Superbase-Promoted Addition of Acetylene Gas to the C=N Bond

Article abstract of DOI:10.1002/ejoc.201900932

A new Csp³–Csp bond forming reaction is reported: the C=N bond of widespread imines reacts with acetylene gas in the presence of superbase KOtBu/DMSO at room temperature to afford terminal α-aminoacetylenes in up to 94 % yield. The reaction all

Full text of DOI:10.1002/ejoc.201900932

A Journal of
Accepted Article
Title: Superbase-Promoted Addition of Acetylene Gas to C=N Bond
Elena Yu. Schmidt, Ivan A. Bidusenko, Nadezhda I. Protsuk, Yan
V. Demyanov, Igor A. Ushakov, and Boris A. Trofimov*
Authors: Elena Schmidt, Ivan Bidusenko, Nadezhda Protsuk, Yan
Demyanov, Igor Ushakov, and Boris A. Trofimov
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
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content of this Accepted Article.
To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201900932
Link to VoR: http://dx.doi.org/10.1002/ejoc.201900932
Supported by

10.1002/ejoc.201900932
European Journal of Organic Chemistry
FULL PAPER
Superbase-Promoted Addition of Acetylene Gas to C=N Bond
Elena Yu. Schmidt, Ivan A. Bidusenko, Nadezhda I. Protsuk, Yan V. Demyanov, Igor A. Ushakov, and
Boris A. Trofimov*
Abstract: A new Csp3-Csp bond forming reaction is reported: the
C=N bond of widespread imines reacts with acetylene gas in the
presence of superbase KOBut/DMSO at room temperature to afford
terminal α-aminoacetylenes in up to 94% yield. The reaction allows
nitrogen heterocycles, e.g. 3H-indoles, to be directly cross-coupled
with acetylene gas.
H bond oxidative coupling with acetylene generated in situ from
CaC2. Recently, acetylene, generated in situ from calcium
carbide, was elegantly employed in a Cu(I)-catalyzed three
component coupling with ω-chlorinated ketones and primary
amines to generate terminal 2-alkynyl-N-heterocycles.[12] The
possible
manufacturing
of
calcium
carbide
from
lignocelluloses[13] makes acetylene renewable feedstock thus
expanding its synthetic impact.[14]
Here we report a new Csp3-Csp bond forming reaction (the
superbase-promoted addition of acetylene gas to imines)
opening a straightforward access to terminal propargylamines.
Introduction
The C-C bond formation is a cornerstone of organic chemistry
and Csp3-Csp bonds are of recognized privilege due to their
higher and versatile reactivity. Now, the most popular methods
for introduction of the C≡C bond into organic molecules are
diverse transition metal catalyzed cross-coupling reactions of
halogenated compounds with terminal alkynes[1] and classic
base-catalyzed Favorsky ethynylation of C=O bond[2] leading to
acetylenic alcohols. Amazingly, no example of transferring
Favorsky ethynylation to the C=N bond was found, evidently,
because of a lower polarity of the C=N bond (compared to the
C=O bond) and its higher basicity (repulsion between lone
electron pair and acetylenic carbanion).
Results and Discussion
As reference process for optimization, the reaction between
imine 1a and acetylene was chosen. The reaction was carried
out both in a steel closed stirred reactor or in a glass flow facility
with acetylene gas from cylinder or generated from calcium
carbide in
a separate apparatus. The following reaction
parameters were optimized: the base loading, concentration of
the reactants, temperature, acetylene pressure, and time (Table
1).
Recently,[3] a narrow group of specifically substituted
alkynes, ethynylarenes, was shown to be capable of nucleophilic
addition to Schiff bases in the presence of KOBut/DMSO
superbase (pKa ~ 30-32)[4] delivering internal propargylamines.
But the parent and most fundamental compound of alkyne series,
unsubstituted acetylene, fell out of the reaction scope due to its
specificity that requires a special research. Indeed, acetylene
stands alone in the alkyne series as having double C-H acidic
functionalities, higher and manifold reactivity, and being much
more available than its congeners because of its industrial
production. In this context, the addition of acetylene to the C=N
bond, if succeeded, could allow directly synthesizing terminal
propargylamines, which are especially reactive and hence most
useful among other α-acetylenic amines.[5] Consequently, many
efforts are now directed to develop their rational syntheses
including the transition metal-catalyzed (Cu, Ru, Rh, Pd, Ir, Pt,
Au)[6] propargylic substitution reactions, metal (Li, Mg, Al)
acetylide addition to imines,[5b,7] oximes,[5b,8] and nitrones[5b,9] as
well as Cu-[10] or Cu/oxidant-catalyzed[11] calcium carbide-based
protocols. The latter is of a particular interest as involving Csp3–
Table 1. Optimization of reaction conditions for superbase-catalyzed addition
of acetylene to imine 1a.[a]
KOBut
[mmol]
2.5
2.5
2.5
5
10
5
P
[atm]
6.9
2.6
2.6
2.6
2.4
1.3
1[e]
t
[h]
0.17
0.17
1
1
1
1
4
Conv. of
1a [%][b]
100
42
1a
[mmol]
5
5
5
5
5
5
5
Yield of 2a
Entry
[%][c]
64
36
61
92
80
85
85
87
89
1[d]
2
3
4
5
6
7
8
9
74
100
100
87
89
100
5
5
5
10
20
2.3
2.6
2
4
100
[a] Reaction conditions: 1a, KOBut, DMSO (50 mL), 20-22 oC, stirred reactor
(V = 250 mL). [b] Conversion was determined by 1H NMR spectroscopy of the
crude reaction mixtures. [c] Isolated yield after column chromatography (SiO2,
n-hexane/ethyl acetate, 50 : 1). [d] Reaction temperature was 40 oC. [e] Flow
process, glass flask (100 mL), atmospheric pressure, acetylene flow rate was
~ 15 cm3/min.
For arbitrary optimized conditions and key advantageous
characteristics of the synthesis can be accepted: 20-22 oC,
atmospheric or slightly elevated (2.3-2.6 atm) acetylenic
pressure, 1-4 h, 5-20 mmol of imine 1a in 50 mL of DMSO, 0.25-
1 mmol of KOBut per 1 mmol of 1a. These conditions ensure ~
100% conversion of starting imine 1a, 85-92% yield of
propargylamine 2a, and good scalability on the gram scale (from
0.98 to 3.90 g of imine 1a). In fact, the reaction is highly
Dr. E. Yu. Schmidt, Dr. I. A. Bidusenko, Dr. N. I. Protsuk, Y. V. Demyanov,
Dr. I. A. Ushakov, Prof. B. A. Trofimov
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the
Russian Academy of Sciences,
1 Favorsky St, 664033 Irkutsk, Russian Federation
E-mail: boris_trofimov@irioch.irk.ru
https://www.irkinstchem.ru/
Supporting information for this article is given via a link at the end of the
document.
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201900932
European Journal of Organic Chemistry
FULL PAPER
selective: in the reaction mixture, no any products except for the
any clear-cut structural effect are not observed. Apparently, here,
target propargylamine 2a are detectable (1H NMR) and therefore, the structural effect is a combination of mutually dependent
the isolated yield, slightly lower than quantitative, is due to the
losses on the isolation step.
factors: inductive, conjugative, and steric ones. Anyway, imines
with bulky alkyl substituents 1o,r,s demonstrate a clear steric
inhibition. Certainly, to reach a higher yield for each imine, an
Evaluation of the imine scope was carried out under the
following optimized conditions: imine 1 (5 mmol), KOBut (5 mmol, additional tuning of the reaction conditions is required.
0.561 g), DMSO (50 mL), steel stirred reactor (V = 250 mL),
acetylene under pressure (2.3-2.6 atm), 20-22 oC, 1 h (Tables 2,
3).
The reaction was proved to be efficiently extendable over
the imines with various aromatic and heteroaromatic
substituents at the nitrogen atom (Table 3).
The effects of the substituent structure at the imine carbon
atom with the fixed substituent (Ph) at the nitrogen atom are
demonstrated in Table 2.
Table 3. The substituents effect at the nitrogen atom of imines.
Table 2. The substituents effect at the carbon moiety of imines.
