Fragmentation during the formic acid/formaldehyde (eschweiler-clarke) methylation of polyamines

Alder, Roger W.; Colclough, David; Mowlam, Rodney W.

doi:10.1016/0040-4039(91)80583-r

Cited by 25 publications

(6 citation statements)

References 27 publications

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“…Unfortunately, the ESI–MS of methylated intermediate 5a led to fragmentation due to rearrangements within the dendrimer, most probably due to ionization 53 or methylation. 54 This prompted us to isolate intermediates 4a (both n = 2 and n = 3) for MS analysis to study the distribution of functional groups over the ZID. MS data nicely showed a fairly small range of distribution of n = 2 and n = 3 with the desired number of n as center of the distribution (Figures S20 and S21).…”

Section: Resultsmentioning

confidence: 99%

“…To confirm with another technique and to obtain information about the distribution of the number of functional groups per dendrimer, we used MS. Unfortunately, the ESI–MS of methylated intermediate 5a led to fragmentation due to rearrangements within the dendrimer, most probably due to ionization or methylation . This prompted us to isolate intermediates 4a (both n = 2 and n = 3) for MS analysis to study the distribution of functional groups over the ZID.…”

Section: Resultsmentioning

confidence: 99%

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Design, Synthesis, and Characterization of Fully Zwitterionic, Functionalized Dendrimers

Roeven

Scheres²,

Smulders

et al. 2019

ACS Omega

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Dendrimers are interesting candidates for various applications because of the high level of control over their architecture, the presence of internal cavities, and the possibility for multivalent interactions. More specifically, zwitterionic dendrimers modified with an equal number of oppositely charged groups have found use in in vivo biomedical applications. However, the design and control over the synthesis of these dendrimers remains challenging, in particular with respect to achieving full modification of the dendrimer. In this work, we show the design and subsequent synthesis of dendrimers that are highly charged while having zero net charge, that is zwitterionic dendrimers that are potential candidates for biomedical applications. First, we designed and fully optimized the synthesis of charge-neutral carboxybetaine and sulfobetaine zwitterionic dendrimers. Following their synthesis, the various zwitterionic dendrimers were extensively characterized. In this study, we also report for the first time the use of X-ray photoelectron spectroscopy as an easy-to-use and quantitative tool for the compositional analysis of this type of macromolecules that can complement techniques such as nuclear magnetic resonance and gel permeation chromatography. Finally, we designed and synthesized zwitterionic dendrimers that contain a variable number of alkyne and azide groups that allow straightforward (bio)functionalization via click chemistry.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Design, Synthesis, and Characterization of Fully Zwitterionic, Functionalized Dendrimers

Roeven

Scheres²,

Smulders

et al. 2019

ACS Omega

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“…Syntheses of 2-hydroxypropyl-p-nitrophenyl phosphate (HPNPP, 3), 22 methyl-p-nitrophenyl phosphate (MPNPP, 4), 23 octahydro-3a,6a,9a-triazaphenalene (a precursor of [12]aneN 3 , 10), 24 1-methyl-1,5,9-triazacyclododecane (5), 25 1,5-dimethyl-1,5,9triazacyclododecane (6), 24 and 1,5,9-trimethyl-1,5,9-triazacyclododecane (7) 26 were synthesized according to the literature procedures and characterized by 1 H-NMR.…”

Section: Synthesismentioning

confidence: 99%

Steric effects on the catalytic activities of zinc(ii) complexes containing [12]aneN3 ligating units in the cleavage of the RNA and DNA model phosphates

et al. 2012

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A series of N-methylated mono- and di-[12]aneN(3) ligands () have been synthesized and characterized. The steric effects on the catalytic activities of their mononuclear and dinuclear zinc(ii) complexes in the cleavage of a RNA model 2-hydroxypropyl 4-nitrophenyl phosphate (HPNPP, ) and a DNA model methyl 4-nitrophenyl phosphates (MPNPP, 4) in methanol have been investigated at 25 °C. In the cleavage of phosphate catalyzed by the mononuclear complexes, derived from the N-methylation in the [12]aneN(3) backbone, the plots of k(obs)versus [Zn(II)] changed from an upward curvature to linearity with increasing level of methylation, indicating that N-methylations led to a reduction of dinuclear association that was responsible for the synergetic effect. Compared to the activities of the complex with non-methylated di-[12]aneN(3) ligand, those of the dinuclear zinc(ii) complex (Zn(2)-8), which has the two N-methyl groups, were reduced by two orders of magnitude as measured by the second-order rate constants and synergetic effect in the cleavage of both model compounds. For reactions catalyzed by the fully N-methylated dinuclear complex (Zn(2)-9), no synergetic effect was observed. Nevertheless, complex Zn(2)-8 still showed the remarkable catalytic efficiency, with rate accelerations of 10(9-10)-fold in the cleavage of each of the two phosphates relative to the background reactions, and the synergetic effects of up to 561 folds. pH jump experiments confirmed that the rate-limiting step in the cleavage of by Zn(2)-8 involved the binding process, while that in the reaction with 4 was the chemical cleavage of the P-O bond. Steric effects in the cleavage reactions were analyzed in detail and were compared with the electronic effect caused by oxy anion bridging group in the di-[12]aneN(3) ligand and also with the hydrophobic effect observed in other systems. The work has further confirmed that the combination of the cooperativity between two metal ions and a medium effect could result in excellent catalytic activities for the cleavage of phosphate diesters.

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“…8 There are no other cation ؒ ؒ ؒ cation interactions of note. Symmetry related chloride anions are bridged by hydrogen bonds from two water molecules to form a planar Methylation of the N atoms by the Eschweiler-Clarke reductive alkylation using formaldehyde is a common procedure but can lead to cleavage of the macrocycle 12 and formation of a mixture of methylated species. We have found however, that the use of sodium borohydride can alleviate these problems.…”

Section: Triazacyclododecane Ligandsmentioning

confidence: 99%

Synthesis, characterisation and polymerisation of vinylbenzene-substituted triazacyclododecanes and their transition metal complexes

Long

Parker

Speyer

et al. 2002

J. Chem. Soc., Dalton Trans.

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Fragmentation during the formic acid/formaldehyde (eschweiler-clarke) methylation of polyamines

Cited by 25 publications

References 27 publications

Design, Synthesis, and Characterization of Fully Zwitterionic, Functionalized Dendrimers

Design, Synthesis, and Characterization of Fully Zwitterionic, Functionalized Dendrimers

Steric effects on the catalytic activities of zinc(ii) complexes containing [12]aneN3 ligating units in the cleavage of the RNA and DNA model phosphates

Synthesis, characterisation and polymerisation of vinylbenzene-substituted triazacyclododecanes and their transition metal complexes

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