Reactions of Ethylenimines. VIII. Dissociation Constants

O'Rourke, Charles E.; Clapp, Leallyn B.; Edwards, John O.

doi:10.1021/ja01591a035

Cited by 22 publications

(3 citation statements)

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“…The enhanced potency of the aziridine inhibitors presumably manifests better spacial congruency with the SS active site than that of the acyclic aza analogue and may indicate a nonclassical, protonated cyclopropane intermediate in the formation of 2 . It is not known whether the aziridine inhibitors bind to SS in the aziridinium ion forms ( 5a and 5b ) or the aziridine forms ( 12a and 12b ). If the latter is true, the aziridine diphosphates may be better regarded as PSPP analogues rather than mimics for a charged transition state.…”

mentioning

confidence: 99%

Synthesis and Evaluation of Aziridine Analogues of Presqualene Diphosphate as Squalene Synthase Inhibitors

Koohang¹,

Coates²,

Owen³

et al. 1998

J. Org. Chem.

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Synthesis and Evaluation of Aziridine Analogues of Presqualene Diphosphate as Squalene Synthase Inhibitors

Koohang¹,

Coates²,

Owen³

et al. 1998

J. Org. Chem.

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“…2961), 3062) und 3163) (X,Y = CH,, 0, NR)die kinetische Stabilitat der Triimine der des Carbocyclus 3 vergleichbar, aber deutlich geringer als die des Trioxids 1 ist. 29 …”

Section: Kinetische Daten Und Klassifizierungunclassified

„cis‐Triaza‐tris‐σ‐homobenzole”︁ („cis‐Benzoltriimine”︁) Synthesen und [_σ2_s + _σ2_s + _σ2_s]‐Cycloreversionen zu 4,7‐Dihydro‐1H‐1,4,7‐triazoninen

et al. 1980

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cis-Triaza-tris-o-homobenzole" (,,cis-Benzoltriimine")Synthesen und [,2, + ,2, + ,2s]-Cycloreversionen zu 4,7-Dihydro-lH-l,4,7-triazoninen i. Br.Eingegangen am 18. Januar 1980 cis-Triaza-tris-o-homobenzol (,,cis-Benzoltriimin") (2) wird ausgehend von cis-Trioxa-tris-ohomobenzol (,,cis-Benzoltrioxid") (1) uber dreifache Epoxidoffnung mit Natriumazid, Tosylierung (92% chiro-/scyNo-Triazido-tritosylate 9 (92 -95070)/11 (5 -8%)) und LAH-Reduktion (40-50%) synthetisiert. Bei pKaI/pKa2-Werten von 6.43 und 1.90 ist mit der speziellen cis-Anordnung der drei Aziridinringe in 2 keine aufiergewtihnliche Basizitat verknupft. Andererseits werden Metall-Ionen leicht komplexiert. Von den dreifach N-akzeptor-bzw. N-donorsubstituierten Derivaten 18b -in gehen beim Erhitzen 18b-jin der Regelhochselektiv die 3 o + 3 n-Isomerisierung zu den 4,7-Dihydro-lH-1,4,7-triazonin-Derivaten 24bj ein. Die Aktivierungsbarrieren sind von der N-Substitution abhangig und sind bei S02R-durchweg hoher als bei COR-oder Alkyl-Substitution. Vor allem auf Grund der kinetischen Daten wird fur die 3 o + 3 n-Umwandlungen 18 -+ 24 in Analogie zu frtiheren Beispielen ein kooperativer Reaktionsablauf uber ,,trishomobenzoide" Ubergangszustande (38) vorgezogen. Mit AH* = 111 & 3kJ .mol-' (AS* = 4 ? 8 J . K -' . mol-' (CD,CN)) fur Mi, als Modell fur 2, besatigt sich, daR der Aziridinring, dem Cyclopropanring vergleichbar, sehr vie1 leichter als der Oxiranring in diesen [& + 2s + 2J-Cycloreversionen partizipiert. %is-Triaza-tris-o-homobenzenes" ("&Benzene Triimine")Syntheses and [Zs + Ss + ,,ZJ-Cycloreversions to 4,7-Dibydro-lH-l,4,7-triazonines cis-Triaza-tris-o-homobenzene ("cis-benzene triimine") (2) has been synthesized from cis-trioxatris-o-homobenzene ("cis-benzene trioxide") (1) via threefold epoxide-ring opening with sodium azide, tosylation (92% chiro-/scyNo-triazido tritosylates 9 (92 -95Vo)/ll (5 -8%)) and LAHreduction (40 -50%). The pKal/pKa2-values of 6.43 and 1.90 show that no extraordinary basicity is connected with the specific orientation of the three aziridine rings. Metal ions, however, are readily complexed. Upon thermal activation, out of the threefold N-donor-and N-acceptorsubstituted derivatives 18 bin, 18 bj undergo, mostly in a highly specific manner, a 3 o + 3 nisomerisation reaction to the 4,7-dihydro-lH-1,4,7-triazonine derivatives 24bj. The activation barriers depend on the nature of the N-substituents and are higher for SO,R than for COR or alkyl groups. Mainly on the basis of the kinetic data and in analogy with earlier examples, a cooperative reaction mechanism via "trishomobenzenoid" transition states (38) is held to be plausible for the 3o+3n-transformations 18-+24. With a AH*-value of 111 f 3 kJ.mo1-l (AS* = 4 8 J . K-' . mol-' (CD,CN)) for 18i, as a model for 2, it is obvious, that the aziridine ring participates much more readily, than the oxirane ring, in these [& + & + &I-cycloreversion reactions and is comparable in this respect to the cyclopropane ring.

