Synthesis of N-Heterocycles-Fused Azasilines by Palladium-Catalyzed Si-Si Bond Activation

Article abstract of DOI:10.1002/cctc.201900609

Azasilines fused nitrogen heterocycles are prepared in excellent yields (from 74 to 98 % according to the structures) for the first time in one operation with high regio- and stereoselectivities. The key step consists of an intramolecular palladium-cataly

Full text of DOI:10.1002/cctc.201900609

Accepted Article
Title: Synthesis of N-Heterocycles-Fused azasilines by palladium-
catalyzed Si-Si bond activation
Authors: Ludovik Noël-Duchesneau, Jacques Maddaluno, and Muriel
Durandetti
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10.1002/cctc.201900609
ChemCatChem
FULL PAPER
Synthesis of N-Heterocycles-Fused azasilines by palladium-
catalyzed Si-Si bond activation
Ludovik Noël-Duchesneau,[a] Jacques Maddaluno,[a] and Muriel Durandetti*[a]
Abstract: Azasilines fused nitrogen heterocycles are prepared in
excellent yields (from 74 to 98% according to the structures) for the
first time in one operation with high regio- and stereoselectivities.
The key step consists of an intramolecular palladium-catalyzed
cyclisation reaction of heteroaryl disilane cores, bearing double or
triple bond. We first studied the reactivity of pyridyl heterocycles,
using xylenes as solvent and Pd(dba)2-P(OEt)3 as catalyst at 130°C.
The Z configuration of the adducts suggested that the reaction
proceeds following a syn addition on the alkyne. This strategy has
then been illustrated by the synthesis of complex polyheterocyclic
scaffolds (phenothiazine, indole, carbazole, quinoline and
tetrahydroquinoline) starting from other nitrogen heteroaryl
compounds, to demonstrate the potential of the process, in order to
obtain promising biological scaffolds.
disilanes[9]) onto triple bond has received particular attention as
the C(sp2)–Z link created can then be functionalized. This
activation is mostly performed using transition metal catalyst,
and a syn addition pathway generally occurs. Over the past
decade, research in our group has opened new strategies and
methods to access at silylated heterocycles through cyclization
reactions.[10] Notably, we have found that intramolecular
rearrangement triggered by a silapalladation reaction can be
easily carried out in high regio- and stereoselectivities using
palladium - phosphite complexe in xylenes.[11] We now report
results, combining our previous works on intramolecular
carbometallation reactions (lithium,[12] nickel[13]
)
and the
synthesis of silylheterocycles,[10-11] in an effort to selectively
access valuable nitrogen heterocycles scaffolds, while
increasing molecular diversity.
Introduction
Results and Discussion
Synthesis of nitrogen heterocycles is one of the central
processes in pharmaceutical chemistry[1] since these cores
(pyridine, pyrimidine, pyrazine, pyrazole, …) are found in most
important pharmacophores. A mild and efficient procedure to
obtain new nitrogen heterocycles is thus of great interest. The
intramolecular carbometallation reaction of internal alkynes
provides a powerful method for C–C bond formation and has
been exploited in various formats giving access to a large panel
of heterocycles.[2] In addition, the incorporation of a silicon atom
in an organic molecule allows to modulate chemical and physical
In a previous paper,[11] we have shown that palladium complexes
allow a selective intramolecular silapalladation of aryl alkynes,
affording a set of silylacyclic compounds. In this work, we
describe the extension of these results to heterocyclic disilane
substrates still using palladium catalysts (Scheme 1).
SiMe3
SiMe3
Si
Z
Si
Z
[Pd]
R'
N
N
R'
Z = NR, O, CH2
properties,
a phenomenon particularly used in medicinal
chemistry.[3] Carbon and silicon have structural similarities
(valence, geometry) allowing silicon to appear as a potent
carbon's isoster.[4] Thus, replacing a carbon atom by silicon in
drug scaffolds is regarded as an innovative strategy to develop
new drugs, and has been widely investigated recently.[3] In
addition to low toxicity, immediate availability and excellent
functional group tolerance make organosilanes attractive
compounds in the current context of sustainable development. In
addition, the presence of a silicon atom is known to increase the
lipophilicity of silylated molecules compared to their carbon
analogues. This has triggered a renewed interest in new
accesses to original silylated structures through reliable and
cheap methods, in particular for medicinal chemistry.[5] Recently,
the addition of Si–Z (silylboranes,[6] silylstannanes,[7] silylzinc[8] or
Scheme 1. Pd-catalyzed synthesis of azasilines fused nitrogen heterocycles.
We chose to launch this study on a relatively simple
substrate and decided to consider pyridines 5 as models
(Scheme 2).
Br
Br
NBS (1.1 equiv)
Boc2O (1.2 equiv)
N
N
N
Boc
ACN
2-4 d.
1,4-Dioxane reflux
5 h
NH2
NH2
N
H
1 58 %
2 93 %
nBuLi
(1.2 equiv)
SiMe2SiMe3
N
1) NaH
ClSiMe3SiMe2
(1.2 equiv)
Br
N
N
N
(1.4 equiv)
R
THF
-95°C => -45°C
2h30
2)
Boc
R
Boc
R
3a-g
(1.4 equiv)
[a]
Dr. L. Noël-Duchesneau, Dr. J. Maddaluno, Dr. M. Durandetti
Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA,
(UMR 6014 & FR 3038), 76000 Rouen – France
E-mail: muriel.durandetti@univ-rouen.fr
Br
5a-g 23-95 %
4a-g 75-95 %
Scheme 2. Synthesis of disilapyridines 5a-g.
Supporting information for this article is given via a link at the end of
the document.
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10.1002/cctc.201900609
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Several routes to access pyridyl disilanes
5
from
With disilapyridines 5 and 8 in hand, we first examined the
reactivity resorting to the previously optimized conditions (i.e.
5% Pd(dba)2 + 10% P(OEt)3, 3h at reflux of xylenes).[11] Results
in Scheme 3 show that the cyclisation takes place in good to
excellent yields and with total stereo- and regio-selectivities
(syn-addition, 6-exo-dig cyclisation).
commercially available amino/hydroxy-pyridines were evaluated.
The simple three-step (bromination - disilane introduction - N/O-
propargylation) procedure used previously[11] was examined first.