2t, 83%
2u, 81%
2v, 35% (74%)
2a, 92%
2b, 78%
2c, 79%
2d, 84%
2w, 76%
2x, 76%
2y, none (0%)
2e, 85%
2f, 82%
2g, 73% (88%)
2h, 62% (69%)
2z, none (0%)
2za, 81%
2zb, 79%
Isolated yields (column chromatography, SiO2, n-hexane/ethyl acetate,
50 : 1) are given. In parentheses, conversion is given, in all other cases
the conversion being 100%.
As exemplified by imine 1y (R3 = Bun), alkyl substituents at
the nitrogen atom suppressed the C=N bond reactivity relative to
ethynyl carbanion (Table 3). The target product was not
detected even when raising the acetylene pressure up to 9 atm
and the reaction time up to 24 h. Obviously, the donor effect of
the alkyl substituent depolarizes the imine moiety thereby
decreasing its electrophilicity and, hence, retarding the
nucleophilic addition.
2i, 81%
2j, 78%
2k, 77%
2l, 79%
2m, 84%
2n, 82%
2o, 65% (79%)
2p, 94%
Surprisingly, the anticipated double addition products, 1,4-
diaminobutynes, have not been detected in the reaction mixtures
in no one case (Tables 2 and 3). This chemoselectivity of the
reaction is likely due to the lower CH acidity of the terminal
aminopropargyl moiety as compared to unsubstituted acetylene
that results in decreasing the corresponding acetylide
concentration. By this feature, the reaction advantageously
differs from the classic Favorsky reaction (base-catalyzed
ethynylation of the C=O bonds), which usually accompanied by
2q, 79%
2r, 64% (79%)
2s, 37% (57%)
Isolated yields after column chromatography (SiO2, n-hexane/ethyl acetate, 50 :
1) are given. In parentheses, conversion (determined by 1H NMR spectroscopy
of the crude reaction mixtures) is given, in all other cases the conversion being
100%.
As seen from Table 2, for imines with aromatic,
heteroaromatic and aliphatic substituents, evident regularities of
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10.1002/ejoc.201900932
European Journal of Organic Chemistry
FULL PAPER
the formation of the acetylenic diols along with acetylenic
alcohols.
nucleophilic addition of acetylene gas to imines at room
temperature. When applied to cyclic imines, the reaction enables
to introduce the acetylenic moiety directly into a heterocyclic
core, i.e. to render a new type of cross-coupling. The synthesis
provides a short-cut to synthetically and pharmaceutically
valuable acetylenic amines (hardly accessible by other methods)
from available imines (Schiff bases) and inexpensive acetylene
gas, industrially produced in multi-thousand ton volume from
natural sources including CaC2. Widespread occurrence of the
C=N bond in organic chemistry warrants growth of interest in the
ethynylation discovered.
The high yield, one-pot efficiency of the additive wasteless
ethynylation of indole 1za and benzo[e]indole 1zb demonstrate
adaptability of the reaction developed for the direct introduction
of terminal acetylenic substituent into nitrogen heterocycles. This
is virtually an alternative to transition metal catalyzed cross-
coupling reactions commonly associated with wasting of
functional substituents and undesirable contamination of the
final products with heavy metals.
Generally, for the whole reaction, the integral substituent
effect is in keeping with the mechanism of the process as a
nucleophilic addition to the C=N bond. Indeed, formation of the
tetrasubstituted carbon center, resulted from the initial
nucleophilic attack of the acetylenic carbanion at Csp2 atom,
should be sterically hindered, while the acceptor substituents in
imine should facilitate the process. Additionally, a possible
coordination of potassium cation from the frustrated ion pair of
KOBut onto electron lone pair of nitrogen that enhances the C=N
bond electrophilicity contributes to facilitation of the addition
(Scheme 1).
Experimental Section
General Remarks: 1Н (400.1 MHz), 13С (100.6 MHz), and 15N (40.5
MHz) NMR spectra were recorded on a Bruker AV400 instrument in
СDCl3. The assignment of signals in the 1Н NMR spectra was made
using COSY and NOESY experiments. Resonance signals of carbon
atoms were assigned based on 1H-13
C C HMBC
HSQC and 1H-13
experiments. The 1H and 13C chemical shifts (δ) were referenced to
HMDS (0.05 ppm and 2.0 respectively). Coupling constants (J) in hertz
(Hz) were measured from one-dimensional spectra and multiplicities
were abbreviated as following: s (singlet), br. s (broad singlet), d
(doublet), dd (doublet of doublets), ddd (doublet of doublet of doublets), t
(triplet), m (multiplet). The chemical shifts were recorded in ppm. The
values of the δ 15N were measured through the 2D 1H-15N HMBC
experiment. The 15N chemical shifts were referenced to CH3NO2. IR
spectra were taken with FT-IR. Melting points (uncorrected) were
measured on a Kofler micro hot-stage apparatus. The microanalyses
were performed on a Flash EA 1112 Series elemental analyzer. Thin
layer chromatography was carried out on Merck silica gel 60 F254 pre-
coated aluminium foil sheets (eluent: Et2O/hexane = 1 : 3) and were
visualized using UV light (254 nm). Column chromatography was carried
out using slurry packed Sigma Aldrich silica gel (SiO2), 70-230 mesh,
pore size 60 Å (eluent: n-hexane/ethyl acetate). DMSO of commercial
grade, prior to use, was additionally dried (distillation over NaOH) to get a
water content ~ 0.2%. Ketones, amines and all other chemicals and
solvents are commercially available and were used without further
purification.
+
t
(K )
Bu O
+
t
HC C (K )
Bu OH
HC CH
3
3
3
R
R
R
t
+
+
Bu OH
(K )
N
(K )
NH
1
N
1
t
-Bu OK
2
2
1
R
2
R
R
R
R
R
HC
C
Scheme 1. KOBut-Catalyzed addition of acetylide to imine C=N bond.
In keeping with the above mechanism stands the adverse
effect of aliphatic surrounding of the C=N bond in
methylsubstituted pyrroline 1z, which appears to be inert toward
acetylene under standard conditions (KOBut/DMSO, 20-22 oC,
1h).
Starting Materials: Imines 1 were synthesized by published procedures
from ketones and amines in the presence of ZnCl2 (1a-j,t,v,x),[16] alumina
(1m,n)[17] or PCl5 (1k,l,r,s,u,w,y).[18] Physical-chemical characteristics of
imines 1a-y were identical to the literature data.[3,19]
Overall, the reaction developed meets PASE[15]
requirements as being one-pot, atom-economic and effecting in
a one operation step. This together with good scalability of the
process renders the reaction technologically feasible. The
excess acetylene employed in this reaction is easily recyclable
that is essential, particularly when the synthesis is realized on a
larger scale. The possibility to implement the ethynylation of
imines under ambient temperature and pressure put out all the
safety concerns.
Synthesis of propargylamines 2 (general procedure): A mixture of
imine 1 (5 mmol) and KOBut (5 mmol, 0.561 g) in DMSO (50 mL) was
placed into a steel stirred reactor (V = 250 mL). The latter was fed with
acetylene under pressure (initial pressure at ambient temperature was ~
10 atm) and then decompressed to atmospheric pressure to remove air.
The reactor was fed with acetylene again and stirred at 20-22 °C for 1 h.
