Superacid-catalyzed reactions of pyridinecarboxaldehydes

Klumpp, Douglas A.; Zhang, Yiliang; Kindelin, Patrick J.; Lau, Siufu

doi:10.1016/j.tet.2006.04.022

Cited by 28 publications

(24 citation statements)

References 28 publications

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“…PyBTM was prepared in 3 steps from commercially available reagents in 61 % yield [8,9] and characterized by FTIR spectroscopy, high-resolution ESI-TOF mass spectrometry, and elemental analysis. The existence of S = 1/2 spin on one PyBTM molecule was confirmed using electron spin resonance (ESR) spectroscopy (Supporting Information).…”

Section: Introductionmentioning

confidence: 99%

Luminescence, Stability, and Proton Response of an Open‐Shell (3,5‐Dichloro‐4‐pyridyl)bis(2,4,6‐trichlorophenyl)methyl Radical

2014

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A luminescent open-shell organic radical with high chemical stability was synthesized. (3,5-Dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radical (PyBTM) was photoluminescent under various conditions. Fluorescence quantum yields of 0.03, 0.26, and 0.81 (the highest value reported for a stable organic radical) were obtained in chloroform, in poly(methyl methacrylate) film at room temperature, and in an EPA matrix (diethyl ether:isopentane:ethanol) at 77 K, respectively. The photostability of PyBTM is up to 115 times higher than that of the tris(2,4,6-trichlorophenyl)methyl radical, a previously reported luminescent radical. The pyridine moiety of PyBTM acts as a proton coordination site, thereby allowing for control of the electronic and optical properties of the radical by protonation and deprotonation.

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Section: Introductionmentioning

confidence: 99%

Luminescence, Stability, and Proton Response of an Open‐Shell (3,5‐Dichloro‐4‐pyridyl)bis(2,4,6‐trichlorophenyl)methyl Radical

2014

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“…The high electrophilic reactivities of dicationic electrophiles have been well documented 11 and pyridinecarboxaldehydes are known to form these types of superelectrophilic species. 12 For example, protonation at the pyridine ring and carbonyl group leads to formation of the superelectrophile 17 (Scheme 3). Upon cyclization, further steps presumably lead to the dicationic oxonium ion ( 18 ) and carbocation ( 19 ).…”

Section: Resultsmentioning

confidence: 99%

Cyclizations of phenylethyl-substituted pyridinecarboxaldehydes

Naredla

Klumpp

2013

Tetrahedron

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Several phenylethyl-substituted pyridinecarboxaldehydes were prepared from 2-bromo-3-pyridinecarboxaldehyde and these substances are found to undergo cyclization reactions in acidic media. In the absence of added nucleophile, acid promoted cyclization and oxidation (MnO2) provides an efficient route to 10,11-dihydro-5H-benzo[4,5]cyclohepta[1,2-b]pyridin-5-ones. Arene nucleophiles may also be added to the acidic mixture to provide good yields of triarylmethane products. Mechanisms are proposed involving dicationic superelectrophilic intermediates.

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“…The structure of products 4-12 reveals that, in addition to compound 4, only the tetralin derivatives of toluene and anisole are able to yield tricyclic compounds. However, the selective formation of compounds 5 and 6 ( Table 1, entries [3][4][5] indicates that alkylation occurs through the exclusive attack of the alkylating agent to the para position. The attack to ortho is, obviously, sterically hindered (compare also to the results with ortho-xylene).…”

Section: Formation Of Substituted Octahydroanthracenes and Octahydrotmentioning

confidence: 99%

“…This is primarily due to its particularly useful and attractive properties, namely, its considerably high acidity (H 0 = -14.1) and the lack of any side-reaction such as sulfonation and oxidation which may be observed using certain other superacids. This high and renewed interest is also attributed to the fact that the involvement of superelectrophilic species [2] in triflic acid-mediated transformations has been often implicated and, in fact, superelectrophiles have been detected by 1 H and 13 C NMR spectroscopy [3][4][5]. Triflic acid has been proved to be particularly useful in various alkylation processes [6][7][8][9][10] and in varied cyclization reactions including the synthesis of carbocyclic [9,[11][12][13][14] and heterocyclic multiple ring systems [3,10,15,16].…”

Section: Introductionmentioning

confidence: 99%

Fused Polycyclic Hydrocarbons Through Superacid-Induced Cyclialkylation of Aromatics

2007

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Benzene and substituted derivatives (toluene, ortho-xylene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, anisole), when applied in large excess, react with 1,4 diols (pentan-1,4-diol, hexan-2,5-diol, and 2,5-dimethylhexan-2,5-diol) or an oxolane (2,2,5,5-tetramethyltetra hydrofuran) in the presence of the Brønsted superacid trifluoromethanesulfonic acid (triflic acid, TFSA) to afford substituted tetralins in excellent yields with high selectivity. Reacting benzene with a small excess of alkylating agents yields octahydroanthracenes. The transformation of naphthalene with oxolane leads to a partially saturated octamethyloctahydrotetracene under similar conditions. Product formation is interpreted by intermolecular FriedelCrafts alkylation followed by cyclialkylative ring closure.

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Superacid-catalyzed reactions of pyridinecarboxaldehydes

Cited by 28 publications

References 28 publications

Luminescence, Stability, and Proton Response of an Open‐Shell (3,5‐Dichloro‐4‐pyridyl)bis(2,4,6‐trichlorophenyl)methyl Radical

Luminescence, Stability, and Proton Response of an Open‐Shell (3,5‐Dichloro‐4‐pyridyl)bis(2,4,6‐trichlorophenyl)methyl Radical

Cyclizations of phenylethyl-substituted pyridinecarboxaldehydes

Fused Polycyclic Hydrocarbons Through Superacid-Induced Cyclialkylation of Aromatics

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