Synthesis of hindered silyl ethers via fragmentation reactions

Article abstract of DOI:10.1080/10426500390228765

Reaction of alcoholic sodium alkoxides with (Me₃Si) ₃CSi(C₆H₄-OMe-p)MeX have been performed. Main products are of the type: (Me₃Si)₂CHSi(An)Me(OR) and Me₃SiCH₂Si(An)Me(OR); An = (C₆H ₄-OMe-p) and OR = OEt, OPr, O iso-Pr, OBu, O iso-Bu, O iso-Amyl, OBenzyl, OAllyl, Ofurfuryl. It is suggested that the reaction proceeds through an elimination-addition mechanism.

Full text of DOI:10.1080/10426500390228765

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Phosphorus, Sulfur, and Silicon and the Related
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Synthesis of Hindered Silyl Ethers via Fragmentation
Reactions
Mohammad G. Asadi a , Kazem D. Safa b & Zahr A. Shamsi b
a Azarbaijan University of Tarbiat Moallem , Tabriz, Iran
b Faculty of Chemistry , University of Tabriz , Iran
Published online: 23 Aug 2006.
To cite this article: Mohammad G. Asadi , Kazem D. Safa & Zahr A. Shamsi (2003) Synthesis of Hindered Silyl Ethers
via Fragmentation Reactions, Phosphorus, Sulfur, and Silicon and the Related Elements, 178:9, 2073-2079, DOI:
10.1080/10426500390228765
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Phosphorus, Sulfur, and Silicon, 178:2073–2079, 2003
ꢀC
Copyright Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500390228765
SYNTHESIS OF HINDERED SILYL ETHERS VIA
FRAGMENTATION REACTIONS
Mohammad G. Asadi,a Kazem D. Safa,b and Zahr A. Shamsib
Azarbaijan University of Tarbiat Moallem, Tabriz, Irana and
Faculty of Chemistry, University of Tabriz, Iranb
(Received February 3, 2003; in final form April 1, 2003)
Reaction of alcoholic sodium alkoxides with (Me3Si)3CSi(C6H4-
OMe-p)MeX have been performed. Main products are of the type:
(Me3Si)2CHSi(An)Me(OR) and Me3SiCH2Si(An)Me(OR); An = (C6H4-
OMe-p) and OR = OEt, OPr,O iso-Pr, OBu, O iso-Bu,O iso-Amyl, OBen-
zyl, OAllyl, Ofurfuryl. It is suggested that the reaction proceeds through
an elimination-addition mechanism.
Keywords: Alkoxides; fragmentation; organosilicon
Because of the large bulk of the (Me3Si)3C group (the “trisyl” group,
often denoted below by Tsi), compounds of the type (Me3Si)3CSiRRꢁX
(e.g., X = halogen or H) undergo direct biomolecular nucleophilic
displacement of X only with difficulty, and this permits obser-
vations of other reactions not normally encountered.1−10 For ex-
ample, the halides (Me3Si)3CSi(C6H4OMe-p)MeX (X = F,Br,I) react
with nucleophilic species such as alkoxides in alcoholic solvents to
give, wholly or in part, fragmented products of the type (Me3Si)2
CHSi(C6H4OMe-p)Me(OR), (Me3Si) CH2Si(C6H4OMe-p)Me(OR), or hy-
drolyzed products.11,12
The iodide (Me3Si)3CSi(C6H4OMe-p)MeI reacts with a electrophilic
reagent such as silver triflouroacetate to give a rearranged product of
the type (Me3Si)2C(SiMe2I)(SiMe2COOCF3).
RESULT AND DISCUSSION
Our first observation was that all halides TsiSi(C6H4OMe-p)MeX
(X = halogen) undergo fragmentation reaction in refluxing sodium
We thank Dr. M. Mahkam for helpful comments.
Address correspondence to Mohammad G. Asadi, Chemistry Department, Faculty of
Science, Azarbaijan University of Tarbiat Moallem, Tabriz, Iran. E-mail: kazemdsafa@
yahoo.com
2073

2074
M. G. Asadi et al.
methoxide in methanol.11 In this work we used 1.5–2.5 M of alkoxide
solutions as reagents.
In an attempt to make TsiSi(C6H4OMe-p)MeF we prepared
Si(C6H4OMe-p)MeCl2 then reacted this with KHF2 salt to give
Si(C6H4OMe-p)MeF2 and then this compound was treated with TsiLi
to give TsiSi(C6H4OMe-p)MeF. The reduction of this compound with
LiAlH4 in THF did not give TsiSi(C6H4OMe-p)MeH. For this reason we
prepared MeSiH(C6H4OMe-p)Cl.
Also, we prepared TsiSi(C6H4OMe-p)MeI from the reaction of
TsiSi(C6H4OMe-p)MeH and ICl/CCl4 at room temperature and
TsiSi(C6H4OMe-p)MeBr from TsiSi(C6H4OMe-p)MeH with Br2/CCl4
at room temperature; the iodide and bromide derivatives were reacted
with alkoxide solutions.
In this way, we prepared (Me3Si)2CHSi(C6H4OMe-p)Me(OR) and
(Me3Si)CH2Si(C6H4OMe-p)Me(OR) compounds.
The mechanism of these reactions include two-steps: elimina-
tion and addition. In the first step with attack of alkoxide a
silaolefin forms and in the later step solvolysis takes place. When
the group of alkoxides is small the reaction of the iodide deriva-
tive is faster than the others, but when alkoxide was a large group
the reaction of the fluoride derivatives was faster than the other
halogens, because of the steric effect of alkoxide and the leaving
group.
In this way we prepared novel organosilicon compounds. These reac-
tions confirm the fragmentation mechanism. With increasing bulkiness
of the alkoxide groups, the reaction was difficult to perform. Also, we
used the new alkoxides that never were used later, and prepared frag-
mentation products of those alkoxides.
EXPERIMENTAL
Solvent and Reagents
The reactions involving lithium metal, organolithium reagents or
LiAlH4, and alkoxides were carried out under dry argon. Solvents were
dried by standard methods.
Spectra
Melting points were taken on an electromental 9100-digital melting
point apparatus. The 1HNMR spectra were recorded with 1HNMR
Bruker FT-500 MHZ and NMR (80 MHZ). The mass spectra were run
on a Shimadzu QP-100X spectrometer Finnigan, 70 ev.

