Synthesis, reactions and theoretical studies of [1,2,4]triazolo[4,3-c]-pyrimidinium- and [1,2,4]triazolo[4,3-a]pyrazinium-3-aminides

Derek L. Crabb, David A. Main, John O. Morley, Peter N. Preston, S. H B Wright

Research output: Contribution to journalArticle

Abstract

[1,2,4]Triazolo[4,3-c]pyrimidinium-3-aminides 5a-h have been synthesised by treating pyrimidin-6-yl thiosemicarbazide derivatives 7f-n with dicyclohexylcarbodiimide (DCC). The above aminides 5a-h were slowly hydrolysed in water but very rapidly hydrolysed in 5 M aqueous hydrochloric acid to give substituted 1,2,4-triazole derivatives (e.g. 5a,d,g ? 8e,a,f, respectively); related nucleophilic ring-opening reactions occurred when the aminides (cf. 5a-h) were treated with (separately) methanol and ethanol (e.g. 5d ? 8c and 8d, respectively). A series of analogous [1,2,4]triazolo[4,3-a]pyrazinium-3-aminides 6a-e was prepared following the procedures described above. The pyrazinium aminides 6 are stable in aq. 2 M HCl, and a stable hydrochloride salt 13 was formed from one such substrate 6a. The structure and electronic properties of condensed triazolium betaines 1, 5d, 6a and 15 have been studied using the semi-empirical PM3/COSMO method and with the ab initio 6-31 basis set; the implications of these results in respect of the potential of such betaines for molecular rearrangement are discussed.

Original languageEnglish
Pages (from-to)49-57
Number of pages9
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number1
Publication statusPublished - Jan 1997

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Betaine
Dicyclohexylcarbodiimide
Derivatives
Hydrochloric Acid
Electronic properties
Methanol
Ethanol
Salts
Water
Substrates
1,2,4-triazole
thiosemicarbazide

Cite this

@article{329c3a3cd3354099aa7da3a5e112dfb5,
title = "Synthesis, reactions and theoretical studies of [1,2,4]triazolo[4,3-c]-pyrimidinium- and [1,2,4]triazolo[4,3-a]pyrazinium-3-aminides",
abstract = "[1,2,4]Triazolo[4,3-c]pyrimidinium-3-aminides 5a-h have been synthesised by treating pyrimidin-6-yl thiosemicarbazide derivatives 7f-n with dicyclohexylcarbodiimide (DCC). The above aminides 5a-h were slowly hydrolysed in water but very rapidly hydrolysed in 5 M aqueous hydrochloric acid to give substituted 1,2,4-triazole derivatives (e.g. 5a,d,g ? 8e,a,f, respectively); related nucleophilic ring-opening reactions occurred when the aminides (cf. 5a-h) were treated with (separately) methanol and ethanol (e.g. 5d ? 8c and 8d, respectively). A series of analogous [1,2,4]triazolo[4,3-a]pyrazinium-3-aminides 6a-e was prepared following the procedures described above. The pyrazinium aminides 6 are stable in aq. 2 M HCl, and a stable hydrochloride salt 13 was formed from one such substrate 6a. The structure and electronic properties of condensed triazolium betaines 1, 5d, 6a and 15 have been studied using the semi-empirical PM3/COSMO method and with the ab initio 6-31 basis set; the implications of these results in respect of the potential of such betaines for molecular rearrangement are discussed.",
author = "Crabb, {Derek L.} and Main, {David A.} and Morley, {John O.} and Preston, {Peter N.} and Wright, {S. H B}",
year = "1997",
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pages = "49--57",
journal = "Journal of the Chemical Society, Perkin Transactions 2",
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Synthesis, reactions and theoretical studies of [1,2,4]triazolo[4,3-c]-pyrimidinium- and [1,2,4]triazolo[4,3-a]pyrazinium-3-aminides. / Crabb, Derek L.; Main, David A.; Morley, John O.; Preston, Peter N.; Wright, S. H B.

In: Journal of the Chemical Society, Perkin Transactions 2, No. 1, 01.1997, p. 49-57.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Synthesis, reactions and theoretical studies of [1,2,4]triazolo[4,3-c]-pyrimidinium- and [1,2,4]triazolo[4,3-a]pyrazinium-3-aminides

AU - Crabb, Derek L.

AU - Main, David A.

AU - Morley, John O.

AU - Preston, Peter N.

AU - Wright, S. H B

PY - 1997/1

Y1 - 1997/1

N2 - [1,2,4]Triazolo[4,3-c]pyrimidinium-3-aminides 5a-h have been synthesised by treating pyrimidin-6-yl thiosemicarbazide derivatives 7f-n with dicyclohexylcarbodiimide (DCC). The above aminides 5a-h were slowly hydrolysed in water but very rapidly hydrolysed in 5 M aqueous hydrochloric acid to give substituted 1,2,4-triazole derivatives (e.g. 5a,d,g ? 8e,a,f, respectively); related nucleophilic ring-opening reactions occurred when the aminides (cf. 5a-h) were treated with (separately) methanol and ethanol (e.g. 5d ? 8c and 8d, respectively). A series of analogous [1,2,4]triazolo[4,3-a]pyrazinium-3-aminides 6a-e was prepared following the procedures described above. The pyrazinium aminides 6 are stable in aq. 2 M HCl, and a stable hydrochloride salt 13 was formed from one such substrate 6a. The structure and electronic properties of condensed triazolium betaines 1, 5d, 6a and 15 have been studied using the semi-empirical PM3/COSMO method and with the ab initio 6-31 basis set; the implications of these results in respect of the potential of such betaines for molecular rearrangement are discussed.

AB - [1,2,4]Triazolo[4,3-c]pyrimidinium-3-aminides 5a-h have been synthesised by treating pyrimidin-6-yl thiosemicarbazide derivatives 7f-n with dicyclohexylcarbodiimide (DCC). The above aminides 5a-h were slowly hydrolysed in water but very rapidly hydrolysed in 5 M aqueous hydrochloric acid to give substituted 1,2,4-triazole derivatives (e.g. 5a,d,g ? 8e,a,f, respectively); related nucleophilic ring-opening reactions occurred when the aminides (cf. 5a-h) were treated with (separately) methanol and ethanol (e.g. 5d ? 8c and 8d, respectively). A series of analogous [1,2,4]triazolo[4,3-a]pyrazinium-3-aminides 6a-e was prepared following the procedures described above. The pyrazinium aminides 6 are stable in aq. 2 M HCl, and a stable hydrochloride salt 13 was formed from one such substrate 6a. The structure and electronic properties of condensed triazolium betaines 1, 5d, 6a and 15 have been studied using the semi-empirical PM3/COSMO method and with the ab initio 6-31 basis set; the implications of these results in respect of the potential of such betaines for molecular rearrangement are discussed.

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JO - Journal of the Chemical Society, Perkin Transactions 2

JF - Journal of the Chemical Society, Perkin Transactions 2

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