Photochemistry of phthaloylcysteine, its methyl ester and C-unprotected S-alkyl derivatives

Griesbeck, Axel G.; Hirt, J.; Krämer, Wolfgang; Dallakian, P.

doi:10.1016/s0040-4020(98)00063-5

Cited by 39 publications

(20 citation statements)

References 21 publications

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“…The organic layer was dried over anhydrous sodium sulfate, concentrated under vacuo and purified by chromatography on silica gel column using a mixture of petroleum ether/ethyl acetate as eluent to furnish the phthalimide or succinimide derivatives in 72–96% yields. Spectral data of the compounds 2a ,32 2b ,33 2c ,34 2d ,35 2e ,36 2f ,37 2i ,38 2j ,39 2k ,40 2l ,41 2n ,42 2q ,43 2r 43 and 2s 34 were in excellent agreement with those in the literature.…”

Section: Methodssupporting

confidence: 87%

Multimetallic Iridium‐Tin (Ir‐Sn₃) Catalyst in N‐Acyliminium Ion Chemistry: Synthesis of 3‐Substituted Isoindolinones via Intra‐ and Intermolecular Amidoalkylation Reaction

Maity

Roy

2014

Adv Synth Catal

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The multimetallic iridium‐tritin (Ir‐Sn3) complex [Cp*Ir(SnCl3)2{SnCl2(H2O)2}] (1) proved to be a highly effective catalyst towards COH bond activation of γ‐hydroxylactams, leading to a nucleophilic substitution reaction known as the α‐amidoalkylation reaction. Catalyst 1 can be easily synthesized from the reaction of (pentamethylcyclocyclopentadienyl)iridium dichloride dimer {[Cp*IrCl2]2} and tin(II) dichloride (SnCl2). In terms of catalyst loading, reaction conditions and yields of the product formed, 1 is found to be superior compared to classical Lewis acid catalysts. Different carbon (arenes, heteroarenes, allyltrimethylsilane, 1,3‐dicarbonyls) and heteroatom (alcohols, thiols, amides and sulfonamides) nucleophiles have been successfully employed in the intramolecular and intermolecular alkylations, as well as in heterocyclization reactions. In the majority of cases good to excellent yields of 3‐substituted isoindolinones and 5‐substituted pyrrolidin‐2‐ones have been obtained. Besides, the reactions are also atom economical and salt free. It is proposed that the multimetallic Ir‐Sn3 catalyst behaves as a mild and selective Lewis acid to activate the γ‐hydroxylactam towards the formation of the N‐acyliminium ion; the latter being trapped by potent nucleophiles leading to the desired products.

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Section: Methodssupporting

confidence: 87%

Multimetallic Iridium‐Tin (Ir‐Sn₃) Catalyst in N‐Acyliminium Ion Chemistry: Synthesis of 3‐Substituted Isoindolinones via Intra‐ and Intermolecular Amidoalkylation Reaction

Maity

Roy

2014

Adv Synth Catal

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“…10 Significantly lower triplet yields were determined for 3a-c and even lower values for 1, 2a-c, and 4a-e (Table 2). Photoinduced intramolecular charge separation between the thioether and the phthalimide moieties has been proposed to account for both decarboxylation and cyclization [1][2][3][4][5][6][7][8] which may be coupled processes. The cyclization products of 1, 2, and 4 are sulfur-containing heterocycles with five-, six-, and seven-membered ring systems.…”

Section: Discussionmentioning

confidence: 99%

“…[6][7][8][9] The large Φ d value (Table 1) mainly refers to production of 3′ (Scheme 1). 7 For 3a we have proposed that the photocyclization is due to the fast intramolecular charge separation reaction in the spectroscopically nondetectable 3 n,π* state in competition with population of the observable nonreactive 3 π,π* state. 11 This competing process is more important than the above-discussed cases, as concluded from the substantial Φ isc value ( Table 2).…”

Section: Discussionmentioning

confidence: 99%

Photodecarboxylation Study of Carboxy-Substituted N-Alkylphthalimides in Aqueous Solution: Time Resolved UV−Vis Spectroscopy and Conductometry

2002

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The photophysical and photochemical properties of N-phthaloyltranexamic acid (3b) and N-methylsulfanylmethylphthalimide (4e) as well as several sulfur-containing carboxylates, N-phthaloylmethionine (1), N-phthaloyl-S-carboxymethylcysteine (2c), phthalimidomethylsulfanyl acetic acid (4a), and its derivatives 4b-4d were studied in aqueous solution by time-resolved UV-vis spectroscopy and conductivity using laser pulses at 248 or 308 nm. From the changes in absorption spectra upon continuous irradiation at 290 nm, the quantum yields of substrate decomposition (Φ d ) were measured for various cases. The quantum yields of formation of the lowest triplet state (Φ isc ) are small, when Φ d is large and vice versa. The quantum yields of decarboxylation, Φ(-CO 2 ), were determined by conductometry. Φ(-CO 2 ) is largest (0.3) for 3b in argonsaturated aqueous solution at pH 6-10 and decreases in the order 4a-c, 2c, 1, and 4d. The increase of Φ d vs pH indicates that carboxylic acids exhibit low decarboxylation efficiencies, whereas the corresponding anions effectively eliminate CO 2 and subsequently cyclize. The mechanisms of photochemical decomposition, decarboxylation, and cyclization are discussed.