Acetylene pressure in reaction course was 2.3-2.6 atm. The reaction
mixture was diluted with H2O (100 mL) and extracted with Et2O (20 mL ×
7). The combined organic extract was washed with H2O (20 mL × 3) and
dried over K2CO3 for 1 h. Et2O was evaporated under reduced pressure,
and the residue was purified by column chromatography [SiO2, eluent
ethyl acetate/hexane = 1 : 50 (or 1 : 1 for 2j,x)]. Physical-chemical
characteristics of propargylamines 2a,m,n,q were identical to the
literature data.[20]
Conclusions
We have disclosed a new atom-economic Csp3-Csp bond
forming reaction allowing straightforward scalable synthesis of
terminal α-aminoacetylenes in good to excellent yields. The
reaction represents
superbase (KOBut/DMSO)-promoted
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10.1002/ejoc.201900932
European Journal of Organic Chemistry
FULL PAPER
N-(2-Phenylbut-3-yn-2-yl)aniline (2a): Following the general procedure,
2a was prepared from imine 1a (5 mmol, 0.976 g); 2a was isolated as a
colorless solid (1.018 g, 92% yield). M.p.: 106 °C. Elemental analysis
calcd (%) for C16H15N (221.297): C, 86.84; H, 6.83; N, 6.33; found: C,
86.95; H, 6.79; N, 6.26. IR (film): νmax = 3416, 3253, 3082, 3043, 3024,
2975, 2922, 2363, 1654, 1602, 1501, 1444, 1366, 1316, 1262, 1217,
1175, 1092, 1024, 752, 688 cm-1. 1H NMR (400.1 MHz, CDCl3): δ = 7.70–
7.65 (m, 2H, Ho'), 7.35–7.30 (m, 2H, Hm'), 7.27–7.21 (m, 1H, Hp'), 7.07–
7.01 (m, 2H, Hm), 6.70–6.65 (m, 1H, Hp), 6.54–6.47 (m, 2H, Ho), 4.22
(br. s, 1H, NH), 2.46 (s, 1H, H4), 1.79 (s, 3H, Me) ppm. 13C{1H} NMR
(100.6 MHz, CDCl3): δ = 145.1 (Ci), 144.09 (Ci'), 128.7 (Cm'), 128.6 (Cm),
127.4 (Cp'), 125.6 (Co'), 118.5 (Cp), 115.9 (Co), 86.1 (C3), 72.5 (C4),
55.4 (C2), 35.9 (Me) ppm.
(400.1 MHz, CDCl3): δ = 7.78–7.71 (m, 2H, H3',5'), 7.60–7.56 (m, 2H,
H2',6'), 7.57–7.52 (m, 2H, H2",6"), 7.44–7.38 (m, 2H, H3",5"), 7.34–7.29
(m, 2H, H4"), 7.09–7.03 (m, 2H, Hm), 6.72–6.67 (m, 1H, Hp), 6.58–6.53
(m, 2H, Ho), 4.26 (br. s, 1H, NH), 2.49 (s, 1H, H4), 1.83 (s, 3H, Me) ppm.
13C{1H} NMR (100.6 MHz, CDCl3): δ = 145.1 (Ci), 143.1 (C4'), 140.8
(C1"), 140.3 (C1'), 128.9 (C3",5"), 128.7 (Cm), 127.5 (C2',6'), 127.4 (C4"),
127.2 (C2",6"), 126.1 (C3',5'), 118.6 (Cp), 115.9 (Co), 86.1 (C3), 72.6
(C4), 55.2 (C2), 35.9 (Me) ppm. 15N NMR (40.5 MHz, CDCl3): δ = -294.3
(NH) ppm.
N-(2-(4-Fluorophenyl)but-3-yn-2-yl)aniline (2f): Following the general
procedure, 2f was prepared from imine 1f (5 mmol, 1.066 g); 2f was
isolated as a beige solid (0.981 g, 82% yield). M.p.: 108 °C. Elemental
analysis calcd (%) for C16H14FN (239.287): C, 80.31; H, 5.90; F, 7.94; N,
5.85; found: C, 80.59; H, 5.83; F, 7.78; N, 5.76. IR (film): νmax = 3860,
3742, 3678, 3648, 3618, 3592, 3562, 3380, 3297, 3263, 2360, 1651,
N-(3-Phenylpent-1-yn-3-yl)aniline (2b): Following the general
procedure, 2b was prepared from imine 1b (5 mmol, 1.046 g); 2b was
isolated as a colorless solid (0.918 g, 78% yield). M.p.: 96 °C. Elemental
analysis calcd (%) for C17H17N (235.324): C, 86.77; H, 7.28; N, 5.95;
found: C, 86.81; H, 7.14; N, 5.83. IR (film): νmax = 3862, 3743, 3405, 3287,
3054, 3026, 2971, 2929, 2879, 2361, 1601, 1499, 1450, 1381, 1311,
1254, 1201, 1158, 1073, 1037, 753, 697, 652 cm-1. 1H NMR (400.1 MHz,
CDCl3): δ = 7.67–7.61 (m, 2H, Ho'), 7.35–7.29 (m, 2H, Hm'), 7.27–7.21
(m, 1H, Hp'), 7.06–6.98 (m, 2H, Hm), 6.70–6.63 (m, 1H, Hp), 6.54–6.48
(m, 2H, Ho), 4.23 (br. s, 1H, NH), 2.47 (s, 1H, H1), 2.12–1.83 (m, 2H, H4),
1
1677, 1601, 1502, 1316, 1223, 1158, 1093, 837, 751, 688 cm-1. H NMR
(400.1 MHz, CDCl3): δ = 7.68–7.59 (m, 2H, Ho'), 7.09–7.03 (m, 2H, Hm),
7.02–6.96 (m, 2H, Hm'), 6.73–6.66 (m, 1H, Hp), 6.53–6.46 (m, 2H, Ho),
4.21 (br. s, 1H, NH), 2.47 (s, 1H, H4), 1.77 (s, 3H, Me) ppm. 13C{1H}
NMR (100.6 MHz, CDCl3): δ = 162.1 (d, 1J = 245.5 Hz, Cp'), 144.9 (Ci),
4
3
139.7 (d, J = 3.2 Hz, Ci'), 128.7 (Cm), 127.4 (d, J = 8.0 Hz, Cm'), 118.7
(Cp), 115.9 (Co), 115.5 (d, 2J = 21.5 Hz, Co'), 85.8 (C3), 72.7 (C4), 54.9
(C2), 36.0 (Me) ppm. 15N NMR (40.5 MHz, CDCl3): δ = -294.7 (NH) ppm.
3
0.95 (t, J = 7.4 Hz, 3H, Me) ppm. 13C{1H} NMR (100.6 MHz, CDCl3): δ =
145.1 (Ci), 142.4 (Ci'), 128.6 (Cm'), 128.5 (Cm), 127.4 (Cp'), 126.4 (Co'),
118.4 (Cp), 115.8 (Co), 84.9 (С2), 73.5 (С1), 59.7 (С3), 40.1 (С4), 8.9
(Me) ppm. 15N NMR (40.5 MHz, CDCl3): δ = -295.9 (NH) ppm.
N-(2-(4-Chlorophenyl)but-3-yn-2-yl)aniline (2g): Following the general
procedure, 2g was prepared from imine 1g (5 mmol, 1.149 g); 2g was
isolated as a yellow solid (0.933 g, 73% yield). M.p.: 124 °C. Elemental
analysis calcd (%) for C16H14ClN (255.742): C, 75.14; H, 5.52; Cl, 13.86;
N, 5.48; found: C, 75.11; H, 5.47; Cl, 13.58; N, 5.59. IR (film): νmax = 3845,
3742, 3620, 3404, 3292, 3053, 2980, 2926, 2361, 1501, 1497, 1429,
1314, 1257, 1214, 1176, 1095, 1015, 630, 750, 689, 651 cm-1. 1H NMR
(400.1 MHz, CDCl3): δ = 7.66–7.58 (m, 2H, Ho'), 7.31–7.26 (m, 2H, Hm'),
7.09–7.02 (m, 2H, Hm), 6.75–6.67 (m, 1H, Hp), 6.51–6.47 (m, 2H, Ho),
4.21 (br. s, 1H, NH), 2.47 (s, 1H, H4), 1.77 (s, 3H, Me) ppm. 13C{1H}
NMR (100.6 MHz, CDCl3): δ = 144.8 (Ci), 142.7 (Ci'), 133.2 (Cp'), 128.9
(Cm'), 128.7 (Cm), 127.2 (Co'), 118.8 (Cp), 115.9 (Co), 85.6 (C3), 72.8
(C4), 55.0 (C2), 35.9 (Me) ppm. 15N NMR (40.5 MHz, CDCl3): δ = -294.4
(NH) ppm.
