Silver(i)-promoted insertion into X-H (X = Si, Sn, and Ge) bonds with N-nosylhydrazones

Article abstract of DOI:10.1039/c6cc09650f

Silver(i)-promoted carbene insertion into X-H (X = Si, Sn, and Ge) bonds has been realized by using unstable diazo compounds, which are generated in situ from N-nosylhydrazones as carbene precursors. The reaction tolerates a wide range of functional groups and delivers a number of valuable silicon-containing compounds in very high yields (up to 96%). Moreover, organostannanes and organogermanes were as well effectively obtained in very good yields under optimal conditions.

Full text of DOI:10.1039/c6cc09650f

ChemComm
View Article Online
View Journal
COMMUNICATION
Silver(I)-promoted insertion into X–H (X = Si, Sn,
and Ge) bonds with N-nosylhydrazones†
Cite this:DOI: 10.1039/c6cc09650f
Zhaohong Liu,‡a Qiangqiang Li,‡a Yang Yanga and Xihe Bi*ab
Received 5th December 2016,
Accepted 2nd February 2017
DOI: 10.1039/c6cc09650f
rsc.li/chemcomm
Silver(I)-promoted carbene insertion into X–H (X = Si, Sn, and Ge)
bonds has been realized by using unstable diazo compounds, which
are generated in situ from N-nosylhydrazones as carbene precursors.
The reaction tolerates a wide range of functional groups and delivers
a number of valuable silicon-containing compounds in very high
yields (up to 96%). Moreover, organostannanes and organogermanes
were as well effectively obtained in very good yields under optimal
conditions.
Organosilicon compounds are well known to be highly attractive
scaffolds and valuable compounds, which have broad applications
in organic synthesis,1 materials chemistry,2 and pharmaceuticals.3
Transition-metal-catalyzed carbenoid insertion into Si–H bonds
Fig. 1 Transition-metal-catalyzed insertion into the Si–H bond.
with diazo compounds represents a particularly important con- transformations,11 particularly in heteroatom–hydrogen insertion
tribution to synthesize such compounds.4 In 1962, Kramer and reactions such as N–H,12 O–H,13 P–H14 and S–H15 insertions. To
Wright first reported the carbene insertion into Si–H bonds from the best of our knowledge, there is no report that demonstrates
diazoalkanes with organosilicon.5 Since then, great efforts the direct use of such diazo precursors in Si–H insertions.
based on transition metal catalysts, such as rhodium,6 copper,7 Promoted by these facts and given the continuous interest in
iron,8 iridium,9 and silver salts,10 have been made in inducing silver catalysis,16 we envisaged that silver salts could be employed
Si–H insertion from diazo compounds. Among them, electron- in catalyzing Si–H insertion reactions with N-tosylhydrazones as
withdrawing-group (EWG)- or trimethylsilyl (TMS)-group-stabilized diazo sources. Herein, we report the first example of donor and
diazo compounds were successfully implemented as carbene pre- donor/donor carbenoid insertion into Si/Sn/Ge–H bonds to access
cursors in Si–H insertion reactions (Fig. 1a). However, the utiliza- a wide range of tetraorganosilanes/stannanes/germanes, which
tion of donor diazo compounds in such transformations was not are difficult to access using other methods (Fig. 1b).17
well documented, which significantly limits their further applica-
An exploratory experiment was conducted with N-tosylhydrazone
tion in organic synthesis. For this reason, the exploration of new 1a0 and triethylsilane 2a in the presence of 30 mol% of AgOTf in
strategies and reagents for the rapid assembly of silicon-containing CH2Cl2 at 40 1C under a N2 atmosphere. The desired insertion
compounds via transition-metal-catalyzed Si–H insertion from product 3aa was obtained, although the yield was only 15% (Table 1,
unstable diazoalkanes would be highly desirable.
entry 1). To improve the yield of the desired product, a nitro
On the other hand, sulfonylhydrazones as reliable diazo group was introduced into the aromatic ring, which stemmed
sources have been widely used in transition-metal catalyzed from our previous observation of the rapid decomposition of
o-nosylhydrazide at room temperature.18 Notably, the yield was
a Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis,
Department of Chemistry, Northeast Normal University, 5268 Renmin Street,
130024 Changchun, China. E-mail: bixh507@nenu.edu.cn
significantly improved to 57% when N-nosylhydrazone 1a was
used to generate the diazo intermediate. Inspired by these results,
further optimization of the reaction conditions was performed.
