TY - JOUR
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
N1 - Funding Information:
We thank the Croatian Ministry of Science, Education and Sports (grant 098-0982933-2911 to K.M.-M.), the US NSF (CHE-1404911 to L.I.) and the Ben-Gurion University Research Fund for Scientific Relations (to R.G.) for financial support of this study. Gratitude is expressed to Prof. Dr. Pavel Hobza and Jiří Hostaš (Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Praha, Czech Republic) for the BLYP-D3/SVP calculation of geometry optimized cationic models, 11 , 13 and 14 .
Publisher Copyright:
© 2016 Elsevier Ltd. All rights reserved.
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
UR - http://www.scopus.com/inward/record.url?scp=84958940875&partnerID=8YFLogxK
U2 - 10.1016/j.tet.2016.02.002
DO - 10.1016/j.tet.2016.02.002
M3 - Article
AN - SCOPUS:84958940875
SN - 0040-4020
VL - 72
SP - 1541
EP - 1546
JO - Tetrahedron
JF - Tetrahedron
IS - 12
ER -