N-(1,1-Diphenylprop-2-yn-1-yl)aniline (2c): Following the general
procedure, 2c was prepared from imine 1c (5 mmol, 1.287 g); 2c was
isolated as a yellow solid (1.119 g, 79% yield). M.p.: 87 °C. Elemental
analysis calcd (%) for C21H17N (283.366): C, 89.01; H, 6.05; N, 4.94;
found: C, 89.12; H, 6.05; N, 4.81. IR (film): νmax = 3394, 3288, 3056, 3028,
2958, 2923, 2856, 2359, 1599, 1496, 1446, 1427, 1311, 1252, 1181,
1059, 1032, 1001, 789, 754, 697, 645 cm-1. 1H NMR (400.1 MHz, CDCl3):
δ = 7.65–7.58 (m, 4H, Ho'), 7.30–7.23 (m, 4H, Hm'), 7.21–7.16 (m, 2H,
Hp'), 7.00–6.94 (m, 2H, Hm), 6.66–6.61 (m, 1H, Hp), 6.50–6.44 (m, 2H,
Ho), 4.18 (br. s, 1H, NH), 2.54 (s, 1H, H3) ppm. 13C{1H} NMR (100.6 MHz,
CDCl3): δ = 145.1 (Ci), 143.8 (Ci'), 128.7 (Cm'), 128.5 (Cm), 127.8 (Cp'),
126.8 (Co'), 118.8 (Cp), 116.5 (Co), 85.0 (C2), 75.1 (C3), 63.2 (C1) ppm.
N-(2-(4-Bromophenyl)but-3-yn-2-yl)aniline (2h): Following the general
procedure, 2h was prepared from imine 1h (5 mmol, 1.371 g); 2h was
isolated as a yellow solid (1.291 g, 62% yield). M.p.: 129 °C. Elemental
analysis calcd (%) for C16H14BrN (300.193): C, 64.02; H, 4.70; Br, 26.62;
N-(2-(p-Tolyl)but-3-yn-2-yl)aniline (2d): Following the general
procedure, 2d was prepared from imine 1d (5 mmol, 1.046 g); 2d was
isolated as a light yellow solid (0.988 g, 84% yield). M.p.: 116 °C.
Elemental analysis calcd (%) for C17H17N (235.324): C, 86.77; H, 7.28; N,
5.95; found: C, 86.68; H, 7.34; N, 5.92. IR (film): νmax = 3399, 3285, 3088,
3049, 3022, 2978, 2923, 2862, 2365, 1600, 1501, 1452, 1429, 1368,
1312, 1256, 1215, 1175, 1093, 1058, 1027, 872, 844, 817, 750, 689, 649
cm-1. 1H NMR (400.1 MHz, CDCl3): δ = 7.59–7.50 (m, 2H, Ho'), 7.14–
7.09 (m, 2H, Hm'), 7.07–7.01 (m, 2H, Hm), 6.71–6.64 (m, 1H, Hp), 6.55–
6.49 (m, 2H, Ho), 4.21 (br. s, 1H, NH), 2.45 (s, 1H, H4), 2.32 (s, 3H,
MePh), 1.77 (s, 3H, Me) ppm. 13C{1H} NMR (100.6 MHz, CDCl3): δ =
145.2 (Ci), 141.1 (Ci'), 137.0 (Cp'), 129.4 (Cm'), 128.6 (Cm), 125.5 (Co'),
118.4 (Cp), 115.9 (Co), 86.3 (C3), 72.3 (C4), 55.1 (C2), 35.9 (Me), 21.1
(MePh) ppm. 15N NMR (40.5 MHz, CDCl3): δ = -294.4 (NH) ppm.
N, 4.67; found: C, 64.18; H, 4.59; Br, 26.45; N, 4.72. IR (film): νmax
=
3845, 3742, 3620, 3404, 3292, 3053, 2980, 2926, 2361, 1501, 1497,
1429, 1314, 1257, 1214, 1176, 1095, 1015, 630, 750, 689, 651 cm-1. 1H
NMR (400.1 MHz, CDCl3): δ = 7.61–7.52 (m, 2H, Ho'), 7.48–7.40 (m, 2H,
Hm'), 7.09–7.03 (m, 2H, Hm), 6.74–6.66 (m, 1H, Hp), 6.52–6.47 (m, 2H,
Ho), 4.21 (br. s, 1H, NH), 2.47 (s, 1H, H4), 1.76 (s, 3H, Me) ppm. 13C{1H}
NMR (100.6 MHz, CDCl3): δ = 144.7 (Ci), 143.2 (Ci'), 131.8 (Cm'), 128.7
(Cm), 127.5 (Co'), 121.4 (Cp'), 118.8 (Cp), 115.9 (Co), 85.5 (C3), 72.9
(C4), 55.0 (C2), 35.8 (Me) ppm.
N-(2-(Naphthalen-2-yl)but-3-yn-2-yl)aniline (2i): Following the general
procedure, 2i was prepared from imine 1i (5 mmol, 1.227 g); 2i was
isolated as a light yellow solid (1.099 g, 81% yield). M.p.: 168°C.
Elemental analysis calcd (%) for C20H17N (271.356): C, 88.52; H, 6.31; N,
5.16; found: C, 88.45; H, 6.26; N, 5.08. IR (film): νmax = 3408, 3249, 3055,
2954, 2923, 2855, 2359, 1658, 1598, 1497, 1437, 1321, 1262, 1161,
1124, 1074, 1026, 809, 743, 681, 637 cm-1. 1H NMR (400.1 MHz, CDCl3):
δ = 8.19 (s, 1H, H1'), 7.87–7.73 (m, 4H), 7.50–7.41 (m, 2H) [HNaphth],
7.06–6.97 (m, 2H, Hm), 6.70–6.64 (m, 1H, Hp), 6.58–6.53 (m, 2H, Ho),
4.30 (br. s, 1H, NH), 2.54 (s, 1H, H4), 1.86 (s, 3H, Me) ppm. 13C{1H}
N-(2-([1,1'-Biphenyl]-4-yl)but-3-yn-2-yl)aniline (2e): Following the
general procedure, 2e was prepared from imine 1e (5 mmol, 1.357 g); 2e
was isolated as a light yellow solid (1.264 g, 85% yield). M.p.: 173 °C.
Elemental analysis calcd (%) for C22H19N (297.393): C, 88.85; H, 6.44; N,
4.71; found: C, 88.59; H, 6.48; N, 4.87. IR (film): νmax = 3780, 3442, 3407,
3290, 3245, 3025, 2963, 2923, 2856, 2365, 1596, 1487, 1445, 1312,
1258, 1216, 1174, 1091, 905, 836, 752, 732, 688, 649 cm-1. 1H NMR
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201900932
European Journal of Organic Chemistry
FULL PAPER
NMR (100.6 MHz, CDCl3): δ = 145.2 (Ci), 141.6 (C1'), 133.5, 132.9 (C9',
C10'), 128.7 (Cm), 128.7, 128.3, 127.7, 126.2, 126.1, 124.6, 123.7
(7CNaphth), 118.6 (Cp), 116.0 (Co), 86.1 (C3), 72.8 (C4), 55.6 (C2), 35.8
(Me) ppm.
analysis calcd (%) for C12H15N (173.254): C, 83.19; H, 8.73; N, 8.08;
found: C, 83.28; H, 8.70; N, 7.97. IR (film): νmax = 3405, 3293, 3092, 3051,
3019, 2974, 2934, 2879, 1601, 1502, 1460, 1315, 1292, 1255, 1189,
1
1160, 1055, 1033, 1002, 845, 750, 693, 645 cm-1. H NMR (400.1 MHz,
CDCl3): δ = 7.16–7.07 (m, 2H, Hm), 6.92–6.84 (m, 2H, Ho), 6.76–6.66 (m,
1H, Hp), 3.54 (br. s, 1H, NH), 2.32 (s, 1H, H5), 1.91–1.67 (m, 2H, H2),
N-(2-(Pyridin-4-yl)but-3-yn-2-yl)aniline (2j): Following the general
procedure, 2j was prepared from imine 1j (5 mmol, 0.981 g); 2j was
isolated as a beige solid (0.867 g, 78% yield). M.p.: 159 °C. Elemental
analysis calcd (%) for C15H14N2 (222.285): C, 81.05; H, 6.35; N, 12.60;
found: C, 80.81; H, 6.26; N, 12.73. IR (film): νmax = 3398, 3265, 3233,
3179, 3109, 3033, 2981, 2927, 2861, 1942, 1597, 1497, 1410, 1317,
1257, 1226, 1174, 1095, 1064, 996, 824, 751, 666, 645 cm-1. 1H NMR
(400.1 MHz, CDCl3): δ = 8.61–8.53 (m, 2H, H2', H6'), 7.62–7.55 (m, 2H,
H3', H5'), 7.08–6.99 (m, 2H, Hm), 6.74–6.67 (m, 1H, Hp), 6.49–6.43 (m,
2H, Ho), 4.39 (br. s, 1H, NH), 2.50 (s, 1H, H4), 1.76 (s, 3H, Me) ppm.
