Selective removal of electron-accepting p-toluene- and naphthalenesulfonyl protecting groups for amino function via photoinduced donor acceptor ion pairs with electron-donating aromatics

Hamada, Takeshi; Nishida, Atsushi; Yonemitsu, Osamu

doi:10.1021/ja00261a023

Cited by 140 publications

(68 citation statements)

References 2 publications

(2 reference statements)

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“…The structure of the tetrahydroimidazol[2.1-a]isoquinoline 7c was proved by X-ray crystal analysis (see Figure 3). Attempts to remove the tosyl protective group from the 2-benzyldihydroimidazo[2,1-a]isoquinoline 5e by photore-duction [17,18] with ascorbic acid in the presence of 1,8-dimethoxynaphthalene resulted in the formation of a polycyclic [2+2] cycloadduct 9, while the tosyl group was not affected (Scheme 4). The configuration of 9 was tentatively assigned on the basis of the NMR data, where the total number of resonance signals is half the number of H-atoms or C-atoms, respectively, and doublets are seen in the 1 H NMR spectra for the cyclobutane H-atoms.…”

Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis of Isoquinoline Derivatives from Amino Acids

2005

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Reaction of isoquinolines 1 with N-arylsulfonylamino acid fluorides 2 provides a highly stereoselective access to new dihydroimidazo[2,1-a]isoquinolin-3-ones 5 via intermediate N-acylisoquinolinium salts 3. Addition reactions to the enamine double bond, such as hydrogenation or epoxidation with dimethyldioxirane, leads to tetrahydroimidazo[2,1-a]isoquinoline-3-ones 6, 7 and oxiranes 8, respectively. Opening of the oxirane ring of the 8 with nucleophiles allows the synthesis of hydroxytetrahydroimidazo[2,1-a]isoquinolin-3-ones

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Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis of Isoquinoline Derivatives from Amino Acids

2005

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“…11). 53) Effect of Electron Donor (Et 3 N) Masanovi's group and other groups reported that sulfonyl esters or sulfonamide derivatives undergo photolysis via intramolecular electron transfer 21,22,30) or intermolecular electron transfer. [18][19][20]31) As described above, the effect of substituent groups on the benzenesulfonyl moiety on the kinetics of the photolysis of 5a-d was negligible ( Table 1), indicating that intramolecular photoinduced electron transfer between two aromatic rings of 5a is a minor pathway.…”

Section: )mentioning

confidence: 99%

“…; protection/deprotection in organic synthesis [1][2][3][4] and uncaging of chemically masked or caged molecules). [5][6][7][8][9][10][11][12][13] To date, the photolysis of sulfonic esters, [14][15][16][17][18][19][20][21][22][23][24] sulfonamides, [25][26][27][28][29][30][31][32] and sulfones 33,34) has been applied to photoresist materials, 15,26) protecting groups, 8,19,20,[27][28][29][30][31][32] and other chemical reactions. 14,[35][36][37] Based on the above findings, the development of new photocleavage reactions of sulfonic acid derivatives and related mechanistic ...…”

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confidence: 99%

Photochemical Cleavage Reactions of 8-Quinolinyl Sulfonates in Aqueous Solution

Kageyama

Ohshima

Sakurama³

et al. 2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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Photochemical cleavage reactions of 8-quinolinyl benzenesulfonate derivatives and related sulfonates in aqueous solutions are reported. The 8-quinolinyl benzenesulfonates undergo photolysis upon photoirradiation at 300-330 nm to give the corresponding 8-quinolinols and benzenesulfonic acids with the production of only negligible amounts of byproducts. The effects of substituent groups of the 8-quinolinyl moiety and the benzene ring on the photolysis reactions were examined. Based on steady-state mechanistic studies using a triplet sensitizer, a triplet quencher, and electron donors, it was suggested that the photolysis proceeds mainly via the homolytic cleavage of S-O bonds in the excited triplet state.

