Lewis acid stabilization and activation of primary N-nitrosamides

Bohle, D. Scott; Chua, Zhijie; Perepichka, Inna; Rosadiuk, Kristopher A.

doi:10.1039/c6ra24421a

Cited by 4 publications

(4 citation statements)

References 65 publications

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“…These examples are derivatives in which the substituent on N1–H is another hydrogen, and they can even include a methyl at the C2 position (ketone derivatives), in which case the orientation of the methyl toward the metal center can probably generate greater steric hindrance. In the current case, taking into account that HL B is an aldehyde derivative and the Z orientation in the C2–N3 bond could give a structurally more relaxed situation, we attribute the presence of this conformation to the inherent ability of rhenium(I) to stabilize normally reactive species in other metal complexes . In fact, the rhenium(I) metal center has recently been used to stabilize isomeric kinetic and thermodynamic derivatives of N -nitrosamides .…”

Section: Resultssupporting

confidence: 77%

Synthesis of Novel Dinuclear N-Substituted 4-(Dimethylamino)benzaldehyde Thiosemicarbazonates of Rhenium(I): Formation of Four- and/or Five-Membered Chelate Rings, Conformational Analysis, and Reactivity

et al. 2020

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The reaction of fac-[ReX(CH3CN)2(CO)3] (X = Cl, Br) with N-phenyl-[4-(dimethylamino)benzaldehyde] thiosemicarbazone (HL A ) or N-4-methoxybenzyl-[4-(dimethylamino)benzaldehyde] thiosemicarbazone (HL B ) under controlled synthetic conditions gave 4 mononuclear [ReX(HL)(CO)3] (X = Cl, Br) and 16 dinuclear [Re2L2(CO)6] compounds. These complexes were obtained as single crystals, and their structures were established by X-ray diffraction. The structural study of these dimers showed the formation of several solvates, the presence of linkage isomerism, and the stabilization of four- and/or five-membered chelate rings. The different ligand coordination modes (a new μ-κ2-S,N2:κ-N3 coordination mode for a thiosemicarbazone ligand was observed), the conformation of the thiosemicarbazone chain in each case, the formal symmetry of the dimers, and the role of the synthetic procedure in the stability of the different chelate rings were analyzed and are discussed. Theoretical calculations in the gas phase were performed for the dimers with the HL A ligand in order to identify the thermodynamically most stable species. The behavior and structural stability of dimers in dimethyl sulfoxide and acetone solutions was investigated by 1H NMR spectroscopy. The strength of the ReI–L bond in solution was evidenced by the formation of [Re2(LNO2 )2(CO)6] and [Re(LA)(py)(CO)3] upon reaction of the corresponding dimer with concentrated nitric acid and pyridine, respectively.

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Section: Resultssupporting

confidence: 77%

Synthesis of Novel Dinuclear N-Substituted 4-(Dimethylamino)benzaldehyde Thiosemicarbazonates of Rhenium(I): Formation of Four- and/or Five-Membered Chelate Rings, Conformational Analysis, and Reactivity

et al. 2020

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“…The only reported reduction of the N -nitro functionality other than in pyrimidines is the reduction of N- nitrourethane and N- nitroguanidine using Zn metal in acid. − Although the reported conditions are compatible with alkyne functionality, we proceeded cautiously with reduction of 28 – 30 as alkyne 18 was sensitive to HCl. Additionally, reductive elimination at higher temperatures is known to occur with these reagents, posing a potential competing reaction to nitro group reduction. , We first assessed Zn and Fe with acetic acid in CH 3 CN to reduce the nitro group of 14 .…”

Section: Resultsmentioning

confidence: 99%

Stereoselective Synthesis of Highly Functionalized Arabinosyl Nucleosides through Application of an N-Nitro Protecting Group

