Tetraarylethylenes from Diarylmethanones and Hexachlorodisilane: The “Sila-McMurry” Reaction

Article abstract of DOI:10.1002/chem.201603720

Hexachlorodisilane reacts with diarylmethanones (aryl=C₆H₅, 4-MeC₆H₄, 4-tBuC₆H₄, 4-ClC₆H₄, 4-BrC₆H₄) to furnish the corresponding tetraarylethylenes in good yields. The reductive conversion requires temperatures of about 160 °C and reaction times of 60–72 h. In the initial step, the Lewis-basic carbonyl groups likely generate low-valent [SiCl₂] as an analogue of [TiCl₂] in the classical McMurry reaction. The coupling sequence further proceeds via benzopinacolones, which have been isolated as key intermediates.

Full text of DOI:10.1002/chem.201603720

DOI: 10.1002/chem.201603720
Communication
&
Alkene Synthesis
Tetraarylethylenes from Diarylmethanones and
Hexachlorodisilane: The “Sila-McMurry” Reaction
Maximilian Moxter, Jan Tillmann, Matthias Fꢀser, Michael Bolte, Hans-Wolfram Lerner, and
Matthias Wagner*[a]
diarylmethanones has previously been studied and found to
Abstract: Hexachlorodisilane reacts with diarylmethan-
ones (aryl=C6H5, 4-MeC6H4, 4-tBuC6H4, 4-ClC6H4, 4-BrC6H4)
result in reductive silylation of the C=O group to furnish
Ar2C(H)SiCl3, but no tetraarylethylenes.[8] We consequently se-
to furnish the corresponding tetraarylethylenes in good
lected hexachlorodisilane, Si2Cl6, as an alternative reagent for
yields. The reductive conversion requires temperatures of
our studies. Even though this compound requires tempera-
about 1608C and reaction times of 60–72 h. In the initial
tures as high as 2408C for the reduction of nitro groups
step, the Lewis-basic carbonyl groups likely generate low-
(Scheme 1), it converts amine oxides to amines and sulfoxides
valent [SiCl2] as an analogue of [TiCl2] in the classical
McMurry reaction. The coupling sequence further pro-
ceeds via benzopinacolones, which have been isolated as
key intermediates.
Redox reactions represent fundamental molecular transforma-
tions and are thus widely applied in synthetic chemistry. Our
group is specifically interested in the reductive coupling of di-
arylmethanones to give tetraarylethylenes, because these com-
pounds are among the most reliable AIE-luminogens in bio-
and materials science (AIE=aggregation induced emission).[1]
The currently most widely used tool in this context is the
McMurry reaction, which exploits low-valent titanium reagents
such as in situ generated [TiCl2][2] and provides access to
a broad range of olefins. However, in various cases issues of re-
producibility have been reported and particularly the prepara-
tion of sterically encumbered double bonds through the
Scheme 1. a) Established methods for the reduction of nitro groups, amine
McMurry approach can be problematic.[3]
oxides, and phosphine oxides with Si2Cl6.[9] b) Literature-known structural
motifs generated by [2+1] and [4+1] cycloaddition reactions of silylenes
with carbonyl compounds.[13,14] (o-DCB=ortho-dichlorobenzene)
Herein, we are therefore considering low-valent silicon com-
pounds as suitable substitutes of corresponding titanium spe-
cies to establish a “Sila-McMurry” reaction. Similar to titanium,
silicon is extremely oxophilic and ketones are well-known to
react with silylated alkyl lithium compounds to furnish highly
substituted olefins (Peterson olefination[4]), even in cases for
which the McMurry reaction fails.[3c,5]
to sulfides already at r.t. Even the challenging reduction of
phosphane oxides is achievable at moderately elevated tem-
peratures of 808C.[9]
It is known that [SiCl2] can be generated from Si2Cl6 and
a Lewis base via a disproportionation reaction ultimately lead-
ing to SiCl4 and the adduct Cl2SiÀLB (LB=Lewis base).[10] Car-
bonyl groups have Lewis basic properties such that treatment
of diarylmethanones with Si2Cl6 should result in adducts
Ar2COÀSiCl2, which, given the formal analogy between [SiCl2]
and [TiCl2], could subsequently undergo a McMurry-type con-
version. Based on experimental studies by Fꢀrstner[11] and Bog-
danovic[12] (TiCl3/Cu/Zn in DME), Frenking et al.[2] have provided
a detailed quantum-chemical assessment of the McMurry reac-
tion mechanism. According to their calculations, one early in-
termediate contains a three-membered TiOC ring, formed