13C{1H} NMR (100.6 MHz, CDCl3): δ = 153.4 (C4'), 150.3 (C2', C6'),
144.4 (Ci), 128.7 (Cm), 120.7 (C3', C5'), 118.9 (Cp), 115.7 (Co), 84.5
(C3), 73.3 (C4), 54.7 (C2), 35.2 (Me) ppm.
3
1.47 (s, 3H, C3-Me), 1.00 (t, J = 7.4 Hz, 3H, C2-Me) ppm. 13C{1H} NMR
(100.6 MHz, CDCl3): δ = 145.7 (Ci), 128.9 (Cm), 118.8 (Cp), 116.7 (Co),
87.0 (C4), 71.8 (C5), 52.1 (C3), 35.2 (C3-Me), 27.4 (C2), 8.78 (C2-Me)
ppm.
N-(3,4,4-Trimethylpent-1-yn-3-yl)aniline (2o): Following the general
procedure, 2o was prepared from imine 1o (5 mmol, 0.876 g); 2o was
isolated as a yellow solid (0.719 g, 65% yield). M.p.: 39 °C. Elemental
analysis calcd (%) for C16H15N (221.297): C, 86.84; H, 6.83; N, 6.33;
found: C, 86.95; H, 6.79; N, 6.26. IR (film): νmax = 3416, 3253, 3082, 3043,
3024, 2975, 2922, 2363, 1654, 1602, 1501, 1444, 1366, 1316, 1262,
1217, 1175, 1092, 1024, 752, 688 cm-1. 1H NMR (400.1 MHz, CDCl3): δ =
7.32–7.26 (m, 2H, Hm), 7.13–7.09 (m, 2H, Ho), 6.94–6.89 (m, 1H, Hp),
3.73 (br. s, 1H, NH), 2.50 (s, 1H, H1), 1.60 (s, 3H, 3-Me), 1.27 (s, 9H,
Me) ppm. 13C{1H} NMR (100.6 MHz, CDCl3): δ = 146.1 (Ci), 128.8 (Cm),
119.2 (Cp), 118.1 (Co), 86.5 (C2), 73.0 (C1), 58.7 (C3), 38.5 (C4), 25.5
(Me), 21.6 (3-Me) ppm.
N-(2-(Furan-2-yl)but-3-yn-2-yl)aniline (2k): Following the general
procedure, 2k was prepared from imine 1k (5 mmol, 0.926 g); 2k was
isolated as a colorless solid (0.813 g, 77% yield). M.p.: 117 °C. Elemental
analysis calcd (%) for C14H13NO (211.259): C, 79.59; H, 6.20; N, 6.63;
found: C, 78.73; H, 5.98; N, 6.40. IR (film): νmax = 3861, 3742, 3679, 3620,
3391, 3287, 3267, 2363, 1649, 1600, 1501, 1313, 1258, 1159, 1095,
1065, 1006, 745 cm-1. 1H NMR (400.1 MHz, CDCl3): δ = 7.36 (dd, 4J =
N-(4-Ethynylheptan-4-yl)aniline (2p): Following the general procedure,
2p was prepared from imine 1p (5 mmol, 0.946 g); 2p was isolated as
yellow oil (1.012 g, 94% yield). Elemental analysis calcd (%) for C15H21N
3
1.0 Hz, J = 1.7 Hz, 1H, H5’), 7.16–7.09 (m, 2H, Hm), 6.82–6.77 (m, 1H,
3
Hp), 6.77–6.72 (m, 2H, Ho), 6.43 (dd, 4J = 1.0 Hz, J = 3.0 Hz, 1H, H3’),
(215.334): C, 83.67; H, 9.83; N, 6.50; found: C, 83.25; H, 9.77; N, 6.47.
IR (film): νmax = 3412, 3298, 3019, 2958, 2872, 1685, 1601, 1502, 1461,
1316, 1255, 1159, 1076, 1035, 998, 872, 747, 691, 642 cm-1. 1H NMR
(400.1 MHz, CDCl3): δ = 7.19–7.10 (m, 2H, Hm), 6.92–6.87 (m, 2H, Ho),
6.77–6.70 (m, 1H, Hp), 3.56 (br. s, 1H, NH), 2.38 (s, 1H, H2'), 1.84–1.68
(m, 4H), 1.57–1.39 (m, 4H) [HAlk], 0.91 (t, 3J = 7.3 Hz, 6H, Me) ppm.
13C{1H} NMR (100.6 MHz, CDCl3): δ = 145.8 (Ci), 128.9 (Cm), 118.4 (Cp),
116.3 (Co), 86.8 (C1'), 72.5 (C2'), 55.2 (C4), 41.5 (С3), 17.3 (С2), 14.3
(Me) ppm.
3
6.32 (dd, J = 1.7 Hz, 3J = 3.0 Hz, 1H, H4’), 4.08 (br. S, 1H, NH), 2.51 (s,
1H, H4), 1.91 (s, 3H, Me) ppm. 13C{1H} NMR (100.6 MHz, CDCl3): δ =
155.0 (C2’), 145.1 (Ci), 142.3 (C5’), 128.7 (Cm), 119.5 (Cp), 116.7 (Co),
110.4 (C4’), 107.4 (C3’), 84.3 (C3), 72.3 (C4), 51.4 (C2), 31.0 (Me) ppm.
15N NMR (40.5 MHz, CDCl3): δ = -296.3 (NH) ppm.
N-(2-(Thiophen-2-yl)but-3-yn-2-yl)aniline (2l): Following the general
procedure, 2l was prepared from imine 1l (5 mmol, 1.006 g); 2l was
isolated as a colorless solid (0.898 g, 79% yield). M.p.: 108 °C. Elemental
analysis calcd (%) for C14H13NS (227.325): C, 73.97; H, 5.76; N, 6.16; S,
14.10; found: C, 74.33; H, 5.35; N, 5.54; S, 14.75. IR (film): νmax = 3861,
3742, 3679, 3620, 3391, 3287, 3267, 2363, 1649, 1600, 1501, 1313,
1258, 1159, 1095, 1065, 1006, 745 cm-1. 1H NMR (400.1 MHz, CDCl3): δ
N-(1-Ethynylcyclohexyl)aniline (2q): Following the general procedure,
2q was prepared from imine 1q (5 mmol, 0.866 g); 2q was isolated as a
colorless solid (0.787 g, 79% yield). M.p.: 97 °C. Elemental analysis
calcd (%) for C14H17N (199.291): C, 84.37; H, 8.60; N, 7.03; found: C,
85.43; H, 7.07; N, 7.12. IR (film): νmax = 3861, 3742, 3621, 3367, 3268,
3018, 2971, 2931, 2852, 1596, 1501, 1450, 1315, 1261, 1172, 1105,
1083, 912, 749, 672 cm-1. 1H NMR (400.1 MHz, CDCl3): δ = 7.20–7.09
(m, 2H, Hm), 6.97–6.86 (m, 2H, Ho), 6.80–6.66 (m, 1H, Hp), 3.58 (br. s,
1H, NH), 2.41 (s, 1H, H2), 2.21–2.03 (m, 2H), 1.75–1.46 (m, 7H), 1.36–
1.16 (m, 1H) [HCycl] ppm. 13C{1H} NMR (100.6 MHz, CDCl3): δ = 145.4
(Ci), 128.8 (Cm), 118.7 (Cp), 116.9 (Co), 86.6 (C1), 73.1 (C2), 52.5 (C1'),
38.5 (C2'), 25.6 (C4'), 22.6 (C3') ppm. 15N NMR (40.5 MHz, CDCl3): δ = -
292.9 (NH) ppm.
3
4
3
4
= 7.16 (dd, J = 3.6 Hz, J = 1.2 Hz, 1H, H5’), 7.14 (dd, J = 5.1 Hz, J =
1.2 Hz, 1H, H3’), 7.08–7.02 (m, 2H, Hm), 6.88 (dd, 3J = 5.1 Hz, 3J = 3.6
Hz, 1H, H4’), 6.73–6.67 (m, 1H, Hp), 6.65–6.60 (m, 2H, Ho), 4.20 (br. S,
1H, NH), 2.46 (s, 1H, H4), 1.88 (s, 3H, Me) ppm. 13C{1H} NMR (100.6
MHz, CDCl3): δ = 150.5 (C2’), 144.9 (Ci), 128.7 (Cm), 126.8 (C4’), 125.1
(C5’), 124.3 (C3’), 119.2 (Cp), 116.2 (Co), 85.4 (C3), 72.4 (C4), 53.0 (C2),
36.1 (Me) ppm. 15N NMR (40.5 MHz, CDCl3): δ = -290.8 (NH) ppm.
