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Synthesis of 2‐Aryl‐ and 2,7‐Diaryl‐1,8‐bis(dimethylamino)naphthalenes. Overview of the “Buttressing effect” in 2,7‐Disubstituted Proton Sponges
Author(s) -
Filatova Ekaterina A.,
Gulevskaya Anna V.,
Pozharskii Alexander F.,
Ermolenko Eugeny A.,
Ozeryanskii Valery A.,
Misharev Alexander D.
Publication year - 2020
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202002745
Subject(s) - aryl , chemistry , steric effects , naphthalene , demethylation , reactivity (psychology) , aryne , medicinal chemistry , proton , alkylation , stereochemistry , organic chemistry , catalysis , medicine , biochemistry , alkyl , gene expression , alternative medicine , physics , pathology , quantum mechanics , dna methylation , gene
Suzuki arylation of 2‐halogeno and 2,7‐dihalogeno derivatives of 1,8‐bis(dimethylamino)naphthalene (proton sponge) was carried out. It was shown that the sterically hindered nature of the starting compounds in combination with the enhanced reactivity of their peri ‐NMe 2 groups allow to obtain the target 2‐aryl and 2,7‐diaryl derivatives in 20–34 % yields only. In most cases, a tandem Pd‐catalyzed hydrodehalogenation/ N ‐demethylation process was predominant. The latter, however, makes it possible to obtain yet unknown and synthetically valuable 2‐aryl‐ N 1 , N 1 , N 8 ‐trimethyl‐1,8‐diaminonaphthalenes (21–50 %), which can be easily converted into the corresponding proton sponges by conventional N ‐methylation. Using the literature data on 2,7‐disubstituted derivatives of the proton sponge as a background together with the XRD and basicity measurements performed in this work, a comprehensive analysis of the so‐called “buttressing effect” in 2‐aryl‐ and 2,7‐diaryl‐1,8‐bis(dimethylamino)naphthalenes, along with previously unknown 2,6‐diphenyl‐ N , N ‐dimethyl‐ p ‐toluidine has been carried out for the first time.