Unfortunately, the early introduction of the disilane appendage
revealed difficulties with amino- or hydroxy-pyridine. We thus
chose to swap the N/O-propargylation and disilane introduction
steps in these cases. Seven pyridyl disilanes 5a-g have been
prepared similarly from intermediate 2 using propargyl bromides
3a-g (Scheme 2). Bromination of commercially available 4-
amino-pyridine by NBS led to the expected pyridine 1 in a
correct yield (58%). After monoprotection of the amine by a Boc
group in 93% yield, an ensuing coupling with propargyl bromides
3a-g allowed the efficient introduction of the triple bond (75-
95%). 3c-g were themselves obtained by Sonogashira coupling
of aryl iodides with propargylic alcohol, followed by alkoxide /
brome exchange. We finally performed a Li-Br exchange on 4a-
g using nbutyllithium in the presence of chloropentadisilane at -
95°C. The reaction was slowly warmed to ≈ -45°C during 2h30,
to give 5a-g in 23-95% yields. Note that due to the instability of
In all cases, the method allows the addition on triple bond
of the two silicon atoms in one step, following a syn addition of
the silapalladium intermediate on the triple bond. Chemical
yields are good to excellent (74–95%), demonstrating that the
process is efficient with pyridyl disilanes 5, whatever the
substituent borne by the triple bond, and in line with the results
observed on the arylic substrates. Indeed, the triple bond
tolerate an alkyl (9a) or an aryl substituent (9b-g). In this latter
case, this method is efficient with aryl bearing electron-donating
(9c-f) as well as electron-withdrawing substituents (9g), even in
ortho position (9d). Replacement of the triple bond by a double
bond decreases the reactivity. In fact, when 8a-b were exposed
to the silapalladation reaction following the same protocol, we
were disappointed to recover mainly starting material. Expecting
to increase the reactivity toward double bond, we have at first,
studied different parameters influencing the activation conditions,
and particularly the ligand, as illustrated in Table 1 for the
silapalladation of compound 8a.
lithiopyridine,
the
simultaneous
introduction
of
chloropentadisilane with nbutyllithium at -95°C appears essential
to prevent degradation or by-product formation. We were also
keen to evaluate the reactivity of our system toward double
bonds (instead of triple ones), and thus the same strategy was
employed starting from 2 and allyl or prenyl bromides 6a-b,
leading to N-allyl bromopyridines 7a-b in 80 and 62% yields,
respectively. Finally, after reaction with chloropentadisilane,
pyridines 8a-b were obtained in 71 and 84% yields.
Table 1. Optimization of the parameters for the sila-palladation of 8a.
SiMe3
Me2
Si
SiMe2SiMe3
N
N
catalyst
N
N
xylenes, T°C
Boc
Boc
8a
10a
SiMe3
Me2
SiMe2SiMe3
N
Si
N
N
N
R
Entry
1
Catalyst
Conditions[a]
130°C 15h
130°C 15h
130°C 15h
130°C 15h
130°C 15h
130°C 15h
130°C 15h
130°C 15h
130°C 15h
130°C µw 2h
130°C 15h
130°C 15h
8a/10a[b]
80/20
100/0
100/0
100/0
100/0
100/0
100/0
100/0
100/0
37/63
45/55
14/86
N
Pd(dba)2 (5 mol%)
P(OEt)3 (10 mol%)
Boc
R
Boc
5a-g
8a-b
9a-ga,b
Pd(dba)2 5 mol% + P(OEt)3 10 mol%
Pd(dba)2 6 mol% + P(OPh)3 12 mol%
SiMe3
R
R
Xylenes reflux
3 h
Me2
Si
SiMe2SiMe3
R
2
N
N
3
Pd(dba)2 5 mol% + P(OCF2CF3)3 10 mol%
Pd(dba)2 6 mol% + PCy3 12 mol%
Pd(OAc)2 6 mol% + PCy3 12 mol%
Pd(dba)2 5 mol% + JohnPhos 10 mol%
Pd(dba)2 5 mol% + Dppf 5 mol%
N
R
10a-ba,b Boc
Boc
4
SiMe3
SiMe3
Me2
Si
SiMe3
Me2
Me2
Si
Si
N
N
N
5
N
N
N
6
Boc
9a 90%
Boc
9b 85%
Boc
9c 81%
7
SiMe3
SiMe3
SiMe3
Me2
Me2
Si
Me2
Si
Si
N
N
N
8
Pd(dba)2 5 mol% + 2,2'-Bipy 5 mol%
SPhosPd G2 5 mol% + NEt3 10 mol%
Pd(dba)2 5 mol% + P(OEt)3 10 mol%
Pd(dba)2 10 mol% + P(OEt)3 20 mol%
Pd(dba)2 20 mol% + P(OEt)3 40 mol%
N
N
N
OMe
9
Boc
9d 95%
Boc
9e 74%
Boc
9f 92%
10
11
12
SiMe3
SiMe3
SiMe3
Me2
Si
Me2
Si
Me2
Si
N
N
N
N
CF3
N
N
Boc
9g 94%
Boc
Boc
10a 40% (75%)c,d
10b tracec
[a] Optimization reaction conditions are run with 0.1 mmol of pyridine disilane
8a in anhydrous xylenes, under argon. [b] Ratio and conversion were
determined by 1H NMR of the crude.
Scheme 3. Silapalladation of disilapyridines 5 and 8. a) Reaction conditions:
pyridine disilane 5 or 8 (0.5 mmol), Pd(dba)2 (5 mol%), P(OEt)3 (10 mol%),
anhydrous xylenes (5 mL), under argon at 130°C for 3 h. b) isolated yields. c)
20 mol% of Pd(dba)2, 40 mol% of P(OEt)3 were used in this case. d) NMR
yields with respect to o-dinitronaphtalene as internal standard.
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10.1002/cctc.201900609
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chemical yields. We thus extended our investigation to other
nitrogen heterocycles, in order to obtain valuable complex
polycyclic scaffolds for medicinal chemistry.
The optimized procedure for the addition onto triple bond does
not apply directly to the addition on double bond: even after
extended reaction times (15h vs 3h, Table 1, entry 1), the
Used at the beginning for their properties in organic
dyes,[15] phenothiazines derivatives have re-emerged recently as
promising biological compounds in the field of pharmacology
and medicinal chemistry.[16] The association of a phenothiazine
core to an azasiline cycle leads to an unusual core that could be
worth exploring for its pharmacophoric properties. Such a
structural motive is found in disilaphenothiazine 17 that can be
accessed easily following a comparable strategy (Scheme 5).