2018

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2'-Deoxy-2',5-disubstituted arabinosyl uridine derivatives bearing a halogen (Cl, Br or I) at C2' and an ethynyl group at C5 have been synthesized in 6 steps from 2',3',5'-tri- O-acetyl-5-iodo-uridine in overall yields of 61% (compound 3, Cl), 47% (compound 4, Br), and 19% (compound 5, I). Stabilization of a 2'- O-triflyl leaving group intermediate to overcome spontaneous intramolecular 2,2'-anhydro uridine formation was pivotal to the synthesis. Specifically, to favor S2 reaction with a halogen nucleophile over intramolecular cyclization, the nucleophilicity of O-2 oxygen was reduced by incorporation of an adjacent electron withdrawing nitro substituent at N-3. The introduction of the 3- N-nitro group proceeded rapidly (nitronium trifluoroacetate, 1 min) and in quantitative yield. A one-pot method to remove the 3- N-nitro group by reductive nitration (zinc metal in acetic acid, 5 min) and the silyl protecting groups of the alkyne and 3',5' hydroxyls (fluoride reagent, 16 h) was established as the final synthetic step. This application of the 3- N-nitro protecting group addresses the significant shortfalls of the conventional approach to synthesis of 2' modified nucleosides, wherein condensation of a 2' modified sugar fragment with a pyrimidine base provides poor stereocontrol of N-glycosylation, low yields and incompatibility with 2' iodo sugars.

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“…27,28 We recently demonstrated some of their potential by isolating and characterizing the first nitrosocarbamides complexes (F). 29,30 Among the unusual hydrolysis and degradation products of F is the release of nitrous oxide, which is attributed to the intermediacy of nitroxyl anions, NO − . As stable nitrosamides make up a small class of reagents, and because we sought to extend this potentially useful chemistry as a source of nitroxyl anions, we are exploring related compounds with carbamate-like character.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Perhaps the best understood set of derivatives, the nitrosocarbamates ( E ), was first described by Joachim Thiele in 1898 . In constrast with their scant chemistry − since Thiele’s pioneering work, the biological interest in this class is burgeoning. , We recently demonstrated some of their potential by isolating and characterizing the first nitrosocarbamides complexes ( F ). , Among the unusual hydrolysis and degradation products of F is the release of nitrous oxide, which is attributed to the intermediacy of nitroxyl anions, NO – . As stable nitrosamides make up a small class of reagents, and because we sought to extend this potentially useful chemistry as a source of nitroxyl anions, we are exploring related compounds with carbamate-like character.…”

Section: Introductionmentioning

confidence: 99%

2,3,5-Metallotriazoles: Amphoteric Mesoionic Chelates from Nitrosoguanidines

et al. 2021

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Soluble nitrosoguanidine- and N-methylnitrosoguanidine-based metallotriazole complexes of ruthenium(II) monocarbonyls have been prepared and characterized. Both nitrosoguanidines prove to be strong chelates with the formally π-accepting nitroso nitrogen binding cis to carbon monoxide and a π-donating amide trans to the CO. The resulting ensemble consists of ruthenium examples of 1-metallo-2,3,5-triazoles. The ruthenium coordination sphere is completed by anions, either H–, Cl–, or Ph–, trans to the nitroso group as well as two mutually trans PPh3 groups. The π-donating amide group is formally sp2 hybridized with a planar nitrogen to give a strongly bound five-membered chelating anion. Together, these results illustrate the remarkable potential for the nitrosoguanidinates as a family of new metal chelates.

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Lewis acid stabilization and activation of primary N-nitrosamides

Abstract: The primary nitrosamides, here exemplified by the N-nitrosoalkylcarbamates, ROC(O)NHNO [R = CH3 (1), R = C2H5 (2)], show a markedly Lewis acid dependent chemistry.

Cited by 4 publications

References 65 publications

Synthesis of Novel Dinuclear N-Substituted 4-(Dimethylamino)benzaldehyde Thiosemicarbazonates of Rhenium(I): Formation of Four- and/or Five-Membered Chelate Rings, Conformational Analysis, and Reactivity

Synthesis of Novel Dinuclear N-Substituted 4-(Dimethylamino)benzaldehyde Thiosemicarbazonates of Rhenium(I): Formation of Four- and/or Five-Membered Chelate Rings, Conformational Analysis, and Reactivity

Stereoselective Synthesis of Highly Functionalized Arabinosyl Nucleosides through Application of an N-Nitro Protecting Group

2,3,5-Metallotriazoles: Amphoteric Mesoionic Chelates from Nitrosoguanidines

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