Steric hindrance to the syntheses and stabilities of 1,5- and 2,6-naphthalene N-permethylated diammonium salts

Dani Škalamera; Liping Cao; Lyle Isaacs; Robert Glaser; Kata Mlinarić-Majerski

doi:10.1016/j.tet.2016.02.002

Steric hindrance to the syntheses and stabilities of 1,5- and 2,6-naphthalene N-permethylated diammonium salts

Dani Škalamera, Liping Cao, Lyle Isaacs, Robert Glaser, Kata Mlinarić-Majerski

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

A series of naphthalene-1,5- and 2,6-diamines and their N-methyl derivatives were synthesized and characterized. ¹H NMR spectroscopy showed that an aqueous solution of naphthalene-2,6-di(NMe₃I) (2) underwent considerable demethylation over a 24 h period after its initial preparation. Exchange of the iodide nucleophilic anion by the triflate non-nucleophilic counter-ion afforded a stable quaternary aminium salt. H/D α-position exchange in D₂O solutions of naphthalene-2,6-di(NH₂MeCl) (3·HCl) and naphthalene-2,6-di(NHMe₂Cl) (4·HCl) with acidic ⁺NH protons was observed, but not in those of naphthalene-2,6-di(NMe₃I) or triflate (2 or 5). Exhaustive per-N-methylation of naphthalene-1,5-di(NMe₂) (7) afforded only the mixed naphthalene-1-NMe₃I-5-NHMe₂I quaternary aminium-tertiary ammonium salt due to severe 1,8-type peri-strain.

Original language	English
Pages (from-to)	1541-1546
Number of pages	6
Journal	Tetrahedron
Volume	72
Issue number	12
DOIs	https://doi.org/10.1016/j.tet.2016.02.002
State	Published - 24 Mar 2016

Keywords

1,8-Type peri-strain
H/D-exchange
Naphthalene diamines
Quaternary aminium salts
Stereochemistry

ASJC Scopus subject areas

Biochemistry
Drug Discovery
Organic Chemistry

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title = "Steric hindrance to the syntheses and stabilities of 1,5- and 2,6-naphthalene N-permethylated diammonium salts",

abstract = "A series of naphthalene-1,5- and 2,6-diamines and their N-methyl derivatives were synthesized and characterized. 1H NMR spectroscopy showed that an aqueous solution of naphthalene-2,6-di(NMe3I) (2) underwent considerable demethylation over a 24 h period after its initial preparation. Exchange of the iodide nucleophilic anion by the triflate non-nucleophilic counter-ion afforded a stable quaternary aminium salt. H/D α-position exchange in D2O solutions of naphthalene-2,6-di(NH2MeCl) (3·HCl) and naphthalene-2,6-di(NHMe2Cl) (4·HCl) with acidic +NH protons was observed, but not in those of naphthalene-2,6-di(NMe3I) or triflate (2 or 5). Exhaustive per-N-methylation of naphthalene-1,5-di(NMe2) (7) afforded only the mixed naphthalene-1-NMe3I-5-NHMe2I quaternary aminium-tertiary ammonium salt due to severe 1,8-type peri-strain.",

keywords = "1,8-Type peri-strain, H/D-exchange, Naphthalene diamines, Quaternary aminium salts, Stereochemistry",

author = "Dani {\v S}kalamera and Liping Cao and Lyle Isaacs and Robert Glaser and Kata Mlinari{\'c}-Majerski",

year = "2016",

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doi = "10.1016/j.tet.2016.02.002",

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T1 - Steric hindrance to the syntheses and stabilities of 1,5- and 2,6-naphthalene N-permethylated diammonium salts

AU - Škalamera, Dani

AU - Cao, Liping

AU - Isaacs, Lyle

AU - Glaser, Robert

AU - Mlinarić-Majerski, Kata

PY - 2016/3/24

Y1 - 2016/3/24

N2 - A series of naphthalene-1,5- and 2,6-diamines and their N-methyl derivatives were synthesized and characterized. 1H NMR spectroscopy showed that an aqueous solution of naphthalene-2,6-di(NMe3I) (2) underwent considerable demethylation over a 24 h period after its initial preparation. Exchange of the iodide nucleophilic anion by the triflate non-nucleophilic counter-ion afforded a stable quaternary aminium salt. H/D α-position exchange in D2O solutions of naphthalene-2,6-di(NH2MeCl) (3·HCl) and naphthalene-2,6-di(NHMe2Cl) (4·HCl) with acidic +NH protons was observed, but not in those of naphthalene-2,6-di(NMe3I) or triflate (2 or 5). Exhaustive per-N-methylation of naphthalene-1,5-di(NMe2) (7) afforded only the mixed naphthalene-1-NMe3I-5-NHMe2I quaternary aminium-tertiary ammonium salt due to severe 1,8-type peri-strain.

AB - A series of naphthalene-1,5- and 2,6-diamines and their N-methyl derivatives were synthesized and characterized. 1H NMR spectroscopy showed that an aqueous solution of naphthalene-2,6-di(NMe3I) (2) underwent considerable demethylation over a 24 h period after its initial preparation. Exchange of the iodide nucleophilic anion by the triflate non-nucleophilic counter-ion afforded a stable quaternary aminium salt. H/D α-position exchange in D2O solutions of naphthalene-2,6-di(NH2MeCl) (3·HCl) and naphthalene-2,6-di(NHMe2Cl) (4·HCl) with acidic +NH protons was observed, but not in those of naphthalene-2,6-di(NMe3I) or triflate (2 or 5). Exhaustive per-N-methylation of naphthalene-1,5-di(NMe2) (7) afforded only the mixed naphthalene-1-NMe3I-5-NHMe2I quaternary aminium-tertiary ammonium salt due to severe 1,8-type peri-strain.

KW - 1,8-Type peri-strain

KW - H/D-exchange

KW - Naphthalene diamines

KW - Quaternary aminium salts

KW - Stereochemistry

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DO - 10.1016/j.tet.2016.02.002

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Steric hindrance to the syntheses and stabilities of 1,5- and 2,6-naphthalene N-permethylated diammonium salts

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