through the [2+1] cycloaddition of a [TiCl2] complex fragment
to the carbonyl group. A related reactivity, the [2+1][13] or
Moreover, HSiCl3 has already been applied for the selective
reduction of nitro groups to amines at 08C under basic condi-
tions.[6] Theoretical and experimental data suggest amine-stabi-
lized dichlorosilylenes, Cl2SiÀNR3, as the actual reducing
agents.[7] Also the reaction of the HSiCl3/NR3 combination with
[a] M. Moxter, Dr. J. Tillmann, M. Fꢀser, Dr. M. Bolte, Dr. H.-W. Lerner,
Prof. Dr. M. Wagner
Institut fꢀr Anorganische Chemie, Goethe Universitꢁt Frankfurt
Max-von-Laue-Straße 7, 60438 Frankfurt am Main (Germany)
E-mail: Matthias.Wagner@chemie.uni-frankfurt.de
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201603720; containing full experimental de-
tails and spectroscopic data, as well as CCDC numbers.
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[4+1][14] cycloaddition with aryl carbonyl compounds, is well-
known also for silylenes and leads to the structural motifs
shown in Scheme 1.
In this communication, we will first describe an optimized
protocol for the “Sila-McMurry” reaction using benzophenone
(A; Scheme 2) as the prototypical substrate. We will continue
with a preliminary screening of substituent effects and con-
clude with a mechanistic proposal for the overall reaction se-
quence.
Scheme 2. “Sila-McMurry” reaction of selected diarylmethanones with Si2Cl6.
Reaction conditions for A as the prototypical example: i) Si2Cl6 (1 equiv),
60 h, 1608C, C6D6; ii) Si2Cl6 (2 equiv), 72 h, 1608C, C6D6; iii) A (1 equiv), Si2Cl6
(3 equiv), 60 h, 1608C, C6D6.
To be able to monitor the reactions between A and varying
amounts of Si2Cl6, C6D6 solutions were prepared in vacuum-
sealed NMR tubes. We first optimized the general conditions
and found that temperatures of 1608C and reaction times of
60–72 h are necessary to drive the transformations to comple-
tion. This way, treatment of A with 1 equivalent of Si2Cl6 fur-
nished benzopinacolone (I) as the major product (>90% ac-
Scheme 3. Mechanistic proposal for the reaction of benzophenone (A) with
Si2Cl6 to give F, I, and M; molecular structure of F obtained by X-ray crystal-
lography (C: black, O: red, Si: blue, Cl: green).
1
cording to H NMR spectroscopy; 71% isolated yield). Increas-
ing the amount of Si2Cl6 to 2 equivalents resulted in the forma-
tion of tetraphenylethylene (M; >90% according to 1H NMR
spectroscopy; 79% isolated yield). Given that a mere electron
count would predict that 0.5 and 1 equivalents of Si2Cl6 should
be sufficient to convert 1 equivalent of A into I and M, respec-
tively, both reactions obviously require an overstoichiometric
amount of the reducing agent. Besides I and M, we identified
a side product F (Scheme 3), which precipitated from the reac-
tion solutions in yields of 10–12%. The structural assignment
of F had to rely on X-ray crystallography and an elemental
analysis, because the compound is only poorly soluble in all
common solvents. The molecules of F show inversion symme-
try in the solid state and contain a ten-membered Si2O4C4 mac-
rocycle, substituted with eight phenyl rings (Scheme 3; cf. the
Supporting Information for the structural parameters). Two of
these phenyl rings became CÀH-activated in their ortho-posi-
tions and then form CÀSi bonds. Importantly, the structural
motif of a benzopinacol moiety occurs twice in each molecule
of F. This observation, together with the fact that benzopinaco-
lone (I) forms from 1:1 mixtures of A and Si2Cl6, indicates that
the “Sila-McMurry” reaction takes place via a pinacol coupling
mechanism, as it is commonly proposed also for the Ti-mediat-
ed McMurry reaction.[2,3]
The “Sila-McMurry” reaction is compatible with a variety of
substituents in the 4-positions of the phenyl rings: Both 4,4’-di-
methylbenzophenone (A1) and the bulkier 4,4’-di-tert-butyl-
benzophenone (A2) could be transformed to I1/I2 and M1/M2
in yields comparable to those of I and M (Scheme 2). 4,4’-Di-
chlorobenzophenone (A3) and 4,4’-dibromobenzophenone
(A4) afford the corresponding tetrahalogenated tetraphenyl-
ethylenes, which have been isolated in yields of 63% (M3) and
35% (M4). M3 and M4 are synthetically useful products, be-
cause they allow for a broad variety of subsequent derivatiza-
tion reactions.