After protection of the nitrogen of phenothiazine with CO2,[17]
leading to a lithio carbamate used as ortho-director group, 15
was selectively deprotonated, then silylated by chloropentadi-
silane, giving 16 in 76% yield after deprotection. Introduction of
the propargyl chain onto the deprotected nitrogen was
performed using NaH and propargyl bromide 3a. An ensuing
cyclisation of disila-phenothiazine 17 under the standard
catalytic reaction conditions defined above allowed its
transformation in tetracycle 18 as a sole Z isomer and in an
excellent yield of 98%.
1
conversion did not exceed 20%, while the H NMR of the crude
mixture showed mainly starting material. The replacement of
triethylphosphite by other known ligands of palladium led to the
sole recovery of 8a in all cases (Table 1, entries 2-9). Actually,
the yield increased when a larger amount of P(OEt)3 palladium
catalyst was used: 55% of conversion using 10 mol% of catalyst
(Table 1, entry 11), or 86% using 20 mol% of catalyst (Table 1,
entry 12). Alternatively, microwave activation helped to reduce
the amount of palladium (63% of conversion with 5 mol% of
catalyst, Table 1, entry 10). This led us to finally apply these
optimized conditions (i.e. 20 mol% of Pd(dba)2, 40 mol% of
P(OEt)3, 15h at 130°C) at a larger scale to obtain a moderate
yield of cyclized product 10a (Scheme 3). Note that the
conversion is good -a NMR yield of 75 % could be obtained
using an internal standard- but the product 10a is a fragile 1,2-
disilane which decomposes on silica gel during the purification.
We also applied this process to the cyclisation of the prenyl-
substituted amine 8b. Unfortunately, probably because of steric
hindrance, the reaction remained ineffective and only traces of
the cyclized product 10b could be detected.
S
S
N
S
1) nBuLi
1) tBuLi
2) CO2
2) ClSiMe2-SiMe3
3) HCl aq.
N
H
N
H
SiMe2-SiMe3
LiO
O
The method also applies nicely to 2-aminopyridine. The
example in Scheme 4 affords a 8-azasilaquinoline, that can be
regarded as a 6-membered sila-analogues of 7-azaindoles,
themselves important targets in medicinal chemistry.[14]
15
16 76%
S
N
S
N
NaH
Br
Pd(dba)2 (5 mol%)
P(OEt)3 (10 mol%)
Xylenes reflux
Me2Si
Me3Si
Me3Si-Me2Si
3 h
Boc2O
Me
Br
Me
Br
Me
Br
18 98%
17 34%
1) NaH (1.4 equiv)
(1.2 equiv)
Boc
N
N
1,4-Dioxane
Δ, overnight
N
NH2
N
N
H
2)
3a
Boc
Scheme 5. Synthesis and silapalladation of phenothiazine derivative 17.
11 39 %
12 81 %
nBuLi
Br (1.4 equiv)
SiMe3
(1.2 equiv)
ClSiMe3SiMe2
(1.2 equiv)
Me2
Si
Pd(dba)2 (5 mol%)
P(OEt)3 (10 mol%)
Me
Me
SiMe2SiMe3
It is probably not necessary to remind the reader that the
indole pattern is found in many products with therapeutic activity
but also in a wide variety of natural products,[18] thus making this
heterocyclic nucleus a particularly interesting candidate for drug
developments.[19] The synthesis of N-propargyl disila-indole 20
has been carried out according to scheme 6.
Me
THF
-95°C => -45°C
2h30
Xylenes reflux
3 h
N
N
N
N
Boc
14 88 %
Boc
13 87 %
Scheme 4. Synthesis and silapalladation of 8-azaquinoline derivative 13.
1) nBuLi
If a Boc monoprotection of 3-bromo-2-aminopyridine in
classical conditions leads to a complete degradation of the
substrate, the monoprotection of 5-methyl-3-bromo-2-amino-
pyridine occurs in a moderate yield of 39%. The resulting
carbamate 11 undergoes the next propargylation step in good
yield. Introduction of the disilane moiety by Li-Br exchange on 12
using nbutyllithium in the presence of chloropentadisilane
at -95°C gives 13 in 87% yield. We finally applied the above
catalytic procedure for the silapalladation, and the expected 8-
azasilaquinoline derivative 14 was recovered in a fine yield of
88%.
2) CO2
SiMe3
SiMe2
SiMe3
SiMe2
3) tBuLi
NaH
N
N
N
4) ClSiMe2-SiMe3
H
H
5) HCl aq.
19 46%
20 60%
Br
6) Toluene, reflux
Pd(dba)2 (5 mol%)
P(OEt)3 (10 mol%)
SiMe2
SiMe3
N
Xylenes reflux
3 h
21 71%
Scheme 6. Synthesis and silapalladation of indole derivative 20.
This result suggests that various pyridine isomers can
undergo this silapalladation procedure which proceeds in good
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Br
N
Br
NaHMDS (2.1 equiv.)
NH2
Boc2O (1.2 equiv)
A
procedure
similar
to
that
employed
for
NH2
NHBoc
NBS
disilaphenothiazine was applied: the protection of nitrogen with
CO2, deprotonation of position 2, then introduction of the disilane
moiety and deprotection led to indole 19 in a 46% global yield.
Indole 19 was reacted with 1-bromobut-2-yne 3a in the presence
of NaH, affording disila-indole derivative 20 in 60% yield. Finally,
the azasiloloindole 21 was obtained in 71% yield by catalytic
silapalladation.
ACN, rt
THF, rt
N
N
26 75 %
27 88 %
NaH
Br
Me3Si
Me2Si
Me3Si
SiMe2
Br
Pd(dba)2
P(OEt)3
nBuLi
(1.2 equiv)
NBoc
NBoc
NBoc
Carbazole is a tricyclic heteroaromatic structure which
appears in some natural product such as Murrayanine 1, a
compound that has attracted significant interest.[20] We thus tried
to also apply the silapalladation reaction to this related family of
compounds. As illustrated in Scheme 7, the synthesis of
azasilinocarbazole 25 follows the previous strategy in four steps.
Protection of the carbazole nitrogen was performed following
Katritsky’s procedure which is based on a Mannich reaction
involving formaldehyde and pyrrolidine. Thus, aminal 22 was
recovered in 70%, of which ortho-deprotonation,[21] disilylation
then silapalladation steps all occurred efficiently and led to
azasilinocarbazole 25 in a good yield of 78%.
Xylenes
ClSiMe3SiMe2
(1.2 equiv)
N
N
N
30 73 %
29 57 %
28 63 %
Scheme 8. Synthesis and silapalladation of quinoline derivative 29.