The reaction temperature was found to be a crucial parameter
for this transformation. When the reaction was carried out at
80 1C, the yield was increased to 84% (Table 1, entry 3). Notably,
b State Key Laboratory of Elemento-Organic Chemistry, Nankai University,
300071 Tianjin, China
† Electronic supplementary information (ESI) available. See DOI: 10.1039/c6cc09650f
‡ These authors contributed equally to this work.
This journal is ©The Royal Society of Chemistry 2017
Chem. Commun.

View Article Online
Communication
ChemComm
Table 1 Optimization of the reaction conditionsa
Table 2 Reaction scopes with respect to N-nosylhydrazonesa,b
Entry
R
Cat. (30 mol%) Solvent
Temp. (1C) Yield 3aab (%)
1
2
3
4
5
6
7
8
Ts AgOTf
Ns AgOTf
Ns AgOTf
Ns AgOAc
Ns AgOTAF
Ns AgF
Ns Ag2CO3
Ns AgOTf
Ns AgOTf
Ns AgOTf
Ns AgOTf
Ns Cu(OTf)2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
1,4-Dioxane 80
PhCl
MeCN
ClCH2CH2Cl 80
40
40
80
80
80
80
80
15
57
84 (81)d
55
60
28
34
20
9
80
80
6
10
11
12
13
14c
o5
32
7
CH2Cl2
80
80
80
Ns Cu(MeCN)4PF6 CH2Cl2
Ns Rh2(OAc)4 CH2Cl2
10
25
a
Reaction conditions: 1a (0.3 mmol), 2a (1.5 mmol), NaH (0.45 mmol), and
the catalyst (30 mol%) in solvent (6.0 mL) for 24 h under a N2-atmosphere.
b
Yield calculated by 1H-NMR spectroscopy with CH2Br2 as the internal
c
d
standard. Rh2(OAc)4 (5 mol%) was used. Isolated yield in brackets.
side products like H2 and NaNs were probably produced from
the decomposition of N-nosylhydrazones. Compared to AgOTf,
other silver catalysts (AgOAc, AgOTAF, AgF and Ag2CO3; Table 1,
entries 4–7) are less effective in this transformation, although
the desired products were obtained. The screening of solvents
a
Reaction conditions: 1b–1u (0.3 mmol), 2a (1.5 mmol), NaH (0.45 mmol),
and AgOTf (30 mol%) in CH2Cl2 (6.0 mL) for 24 h under a N2-atmosphere.
b
Isolated yield.
(Table 1, entries 8–11) identified CH2Cl2 as the most suitable from aliphatic aldehydes or ketones, such as 3ta and 3ua, were not
solvent. Other commonly used transition-metal catalysts in catalytic compatible under the current conditions (Table 2).