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“…a positive charge might have an affinity to the metal binding sites. Ethylenimine has a pXa of 8.01 (O'Rourke et al, 1956) and a positive charge by protonation in neutral or acidic solution. Moreover, nucleophilic attack of a carboxylate anion to the protonated ethylenimine occurs to give an aminoethyl ester as shown in eq 1 (Earley et al, 1958)…”

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Modification of catalytic groups in lysozyme with ethylenimine

Yamada¹,

Imoto²,

Noshita³

1982

Biochemistry

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The reaction of lysozyme with ethylenimine has been studied at neutral and acidic pH. At least four singly modified lysozyme derivatives have been isolated. From the product analyses, only carboxyl groups in the protein were found to react. One of the derivatives, 1, was very labile and reverted back to native lysozyme during the isolation procedure. Its formation was markedly inhibited by the presence of tri(N-acetyl-D-glucosamine), indicating that the modified carboxyl residue in 1 is at or close to the binding site of lysozyme for the trisaccharide. Two other derivatives were identified as 2-aminoethyl esters of Glu-35 (2) and Asp-52 (3). At pH 10 and room temperature, these derivatives rearranged to the corresponding 2-hydroxyethylamide derivatives (5 and 6). A fourth derivative (4) did not contain an ethanolamine moiety; nevertheless, its Glu-35 was found to be modified by sequence analysis. Lysozyme derivatives modified at Glu-35 and Asp-52 were inactive toward glycol chitin but retained high affinity for tri(N-acetyl-D-glucosamine). Thus, Glu-35 and Asp-52 are essential for enzyme activity. A mechanism for the selective modification of these carboxyl residues in lysozyme has been proposed and related to the metal binding ability of lysozyme.

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Reactions of Ethylenimines. VIII. Dissociation Constants

Cited by 22 publications

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Synthesis and Evaluation of Aziridine Analogues of Presqualene Diphosphate as Squalene Synthase Inhibitors

Synthesis and Evaluation of Aziridine Analogues of Presqualene Diphosphate as Squalene Synthase Inhibitors

„cis‐Triaza‐tris‐σ‐homobenzole”︁ („cis‐Benzoltriimine”︁) Synthesen und [_σ2_s + _σ2_s + _σ2_s]‐Cycloreversionen zu 4,7‐Dihydro‐1H‐1,4,7‐triazoninen

Modification of catalytic groups in lysozyme with ethylenimine

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Reactions of Ethylenimines. VIII. Dissociation Constants

Cited by 22 publications

References 0 publications

Synthesis and Evaluation of Aziridine Analogues of Presqualene Diphosphate as Squalene Synthase Inhibitors

Synthesis and Evaluation of Aziridine Analogues of Presqualene Diphosphate as Squalene Synthase Inhibitors

„cis‐Triaza‐tris‐σ‐homobenzole”︁ („cis‐Benzoltriimine”︁) Synthesen und [σ2s + σ2s + σ2s]‐Cycloreversionen zu 4,7‐Dihydro‐1H‐1,4,7‐triazoninen

Modification of catalytic groups in lysozyme with ethylenimine

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Resources

About

„cis‐Triaza‐tris‐σ‐homobenzole”︁ („cis‐Benzoltriimine”︁) Synthesen und [_σ2_s + _σ2_s + _σ2_s]‐Cycloreversionen zu 4,7‐Dihydro‐1H‐1,4,7‐triazoninen