The final extension brought to this process was directed
toward the functionalization of tetrahydroquinolines, another
motive found in bioactive molecules.[24] But we also prepared
tetrahydroquinoline 35 in the perspective of the synthesis of
substituted julolidine,
a
compound exhibiting interesting
properties as photoconductive materials or chemiluminescence
substrates.[25] After N-protection of the tetrahydroquinoline with a
Boc appendage, used as ortho-director group, iodine is
introduced in position 8 of compound 32 in a global yield of 46%
(Scheme 9). Then, deprotection, introduction of the propargyl
chain on the nitrogen and finally introduction of the disilane
moiety gave tetrahydroquinoline 35 in a good overall yields.
Finally, the silapalladation occured efficiently, and the
azasilinoquinoline 36 was obtained in 74% isolated yield and as
a single Z isomer.
O
H
H
1) tBuLi
(1.3 equiv.)
2) ClSiMe2-SiMe3
3) HCl (1M), 80°C
N
N
N
H
NH
H
(1.3 equiv.)
EtOH, reflux
overnight
SiMe2-SiMe3
N
22 70%
23 46%
NaH
Pd(dba)2 (5 mol%)
P(OEt)3 (10 mol%)
(1.3 equiv.)
Br
N
N
(1.3 equiv.)
Xylenes reflux
3 h
Me3Si-Me2Si
Me2Si
Me3Si
25 78%
24 48%
1) NaH
2) Boc2O
HCl in
Dioxane (4 M)
1) tBuLi
2) I2
Scheme 7. Synthesis and silapalladation of carbazole derivative 24.
N
H
N
N
N
r.t. 1h
THF, reflux
1 d.
H
Boc
I
Boc
I
31 70 %
32 66 %
33 96 %
The quinoline scaffold is another motive highly regarded in
medicinal chemistry.[22] Substituted quinoline derivatives
possess a wide range of bioactivities as anticancer, antibiotic,
platelet-derived growth factor, kinase inhibitor, and many other
properties.[23] It was thus tempting to introduce a new series in
this family of substrates using the same silapalladation reaction.
On the basis of the preparation of disilapyridines 5 and 13, we
investigated the formation of disilaquinoline 29 in four steps in
an overall yield of 24%, as reported in Scheme 8. The
silapalladation process was next successfully applied to convert
29 into tricyclic derivative 30 in 73% yield.
NaH
Br
N
ClSiMe2SiMe3
(1.2 equiv.)
Pd(dba)2 (5 mol%)
P(OEt)3 (10 mol%)
N
Xylenes reflux
3 h
Me2Si
Me3Si
nBuLi
(1.2 equiv.)
N
SiMe2
I
Me3Si
36 74 %
35 60 %
34 59 %
Scheme 9. Synthesis and silapalladation of tetrahydroquinoline derivative 35.
Conclusions
In conclusion, this study shows that the simple intramolecular
silapalladation reaction we describe can be efficiently applied to
heterocyclic propargylamines and leads, in a chemo-, regio- and
stereo-selective fashion to new and possibly important
structures incorporating 1,4-silapiperidine motives. The scope of
the reaction includes aryne, pyridine, phenothiazine, indole,
carbazole, quinoline or tetrahydroquinoline scaffolds. The
reaction follows a 6-exo-dig route and affords syn-disilylated
products in good yields.
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Mp = 116°C; 1H NMR (300 MHz, CDCl3): δ = 8.61 (s, 1H, CH Pyridyl), 8.45
(d, J = 5.4 Hz, 1H, CH Pyridyl), 7.22 (d, J = 5.6 Hz, 1H, CH Pyridyl), 7.19-7.06
(m, 3H, CH Aryl), 6.74-6.66 (m, 1H, CH Aryl), 4.10 (d, J = 16.1 Hz, 1H, 1xN-
CH2, AB system), 3.97 (d, J = 16.1 Hz, 1H, 1xN-CH2, AB system), 2.12 (s,
3H, C Aryl-CH3), 1.37 (s, 9H, CH3 Boc), 0.63 (s, 3H, 1xSi(CH3)2), 0.52 (s, 3H,
1xSi(CH3)2), 0.08 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.5 MHz, CDCl3): δ =
159.3 (C Alkene), 156.0 (C Pyridyl), 154.3 (CH Pyridyl), 152.8 (C=O), 150.1
(CH Pyridyl), 148.8 (C Alkene), 144.2 (C Aryl), 133.1 (C Aryl), 130.1 (CH Aryl),
126.9 (C Pyridyl), 126.1 (CH Aryl), 125.9 (2xCH Aryl), 119.3 (CH Pyridyl), 81.3 (C
Boc), 53.0 (N-CH2), 28.1 (CH3 Boc), 20.0 (C Aryl-CH3), 0.9 (Si(CH3)3), 0.1
(1xSi(CH3)2), -0.4 (1xSi(CH3)2); IR (ATR): υ = 2982, 2899, 1710, 1578,
1470, 1368, 1335, 1303, 1270, 1249, 1230, 1158, 1113, 1082, 905, 869,
832, 809, 783, 763, 748, 728, 680, 666, 622, 531, 447 cm-1; HRMS (ESI,
positive mode) calcd (m/z) for C25H36N2O2Si2H [M+H]+: 453.2394, found:
453.2387, εr: 1.5 ppm.
Experimental Section
Typical silapalladation procedure, exemplified with 9a
To a solution of pyridyl disilanes 5a (0.45 mmol) in xylenes (0.1 M) under
an argon atmosphere Pd(dba)2 (5 mol%) and triethylphosphite (10 mol%)
were successively added. The reaction mixture was heated at 130°C for
3 h in a sealed Schlenk tube. After cooling to room temperature, the
volatile materials were removed under reduce pressure. The resulting
residue was purified by flash chromatography (SiO2, EtOAc/cyclohexane:
1:4), allowing the pure 9a (151.0 mg, 0.40 mmol, 89 %) as an off-white
solid.
