Hydrogen abstraction from primary amines. Substituent effects on the carbon–nitrogen bond rotation barriers in aminoalkyl radicals

MacInnes, Iain; Walton, John C.; Nonhebel, D. C.

doi:10.1039/p29870001789

Cited by 42 publications

(29 citation statements)

References 5 publications

(6 reference statements)

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“…The obtained 1 H NMR spectrum was in accordance with the literature. 14 To a solution of the alcohol (203 mg, 1.81 mmol) in dry ether (1.25 mL) was added pyridine (12.5 mL) at À30 C followed by the addition of PBr 3 (60 mL, 168 mg, 0.62 mmol) over 15 min. The solution was slowly heated to room temperature over 3 h and finally refluxed for 1 h. The reaction mixture was added dropwise to brine (10 mL) at 0 C and the aqueous layer was extracted with diethyl ether (3Â10 mL).…”

Section: Generalmentioning

confidence: 99%

Gold catalysed cyclisation reactions of 1,6-diynes triggered by the addition of methanol

2010

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Section: Generalmentioning

confidence: 99%

Gold catalysed cyclisation reactions of 1,6-diynes triggered by the addition of methanol

2010

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“…If the hypothesis of an allyl radical is correct, then the greater tendency to form a constrained substrate radical with AA than with d 8 -AA suggests that the proteins have a different interaction with unlabeled substrate, stabilizing the thermodynamically disfavored twisted allyl radical. To place the required stabilization in a more quantitative context, the barrier of rotation to take one of the -systems out of conjugation has been reported to be 11.7 kcal/mol for the parent pentadienyl radical in solution (48). The initial penalty for rotation of a 1,5-disubstituted radical with both substituents in the endo position may be somewhat lower than for the parent pentadienyl radical because of relief of unfavorable steric interactions (1,3-strain), but it is likely to still be considerable.…”

Section: Oxidation Of Aa By Peroxide-induced Asa-pghs-2 Radical(s)-mentioning

confidence: 99%

Structural Characterization of Arachidonyl Radicals Formed by Aspirin-treated Prostaglandin H Synthase-2

Tsai¹,

Palmer²,

Wu³

et al. 2002

Journal of Biological Chemistry

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Peroxide-generated tyrosyl radicals in both prostaglandin H synthase (PGHS) isozymes have been demonstrated to couple the peroxidase and cyclooxygenase activities by serving as the immediate oxidant for arachidonic acid (AA) in cyclooxygenase catalysis. Acetylation of Ser-530 of PGHS-1 by aspirin abolishes all oxygenase activity and transforms the peroxide-induced tyrosyl radical from a functional 33-35-gauss (G) wide doublet/wide singlet to a 26-G narrow singlet unable to oxidize AA. In contrast, aspirin-treated PGHS-2 (ASA-PGHS-2) no longer forms prostaglandins but retains oxygenase activity forming 11(R)-and 15(R)-hydroperoxyeicosatetraenoic acid and also retains the EPR line-shape of the native peroxide-induced 29 -30-G wide singlet radical. To evaluate the functional role of the wide singlet radical in ASA-PGHS-2, we have examined the ability of this radical to oxidize AA in singleturnover EPR studies. Anaerobic addition of AA to ASA-PGHS-2 immediately after formation of the wide singlet radical generated either a 7-line EPR signal similar to the pentadienyl AA radical obtained in native PGHS-2 or a 26 -28-G singlet radical. These EPR signals could be accounted for by a pentadienyl radical and a strained allyl radical, respectively. Experiments using 11d-AA, 13(R)d-AA, 15d-AA, 13,15d 2 -AA, and octadeuterated AA (d 8 -AA) confirmed that the unpaired electron in the pentadienyl radical is delocalized over C11, C13, and C15. A 6-line EPR radical was observed when 16d 2 -AA was used, indicating only one strongly interacting C16 hydrogen. These results support a functional role for peroxide-generated tyrosyl radicals in lipoxygenase catalysis by ASA-PGHS-2 and also indicate that the AA radical in ASA-PGHS-2 is more constrained than the corresponding radical in native PGHS-2.

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“…Following the procedure for the preparation of 11b, starting from 14 (2.18 g, 14.6 mmol) and 3-trimethylsilyl-2propyn-1-ol 23 (2.8 g, 21.8 mmol), 15f (2.5 g, 66%, pale yellow oil) was obtained: TLC R f 0.50 (…”

Section: -[3-methyl-2-(3-trimethylsilyl-2propynyloxy)phenyl]ethanonementioning

confidence: 99%

Enantioselective Tandem Formation and [2,3]-Sigmatropic Rearrangement of Cyclic Propargylic Oxonium Ylides Catalyzed by Dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate]

Tsutsui

Matsuura

MAKINO

et al. 2001

Israel Journal of Chemistry

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This paper describes the first examples of catalyst-dependent asymmetric induction in the periselective [2,3]-sigmatropic rearrangement of propargylic oxonium ylides generated by catalytic diazo decomposition. Catalysis of α-diazo-βketo esters 4a-g using dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate] in toluene has led to the virtually exclusive formation of benzofuran-3-ones bearing an allenic group with up to 79% ee.

show abstract

Hydrogen abstraction from primary amines. Substituent effects on the carbon–nitrogen bond rotation barriers in aminoalkyl radicals

Cited by 42 publications

References 5 publications

Gold catalysed cyclisation reactions of 1,6-diynes triggered by the addition of methanol

Gold catalysed cyclisation reactions of 1,6-diynes triggered by the addition of methanol

Structural Characterization of Arachidonyl Radicals Formed by Aspirin-treated Prostaglandin H Synthase-2

Enantioselective Tandem Formation and [2,3]-Sigmatropic Rearrangement of Cyclic Propargylic Oxonium Ylides Catalyzed by Dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate]

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