N-(2-Methylbut-3-yn-2-yl)aniline (2m): Following the general procedure,
2m was prepared from imine 1m (5 mmol, 0.666 g); 2m was isolated as
a colorless solid (0.669 g, 84% yield). M.p.: 51 °C. Elemental analysis
calcd (%) for C11H13N (159.228): C, 82.97; H, 8.23; N, 8.80; found: C,
83.11; H, 8.20; N, 8.59. IR (film): νmax = 3401, 3288, 3091, 3050, 2983,
2931, 2870, 2105, 1601, 1502, 1431, 1379, 1316, 1258, 1210, 1184,
1080, 1032, 996, 751, 692, 649 cm-1. 1H NMR (400.1 MHz, CDCl3): δ =
7.22–7.12 (m, 2H, Hm), 6.97–6.86 (m, 2H, Ho), 6.83–6.72 (m, 1H, Hp),
3.63 (br. s, 1H, NH), 2.35 (s, 1H, H4), 1.59 (s, 6H, Me) ppm. 13C{1H}
NMR (100.6 MHz, CDCl3): δ = 145.7 (Ci), 128.9 (Cm), 119.1 (Cp), 117.0
(Co), 88.1 (C3), 70.6 (C4), 48.3 (C2), 30.6 (Me) ppm.
1-Ethynyl-N-phenylcycloheptan-1-amine (2r): Following the general
procedure, 2r was prepared from imine 1r (5 mmol, 0.936 g); 2r was
isolated as a yellow solid (0.683 g, 64% yield). M.p.: 86 °C. Elemental
analysis calcd (%) for C15H19N (213.318): C, 84.46; H, 8.98; N, 6.57;
found: C, 84.81; H, 8.75; N, 6.37. IR (film): νmax = 3440, 3370, 3266, 3090,
3051, 3021, 2928, 2855, 1922, 1743, 1696, 1651, 1589, 1503, 1464,
1318, 1292, 1262, 1075, 1051, 875, 750, 681 cm-1. 1H NMR (400.1 MHz,
CDCl3): δ = 7.23–7.15 (m, 2H, Hm), 6.98–6.93 (m, 2H, Ho), 6.81–6.75 (m,
1H, Hp), 3.65 (br. S, 1H, NH), 2.44 (s, 1H, H2), 2.26–2.14 (m, 2H), 1.98–
1.85 (m, 2H) [H2’], 1.76–1.54 (m, 8H, HCycl) ppm. 13C{1H} NMR (100.6
MHz, CDCl3): δ = 145.5 (Ci), 128.9 (Cm), 118.6 (Cp), 116.7 (Co), 87.9
(C1), 72.1 (C2), 55.5 (C1’), 41.1 (C2’), 28.5, 22.6 (4С, CCycl) ppm.
N-(3-Methylpent-1-yn-3-yl)aniline
(2n): Following the general
procedure, 2n was prepared from imine 1n (5 mmol, 0.736 g); 2n was
isolated as a beige solid (0.710 g, 82% yield). M.p.: 34 °C. Elemental
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201900932
European Journal of Organic Chemistry
FULL PAPER
1
1-Ethynyl-N-phenylcyclooctan-1-amine (2s): Following the general
procedure, 2s was prepared from imine 1s (5 mmol, 1.007 g); 2s was
isolated as a colorless solid (0.421 g, 37% yield). M.p.: 68 °C. Elemental
analysis calcd (%) for C16H21N (227.345): C, 84.53; H, 9.31; N, 6.16;
found: C, 84.49; H, 9.31; N, 5.99. IR (film): νmax = 3353, 3300, 3151, 2922,
2856, 1920, 1740, 1682, 1601, 1501, 1444, 1314, 1248, 1156, 1077,
1032, 749, 694, 642 cm-1. 1H NMR (400.1 MHz, CDCl3): δ = 7.23–7.15
(m, 2H, Hm), 7.01–6.96 (m, 2H, Ho), 6.83–6.76 (m, 1H, Hp), 3.58 (br. s,
1282, 1222, 1170, 1100, 1027, 909, 767, 700, 648 cm-1. H NMR (400.1
MHz, CDCl3): δ = 7.95–7.90 (m, 1H), 7.79–7.74 (m, 1H) [HNaphth], 7.73–
7.67 (m, 2H, Ho), 7.53–7.40 (m, 2H), 7.34–7.27 (m, 2H, Hm), 7.27–7.23
(m, 1H), 7.22–7.18 (m, 1H), 7.13–7.07 (m, 1H), 6.50–6.45 (m, 1H)
[HNaphth, Hp], 4.89 (br. s, 1H, NH), 2.50 (s, 1H, H4), 1.95 (s, 3H, Me) ppm.
13C{1H} NMR (100.6 MHz, CDCl3): δ = 143.6 (Ci), 139.4, 134.3, 129.0
(3CNaphth], 128.8 (Cm), 127.5, 126.0, 125.6, 125.0, 124.3, 119.9, 118.6,
110.5 [10C, CPh, CNaphth], 86.0 (C3), 72.8 (C4), 55.4 (C2), 36.4 (Me) ppm.
1H, NH), 2.42 (s, 1H, H2), 2.13–2.00 (m, 4H), 1.76–1.52 (m, 10H) [HCycl
]
ppm. 13C{1H} NMR (100.6 MHz, CDCl3): δ = 145.5 (Ci), 128.7 (Cm),
118.8 (Cp), 117.2 (Co), 87.9 (C1), 71.9 (C2), 55.4 (C1'), 35.6 (C2'), 28.1
(2СCycl), 25.0 (C5'), 22.1 (2СCycl) ppm.
N-(2-Phenylbut-3-yn-2-yl)pyridin-3-amine (2x): Following the general
procedure, 2x was prepared from imine 1x (5 mmol, 0.981 g); 2x was
isolated as a yellow solid (0.411 g, 76% yield). M.p.: 136 °C. Elemental
analysis calcd (%) for C15H14N2 (222.285): C, 81.05; H, 6.35; N, 12.60;
found: C, 80.63; H, 6.31; N, 12.58. IR (film): νmax = 3861, 3743, 3287,
3253, 3173, 3097, 3033, 2986, 2929, 1585, 1529, 1482, 1449, 1412,
1369, 1304, 1245, 1215, 1180, 1100, 1069, 1022, 911, 796, 730, 703,
644 cm-1. 1H NMR (400.1 MHz, CDCl3): δ = 8.02 (d, 4J = 2.7 Hz, 1H, H2'),
7.93 (dd, 3J = 4.7 Hz, 4J = 1.2 Hz, 1H, H6'), 7.69–7.60 (m, 2H, Ho), 7.35–
7.29 (m, 2H, Hm), 7.27–7.22 (m, 1H, Hp), 6.89 (dd, J = 8.3 Hz, J = 4.7
Hz, 1H, H5'), 6.71 (ddd, 3J = 8.3 Hz, 4J = 2.7 Hz, 4J = 1.2 Hz, 1H, H4'),
4.62 (br. s, 1H, NH), 2.49 (s, 1H, H4), 1.80 (s, 3H, Me) ppm. 13C{1H}
NMR (100.6 MHz, CDCl3): δ = 143.1 (Ci), 141.4 (C3'), 139.6, 138.54
(2CPyr), 128.8 (Cm), 127.7 (Cp), 125.5 (Co), 123.0, 121.7 (2CPyr), 85.3
(C3), 73.0 (C4), 55.3 (C2), 35.5 (Me) ppm.