(Z)-tert-butyl
4,4-dimethyl-3-(1-(trimethylsilyl)ethylidene)-3,4-
dihydropyrido[4,3-b][1,4]azasiline-1(2H)-carboxylate (9a)
(Z)-tert-butyl
4,4-dimethyl-3-(p-tolyl(trimethylsilyl)methylene)-3,4-
Mp = 86°C; 1H NMR (300 MHz, CDCl3): δ = 8.55 (s, 1H, CH Pyridyl), 8.45
(d, J = 5.0 Hz, 1H, CH Pyridyl), 7.33 (d, J = 5.4 Hz, 1H, CH Pyridyl), 4.42 (s,
2H, N-CH2), 1.97 (s, 3H, C Alkene-CH3), 1.48 (s, 9H, CH3 Boc), 0.44 (s, 6H,
Si(CH3)2), 0.21 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.5 MHz, CDCl3): δ =
155.6 (C Pyridyl), 154.6 (CH Pyridyl), 153.0 (C=O), 152.5 (C Alkene), 149.7 (CH
Pyridyl), 145.9 (C Alkene), 127.5 (C Pyridyl), 119.1 (CH Pyridyl), 81.4 (C Boc), 50.9
(N-CH2), 28.2 (CH3 Boc), 19.7 (C Alkene-CH3), 0.5 (Si(CH3)3), 0.2 (Si(CH3)2);
IR (ATR): υ = 2982, 2965, 2888, 1694, 1556, 1434, 1419, 1391, 1364,
1340, 1296, 1248, 1233, 1168, 1140, 869, 838, 780, 757, 688, 420;
HRMS (ESI, positive mode) calcd (m/z) for C19H32N2O2Si2 [M+H]+:
377.2081, found: 377.2087, εr: 1.6 ppm.
dihydropyrido[4,3-b][1,4]azasiline-1(2H)-carboxylate (9e)
1H NMR (300 MHz, CDCl3): δ = 8.60 (s, 1H, CH Pyridyl), 8.45 (d, J = 5.6 Hz,
1H, CH Pyridyl), 7.21 (d, J = 5.6 Hz, 1H, CH Pyridyl), 7.11 (d, J = 7.7 Hz, 2H,
CH Aryl), 6.75 (d, J = 7.7 Hz, 2H, CH Aryl), 4.09 (s, 2H, N-CH2), 2.32 (s, 3H,
C
Aryl-CH3), 1.39 (s, 9H, CH3 Boc), 0.55 (s, 6H, Si(CH3)2), 0.09 (s, 9H,
Si(CH3)3); 13C{1H} NMR (75.5 MHz, CDCl3): δ = 160.1 (C Alkene), 156.1 (C
Pyridyl), 154.2 (CH Pyridyl), 152.9 (C=O), 150.1 (CH Pyridyl), 148.7 (C Alkene),
141.6 (C Aryl), 134.9 (C Aryl), 129.0 (CH Aryl), 127.5 (C Pyridyl), 126.4 (CH Aryl),
119.5 (CH Pyridyl), 81.1 (C Boc), 53.2 (N-CH2), 28.1 (CH3 Boc), 21.0 (C Aryl
-
CH3), 0.8 (Si(CH3)3), -0.1 (Si(CH3)2; IR (ATR): υ = 2971, 2894, 1705,
1576, 1471, 1368, 1344, 1266, 1247, 1158, 1116, 1091, 907, 831, 808,
779, 759, 729, 684, 510, 445 cm-1; HRMS (ESI, positive mode) calcd
(m/z) for C25H36N2O2Si2H [M+H]+: 453.2394, found: 453.2388, εr: 1.3 ppm.
(Z)-tert-butyl
4,4-dimethyl-3-(phenyl(trimethylsilyl)methylene)-3,4-
dihydropyrido[4,3-b][1,4]azasiline-1(2H)-carboxylate (9b)
Mp = 116°C ; 1H NMR (300 MHz, CDCl3): δ = 8.61 (d, J = 0.6 Hz, 1H, CH
Pyridyl), 8.46 (d, J = 5.6 Hz, 1H, CH Pyridyl), 7.33-7.26 (m, 2H, CH Aryl), 7.21
(dd, J = 5.6, 0.7 Hz, 1H, CH Pyridyl), 7.20-7.14 (m, 1H, CH Aryl), 6.89-6.83
(m, 2H, CH Aryl), 4.09 (s, 2H, N-CH2), 1.39 (s, 9H, CH3 Boc), 0.56 (s, 6H,
Si(CH3)2), 0.09 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.5 MHz, CDCl3): δ =
159.9 (C Alkene), 156.0 (C Pyridyl), 154.3 (CH Pyridyl), 152.8 (C=O), 150.1
(CH Pyridyl), 148.8 (C Alkene), 144.7 (C Aryl), 128.3 (CH Aryl), 127.4 (C Pyridyl),
126.5 (CH Aryl), 125.5 (CH Aryl), 119.5 (CH Pyridyl), 81.2 (C Boc), 53.2 (N-CH2),
28.1 (CH3 Boc), 0.8 (Si(CH3)3), -0.1 (Si(CH3)2); IR (ATR): υ = 2971, 1957,
2899, 1709, 1574, 1469, 1381, 1242, 1151, 928, 895, 840, 808, 783, 760,
705, 663, 610, 502 cm-1; HRMS (ESI, positive mode) calcd (m/z) for
C24H34N2O2Si2H [M+H]+: 439.2237, found: 439.2245, εr: 1.8 ppm.
(Z)-tert-butyl 3-((4-methoxyphenyl)(trimethylsilyl)methylene)-4,4-di-
methyl-3,4-dihydropyrido[4,3-b][1,4]azasiline-1(2H)-carboxylate (9f)
Mp = 93°C; 1H NMR (300 MHz, CDCl3): δ = 8.60 (s, 1H, CH Pyridyl), 8.46
(d, J = 5.5 Hz, 1H, CH Pyridyl), 7.21 (d, J = 5.5 Hz, 1H, CH Pyridyl) 6.85 (d, J
= 8.8 Hz, 2H, CH Aryl), 6.77 (d, J = 8.8 Hz, 2H, CH Aryl), 4.09 (s, 2H, N-
CH2), 3.79 (s, 3H, O-CH3), 1.39 (s, 9H, CH3 Boc), 0.55 (s, 6H, Si(CH3)2),
0.09 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.5 MHz, CDCl3): δ = 159.7
(C Alkene), 157.5 (C Aryl-O), 156.1 (C Pyridyl), 154.3 (CH Pyridyl), 152.9 (C=O),
150.1 (CH Pyridyl), 149.3 (C Alkene), 136.9 (C Aryl), 127.6 (CH Aryl + C Pyridyl),
119.5 (CH Pyridyl), 113.8 (CH Aryl), 81.1 (C Boc), 55.1 (O-CH3), 53.3 (N-CH2),
28.2 (CH3 Boc), 0.8 (Si(CH3)3), -0.1 (Si(CH3)2); IR (ATR): υ = 2954, 2910,
2833, 1709, 1499, 1468, 1378, 1240, 1164, 1145, 1033, 902, 833, 808,
771, 753, 678, 541, 450 cm-1; HRMS (ESI, positive mode) calcd (m/z) for
C25H36N2O3Si2H [M+H]+: 469.2343, found: 469.2340, εr: 0.6 ppm.
