials (1) While direct synthesis of the phenyl and carbomethoxy compounds from PN and/or PX was attempted, this approach was unsuccessful due to the sluggish reactivity of the norbornenyl double bonds in these molecules (2). A successful approach to CBN and (fiBN based on N-phenyl maleimide (NPMI) trapping of the respective thermodynamically favored 1-substituted cyclopentadienes is shown in Equation 1. Similarly, kinetic trapping of 2-phenyl cyclopentadiene, from the in situ dehydration of 3-hydroxy, 3-phenyl cyclopentene, gives a clean yield of (f)VN (Equation 2). The remaining phenyl isomer (VX) and the three other carbomethoxy isomers (CBX, CVN, CVX) were all obtained by the thermal isomerization chemistry described in the next section of this paper. They were each isolated in pure form by liquid chromatography We were unable to obtain any (f)BX or any of the 7-substituted isomers by any means. 

Scheme 6.72 Mechanistic proposal for the 12-catalyzed enantio- and diastereoselective domino Michael-aldol reaction between N-phenyl maleimides and 2-mercaptobenzaldehyde bifunctional mode of action of 12.

The cross-linking rate of EPR by radiation comes close to that of polypropylene. EPDM terpolymers exhibit an enhanced cross-linking rate, and it increases with the diene content. However, not only the cross-linking rate, but also a greater yield of scissions results from the addition of the third monomer. Cross-linking of EPR can be promoted by the addition of a variety of additives, particularly by those that were found effective in polypropylene. Tetravinyl silane, chlorobenzene, nitrous oxide, allyl acrylate, neopentyl chloride, and N-phenyl maleimide were reported to promote the process. 

The Diels-Alder reaction of pyrrole-3-carboxyhc esters with TV-methyl- and N-phenyl-maleimides yield exclusively endo adducts.243 The Diels-Alder reaction of... 

As previously described, the 3//-pyrrolium adduct 50 is obtained from the TBSOTf-promoted aldol reaction between the 1-methylpyrrole complex 21 and acetaldehyde diethylacetal (Figure 11). Deprotonation of 50 occurs at C-3 with i-Pr2EtN to give the corresponding -substituted lH-pyrrole complex. Addition of triflic acid results in the elimination of ethanol to give the azafulvenium complex 141 as a 3 2 mixture of diastereomers (Figure 25). Deprotonation of 141 results in formation of the unstable unsubstituted P-vinylpyrrole complex 142, which can be trapped in situ with N-phenyl maleimide (vide infra). 

A donor-acceptor zwitterionic polymerization has been mentioned 2-ethyl-oxazoline nucleophilic monomer reacts with the electrophilic N-phenyl maleimide giving a 1 1 adduct which polymerizes upon heating (Fig. 20). A similar reaction was observed between bismaleimide and bis-oxazoline giving a crosslinked network stable up to 300 °C [72]. 

In order to justify the stereochemistry of the major adducts 155, the authors proposed that they result from an exclusive endo approach toward the less hindered face of the diene (opposite to the p-tolyl group), with the sulfinyl group adopting the s-trans conformation with respect to the C(l)-C(2) double bond (B in Fig. 13). Nevertheless, this conformational preference is not rationalized in the paper. Aversa et al. [137c] have recently reported that uncatalyzed reactions of (Rs)-152 with maleimide and N-phenyl maleimide occurred with complete endo- and very high facial diastereoselectivities. In this sense, the results ob-... 

The pyrrolo[3,4-c]benzopyrazole (51 R1 =Ph, R2 = Me, R3 = C02Et) reacts with DMAD giving the cycloadduct (52 R1 = Ph, Rz = Me, R3 = C02Et). Reaction with N-phenyl-maleimide in boiling xylene slowly gives compound (53), presumably formed by elimination of methylamine from the primary adduct (79JOC622). 

Azo compounds like esters or imides of azo dicarboxylic acid act as reactive dienophiles in normal electron demand hetero Diels-Alder reactions due to the strong activation caused by two electron-withdrawing moieties. In the last years, considerable attention has focused on alkyl and phenyl derivatives of 1,2,4-tria-zoline-3,5-diones since their cycloadditions to chiral dienes proceed with often excellent facial selectivities. Thus, when reacting an oxapropellane derived diene with N -methyltriazolinedione, Paquette et al. obtained the cycloadduct as single diastereomer, but both maleic anhydride and N-phenyl maleimide were distinctly less reactive and turned out to undergo cycloadditions with poor selectivities [289]. 

Such syntheses take advantage of transannular intramolecular hetero Diels-Alder reactions [426], another impressive example is the diene transmissive hetero Diels-Alder reaction of the thioketone 5-14. The diene 5-15 formed by this cycloaddition underwent a second Diels-Alder reaction with N-phenyl-maleimide to yield the fused polycycle 5-16 as single diastereomer (Fig. 5-5) [427]. 

More or less similar behavior has been observed (8) in the blends of the copolymer or the terpolymer with the following bis-A polycarbonate, polyvinyl chloride, poly (ethyl methacrylate), and a terpolymer made from methyl methacrylate, N,N -dimethyl acrylamide, and N-phenyl-maleimide. Because of this unique miscibility characteristic of the a-methyl styrene interpolymers, an attempt was made at compati-bilizing polyarylethers with the interpolymers by attaching pendant chemical groups known to exist in systems with which the interpolymers are miscible. 

Reaction of 5,5-dimethyl-l,3-cyclohexanedione and arylidenemalononitrile gave 5, and of 1,3-diarylthiobarbituric acids with hippuric acid and triethyl orthoacetate or triethyl orthoformate and malononitrile or alkylnitriles gave pyranopyrimidines 6 or 7. Pyranopyrimidines 8 were obtained from reaction of arylidenemalononitriles or N-phenyl maleimides with barbituric acid . ... 

Figure 2.4. Schematic illustrations of repeat units of several of the polymers listed in Table 2.2. (a) Poly(thiocarbonyl fluoride), (b) Poly(glycolic acid), (c) Polyepichlorohydrin. (d) Poly(maleic anhydride), (e) Poly(N-methyl glutarimide). (f) Poly(N-phenyl maleimide). (g) Poly[3,5-(4-phenyl-1,2,4-triazole)-1,4-phenylene]. (h) Phenoxy resin, (i) Poly(oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-l,4-phenylene). (j) Udel. (k) Victrex. (1) Tori on. (m) Ultem. (n) Resin F.

Harth et al. [223] recently developed a new methodology to replace the terminal aminoxyl based on the addition of one single maleic anhydride unit, considering that addition of a second unit is disfavored. To mimic this approach, a-hydrido alkoxyamine (Scheme 39, 1) was reacted with 2 equiv of N-phenyl maleimide, leading to addition of one unit. Upon heating, the cor-... 

Some imidized derivatives of SMA resins, containing N-phenyl maleimide units in place of maleic anhydride comonomer units have been offered commercially (Denki Kagaku, Japan) as blend components to modify the heat distortion temperature of styrenics (HIPS and ABS). Blends of such resins with ABS have been commercialized in Japan (Malecca , Denki Kagaku). 

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