2-Methyl-N-(2-phenylbut-3-yn-2-yl)aniline (2t): Following the general
procedure, 2t was prepared from imine 1t (5 mmol, 1.046 g); 2t was
isolated as a colorless solid (0.977 g, 83% yield). M.p.: 104 °C. Elemental
analysis calcd (%) for C17H17N (235.324): C, 86.77; H, 7.28; N, 5.95;
found: C, 86.73; H, 7.29; N, 5.79. IR (film): νmax = 3423, 3284, 3057, 3026,
2972, 2924, 2859, 2361, 1602, 1508, 1447, 1370, 1312, 1259, 1218,
3
3
1
1175, 1124, 1092, 1063, 1039, 845, 752, 700, 651 cm-1. H NMR (400.1
MHz, CDCl3): δ = 7.63–7.57 (m, 2H, Ho), 7.29–7.24 (m, 2H, Hm), 7.22–
7.17 (m, 1H, Hp), 7.02–6.98 (m, 1H), 6.83–6.76 (m, 1H), 6.60–6.55 (m,
1H), 6.36–6.32 (m, 1H) [HPh'], 4.02 (br. s, 1H, NH), 2.43 (s, 1H, H4), 2.20
(s, 3H, MePh), 1.80 (s, 3H, Me) ppm. 13C{1H} NMR (100.6 MHz, CDCl3): δ
= 143.9 (Ci), 142.8 (C1'), 130.0 (CPh'), 128.7 (Cm), 127.4 (Cp), 126.2
(CPh'), 125.5 (Co), 122.9 (C2'), 118.0, 114.8 (2CPh'), 86.3 (С3), 72.5 (С4),
55.1 (C2), 36.2 (Me), 17.9 (MePh') ppm.
2-Ethynyl-2,3,3-trimethylindoline (2za): Following the general
procedure, 2za was prepared from indole 1za (0.796 g, 5 mmol); 2za was
isolated as a light yellow solid (0.750 g, 81% yield). M.p.: 56 °C.
Elemental analysis calcd (%) for C13H15N (185.265): C, 84.28; H, 8.16; N,
7.56; found: C, 84.86; H, 8.31; N, 6.73. IR (film): νmax = 3358, 3289, 3046,
2970, 2929, 2869, 2367, 1616, 1480, 1459, 1374, 1319, 1254, 1209,
1112, 1070, 1020, 930, 855, 748, 686, 640 cm-1. 1H NMR (400.1 MHz,
CDCl3): δ = 7.06–7.03 (m, 1H, H6), 7.03–7.00 (m, 1H, H4), 6.81–6.75 (m,
1H, H5), 6.65–6.61 (m, 1H, H7), 3.94 (br. s, 1H, NH), 2.25 (s, 1H, H2'),
1.45 (s, 3H, C2-Me), 1.40 (s, 3H), 1.16 (s, 3H) [C3-Me2] ppm. 13C{1H}
NMR (100.6 MHz, CDCl3): δ = 147.5 (C7a), 137.7 (C3a), 127.5 (C6),
122.4 (C4), 119.8 (C5), 110.1 (C7), 87.7 (C1'), 71.3 (C2'), 65.9 (C2), 47.0
(C3), 24.6, 23.5, 23.0 (C2-Me, C3-Me2) ppm. 15N NMR (40.5 MHz,
CDCl3): δ = -285.3 (NH) ppm.
2-Fluoro-N-(2-phenylbut-3-yn-2-yl)aniline (2u): Following the general
procedure, 2u was prepared from imine 1u (5 mmol, 1.066 g); 2u was
isolated as a light yellow solid (0.969 g, 81% yield). M.p.: 98 °C.
Elemental analysis calcd (%) for C16H14FN (239.287): C, 80.31; H, 5.90;
F, 7.94; N, 5.85; found: C, 80.28; H, 5.96; F, 7.81; N, 5.74. IR (film): νmax
= 3421, 3292, 3062, 3033, 2981, 2928, 2868, 1886, 1752, 1620, 1590,
1513, 1447, 1330, 1298, 1258, 1216, 1187, 1098, 1031, 745, 701, 651
cm-1. 1H NMR (400.1 MHz, CDCl3): δ = 7.71–7.65 (m, 2H, Ho), 7.37–7.30
(m, 2H, Hm), 7.29–7.25 (m, 1H, Hp), 7.00–6.91 (m, 1H), 6.75–6.69 (m,
1H), 6.64–6.56 (m, 1H), 6.46–6.38 (m, 1H) [HPh'], 4.53 (br. s, 1H, NH),
2.49 (s, 1H, H4), 1.84 (s, 3H, Me) ppm. 13C{1H} NMR (100.6 MHz,
CDCl3): δ = 152.3 (d, 1J = 238.3 Hz, C2'), 143.7 (Ci), 133.5 (d, 2J = 10.6
Hz, C1'), 128.8 (Cm), 127.6 (Cp), 125.6 (Co), 123.7 (d, J = 3.6 Hz), 118.0
(d, J = 7.2 Hz), 116.6 (d, J = 2.6 Hz) [CAr'], 114.3 (d, 2J = 19.0 Hz, C3'),
85.8 (C3), 72.8 (C4), 55.3 (C2), 35.8 (Me) ppm.
2-Ethynyl-1,1,2-trimethyl-2,3-dihydro-1H-benzo[e]indole
(2zb):
Following the general procedure, 2zb was prepared from indole 1zb (5
mmol, 1.046 g); 2zb was isolated as a light yellow solid (0.930 g, 79%
yield). M.p.: 110 °C. Elemental analysis calcd (%) for C17H17N (235.324):
C, 86.77; H, 7.28; N, 5.95; found: C, 86.92; H, 7.11; N, 5.72. IR (film):
νmax = 3354, 3290, 3053, 2970, 2932, 2872, 2105, 1894, 1621, 1593,
4-Bromo-N-(2-phenylbut-3-yn-2-yl)aniline (2v): Following the general
procedure, 2v was prepared from imine 1v (5 mmol, 1.371 g); 2v was
isolated as a colorless solid (0.525 g, 35% yield). M.p.: 88 °C. Elemental
analysis calcd (%) for C16H14BrN (300.193): C, 64.02; H, 4.70; Br, 26.62;
1
1520, 1448, 1358, 1262, 1206, 1132, 1062, 811, 747, 645 cm-1. H NMR
(400.1 MHz, CDCl3): δ = 7.98–7.91 (m, 1H), 7.80–7.70 (m, 1H), 7.62–
7.57 (m, 1H) [H5, H6, H9], 7.42–7.34 (m, 1H), 7.24–7.16 (m, 1H) [H7,
H8], 6.99– 6.93 (m, 1H, H4), 4.09 (br. s, 1H, NH), 2.22 (s, 1H, H2'), 1.68
(s, 3H), 1.53 (s, 3H), 1.40 (s, 3H) [C1-Me2, C2-Me] ppm. 13C{1H} NMR
(100.6 MHz, CDCl3): δ = 145.6, 131.0, 130.1, 129.6, 129.0, 126.5, 126.4,
122.0, 121.5 [9CAr], 113.3 (C4), 88.0 (C1'), 70.9 (C2'), 66.6 (C2), 48.8
(C1), 25.1, 23.1, 22.5 (C1-Me2, C2-Me) ppm.
N, 4.67; found: C, 64.27; H, 4.63; Br, 26.78; N, 4.21. IR (film): νmax
=
3744, 3406, 3289, 3060, 2976, 2925, 2871, 2112, 1593, 1494, 1445,
1
1312, 1254, 1177, 1072, 814, 761, 700, 652 cm-1. H NMR (400.1 MHz,
CDCl3): δ = 7.62–7.56 (m, 2H, Ho'), 7.32–7.26 (m, 2H, Hm'), 7.24–7.18
(m, 1H, Hp'), 7.11–7.04 (m, 2H, Hm), 6.38–6.32 (m, 2H, Ho), 4.22 (br. s,
1H, NH), 2.44 (s, 1H, H4), 1.74 (s, 3H, Me) ppm. 13C{1H} NMR (100.6
MHz, CDCl3): δ = 144.0, 143.4 (Ci, Ci'), 131.4 (2CAr), 128.8 (Cm'), 127.6
(Cp'), 125.5 (Co'), 117.4 (2CAr), 110.5 (Cp), 85.6 (C3), 72.7 (C4), 55.4
(C2), 35.8 (Me) ppm.
Acknowledgments
N-(2-Phenylbut-3-yn-2-yl)naphthalen-1-amine (2w): Following the
general procedure, 2w was prepared from imine 1w (5 mmol, 1.227 g);
2w was isolated as a colorless solid (1.031 g, 76% yield). M.p.: 155 °C.