(Z)-tertbutyl 3-((4-(tert-butyl)phenyl)(trimethylsilyl)methylene)-4,4-di-
methyl-3,4-dihydropyrido[4,3-b][1,4]azasiline-1(2H)-carboxylate (9c)
1H NMR (300 MHz, CDCl3): δ = 8.61 (s, 1H, CH Pyridyl), 8.45 (d, J = 5.5 Hz,
1H, CH Pyridyl), 7.30 (d, J = 8.5 Hz, 2H, CH Aryl), 7.23 (d, J = 5.5 Hz, 1H,
CH Pyridyl), 6.77 (d, J = 8.5 Hz, 2H, CH Aryl), 4.12 (s, 2H, N-CH2), 1.37 (s,
9H, CH3 Boc), 1.30 (s, 9H, CH3 tBu), 0.56 (s, 6H, Si(CH3)2), 0.08 (s, 9H,
Si(CH3)3); 13C{1H} NMR (75.5 MHz, CDCl3): δ =160.1 (C Alkene), 156.1 (C
Pyridyl), 154.3 (CH Pyridyl), 153.0 (C=O), 150.1 (CH Pyridyl), 148.6 (C Alkene),
148.2 (C Aryl), 141.5 (C Aryl), 127.4 (C Pyridyl), 126.1 (CH Aryl), 125.1 (CH Aryl),
119.4 (CH Pyridyl), 81.1 (C Boc), 53.3 (N-CH2), 34.3 (C tBu), 31.4 (CH3 tBu),
28.2 (CH3 Boc), 0.9 (Si(CH3)3), -0.0 (Si(CH3)2); IR (ATR): υ = 2960, 2905,
1705, 1575, 1471, 1367, 1343, 1299, 1266, 1246, 1159, 1116, 1091, 908,
822, 808, 779, 761, 731, 682, 564 cm-1; HRMS (ESI, positive mode)
calcd (m/z) for C28H42N2O2Si2H [M+H]+: 495.2863, found: 495.2863, εr:
0.0 ppm.
(Z)-tert-butyl
4,4-dimethyl-3-((4-(trifluoromethyl)phenyl)-
(trimethylsilyl)-methylene)-3,4-dihydropyrido[4,3-b][1,4]azasiline-
1(2H)-carboxylate (9g)
1H NMR (300 MHz, CDCl3): δ = 8.61 (s, 1H, CH Pyridyl), 8.47 (d, J = 5.6 Hz,
1H, CH Pyridyl), 7.58 (d, J = 7.9 Hz, 2H, CH Aryl), 7.20 (d, J = 5.6 Hz, 1H,
CH Pyridyl), 7.01 (d, J = 7.9 Hz, 2H, CH Aryl), 4.03 (s, 2H, N-CH2), 1.39 (s,
9H, CH3 Boc), 0.57 (s, 6H, Si(CH3)2), 0.10 (s, 9H, Si(CH3)3); 19F{1H} NMR
(282.2 MHz, CDCl3): δ = -62.3; 13C{1H} NMR (75.5 MHz, CDCl3): δ =
158.7 (C Alkene), 156.1 (C Pyridyl), 154.5 (CH Pyridyl), 152.9 (C=O), 150.5
(CH Pyridyl), 150.1 (C Alkene), 149.0 (q, JC-F = 1.3 Hz, C Aryl), 128.1 (q, JC-F
=
32.4 Hz, C Aryl-CF3), 127.3 (C Pyridyl), 127.1 (CH Aryl), 125.6 (q, JC-F = 3.8
Hz, CH Aryl), 124.5 (q, JC-F = 271.4 Hz, CF3), 119.8 (CH Pyridyl), 81.6 (C Boc),
53.4 (N-CH2), 28.3 (CH3 Boc), 1.0 (Si(CH3)3), 0.0 (Si(CH3)2); IR (ATR): υ =
2971, 2905, 1705, 1576, 1471, 1369, 1322, 1267, 1249, 1159, 1120,
(Z)-tert-butyl
4,4-dimethyl-3-(o-tolyl(trimethylsilyl)methylene)-3,4-
dihydropyrido[4,3-b][1,4]azasiline-1(2H)-carboxylate (9d)
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10.1002/cctc.201900609
ChemCatChem
FULL PAPER
1105, 1066, 1017, 907, 830, 809, 781, 761, 666, 625 cm-1; HRMS (ESI,
positive mode) calcd (m/z) for C25H33F3N2O2Si2H [M+H]+: 507.2111,
found: 507.2111, εr: 0.0 ppm.
(75.4 MHz, CDCl3): δ = 152.0 (C Alkene), 149.1 (C Alkene), 142.2 (C(2)), 136.3
(C Aryl), 132.1 (C Aryl), 121.4 (CH Aryl), 121.0 (CH Aryl), 119.6 (CH Aryl), 109.9
(CH Aryl), 104.8 (C(3)H), 51.8 (N-CH2), 20.8 (C Alkene -CH3), 0.9 (Si(CH3)2),
0.2 (Si(CH3)3); IR (ATR): υ = 2956, 1338, 1252, 1241, 1211, 1081, 1031,
911, 829, 805, 767, 742, 724, 682, 670, 629, 477, 429 cm-1; HRMS
(APCI, positive mode) calcd (m/z) for C17H25NSi2H [M+H]+: 300.1604,
found: 300.1599, εr: 1.7 ppm.