However, we also found that certain steric and electronic
substituent effects can impose limits to the “Sila-McMurry” re-
action of ketones Ar2CO: Exceptionally bulky derivatives (Ar=
2,6-iPr2C6H3, 2,4,6-Me3C6H2) failed to give tetraarylethylenes
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cle. Indeed, on one occasion we have been able to isolate
a few single crystals consisting of the heterodimer EE* (cf. the
Supporting Information for more detail).
Table 1. Reaction of arylmethanones with Si2Cl6.
Entry
Reactant(s)
Equiv
Si2Cl6
Reaction
Product
(yield [%])
conditions
How are the main products, benzopinacolone (I) and tetra-
phenylethylene (M), generated? As a preferred alternative
pathway to the [4+1] cycloaddition, intermediate B is expect-
ed to rearrange via a [2+1] cycloaddition reaction to give the
three-membered ring compound G,[13] which subsequently in-
serts a second benzophenone molecule with formation of the
pinacol ester H (Scheme 3).[14a] Importantly, there is also a po-
tential direct link between the benzophenone diadduct C and
the pinacol silyl ester H, which proceeds via an intramolecular
electron transfer process and CÀC coupling of the thus gener-
ated ketyl radicals (a comparable scenario has been postulated
for a (CAAC)2SiCl2 complex[16] and for Ti-mediated McMurry re-
actions;[3a,17] CAAC=cyclic (alkyl)(amino)carbene). Under the
forcing conditions applied, H then eliminates one molecule of
dichlorosilanone[18] to yield the experimentally observed ben-
zopinacolone I. Provided that Si2Cl6 is still available in sufficient
supply, compound I either attacks the SiÀSi bond or accepts
an [SiCl2] moiety from B. In both cases this results in adduct J,
which, via the [2+1] cycloaddition product K,[13] can undergo
a ring-expansion reaction to afford the oxasilacyclobutane L. A
subsequent literature-known cycloreversion reaction ultimately
furnishes tetraphenylethylene (M) and a second molecule of
Cl2SiO.[13a,19] Given that the “Sila-McMurry” reaction is compara-
tively slow, any liberated Cl2SiO is likely unable to stabilize
itself through direct oligomerization, because the concentra-
tion of this species at any point in time should be too low. It is
thus more plausible to assume that most Cl2SiO consumes fur-
ther Si2Cl6,[18b] which would immediately explain why more
than the stoichiometric amount of the disilane is required for
the full conversion of A to M.
We also tested whether it is indeed possible to reduce I to
M by addition of Si2Cl6 and found the reaction to be slow with
poorly reproducible yields. This situation changed when I was
treated not only with Si2Cl6, but also with A. Now, the full
quantity of M, corresponding to the sum of A and I, could be
isolated. Thus, A apparently mediates the conversion of I into
M, aside from itself being a substrate for the formation of M
[note that the overall amount of Si2Cl6 required for step (iii) fits
to the stoichiometries established for steps (i) and (ii)]. We next
treated 1:1 mixtures of I and A1 or I1 and A with Si2Cl6 under
our standard conditions. In both cases, we found exclusively
the homocoupling products M and M1. In the first experiment,
some of the unsubstituted benzopinacolone I remained un-
reacted; in the second experiment, residual A and I were de-
tected (GC-MS, NMR spectroscopy). These results support two
key aspects of the postulated reaction mechanism: i) No
heterocoupling products should be generated as soon as one
of the ketones has reached the stage of a benzopinacolone,
and ii) the conversion of electron-rich ketones (i.e. A1 and I1)
should be faster than that of electron-poorer derivatives (i.e., A
and I).