Si–H insertion reaction with diazo compounds, such as Cu(OTf)2,7b
Next, the scope of silanes was evaluated. A broad range of
Cu(MeCN)4PF6,7d and Rh2(OAc)4,6 were also tested but did not silanes reacted smoothly with N-nosylhydrazone 1b. As illustrated
produce better results (Table 1, entries 12–14). in Table 3, the reaction between trialkyl-substituted silanes and
Once the optimal reaction conditions were established, efforts N-nosylhydrazone 1b proceeded efficiently to afford the insertion
were then focused on the scope of this method. As shown in products 3bb–be in very high yields. For aryl-substituted silanes,
Table 2, a series of N-nosylhydrazones 1b–s worked well with there is a significant drop in yields with the increasing number of
triethylsilane 2a, furnishing the corresponding insertion products aryl substituents on the silicon atom (3bg, 3bh), presumably due
3ba–sa efficiently. For N-nosylhydrazones derived from benzalde- to steric hindrance. It is worth mentioning that strong electron-
hyde derivatives, a variety of electron-donating (Ph or MeO) or withdrawing groups, i.e.–CF3, have a negative impact on the yield
electron-withdrawing groups (Cl, CN, CO2Me, I, Br, or F3C) located of the desired insertion product (3bf). Silane bearing flexible
at the para-, meta- or ortho-position of the aromatic ring were all tri-TMS groups was amenable to this transformation, affording
compatible, thus affording the corresponding insertion products desired compounds in 68% yield (3bi).
(3ba–ja) in good to high yields. Among these cases, the tolerance
Encouraged by the successful carbenoid Si–H bond insertion,
of iodo (3ga) and bromo (3ja) groups on the aromatic rings, which we proceeded to explore the same strategy for other similar types
provide a basis for subsequent derivatization of the product of s bonds, including Sn–H and Ge–H bonds, which have
into more-complex molecules, is especially noteworthy. More received little attention to date.5a,7a,19 As shown in Table 3, a
importantly, this reaction is compatible with N-nosylhydrazones variety of N-nosylhydrazones, both derived from aldehydes and
bearing a heteroaryl group such as furan (3ka), thiophene (3la) ketones, were excellent substrates for Sn–H bond (3bj–br) and
and indole (3ma). This feature makes the reaction particularly Ge–H bond (3bs) insertions, thus affording the desired products
useful for the synthesis of silicon-based materials.2 Furthermore, in moderate-to-good yields, which further expanded the scope of
N-nosylhydrazones derived from aromatic ketones can be employed this protocol in X–H bond insertion.
without loss in efficiency (3na–qa, 45–84% yields). Finally, the
To establish practical laboratory-scale utility, scale-up experi-
reaction was also efficient with N-nosylhydrazones derived ments were carried out for N-nosylhydrazones 1a and 1b
from unsaturated aldehydes and gave allylic and propargylic (Scheme 1). The reaction proceeded efficiently, and the corres-
silane products (3ra and 3sa), which are hard to access using ponding silanes could be isolated on a gram scale. Further-
conventional methods. Unfortunately, N-nosylhydrazones generated more, the silane 3aa can be further transformed into diversely
Chem. Commun.
This journal is ©The Royal Society of Chemistry 2017

View Article Online
ChemComm
Communication
Table 3 Reaction scopes with respect to organic Si/Sn/Ge–Ha,b
Obviously, these functionalized organosilicon compounds are
potentially powerful synthetic intermediates.20
In summary, we have developed the first practical and efficient
silver(I)-promoted carbenoid insertion into X–H (X = Si, Sn, and Ge)
bonds with donor diazo compounds generated in situ from N-nosyl-
hydrazones. Moreover, the wide substrate scope and high efficiency
of the current transformations make them attractive methods to
access organosilanes, organostannanes and organogermanes.
Notes and references
1 P. L. Fuchs, Handbook of Reagents for Organic Synthesis: Reagents for
Silicon-Mediated Organic Synthesis, Wiley, Chichester, UK, 2011.
2 (a) N. Auner and J. Weis, Organosilicon Chemistry V: From Molecules to
Materials, Wiley-VCH, Weinheim, Germany, 2004; (b) B. A. Kamino
and T. P. Bender, Chem. Soc. Rev., 2013, 42, 5119.