tert-butyl 4,4-dimethyl-3-((trimethylsilyl)methyl)-3,4-dihydropyrido-
[4,3-b][1,4]azasiline-1(2H)-carboxylate (10a)
Mp = 74°C; 1H NMR (300 MHz, Acetone-d6): δ = 8.57 (br. s, 1H, CH
Pyridyl), 8.39 (br. s, 1H, CH Pyridyl), 7.40 (d, J = 4.3 Hz, 1H, CH Pyridyl), 4.28
(dd, J = 13.6, 4.3 Hz, 1H, 1xN-CH2), 3.15 (dd, J = 13.6, 11.6 Hz, 1H,
1xN-CH2), 1.51 (s, 9H, CH3 Boc), 1.31 (dddd, J = 11.6, 8.8, 5.3, 4.4 Hz, 1H,
CH-Si(CH3)2), 0.78 (dd, J = 15.1, 5.3 Hz, 1H, 1xCH2-Si(CH3)3), 0.51 (dd,
J = 15.1, 8.7 Hz, 1H, 1xCH2-Si(CH3)3), 0.31 (s, 3H, Si(CH3)2), 0.29 (s, 3H,
Si(CH3)2), 0.12 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.4 MHz, Acetone-d6): δ
= 156.3 (CH Pyridyl), 156.1 (C Pyridyl), 153.8 (C=O), 150.5 (CH Pyridyl), 124.9
(C Pyridyl), 120.9 (CH Pyridyl), 81.8 (C Boc), 52.1 (N-CH2), 28.4 (CH3 Boc), 20.6
(CH-Si(CH3)2), 14.7 (CH2-Si(CH3)3), -0.8 (Si(CH3)3), -1.8 (1xSi(CH3)2), -
4.5 (1xSi(CH3)2.); IR (ATR): υ = 2951, 1695, 1602, 1558, 1451, 1416,
1247, 1216, 837, 797, 755, 728, 686, 563, 426 cm-1; HRMS (APCI,
positive mode) calcd (m/z) C18H32N2O2Si2H for [M+H]+: 365.2081, found:
365.2092, εr: 3.0 ppm.
(Z)-3,3-dimethyl-2-(1-(trimethylsilyl)ethylidene)-2,3-dihydro-1H-
[1,4]azasilino[3,2,1-jk]carbazole (25)
Mp = 92°C; 1H NMR (300 MHz, Acetone-d6): δ = 8.22-7.98 (m, 2H, CH
Aryl), 7.68-7.61 (m, 1H, CH Aryl), 7.58 (dd, J = 7.1, 1.1 Hz, 1H, CH Aryl), 7.47
(ddd, J = 8.3, 7.2, 1.2 Hz, 1H, CH Aryl), 7.29-7.17 (m, 2H, CH Aryl), 5.06 (q,
J = 0.6 Hz, 2H, N-CH2), 2.17 (t, J = 0.6 Hz, 3H, C Alkene-CH3), 0.59 (s, 6H,
Si(CH3)2), 0.30 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.4 MHz, Acetone-d6): δ
= 153.7 (C Alkene), 146.0 (C Aryl), 144.5 (C Alkene), 141.7 (C Aryl), 131.1 (CH
Aryl), 126.4 (CH Aryl), 123.8 (C Aryl), 121.7 (CH Aryl), 121.6 (C Aryl), 121.2 (CH
Aryl), 120.3 (CH Aryl), 119.9 (C Aryl), 119.7 (CH Aryl), 109.7 (CH Aryl), 46.9 (N-
CH2), 20.7 (C Alkene -CH3), 1.5 (Si(CH3)2), 1.4 (Si(CH3)3); IR (ATR): υ =
3045, 2949, 2899, 1602, 1558, 1481, 1451, 1417, 1318, 1245, 1216,
1029, 1014, 925, 837, 818, 797, 772, 754, 723, 685, 642, 577, 563, 552,
501, 456, 426 cm-1; HRMS (APCI, positive mode) calcd (m/z) for
C21H27NSi2H [M+H]+: 350.1760, found: 350.1758, εr: 0.6 ppm.
(Z)-tert-butyl
1,1,7-trimethyl-2-(1-(trimethylsilyl)ethylidene)-2,3-di-
hydropyrido[2,3-b][1,4]azasiline-4(1H)-carboxylate (14)
Mp = 104°C; 1H NMR (300 MHz, CDCl3): δ = 8.29 (dd, J = 2.5, 0.7 Hz,
1H, CH Pyridyl), 7.57 (dd, J = 2.5, 0.6 Hz, 1H, CH Pyridyl), 4.42 (s, 2H, N-
CH2), 2.31 (s, 3H, C Pyridyl-CH3), 1.88 (s, 3H, C Alkene-CH3), 1.43 (s, 9H,
CH3 Boc), 0.41 (s, 6H, Si(CH3)2), 0.21 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.5
MHz, CDCl3): δ = 157.6 (C Pyridyl), 153.9 (C=O), 151.1 (C Alkene), 149.7
(CH Pyridyl), 148.0 (C Alkene), 142.9 (CH Pyridyl), 130.3 (C Pyridyl), 128.1 (C
Pyridyl), 80.3 (C Boc), 51.9 (N-CH2), 28.3 (CH3 Boc), 19.7 (C Pyridyl-CH3), 18.1
(C Alkene-CH3), 0.6 (Si(CH3)3), -0.3 (Si(CH3)2); IR (ATR): υ = 2976, 2864,
1694, 1558, 1440, 1419, 1391, 1364, 1340, 1296, 1264, 1248, 1233,
1167, 1140, 869, 837, 825, 801, 779, 756, 688, 641, 421 cm-1; HRMS
(ESI, positive mode) calcd (m/z) for C20H34N2O2Si2H [M+H]+: 391.2237,
found: 391.2250, εr: 3.3 ppm.
tert-butyl
(Z)-1,1-dimethyl-2-(1-(trimethylsilyl)ethylidene)-2,3-di-
hydro-[1,4]azasilino[2,3-c]quinoline-4(1H)-carboxylate (30)
Mp = 57°C; 1H NMR (300 MHz, Acetone-d6): δ = 8.84 (s, 1H, C(2)H),
8.09-8.00 (m, 2H, CH Quinolyl), 7.66 (ddd, J = 8.3, 6.9, 1.5 Hz, 1H, CH
Quinolyl), 7.58 (ddd, J = 8.3, 6.9, 1.5 Hz, 1H, CH Quinolyl), 4.57 (s, 2H, N-CH2),
2.13 (s, 3H, C Alkene-CH3), 1.46 (s, 9H, CH3 Boc), 0.69 (s, 6H, Si(CH3)2),
0.30 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.4 MHz, Acetone-d6): δ = 154.4
(C=O), 151.5 (C Alkene), 150.0 (C(2)H), 147.5 (C Alkene), 146.0 (C Quinolyl),
143.8 (C Quinolyl), 136.6 (C Quinolyl), 131.5 (C Quinolyl), 131.4 (CH Quinolyl), 128.5
(CH Quinolyl), 128.2 (CH Quinolyl), 127.4 (CH Quinolyl), 81.5 (C Boc), 51.2 (N-
CH2), 28.3 (CH3 Boc), 20.1 (C Alkene-CH3), 1.9 (Si(CH3)2), 1.0 (Si(CH3)3); IR
(ATR): υ = 2966, 1685, 1388, 1366, 1240, 1142, 1067, 1000, 918, 826,
776, 750, 690, 665, 432 cm-1; HRMS (ESI, positive mode) calcd (m/z) for
C23H34N2O2Si2H [M+H]+: 427.2237, found: 427.2234, εr: 0.7 ppm.