Elemental analysis calcd (%) for C16H14N (239.287): C, 88.52; H, 6.31; N,
5.16; found: C, 88.32; H, 6.48; N, 5.02. IR (film): νmax = 3424, 3287, 3058,
2979, 2926, 2864, 1906, 1583, 1524, 1480, 1446, 1406, 1363, 1348,
This work was financially supported by a grant from the Russian
Scientific Foundation (Project No. 19-13-00052). We thank the
Baikal Analytical Centre for collective use of the Siberian Branch
of the Russian Academy of Sciences for the equipment.
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[18] D. Y. Curtin, E. J. Grubbs, C. G. McCart, J. Am. Chem. Soc. 1966, 88,
2775-2786.
Keywords: acetylene gas• imines • superbases • nucleophilic
addition • terminal propargylamines
[19] a) J. J. Sirois, R. Davis, B. DeBoef, Org. Lett. 2014, 16, 868-871; b) J.
M. Brunel, G. Buono, Synlett 1996, 177-178; c) M. Minato, Y. Fujiwara,
M. Koga, N. Matsumoto, S. Kurishima, M. Natori, N. Sekizuka, K.-I.
Yoshioka, T. Ito, J. Organomet. Chem. 1998, 569, 139-145; d) A.
Palma, W. Rozo, E. Stashenko, D. Molina, V. Kouznetsov, J.
Heterocycl. Chem. 1998, 35, 183-188; e) R. Sarma, D. Prajapati, Chem.
Commun. 2011, 47, 9525-9527; f) L. V. Kudzma, Synthesis 2003, 11,
1661-1666; g) C. R. V. Reddy, S. Urgaonkar, J. G. Verkade, Org. Lett.
2005, 7, 4427-4430.
[1]
For recent reviews on transition metal catalyzed cross-coupling
reactions of halogenated compounds with terminal alkynes, see a) R.
Akhtar, A. F. Zahoor, B. Parveen, M. Suleman, Synth. Commun. 2019,
49, 167-192; b) M. M. Heravi, M. Ghanbarian, N. Ghalavand, N. Nazari,
Curr. Org. Chem. 2018, 22, 1420-1457; c) S. B. Alyabyev, I. P.
Beletskaya, Russ. Chem. Rev. 2018, 87, 984-1047; d) A. S. Santos, A.
C. Mortinho, M. M. B. Marques, Molecules 2018, 23, 2673.
[2]
a) A. E. Favorsky, Zh. Ross. Khim. Obshchestva 1905, 37, 643; b) M.
Smith, J. March, in March,s Advanced Organic Chemistry, 6th ed.,
Wiley, New York, 2007, p. 1360.
[20] a) H. Frey, G. Kaupp, Synthesis 1990, 931-934; b) L. G. Hamann, R. I.
Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong,
L. J. Farmer, T. K. Jones, J. Med. Chem. 1998, 41, 623-639.
[3]
[4]
I. A. Bidusenko, E. Yu. Schmidt, I. A. Ushakov, B. A. Trofimov, Eur. J.
Org. Chem. 2018, 4845-4849.
a) W. N. Olmstead, Z. Margolin, F. G. Bordwell, J. Org. Chem. 1980, 45,
3295-3299; b) Y. Yuan, I. Thome, S. H. Kim, D. Chen, A. Beyer, J.
Bonnamour, E. Zuidema, S. Chang, C. Bolm, Adv. Synth. Catal. 2010,
352, 2892-2898.
[5]
For recent reviews on the synthesis and applications of internal
propargylamines, see a) T. K. Saha, R. Das, ChemistrySelect 2018, 3,
147-169; b) K. Lauder, A. Toscani, N. Scalacci, D. Castagnolo, Chem.
Rev. 2017, 117, 14091-14200; c) S. Arshadi, E. Vessally, M. Sobati, A.
Hosseinian, A. Bekhradnia, J. CO2 Util. 2017, 19, 120-129; d) O. Bar-
Am, T. Amit, M. B. Youdim, O. Weinreb, J. Neural Transm. 2016, 123,
125-135.
[6]
[7]
For examples, see a) R. J. Detz, H. Hiemstra, J. H. van Maarseveen,
Eur. J. Org. Chem. 2009, 6263-6276; b) G. W. Kabalka, M.-L. Yao, Curr.
Org. Chem. 2008, 5, 28-32; c) N. Ljungdahl, N. Kann, Angew. Chem.
Int. Ed. 2009, 48, 642-644; d) O. Debleds, E. Gayon, E. Vrancken, J.-M.
Campagne, Beilstein J. Org. Chem. 2011, 7, 866–877.
a) T. Murai, Y. Mutoh, Y. Ohta, M. Murakami, J. Am. Chem. Soc. 2004,
126, 5968-5969; b) L. Ye, W. He, L. Zhang, Angew. Chem. Int. Ed.
2011, 50, 3236-3239; c) B.-L. Chen, B. Wang, G.-Q. Lin, J. Org. Chem.
2010, 75, 941-944; d) M. Crucianelli, F. De Angelis, F. Lazzaro, L.
Malpezzi, A. Volonterio and M. Zanda, J. Fluorine Chem. 2004, 125,
573-577; e) D. Sémeril, J. Le Nôtre, C. Bruneau, P. H. Dixneuf, A. F.
Kolomiets and S. N. Osipov, New J. Chem. 2001, 25, 16-18.
a) K. E. Rodriques, A. Basha, J. B. Summers, D. W. Brooks,
Tetrahedron Lett. 1988, 29, 3455-3458; b) T. Ullrich, P. Sulek, D.
Binder, M. Pyerin, Tetrahedron 2000, 56, 3697-3701.
[8]
[9]
Tetrahedron-Asymmetry 2005, 16, 1807-1816; b) M. Bonanni, M.
Marradi, S. Cicchi, C. Faggi, A. Goti, Org. Lett. 2005, 7, 319-322; c) P.
Merino, S. Anoro, E. Castillo, F. Merchan, T. Tejero, Tetrahedron-
Asymmetry 1996, 7, 1887-1890.
[10] Z. Lin, D. Yu, Y. N. Sum, Y. Zhang, ChemSusChem. 2012, 5, 625-628.
[11] S. P. Teong, D. Yu, Y. N. Sum, Y. Zhang, Green Chem. 2016, 18,
3499-3502.
[12] W. E. Van Beek, K. Gadde, K. A. Tehrani, Chem. Eur. J. 2018, 24,
16645-16651.
[13] a) G. Li, Q. Liu, Z. Liu, Z. C. Zhang, C. Li, W. Wu, Angew. Chem. Int.
Ed. 2010, 49, 8480-8483; b) J. Lehmann, Nature 2007, 447, 143-144.
[14] For recent reviews, see (a) V. V. Voronin, M. S. Ledovskaya, A. S.
Bogachenkov, K. S. Rodygin, V. P. Ananikov, Molecules 2018, 23,
2442; b) B. A. Trofimov, E. Yu. Schmidt, Acc. Chem. Res. 2018, 51,
1117-1130; c) I.-T. Trotuş, T. Zimmermann, F. Schueth, Chem. Rev.
2014, 114, 1761-1782; d) H. Schobert, Chem. Rev. 2014, 114, 1743-
1760.
[15] a) P. A. Clarke, S. Santos, W. H. C. Martin, Green Chem. 2007, 9, 438-
440; b) H. Xiang, Y. Chen, Q. He, Y. Xie, C. Yang, RSC Adv. 2013, 3,
5807-5810.
[16] J. H. Billmann, K. M. Tai, J. Org. Chem. 1958, 23, 535-539.
[17] F. Texier-Boullet, Synthesis 1985, 1985, 679-681.
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Entry for the Table of Contents (Please choose one layout)
Layout 2:
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Acetylene chemistry
Elena Yu. Schmidt, Ivan A. Bidusenko,
Nadezhda I. Protsuk, Yan V. Demyanov,
Igor A. Ushakov, Boris A. Trofimov*
Page No. – Page No.
Acetylene gas readily adds to the C=N bond of ketimines in KOBut/DMSO solution
at room temperature to afford terminal propargylamines with a quaternary carbon
center in up to 94% yield. The reaction represents a new Csp3-Csp bond formation
under mild transition metal free conditions using available widespread starting
materials covering a broad scope of ketimines.
Superbase-Promoted
Acetylene Gas to C=N Bond
Addition of
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