1
2
3
4
5
6
7
8
9
A
A
1
2
1
2
1
2
2
2
3
[a]
[b]
[b]
[a]
[b]
[a]
[b]
[c]
[a]
I (71)
M (79)
I1[d]
M1 (80)
I2[d]
M2 (84)
M3 (63)
M4 (35)
M (87)
A1
A1
A2
A2
A3
A4
0.5 I, A
[a] 60 h, 1608C, C6D6. [b] 72 h, 1608C, C6D6. [c] 5 d, 1808C, C6D6. [d] Puri-
fied by analytical-scale HPLC.
(notably, some Si3Cl8 was generated in the case of Ar=2,6-
iPr2C6H3). Electron-poor ketones of low Lewis basicity (Ar=
C6F5), or benzophenones carrying substituents that are able to
engage in unwanted background reactions with Si2Cl6 (Ar=4-
MeOC6H4) are also not suitable substrates. Besides diaryl-
methanones we have also tested dialkylmethanones in the
“Sila-McMurry” reaction and observed the initial formation of
silyl enol ethers, which react further to furnish complex mix-
tures of follow-up products (see the Supporting Information
for more details).
Using the reductive coupling of parent benzophenone (A)
as a representative example, we suggest in the following
a plausible reaction mechanism, which is largely composed of
a sequence of literature-known transformations and fortified
by a number of control experiments (Scheme 3).
In the first step, the carbonyl oxygen atom of A attacks
Si2Cl6 to furnish the [SiCl2] adduct B.[13e,14,15] Since [SiCl2] has
a tendency to coordinate more than one ligand,[10,16] B should
be able to bind a second equivalent of A and thereby engage
in an equilibrium with diadduct C. Formation of the macrocy-
clic precipitate F likely begins with a [4+1] cycloaddition reac-
tion involving one phenyl double bond and the carbonyl
group of B.[14] The resulting intermediate D subsequently trans-
fers a proton onto the oxygen atom of an incoming benzophe-
none molecule with concomitant re-aromatization of the
phenyl ring and formation of a new CÀC single bond (E). Di-
merization of E finally leads to the crystallographically charac-
terized side product F. This mechanistic picture is in line with
three important experimental observations: a) As alluded to
above, (2,6-iPr2C6H3)2CO mediates the formation of Si3Cl8 from
Si2Cl6, which shows the general ability of ketones to generate
B-type [SiCl2] adducts.[10] b) We never encountered F-type spe-
cies with any of the 4-substituted diarylmethanones, possibly
because of unfavorable steric interactions that destabilize the
p-stacked transition state connecting (D+A) with E. c) A cer-
tain fraction of the pinacol derivative E should be able to un-
dergo intramolecular transesterification prior to dimerization.
The oxygen atom of the terminal (OH)*-group would thereby
get attached to the silicon center and an internal (OH)-group
would be formed to furnish isomer E* containing a six-mem-
bered C4SiO ring instead of the five-membered C3SiO heterocy-
The mechanistic scenario outlined in Scheme 3 does not ex-
clude the formation of heterocoupling products from mixtures
of two different diarylmethanones. We therefore performed
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Q. Chen, X. Meng, M.-Q. Zhu, Chem. Mater. 2014, 26, 4433–4446; c) J.
Liang, B. Z. Tang, B. Liu, Chem. Soc. Rev. 2015, 44, 2798–2811; d) C.
Song, Y. Sun, J. Wang, H. Chen, J. Yao, C.-H. Tung, Z. Xu, Org. Chem.
Front. 2015, 2, 1366–1373; e) M. T. Gabr, F. C. Pigge, RSC Adv. 2015, 5,
90226–90234.
the reaction between A and A1 (1:1) with 4 equivalents of
Si2Cl6. GC-MS analysis of the crude reaction solution showed
three fractions corresponding to the homocoupling products
M, M1 and the heterocoupling product C2Ph2Tol2. The relative
ratios of 19% (m/z 332), 25% (m/z 388), and 56% (m/z 360), re-
spectively, are close to a statistical distribution; the somewhat
lower yield of Ph-containing compared to Tol-containing com-
pounds may be attributed to the formation of the non-volatile
macrocyclic byproduct F. NMR spectra of the product mixture
revealed all the resonances required for M, M1, and Ph2C=
CTol2.[20] However, in close vicinity to these resonances,
a number of additional signals could be observed. For exam-
[2] M. Stahl, U. Pidun, G. Frenking, Angew. Chem. Int. Ed. Engl. 1997, 36,
2234–2237; Angew. Chem. 1997, 109, 2308–2311.