(Z)-3,3-dimethyl-2-(1-(trimethylsilyl)ethylidene)-2,3-dihydro-1H-
[1,4]azasilino[3,2,1-kl]phenothiazine (18)
Mp = 94°C; 1H NMR (300 MHz, C6D6): δ = 7.14-7.02 (m, 3H, CH Aryl),
6.94 (ddd, J = 8.0, 7.4, 1.5 Hz, 1H, CH Aryl), 6.81 (t, J = 7.4 Hz, 1H, CH
Aryl), 6.75 (dd, J = 8.1, 1.1 Hz, 1H, CH Aryl), 6.67 (td, J = 7.5, 1.2 Hz, 1H,
CH Aryl), 4.38 (pseudo-d, J = 0.4 Hz, 2H, N-CH2), 1.83 (t, J = 0.7 Hz, 3H,
C Alkene -CH3), 0.29 (s, 6H, Si(CH3)2), 0.14 (s, 9H, Si(CH3)3); 13C{1H} NMR
(75.4 MHz, C6D6): δ = 150.2 (C Aryl), 149.5 (C Alkene), 149.1 (C Alkene), 148.0
(C Aryl), 132.6 (CH Aryl), 127.9 (CH Aryl), 127.7 (CH Aryl), 127.5 (CH Aryl),
126.8 (C Aryl), 126.0 (C Aryl), 123.4 (CH Aryl), 122.5 (CH Aryl), 115.6 (CH Aryl),
(Z)-1,1-dimethyl-2-(1-(trimethylsilyl)ethylidene)-2,3,6,7-tetrahydro-
1H,5H-[1,4]azasilino[3,2,1-ij]quinolone (36)
1H NMR (300 MHz, CDCl3): δ = 7.29-7.23 (m, 1H, CH Aryl), 7.07-7.00 (m,
1H, CH Aryl), 6.79 (pseudo-t, J = 7.3 Hz, 1H, CH Aryl), 3.86 (q, J = 0.6 Hz,
2H, N-CH2-C Alkene), 3.34-3.28 (m, 2H, N-CH2), 2.84 (pseudo-t, J = 6.4 Hz,
2H, C Aryl-CH2), 2.13-2.04 (m, 2H, CH2), 1.99 (t, J = 0.6 Hz, 3H, C Alkene
-
CH3), 0.50 (s, 6H, Si(CH3)2), 0.30 (s, 9H, Si(CH3)3); 13C{1H} NMR (75.4
MHz, CDCl3): δ = 153.2 (C Aryl), 149.2 (C Alkene), 148.9 (C Alkene), 132.4 (CH
Aryl), 130.1 (CH Aryl), 124.6 (C Aryl), 123.1 (C Aryl), 118.0 (CH Aryl), 58.9 (N-
54.9 (N-CH2), 19.3 (C
-CH3), 1.0 (Si(CH3)2), 0.9 (Si(CH3)3); IR
Alkene
(ATR): υ = 3064, 2954, 2894, 1477, 1443, 1428, 1408, 1357, 1246, 1222,
1121, 932, 838, 817, 796, 747, 673, 642, 465, 444, 422; cm-1; HRMS
(APCI, positive mode) calcd (m/z) for C21H27NSSi2H [M+H]+: 382.1481 ,
found: 382.1493, εr: 3.1 ppm.
CH2-C Alkene), 52.5 (N-CH2), 28.3 (C Aryl-CH2), 22.6 (CH2), 19.6 (C Alkene
-
CH3), 1.0 (Si(CH3)2), 0.8 (Si(CH3)3); IR (ATR): υ = 2950, 1414, 1285,
1245, 940, 834, 805, 753, 668, 460, 433 cm-1; HRMS (APCI, positive
mode) calcd (m/z) for C18H29NSi2H [M+H]+: 316.1917, found: 316.1910,
εr: 2.2 ppm.
(Z)-1,1-dimethyl-2-(1-(trimethylsilyl)ethylidene)-2,3-dihydro-1H-
[1,3]azasilolo[1,2-a]indole (21)
Mp = 92°C; 1H NMR (300 MHz, CDCl3): δ = 7.73-7.68 (m, 1H, CH Aryl),
7.41 (ddd, J = 8.1, 1.8, 0.9 Hz, 1H, CH Aryl), 7.24 (ddd, J = 8.2, 7.0, 1.4 Hz,
1H, CH Aryl), 7.15 (ddd, J = 7.9, 7.0, 1.1 Hz, 1H, CH Aryl), 6.71 (d, J = 0.8
Hz, 1H, C(3)H), 4.92 (q, J = 1.2 Hz, 2H, N-CH2), 2.02 (t, J = 1.2 Hz, 3H, C
Alkene -CH3), 0.58 (s, 6H, Si(CH3)2), 0.29 (s, 9H, Si(CH3)3); 13C{1H} NMR
Acknowledgements
This study was funded by the Région Normandie (RIN GREEN
CHEM program). The authors would like to thank the European
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10.1002/cctc.201900609
ChemCatChem
FULL PAPER
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2019, 25, 2407–2422.
Regional Development Fund (ERDF) and the Region Normandie
for their financial support. The authors also thank the LABEX
SynOrg (ANR-11-LABX-0029) as well as the Interreg France
(Channel) England V project LabFact, for their financial supports
to our general research projects.
Keywords: azasilines • disilane • heterocycles • palladium •
silapalladation
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10.1002/cctc.201900609
ChemCatChem
FULL PAPER
FULL PAPER
A simple synthesis of azasilines
fused nitrogen heterocycles is
proposed. It relies on an efficient and
highly regio- and stereo-selective (syn
addition, 6-exo-dig cyclisation)
silapalladation of alkynes. New
polyheterocyclic motives are thus
obtained in high yields, starting from
various nitrogen heteroaryl substrates,
leading to scaffolds potentially useful
in medicinal chemistry.
Ludovik Noël-Duchesneau, Jacques
Maddaluno] and Muriel Durandetti*
Page No. – Page No.
Synthesis of N-Heterocycles-Fused
azasilines by palladium-catalyzed Si-
Si bond activation
This article is protected by copyright. All rights reserved.