Phthalimide system

The photochemistry of phthalimide systems was thoroughly investigated by many groups over the last two decades. This chromophore shows a broad spectrum of reactivity leading mainly to cycloaddition and photoreduction products by either intermolecular or intramolecular processes. In the presence of electron donors, the electronically excited phthalimide could also undergo electron transfer and act as an electron acceptor. 

Interest in the photochemistry of the phthalimide systems has continued. The phthalimide derivatives (316) are phot ochemically reactive and on irradiation in acetone yields the cyclized products (317). The reaction involves hydrogen abstraction to yield the biradical (318) which subsequently bonds to afford the observed products. A recent study has examined the behaviour of the anion (319) in an attempt to reduce electron transfer processes. In t-butanol irradiation affords the solvent addition product (320) as the principal product presumably by a free radical path. Minor products (321) and (322) are also formed but are probably artefacts of the work-up procedure. Irradiation of (319) in methanol with added cyclohexene follows a different reaction path. In this system the reaction with methanol is minor while the dominant reaction is addition of the alkene to afford the adduct (323) in 20 % yield. The Dewar benzene derivative (324) is photocheraically unstable and irradiation affords t etramet hyl cyclobutadiene. ... 

Intramolecular single electron transfer occurs within the supramolecular systems (224). " The electron transfer only occurs from the nitrogen function attached to the 4-amino substituent. A comparison between redox potentials and the photophysical behaviour of the phthalimides (225) has been made. Other work dealing with electron transfer in phthalimide systems has examined the behaviour of (226). The singlet excited state of (227) is fluorescent and this can be effectively quenched by ferrocene. ... 

Further work on the phthalimide system has shown that iV-methylphthalimide undergoes intramolecular hydrogen abstraction when irradiated in ethers (THF, dioxan, and diethyl ether) to yield the adducts (257).151 Hydrogen abstraction also occurs in the presence of cyclopentene or cyclohexene. Intramolecular hydrogen abstraction in the phthalimides (258) gives the oxazoloisoindoles (259).152 Similar hydrogen abstraction and cyclization in the phthalimides (260) affords a route to the multi-cyclic benzazepines (261) (Scheme 25).153 The... 

Machida M, Takechi H et al (1982) Photochemistry of the phthalimide system. 32. Photoreaction of N-(w-indol-3-ylalkyl)phthalimides intramolecular oxetane formation of the aromatic imide system. Tetrahedron Lett 23 4981 982... 

Takechi H, Machida M et al (1994) Photochemistry of the phthalimide system XLIV. Intramolecular photoreactions of phthalimide-alkene systems. Macrocyclic synthesis through the remote Patemo-Buechi reaction of phthalimide with indole derivatives. Chem Pharm Bull 42 188-196... 

Electronically excited phthalimides can act as good electron acceptors and carboxylic acids are documented to serve as electron donors in photoinduced SET reactions. It is likely then, that in the excited state, an electron transfer process between the phthalimide system and the carboxylic acid would occur, leading to charge-separated diradical 6. Proton transfer from the carboxylic acid function (iT" is an electrofugal group) would form a carboxy radical 7, which could undergo rapid decarboxylation to azomethyne ylide 8. This reactive species is transformed into the final decarboxylated product 3 by intramolecular proton transfer (Scheme 16.4). 

To justify the experimental result we could follow the stepwise mechanism discussed in the previous section. The phthalimide system is a good electron acceptor in the excited state and the alkylsilane can be an electron donor, so a photoinduced electron transfer process could lead to the charged separated diradical 13. Transfer of the electrofugal TMS group to the oxyanion carbonyl oxygen would form azo-methyne ylide 14 that can be trapped by the mefliyl acrylate to yield the endo-reaction product 12 (Scheme 16.9). 

The main chain of these polymers contains, as the principal component, five- or six-membered heteroaromatic rings, ie, imides, which are usually present as condensed aromatic systems, such as with benzene (phthalimides, 3) and naphthalene (naphthalimides, 4) rings. 

It was found that a high-impact strength is obtained in PP-EPDM blends by slow curing with sulfur. Thiuram disulfide N-(cyclohexylthio)phthalimide was used as an inhibitor of curing, and its effect on the impact strength of dynamically cured PP-EPDM blends was studied (Table 6). It was also found that the one-step method of blend preparation also has a favorable effect on the impact strength of the resultant blend system. 

Cure system (species) Sulfur-based phthalimide (PVI)... 

The starting reagents in Gabriel amine synthesis, N-alkylphthalimides, were obtained under the action of microwave irradiation in a solid-liquid PTC system. The reactions were conducted with high yield (50-90%) simply by mixing phthalimide... 

The simplicity of the two-phase modification of the Gabriel synthesis of primary amines, via the N-alkylation of potassium phthalimide, makes the procedure considerably more convenient than the traditional method, which normally requires the use of anhydrous dipolar aprolic solvents. The reaction can be conducted under solid liquid conditions using potassium hydroxide in toluene [25], or with preformed potassium phthalimide [26, 27] (cf ref. 28). As is normal for acylation reactions, relatively mild conditions are required for the preparation of the A-ethoxycarbonyl derivative [29], whereas a reaction temperature of 100°C is generally used for N-alkylation (Table 5.16). The reaction time for the soliddiquid two-phase system can be reduced dramatically with retention of the high yields, when the reaction mixture is subjected to microwave irradiation [30]. 

Phases with phenyl groups are less retentive than C8 bonded phases. They show a pronounced selectivity and retention toward solutes with aromatic ring systems, attributed to n-n interactions. These n-n interactions can be improved when nitro substituted phenyl groups are bonded to silica. The strongest interactions have been reported with tetra nitro or tetra chloro phthalimide substituents. 

Eine ahnliche Umwandlung von sekundaren Alkoholen in primare Amine mittels der Mit-sunobu-Reaktion ist am Beispiel dcr 7-Hydroxy- untersucht worden1. Behandlung dieser Alkohole mit Triphenylphosphan, Phthalimid und Dieth-oxycarbonyl-diazen in Tetrahydrofuran ergibtdie 2-Phthalimido-Derivate, die isoliert und mittels Hydrazin unter Bildung der freien Amine gespalten werden. Bei dem beschriebenen System entstehen auf diese Weise aus den 7-m/o-Alkoholen die 7-exo-Amine und aus den 7-exo-Alkoholen Gemische der 1-endo- und 7-eJto-Amine. 

In general, amino-containing compounds are poor partners in CM due to their tendency to coordinate to the metal catalyst, even when late-transition metal systems are employed. To preserve catalyst activity, amino groups are therefore typically masked as cyanides, carbamates, amides, or phthalimides. In substrates where iV-coordination to the catalyst is less favored, such as with hindered /V-aryl-/V-allylamines, no protecting group is required. 

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