´
[3] a) A. Fꢀrstner, B. Bogdanovic, Angew. Chem. Int. Ed. Engl. 1996, 35,
2442–2469; Angew. Chem. 1996, 108, 2582–2609; b) M. Ephritikhine,
Chem. Commun. 1998, 2549–2554; c) V. M. Hertz, M. Bolte, H.-W. Lerner,
M. Wagner, Angew. Chem. Int. Ed. 2015, 54, 8800–8804; Angew. Chem.
2015, 127, 8924–8928.
[4] D. J. Peterson, J. Org. Chem. 1968, 33, 780–784.
[5] V. M. Hertz, H.-W. Lerner, M. Wagner, Org. Lett. 2015, 17, 5240–5243.
[6] M. Orlandi, F. Tosi, M. Bonsignore, M. Benaglia, Org. Lett. 2015, 17,
3941–3943.
[7] M. Orlandi, M. Benaglia, F. Tosi, R. Annunziata, F. Cozzi, J. Org. Chem.
2016, 81, 3037–3041.
[8] R. A. Benkeser, W. E. Smith, J. Am. Chem. Soc. 1969, 91, 1556–1557.
[9] a) K. Naumann, G. Zon, K. Mislow, J. Am. Chem. Soc. 1969, 91, 2788–
2789; b) G. Zon, K. E. DeBruin, K. Naumann, K. Mislow, J. Am. Chem. Soc.
1969, 91, 7023–7027; c) F.-P. Tsui, T. M. Vogel, G. Zon, J. Org. Chem.
1975, 40, 761–766; d) E. H. Krenske, J. Org. Chem. 2012, 77, 1–4;
e) E. H. Krenske, J. Org. Chem. 2012, 77, 3969–3977.
[10] F. Meyer-Wegner, A. Nadj, M. Bolte, N. Auner, M. Wagner, M. C. Holthau-
sen, H.-W. Lerner, Chem. Eur. J. 2011, 17, 4715–4719, and literature
cited herein.
1
ple, 4 rather than 2 methyl resonances were resolved in the H
as well as the 13C NMR spectrum. This indicates that, apart
from Ph2C=CTol2, further isomers with the same molecular
masses must be present, that is, E/Z-Ph(Tol)C=CPh(Tol).[21] To
confirm this conclusion, we repeated the cross-coupling ex-
periment with A1 and A4. Now, already the GC peak corre-
sponding to C2Tol2(4-BrC6H4)2 showed a resolved accompany-
ing signal. For both fractions, MS analysis gave identical pat-
terns with molecular ion peaks at m/z 518 in line with the for-
mation of E/Z-Tol(4-BrC6H4)C=CTol(4-BrC6H4) besides (4-
BrC6H4)2C=CTol2. The observed substituent scrambling about
the central olefinic bond nicely agrees with the postulated 1,2-
phenyl shifts along the way from H to I and K to L (Scheme 3).
In summary, diarylmethanones can be coupled by Si2Cl6 in
a “Sila-McMurry”-type reaction, provided that the aryl rings are
neither too sterically demanding nor too electron withdrawing.
Presently, the transformations require elevated temperatures of
1608C and reaction times of 60–72 h. We are currently explor-
ing potential Lewis-basic catalysts with the aim to perform the
reactions under less forcing conditions.
[11] a) A. Fꢀrstner, D. N. Jumbam, Tetrahedron 1992, 48, 5991–6010; b) A.
Fꢀrstner, A. Hupperts, A. Ptock, E. Janssen, J. Org. Chem. 1994, 59,
5215–5229.
´
[12] B. Bogdanovic, A. Bolte, J. Organomet. Chem. 1995, 502, 109–121.