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“…Attempted photolysis of 8 at 254 nm as a dilute solution in isopropanol produced the deprotected crown tetraamide 14 in poor yields (<25%) as a mixture that was difficult to separate. An improved photochemical procedure, exploiting the photosensitized electron transfer reactions of arylsulfonamides (28), finally achieved the required cleavage and left a product which could be purified. In our hands the most successful conditions utilized a ten-fold molar excess of p-dimethoxybenzene as sensitizer and hydrazine as the reducing agent.…”

Section: Ligand Synthesismentioning

confidence: 99%

Polycarboxylate diaza crown ethers derived from R,R-(+)-tartaric acid: synthesis and complexation of metal ions

Anantanarayan¹,

Fyles²

1990

Can. J. Chem.

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ASHOK ANANTANARAYAN and THOMAS M. FYLES. Can. J. Chem. 68, 1338 (1990.The synthesis and complexation properties of polycarboxylate diaza crown ethers based on R,R-(+)-tartaric acid are described. Cesium carbonate mediated macrocyclization of a bis-tosylamide precursor with a bis-tosylate precursor provided the protected crown ethers. Photochemical deprotection of the tosylamides and hydrolysis of the carboxamides yielded dicarboxylic and tetracarboxylic acid derivatives of 1, lO-diaza-18-crown-6. N-Methylenecarboxylate (N-acetate) derivatives were prepared by N-alkylation with bromoacetic acid. The synthetic and purification procedures developed provide samples of the ligands in a metal-free form. Acidity and stability constants for complexation of alkali metal, alkaline earth, late-and post-transition metal cations were determined by potentiometric titration. The ligands form complexes which show enhancement of stability by charge-charge and chelate interaction with the carboxylates. In comparison with crown ether polycarboxylates these aza crown ethers showed a selectivity for softer metal ions relative to alkali and alkaline earth metal ions. N-Methylenecarboxylate chelate ligands were found to bind almost all types of metal ions, due to a highly co-operative array of charge-charge, chelate and crown ether interactions. Metal ion recognition by synthetic and naturally occurring ligands is a complex process involving a cooperative match of the complementary properties of the host and the guest. A key factor in the design of new ligands with unique complexation behaviors is the choice of ligand donor sites (1). Within a class of ligands, such as the crown ethers or cryptands, clear changes in selectivity of cation binding are provoked by substitution of the oxygen donors of a parent ring system for nitrogen or sulfur donor sites (2). Such substitutions alter the primary character of the donor (Lewis basicity) as well as the geometrical and conformational properties of the ligand (3). Thus in a system involving highly cooperative binding interactions, donor atom substitution can profoundly influence binding selectivity.Our interest in ligand design has centered on crown ethers derived from R,R-(+)-tartaric acid: the di-, tetra-, and hexaacids illustrated at the top of Fig. 1 (4-6). The tartarate derived units impart rigidity to the ligands, leading to well defined conformations, and the carboxylates, when ionized, provide a strong electrostatic field which greatly enhances complex stability for alkali metal and alkaline earth cations. Despite the favorable Coulombic interactions, binding of heavy metal cations occurs only to a limited extent due to a mismatch of the hard oxygen donor set and the softer guest cations (6). An obvious ligand modification which might lead to stabilized crown ether type complexes of heavier cations would be the substitution of some of the donor atoms for N or S. We have previously reported dithia crown ethers bearing four carboxylates (7); the purpose of this report is to describe th...

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Selective removal of electron-accepting p-toluene- and naphthalenesulfonyl protecting groups for amino function via photoinduced donor acceptor ion pairs with electron-donating aromatics

Cited by 140 publications

References 2 publications

Asymmetric Synthesis of Isoquinoline Derivatives from Amino Acids

Asymmetric Synthesis of Isoquinoline Derivatives from Amino Acids

Photochemical Cleavage Reactions of 8-Quinolinyl Sulfonates in Aqueous Solution

Polycarboxylate diaza crown ethers derived from R,R-(+)-tartaric acid: synthesis and complexation of metal ions

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