3 (a) Z. Rappoport and Y. Apeloig, The Chemistry of Organic Silicon
Compounds, Wiley, Chichester, UK, 1998; (b) A. K. Franz and
S. O. Wilson, J. Med. Chem., 2013, 56, 388.
4 For selected reviews, see: (a) A. Ford, H. Miel, A. Ring, C. N. Slattery,
A. R. Maguire and M. A. McKervey, Chem. Rev., 2015, 115, 9981;
(b) X. Zhao, Y. Zhang and J. Wang, Chem. Commun., 2012, 48, 10162;
(c) M. P. Doyle and D. C. Forbes, Chem. Rev., 1998, 98, 911.
5 (a) K. A. W. Kramer and A. N. Wright, J. Chem. Soc., 1963, 3604;
(b) K. Kramer and A. Wright, Angew. Chem., 1962, 74, 468.
6 For selected examples of rhodium-catalyzed carbenoid Si–H insertion,
see: (a) V. Bagheri, M. P. Doyle, J. Taunton and E. E. Claxton, J. Org.
Chem., 1988, 53, 6158; (b) H. M. L. Davies, T. Hansen, J. Rutberg and
P. R. Bruzinski, Tetrahedron Lett., 1997, 38, 1741; (c) M. P. Doyle, W. Hu,
I. M. Phillips, C. J. Moody, A. G. Pepper and A. G. Z. Slawin, Adv. Synth.
Catal., 2001, 343, 112; (d) Z. Qu, W. Shi and J. Wang, J. Org. Chem.,
2001, 66, 8139; (e) F. M. Wong, J. Wang, A. C. Hengge and W. Wu, Org.
Lett., 2007, 9, 1663; ( f ) R. Sambasivan and Z. T. Ball, J. Am. Chem. Soc.,
2010, 132, 9289; (g) D. Chen, D. Zhu and M. Xu, J. Am. Chem. Soc., 2016,
138, 1498; (h) During the preparation of our manuscript, a rhodium(II)-
alkynyl carbenoid insertion into Si–H bonds was published, which
provides an entry to propargylic geminal bis(silanes). T. Courant,
R. Kumar, S. Turcaud and L. Micouin, Org. Lett., 2016, 18, 4818.
7 For copper-catalyzed carbenoid Si–H insertion examples, see:
(a) F. Rijkens, M. J. Janssen, W. Drenth and G. J. M. Van der Kerk,
J. Organomet. Chem., 1964, 2, 347; (b) Y. Zhang, S. Zhu, L. Wang and
Q. Zhou, Angew. Chem., Int. Ed., 2008, 47, 8496; (c) J. Barluenga,
L. Riesgo, R. Vicente, L. A. Lopez and M. Tomas, J. Am. Chem. Soc.,
2008, 130, 13528; (d) S. Hyde, J. Veliks, B. Liegault, D. Grassi and
M. Taillefer, V Gouverneur, Angew. Chem., Int. Ed., 2016, 55, 3785.
8 E. Scharrer and M. Brookhart, J. Organomet. Chem., 1995, 497, 61.
9 (a) Y. Yasutomi, H. Suematsu and T. Katsuki, J. Am. Chem. Soc.,
2010, 132, 4510; (b) J. Wang, Z. Xu, Z. Guo, Q. Deng, C. Zhou, X. Wan
and C. Che, Chem. Commun., 2012, 48, 4299.
a
Reaction conditions: 1 (0.3 mmol), 2b–2m (1.5 mmol), NaH (0.45 mmol),
and AgOTf (30 mol%) in CH2Cl2 (6.0 mL) for 24 h under a N2-atmosphere.
b
Isolated yield.
10 M. J. Iglesia, M. C. Nicasio, A. Caballero and P. J. Perez, Dalton
Trans., 2013, 42, 1191.
