Synthesis of amine-dicyanohydroboranes, [amine-bis(ethylnitrilium)hydroboron(2+)] tetrafluoroborates, and their derivatives as precursors of amine-dicarboxyboranes

Z. Berente, Béla Györi

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9 Citations (Scopus)

Abstract

Numerous amine-dicyanohydroboranes [A·BH(CN)2, 1, A = quinuclidine (Q, c), trimethylamine (Me3N, d), 4-picoline (Pic, e), 4-(dimethylamino)pyridine (DMAP, f), N,N,N′N′-tetramethylethylenediamine (TMEDA, j), 1,4-diazabicyclo[2.2.2]octane (DABCO, k)] have been prepared by base exchange reactions from 4-cyanopyridine-dicyanohydroborane (4-CN-py·BH(CN)2, la). In analogous experiments with secondary amines [piperidine (g), diethylamine (h), and morpholine (i)] 1a underwent aminodecyanation also, probably via SNAr mechanism, which demonstrates the strong electron-withdrawing effect of the >N·BHX2 moiety toward the substituents on the nitrogen. Amine-dicyanohydroboranes have been transformed into [amine-bis(C-hydroxy-N-ethylimidate)hydroboron(2+)] (3), [amine-N-ethylcarbamoyl(C-hydroxy-N-ethylimido)hydroboron(1+)] (4), [amine-bis(C-methoxy-N-ethylimidate)hydroboron(2+)] (5), [amine-bis(amidinium)hydroboron(2+)] (6), and [amine-bis(triethylamidinium)-hydroboron(2+)] (7) cations, precursors of amine-dicarboxyboranes and their derivatives. These transformations were carried out in two steps. First, the otherwise nonreactive cyano groups were activated by ethylation employing Et3OBF4, yielding [amine-bis(ethylnitrilium)hydroboron(2+)] tetrafluoroborates (2), then 3-7 were obtained by nucleophilic addition to 2. The pKa values corresponding to the protonation of the N-ethylamide group were found to be extremely high (3.1-3.3), which demonstrates the strong electron-donating effect of >N·BHX2 moiety toward the substituents on the boron.

Original languageEnglish
Pages (from-to)5250-5256
Number of pages7
JournalInorganic Chemistry
Volume38
Issue number23
Publication statusPublished - 1999

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Amines
amines
Derivatives
synthesis
Quinuclidines
Picolines
Boron
piperidine
Electrons
Protonation
octanes
Cations
pyridines
boron
electrons
Nitrogen
nitrogen
cations

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

@article{5f90fb32f2ce40f09214abb937a67439,
title = "Synthesis of amine-dicyanohydroboranes, [amine-bis(ethylnitrilium)hydroboron(2+)] tetrafluoroborates, and their derivatives as precursors of amine-dicarboxyboranes",
abstract = "Numerous amine-dicyanohydroboranes [A·BH(CN)2, 1, A = quinuclidine (Q, c), trimethylamine (Me3N, d), 4-picoline (Pic, e), 4-(dimethylamino)pyridine (DMAP, f), N,N,N′N′-tetramethylethylenediamine (TMEDA, j), 1,4-diazabicyclo[2.2.2]octane (DABCO, k)] have been prepared by base exchange reactions from 4-cyanopyridine-dicyanohydroborane (4-CN-py·BH(CN)2, la). In analogous experiments with secondary amines [piperidine (g), diethylamine (h), and morpholine (i)] 1a underwent aminodecyanation also, probably via SNAr mechanism, which demonstrates the strong electron-withdrawing effect of the >N·BHX2 moiety toward the substituents on the nitrogen. Amine-dicyanohydroboranes have been transformed into [amine-bis(C-hydroxy-N-ethylimidate)hydroboron(2+)] (3), [amine-N-ethylcarbamoyl(C-hydroxy-N-ethylimido)hydroboron(1+)] (4), [amine-bis(C-methoxy-N-ethylimidate)hydroboron(2+)] (5), [amine-bis(amidinium)hydroboron(2+)] (6), and [amine-bis(triethylamidinium)-hydroboron(2+)] (7) cations, precursors of amine-dicarboxyboranes and their derivatives. These transformations were carried out in two steps. First, the otherwise nonreactive cyano groups were activated by ethylation employing Et3OBF4, yielding [amine-bis(ethylnitrilium)hydroboron(2+)] tetrafluoroborates (2), then 3-7 were obtained by nucleophilic addition to 2. The pKa values corresponding to the protonation of the N-ethylamide group were found to be extremely high (3.1-3.3), which demonstrates the strong electron-donating effect of >N·BHX2 moiety toward the substituents on the boron.",
author = "Z. Berente and B{\'e}la Gy{\"o}ri",
year = "1999",
language = "English",
volume = "38",
pages = "5250--5256",
journal = "Inorganic Chemistry",
issn = "0020-1669",
publisher = "American Chemical Society",
number = "23",