[13] a) W. Ando, M. Ikeno, A. Sekiguchi, J. Am. Chem. Soc. 1977, 99, 6447–
6449; b) R. Becerra, J. P. Cannady, R. Walsh, J. Phys. Chem. A 1999, 103,
4457–4464; c) R. S. Ghadwal, S. S. Sen, H. W. Roesky, M. Granitzka, D.
Kratzert, S. Merkel, D. Stalke, Angew. Chem. Int. Ed. 2010, 49, 3952–
3955; Angew. Chem. 2010, 122, 4044–4047; d) S. Ishida, T. Iwamoto, M.
Kira, Organometallics 2010, 29, 5526–5534; e) S. Ishida, K. Uchida, T.
Iwamoto, Heteroat. Chem. 2014, 25, 348–353.
[14] a) P. Jutzi, D. Eikenberg, E.-A. Bunte, A. Mçhrke, B. Neumann, H.-G.
Stammler, Organometallics 1996, 15, 1930–1934; b) Y. Xiong, S. Yao, M.
Driess, Chem. Eur. J. 2009, 15, 5545–5551.
[15] a) N. Takeda, H. Suzuki, N. Tokitoh, R. Okazaki, S. Nagase, J. Am. Chem.
Soc. 1997, 119, 1456–1457; b) Y.-W. Kwak, K.-K. Lee, J. Organomet.
Chem. 1997, 542, 219–225.
Experimental Details
CCDC 1491660, 1491661, and 1491662 for F, M1, and M2, respec-
tively, contain the supplementary crystallographic data for this
paper. These data are provided free of charge by The Cambridge
Crystallographic Data Centre.
[16] K. C. Mondal, H. W. Roesky, M. C. Schwarzer, G. Frenking, I. Tkach, H.
Wolf, D. Kratzert, R. Herbst-Irmer, B. Niepçtter, D. Stalke, Angew. Chem.
Int. Ed. 2013, 52, 1801–1805; Angew. Chem. 2013, 125, 1845–1850.
[17] J. E. McMurry, Chem. Rev. 1989, 89, 1513–1524.
[18] a) H. Schnçckel, Z. Anorg. Allg. Chem. 1980, 460, 37–50; b) E. A. Cherny-
shev, T. L. Krasnova, A. P. Sergeev, E. S. Abramova, Russ. Chem. Bull.
1997, 46, 1586–1589; c) M. Junker, A. Wilkening, M. Binnewies, H.
Schnçckel, Eur. J. Inorg. Chem. 1999, 1531–1535; d) M. Hargittai, B.
Rꢂffy, J. Phys. Chem. A 2004, 108, 10194–10199.
Acknowledgements
M.F. wishes to thank the Fonds der Chemischen Industrie for
a Ph.D. grant.
[19] N. Wiberg, H.-S. Hwang-Park, H.-W. Lerner, S. Dick, Chem. Ber. 1996, 129,
471–478.
[20] W. Dai, J. Xiao, G. Jin, J. Wu, S. Cao, J. Org. Chem. 2014, 79, 10537–
10546.
[21] S. Wilker, G. Erker, J. Am. Chem. Soc. 1995, 117, 10922–10930.
Keywords: alkenes · CÀC coupling · dichlorosilylene · reaction
mechanism · Sila-McMurry reaction
Received: August 3, 2016
[1] a) M. Wang, G. Zhang, D. Zhang, D. Zhu, B. Z. Tang, J. Mater. Chem.
2010, 20, 1858–1867; b) G.-F. Zhang, H. Wang, M. P. Aldred, T. Chen, Z.-
Published online on && &&, 0000
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COMMUNICATION
Successful with silanes: Diarylmethan-
ones Ar2C=O react with Si2Cl6 at 1608C
to give tetraarylethylenes in good yields
(see scheme). This novel reductive cou-
pling reaction likely proceeds via inter-
mediary [SiCl2] generation and is thus
related to the [TiCl2]-mediated McMurry
reaction.
&
Alkene Synthesis
M. Moxter, J. Tillmann, M. Fꢀser, M. Bolte,
H.-W. Lerner, M. Wagner*
&& – &&
Tetraarylethylenes from
Diarylmethanones and
Hexachlorodisilane: The “Sila-
McMurry” Reaction
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