11 (a) Z. Shao and H. Zhang, Chem. Soc. Rev., 2012, 41, 560; (b) Q. Xiao,
Y. Zhang and J. Wang, Acc. Chem. Res., 2013, 46, 236; (c) J. Barluenga
´
and C. Valdes, Angew. Chem., Int. Ed., 2011, 50, 7486; (d) Y. Xia,
Y. Zhang and J. B. Wang, ACS Catal., 2013, 3, 2586; (e) J. R. Fulton,
V. K. Aggarwal and J. de Vicente, Eur. J. Org. Chem., 2005, 1479.
12 (a) P. Xu, F. Qi, F. Han and Y. Wang, Chem. – Asian J., 2016, 11, 2030;
(b) J. Aziz, J. D. Brion, A. Hamze and M. Alamia, Adv. Synth. Catal.,
´
2013, 355, 2417; (c) A. Hamze, B. Treguier, J. D. Brion and M. Alamia,
Org. Biomol. Chem., 2011, 9, 6200.
´
´
13 J. Barluenga, M. Tomas-Gamasa, F. Aznar and C. Valdes, Angew.
Chem., Int. Ed., 2010, 49, 4993.
14 (a) W. J. Miao, Y. H. Gao, Y. X. Gao, G. Tang and Y. F. Zhao, Adv.
Synth. Catal., 2012, 354, 2659; (b) L. Wu, X. Zhang, Q. Q. Chen and
A. K. Zhou, Org. Biomol. Chem., 2012, 10, 7859.
Scheme 1 Gram-scale experiment and synthetic application.
15 Q. Ding, B. Cao, J. Yuan, X. Liu and Y. Peng, Org. Biomol. Chem.,
2011, 9, 748.
16 For examples of our reports on silver catalysis, see: (a) J. Liu, Z. Liu,
P. Liao, L. Zhang, T. Tu and X. Bi, Angew. Chem., Int. Ed., 2015,
54, 10618; (b) Z. Liu, J. Liu, L. Zhang, P. Liao, J. Song and X. Bi,
Angew. Chem., Int. Ed., 2014, 53, 5305; (c) J. Q. Liu, Z. X. Fang, Q. Liu
functionalized silanes. For example, phenyl-(triethylsilyl)-
methanone 4 and geminal bis(silane) product 5 can be readily
prepared from 3aa via multi-step procedures, respectively.
This journal is ©The Royal Society of Chemistry 2017
Chem. Commun.

View Article Online
Communication
ChemComm
and X. Bi, Angew. Chem., Int. Ed., 2013, 52, 6953; (d) G. Fang and
X. Bi, Chem. Soc. Rev., 2015, 44, 8124.
52, 5936; (c) A. Myers and B. Zheng, J. Am. Chem. Soc., 1996,
118, 4492.
17 For recent examples of the synthesis of tetraorganosilanes, see: 19 During the review of this manuscript, a related work on carbene
(a) C. Chu, Y. Liang and G. C. Fu, J. Am. Chem. Soc., 2016,
138, 6404; (b) Y. Hua, P. Asgari, T. Avullala and J. Jeon, J. Am. Chem.
Soc., 2016, 138, 7982; (c) A. A. Toutov, W. B. Liu, K. N. Betz,
A. Fedorov, B. M. Stoltz and R. H. Grubbs, Nature, 2015, 518, 80.
18 (a) Z. Liu, P. Liao and X. Bi, Chem. – Eur. J., 2014, 20, 17277; (b) Z. Yang,
R. K. Kumar, P. Liao, Z. Liu, X. Li and X. Bi, Chem. Commun., 2016,
insertion into Sn–H bonds was reported by Wang and co-workers,
D. Qiu, S. Wang, H. Meng, S. Tang, Y. Zhang and J. Wang, J. Org.
Chem., 2017, 82, 624.
20 (a) J. Cossrow and S. D. Rychnovsky, Org. Lett., 2002, 4, 147;
(b) M. Das, A. Manvar, M. Jacolot, M. Blangetti, R. C. Jones and
D. F. O’Shea, Chem. – Eur. J., 2015, 21, 8737.
Chem. Commun.
This journal is ©The Royal Society of Chemistry 2017