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TY - JOUR

T1 - Synthesis of amine-dicyanohydroboranes, [amine-bis(ethylnitrilium)hydroboron(2+)] tetrafluoroborates, and their derivatives as precursors of amine-dicarboxyboranes

AU - Berente, Z.

AU - Györi, Béla

PY - 1999

Y1 - 1999

N2 - Numerous amine-dicyanohydroboranes [A·BH(CN)2, 1, A = quinuclidine (Q, c), trimethylamine (Me3N, d), 4-picoline (Pic, e), 4-(dimethylamino)pyridine (DMAP, f), N,N,N′N′-tetramethylethylenediamine (TMEDA, j), 1,4-diazabicyclo[2.2.2]octane (DABCO, k)] have been prepared by base exchange reactions from 4-cyanopyridine-dicyanohydroborane (4-CN-py·BH(CN)2, la). In analogous experiments with secondary amines [piperidine (g), diethylamine (h), and morpholine (i)] 1a underwent aminodecyanation also, probably via SNAr mechanism, which demonstrates the strong electron-withdrawing effect of the >N·BHX2 moiety toward the substituents on the nitrogen. Amine-dicyanohydroboranes have been transformed into [amine-bis(C-hydroxy-N-ethylimidate)hydroboron(2+)] (3), [amine-N-ethylcarbamoyl(C-hydroxy-N-ethylimido)hydroboron(1+)] (4), [amine-bis(C-methoxy-N-ethylimidate)hydroboron(2+)] (5), [amine-bis(amidinium)hydroboron(2+)] (6), and [amine-bis(triethylamidinium)-hydroboron(2+)] (7) cations, precursors of amine-dicarboxyboranes and their derivatives. These transformations were carried out in two steps. First, the otherwise nonreactive cyano groups were activated by ethylation employing Et3OBF4, yielding [amine-bis(ethylnitrilium)hydroboron(2+)] tetrafluoroborates (2), then 3-7 were obtained by nucleophilic addition to 2. The pKa values corresponding to the protonation of the N-ethylamide group were found to be extremely high (3.1-3.3), which demonstrates the strong electron-donating effect of >N·BHX2 moiety toward the substituents on the boron.

AB - Numerous amine-dicyanohydroboranes [A·BH(CN)2, 1, A = quinuclidine (Q, c), trimethylamine (Me3N, d), 4-picoline (Pic, e), 4-(dimethylamino)pyridine (DMAP, f), N,N,N′N′-tetramethylethylenediamine (TMEDA, j), 1,4-diazabicyclo[2.2.2]octane (DABCO, k)] have been prepared by base exchange reactions from 4-cyanopyridine-dicyanohydroborane (4-CN-py·BH(CN)2, la). In analogous experiments with secondary amines [piperidine (g), diethylamine (h), and morpholine (i)] 1a underwent aminodecyanation also, probably via SNAr mechanism, which demonstrates the strong electron-withdrawing effect of the >N·BHX2 moiety toward the substituents on the nitrogen. Amine-dicyanohydroboranes have been transformed into [amine-bis(C-hydroxy-N-ethylimidate)hydroboron(2+)] (3), [amine-N-ethylcarbamoyl(C-hydroxy-N-ethylimido)hydroboron(1+)] (4), [amine-bis(C-methoxy-N-ethylimidate)hydroboron(2+)] (5), [amine-bis(amidinium)hydroboron(2+)] (6), and [amine-bis(triethylamidinium)-hydroboron(2+)] (7) cations, precursors of amine-dicarboxyboranes and their derivatives. These transformations were carried out in two steps. First, the otherwise nonreactive cyano groups were activated by ethylation employing Et3OBF4, yielding [amine-bis(ethylnitrilium)hydroboron(2+)] tetrafluoroborates (2), then 3-7 were obtained by nucleophilic addition to 2. The pKa values corresponding to the protonation of the N-ethylamide group were found to be extremely high (3.1-3.3), which demonstrates the strong electron-donating effect of >N·BHX2 moiety toward the substituents on the boron.

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