In situ NMR spectroscopic studies of aniline ortho acylation (“sugasawa reaction”): The nature of reaction intermediates and Lewis acid influence on yield

Douglas, Alan W.; Abramson, N. L.; Houpis, Ioannis N.; Karady, Sandor; Molina, Audrey; Xavier, Lyndon C.; Yasuda, Nobuyoshi

doi:10.1016/0040-4039(94)85010-0

Cited by 30 publications

(9 citation statements)

References 4 publications

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“…As a last-ditch effort in using the bromoanilines, an alternative directed ortho C–H functionalization approach was envisioned involving Sugasawa coupling of 3-bromoaniline 7b with 4-fluorobenzonitrile 18c in the presence of BCl 3 and AlCl 3 (Scheme ). We anticipated that the use of 7b in the Sugasawa reaction would give a mixture of the regiosiomeric benzophenones. However, the reaction afforded 22% of 9bc as the only benzophenone isomer.…”

Section: Results and Discussionmentioning

confidence: 99%

Synthesis of Flubromazepam Positional Isomers for Forensic Analysis

et al. 2019

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Designer benzodiazepines have recently appeared in many forensic cases as legal alternatives to federally scheduled drugs such as diazepam (Valium) and alprazolam (Xanax). Though current forensic instrumental techniques are often sufficient for identifying novel psychoactive substances, they may not readily differentiate between potential positional isomers. Additionally, characterization data for positional isomers of known designer benzodiazepines are widely nonexistent. In this study, flubromazepam, a recognized designer benzodiazepine since 2012, was targeted for synthesis and characterization due to its potential for federal scheduling and current legal status within the United States. A practical synthetic method was developed to prepare purified reference materials for each positional isomer of flubromazepam in which the positions of the bromine and fluorine substituents were varied. Possible isomers (9 of the 12) were successfully prepared and used for further analysis.

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Section: Results and Discussionmentioning

confidence: 99%

Synthesis of Flubromazepam Positional Isomers for Forensic Analysis

et al. 2019

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“…14,15 Chloroacetylation of 1 with chloroacetonitrile, 2 M boron trichloride-dimethyl sulfide and aluminum trichloride in dichloromethane afforded compound 2 as the only product in 90% yield (whereas the Fisher method produces a mixture of C-6 and C-8 isomers). 11 The use of gallium trichloride instead of aluminium trichloride, though previously reported to improve the chloroacetylation of indoles, 16 gave similar yields. The occurrence of electrophilic substitution at C-8 but not at C-6 is presumably due to valence-bond stabilization brought about by the aromatic nature of the pyrone ring of the coumarin.…”

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confidence: 86%

Synthesis of Angular Pyrrolocoumarins

Gonzalez¹,

Lobo‐Antunes²,

Pérez‐Lourido³

et al. 2002

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The new pyrrolocoumarin 3 was synthesized in two steps from 7-amino-4-methylcoumarin by selective o-chloroacetylation at position 8 and subsequent cyclization (the Sugasawa route to indoles). Regioselective inverse electron demand Diels-Alder reaction of 3 with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate or 3,6bis(trifluoromethyl)-1,2,4,5-tetrazine then gave the angular pyridazinepyrrolocoumarins 4 and 5, respectively, in good yield.

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“…Importantly, both singly bridged dimers 54 and ion pairs 53 fall under Olah’s definition of superelectrophiles by exhibiting reactivity that substantially exceeds that of their corresponding monomer 55 . While the synthetic realization and application of heterobimetallic superelectrophiles that result from the association of Lewis acids comprised of two different metals has led to important developments in organometallic chemistry, the related homobimetallic case is still considered uncommon . Consequently, the principle of homobimetallic association of Lewis acids has remained unexplored in catalysis.…”

Section: Resultsmentioning

confidence: 99%

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) Homo-Dimers as Lewis Acidic Superelectrophiles

et al. 2018

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Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly bridged iron(III)-dimer as the postulated active catalytic species. These "superelectrophiles" function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of "superelectrophiles" and to broaden the current scope of catalytic carbonyl-olefin metathesis reactions.

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In situ NMR spectroscopic studies of aniline ortho acylation (“sugasawa reaction”): The nature of reaction intermediates and Lewis acid influence on yield

Cited by 30 publications

References 4 publications

Synthesis of Flubromazepam Positional Isomers for Forensic Analysis

Synthesis of Flubromazepam Positional Isomers for Forensic Analysis

Synthesis of Angular Pyrrolocoumarins

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) Homo-Dimers as Lewis Acidic Superelectrophiles

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