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“…After quenching of 3 K*, however, practically no triplet could be generated for 1 (Figure 5, parts b and c, Figure 6, parts a and b) and 2′ (Figure 6, part c); that is, the energy transfer reaction (8) is too fast for observation or does not take place at all. The low amount of observed 3 π,π* state should not be due to physical quenching without chemical reactivity, since the quantum yield of formation of photoproduct 2 a is 0.08 upon acetone‐sensitized excitation 2, 9. One possibility might be a too rapid charge separation in the 3 n,π* state ( 3 *P′−S−Me→P′ .− −S−Me .+ ) and another that quenching of 3 K* generates, to some degree, the 3 n,π* state in which charge separation should occur.…”

Section: Discussionmentioning

confidence: 99%

Time-Resolved Spectroscopy of Sulfur- and Carboxy-SubstitutedN-Alkylphthalimides

et al. 2001

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The photophysical and photochemical properties of N-phthaloyl-methionine (1), S-methyl-N-phthaloyl-cysteine methyl ester (2) and N-phthaloyltranexamic acid (3) were studied by time-resolved UV/Vis spectroscopy, using laser pulses at 248 or 308 nm. The quantum yield of fluorescence is low (phi(f)< 10(-2)) for 1-3 in fluid and glassy media, whereas that of phosphorescence is large (0.3-0.5) in ethanol at - 196 degrees C. The triplet properties were examined in several solvents, at room temperature and below. The spectra and decay kinetics are similar, but the population of the pi(pi*) triplet state, as measured by T-T absorption, is much lower for 1 and 2 than for 3 or N-methyltrimellitimide (5') at ambient temperatures. The quantum yield (phi(delta)) of singlet molecular oxygen O2(1deltag) formation is substantial for 3 and 5' in several air- or oxygen-saturated solvents at room temperature, but small for 2 and 1. The quantum yield of decomposition is substantial (0.2-0.5) for 3 and small (<0.05) for 2 and 1. It is postulated that photoinduced charge separation in the spectroscopically undetectable 3n,pi* state may account for the cyclization products of 1 and 2. In aqueous solution, this also applies for 3, whereas in organic solvents cyclization involves mainly the lower lying 3pi,(pi*) state. Triplet acetone, acetophenone and xanthone are quenched by 1-3 in acetonitrile; the rate constant is close to the diffusion-controlled limit, but smaller for benzophenone. While the energy transfer from the triplet ketone occurs for 3, a major contribution of electron transfer to the N-phthalimide derivative is suggested for 1 and 2, where the radical anion of benzophenone or 4-carboxybenzophenone is observed in alkaline aqueous solution.

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Photochemistry of phthaloylcysteine, its methyl ester and C-unprotected S-alkyl derivatives

Cited by 39 publications

References 21 publications

Multimetallic Iridium‐Tin (Ir‐Sn₃) Catalyst in N‐Acyliminium Ion Chemistry: Synthesis of 3‐Substituted Isoindolinones via Intra‐ and Intermolecular Amidoalkylation Reaction

Multimetallic Iridium‐Tin (Ir‐Sn₃) Catalyst in N‐Acyliminium Ion Chemistry: Synthesis of 3‐Substituted Isoindolinones via Intra‐ and Intermolecular Amidoalkylation Reaction

Photodecarboxylation Study of Carboxy-Substituted N-Alkylphthalimides in Aqueous Solution: Time Resolved UV−Vis Spectroscopy and Conductometry

Time-Resolved Spectroscopy of Sulfur- and Carboxy-SubstitutedN-Alkylphthalimides

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Photochemistry of phthaloylcysteine, its methyl ester and C-unprotected S-alkyl derivatives

Cited by 39 publications

References 21 publications

Multimetallic Iridium‐Tin (Ir‐Sn3) Catalyst in N‐Acyliminium Ion Chemistry: Synthesis of 3‐Substituted Isoindolinones via Intra‐ and Intermolecular Amidoalkylation Reaction

Multimetallic Iridium‐Tin (Ir‐Sn3) Catalyst in N‐Acyliminium Ion Chemistry: Synthesis of 3‐Substituted Isoindolinones via Intra‐ and Intermolecular Amidoalkylation Reaction

Photodecarboxylation Study of Carboxy-Substituted N-Alkylphthalimides in Aqueous Solution: Time Resolved UV−Vis Spectroscopy and Conductometry

Time-Resolved Spectroscopy of Sulfur- and Carboxy-SubstitutedN-Alkylphthalimides

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Multimetallic Iridium‐Tin (Ir‐Sn₃) Catalyst in N‐Acyliminium Ion Chemistry: Synthesis of 3‐Substituted Isoindolinones via Intra‐ and Intermolecular Amidoalkylation Reaction

Multimetallic Iridium‐Tin (Ir‐Sn₃) Catalyst in N‐Acyliminium Ion Chemistry: Synthesis of 3‐Substituted Isoindolinones via Intra‐ and Intermolecular Amidoalkylation Reaction