IV-phenyl maleimide

A stable o-thioquinomethide (116) has been isolated from naphtho[2,l-t/]-1,2-dithiole-3-thione 117 and cyclohexene in the crystalline state. The product 118 derived from the isomeric naphtho[l,2-r/]-l,2-dithiole-3-thione could not be isolated in the pure state, but only as an adduct with IV-phenyl-maleimide.165... 

The pyrrolo[3,4-c]benzopyrazole (51 R1=Ph, R2 = Me, R3 = C02Ht) reacts with DMAD giving the cycloadduct (52 R1 = Ph, R2 = Me, R3 = C02Et). Reaction with IV-phenyl-maleimide in boiling xylene slowly gives compound (53), presumably formed by elimination of methylamine from the primary adduct (79JOC622). 

The effect of pressure on the rate and product distribution of oxazole Diels-Alder reactions has been studied for 5-methoxy-2-methyl-4-(4-nitrophenyl)oxazole 61, a 5-alkoxyoxazole (Fig. 3.18). " " At atmospheric pressure, 61 gave low yields of cycloaddition products with A -phenyl maleimide and did not react at all with dimethyl maleate or dimethyl fumarate, even when heated at 110°C for 100 h. However, after 10 min at 10 kbar, a benzene solution of 61 and iV-phenyl maleimide provided a 4 1 mixture of endo (62) and exo (63) adducts in quantitative yield. Longer reaction times result in equilibration of 62 and 63, which is postulated to occur via a retro-Diels-Alder reaction, producing a 65 35 ratio after 25 h at 10 kbar. If the reaction is carried out at 10 kbar for 25 h using methanol as the solvent, hydroxypyridine 64 is isolated in quantitative yield. Dimethyl maleate could be induced to react with 61 only at elevated temperature and pressure (10 kbar, 60°C, lOOh, CgHg) to give a 71% yield of hydroxypyridine 65. However, even these... 

The spirane (113) was obtained on refluxing the diazopyrroline (114 R = CHjPh or Bu) with iV-phenyl maleimide, but with ADE the heterocycle (115) was formed by Alphen rearrangement of the initially formed pyrazole adduct. 

The reaction of 5(4H)-oxazolones (32) and miinchnones with triphenylvinylphos-phonium bromide (33) provides a mild synthesis of substituted pyrroles (34) (Scheme 11). The cycloaddition-elimination reactions of 5-imino-l,2,4-thiadiazolidin-3-ones with enamines and ester enolates produce 2-iminothiazolidines. " Chiral isomtinchnone dipoles show jr-facial diastereoselectivity with IV-phenyl- or A -methyl-maleimide in refluxing benzene. ... 

Tetradehydrodianthracene undergoes 4 + 2-cycloaddition with electron-deficient dienes such as 1,2,4,5-tetrazines.263 The Diels-Alder reactions of [2>3]ortho-anthracenophanes with iV-(p-nitro, chloro, or methoxy-substituted phenyl)maleimides yield approximately equal quantities of inside and outside adducts.264 The photooxidation of bulky water-soluble 1,4-disubstituted naphthalenes with singlet oxygen yields both the expected 1,4- and the unexpected 5,8-endoperoxides.265... 

The reactivity of the maleimide monomer was dependent on the substitution pattern of the phenyl ring, with the substituents in the ortho position tending to lower the molecular weight of the polymer formed. The THP substituent is readily removed either chemically or thermally to yield poly(iV-(hydroxyphenyl)maleimides). All polymers exhibited excellent thermal stability and showed no evidence of degradation below 360 °C. Reaction occurs between the phenolic ring of the polyimide and HMTA, to form benzoxazine-type derivatives. These reactions have been studied comprehensively using the monomeric model systems, Ai-(hydroxyphenyl)succinimides (Figure 8) . 

The thiocarbonyl ylide intermediate (378), generated by thermal extrusion of trimethylsilyl bromide from (377), undergoes 1,3-dipolar cycloaddition with iV-phenyl- and JV-methyl-maleimides... 

Bradshaw [74] reported in 1966 that maleimide undergoes sensitized photochemical addition to benzene, producing the imide analog of the corresponding maleic anhydride photoadduct. The author observed that the reaction probably proceeds by the addition of electronically excited maleimide to benzene. The photoaddition proved successful also with toluene, /-butylbenzene, and ethylbenzene. Simultaneously, Bryce-Smith and Hems [75] reported that 2 1 photoadducts are formed from maleimide, iV-n-butyl-,. V-benzyl-, iV-o-tolyl-, and iV-2,6-xylylmaleimide with benzene.. V-Phenyl, N-p-tolyl-, and A-p-methoxyphenylmaleimide did not form photoadducts. Trifluoroacetic acid was found to be virtually without effect on the photoaddition of N-n - bulyI maleimide No phenyl-A- -butylsuccinimide was detected [36], It was concluded that a dipolar intermediate is not involved. When N-n-bulylmalcimide and benzene were irradiated in the presence of tetra-cyanoethylene, a 1 1 1 adduct was formed [37],... 

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