Hindered Silyl Ethers
2075
TABLE I Reaction of TsiSi(C6H4-OMe-p)MeX
Alkoxide
solution
Product
Time (h) yield (%)
Substrate
TsiSiAnMe F
TsiSiAnMe F
TsiSiAnMe F
TsiSiAnMe F
TsiSiAnMe I
TsiSiAnMe I
TsiSiAnMe I
TsiSiAnMe I
TsiSiAnMe Br
EtONa/EtOH
7
12
28
8
52
20
22
51
30
10
16
36
20
nBuONa/nBuOH
iAmONa/iAmOH
CH2 CH CH2ONa/CH2 CH CH2OH
EtONa/EtOH
5
nBuONa/nBuOH
18
35
11
5
iAmONa/iAmOH
CH2 CH CH2Ona/CH2 CH CH2OH
EtONa/EtOH
Preparation of TsiSi(C6H4-OMe-p)MeF
(C6H4-OMe-p) SiMeCl2 (0.22 g, 0.1 mmol), KHF2 (16 g, 0.2 mmol), and
n-heptan (150 ml) were mixed at 70–80◦C for 1 h, then KF filtered and
the solution cooled to form the solid, which was recrystallized to give
(C6H4 OMe-p)SiMeF2 (70%). (C6H4 OMe-p) SiMeF2 (9.4 g, 59 mmol)
was added to a solution of TsiLi (50 mmol) in THF (100 ml) and the
mixture was refluxed for 3 h. The solution was treated with an aqueous
solution of NH4Cl, the organic layer was separated, dried (Na2 SO4),
and the solvent was removed. The pure product was obtained from
recrystalization in EtOH to give TsiSi(C6H4 OMe-p)MeF (70%), m.p.
109◦C FT-1HNMR (CDCl3) 0.25(s, 27H, Tsi), 0.39(s, 3H, SiMe), 3.82(s,
3H, OMe-aryl), 6.8–7.8 ppm (m, 4H, C H aryl), m/z (EI): 385(22%,
[M-Me]+), 293(18), 205(80), 201(100), 185(65). (Found: C, 53.5; H, 8.7.
C18H37Si4FO), (Mw = 400). (Calculated: C, 54; H, 9.2%).
Reaction of TsiSi(C6H4-OMe-p)MeF with NaOEt/EtOH
TsiSi (C6H4-OMe-p)MeF (0.5 g, 1.25 mmol) was refluxed in 2.5 M
NaOEt/EtOH solution (30 ml) for 7 h. The solution was added to
petroleum ether, the organic layer was washed several times with wa-
ter, the organic layer was separated, dried (Na2 SO4), filtered, and
the solvent evaporated and the residue was purified by TLC (silicagel,
60:40 dichloromethane: petroleum ether as eluent) to give the following
products:
i) (Me3Si)2 CHSiMe(An)OEt FT-1HNMR (CDCl3) 0.27(s, lH, CH),
−0.001(d, 18H, Me3Si), 0.48. (s, 3H, Si Me), 3.5(q, 2H, Si OCH2),
1.1(t, 3H, Si OCH2 CH3), 3.82(s, 3H, OMe-aryl), 6.8–7.5 ppm (m, 4H,
aryl). m/z (EI): 339(100%, [M-Me]+), 309(12), 294(4), 266(4), 281(1).

2076
M. G. Asadi et al.
(Found: C, 58; H, 9.7. C17H34Si3O2), (Mw = 354), (Calculated: C, 57.6;
H, 9.6%).
ii) Me3SiCH2SiMe(An)OEt FT-1HNMR (CDCl3) 0.2(s, 2H, CH2), 0.09(s,
9H, Me3Si), 0.4(s, 3H, Si Me), 3.5(q, 2H, Si OCH2), 1.1(t, 3H,
Si OCH2 CH3), 3.82(s, 3H, OMe-aryl), 6.89–7.5 ppm (m, 4H aryl-
H). m/z (EI): 282(6%, [M]+), 267(10%, [M-Me]+). (Found: C, 59.2; H,
8.9. C14H26Si2O2),(Mw = 282). (Calculated: C, 59.5; H, 9.2%).
Reaction of TsiSi(C6H4-OMe-p)MeF with NaOnPr/nPrOH
A solution of TsiSi(C6H4-OMe-p)MeF (0.3 g, 0.75 mmol) in 2.5 M
NaOnPr/nPrOH (40 ml) was refluxed for 15 h, then worked up with
a solution of water and petroleum ether. The organic layer was sepa-
rated, washed several times with water, dried (Na2 SO4), filtered, and
the filtrate evaporated. The resulting liquid product mixture was sub-
jected to preparative TLC (silicagel, 50:50 dichloromethane: petroleum
ether as eluent) to give Me3SiCH2SiMe(An)OnPr.
FT-1HNMR (CDCl3), 0.0089(s, 9H, Me3Si), 0.058(s, 2H, CH2), 0.4(s,
3H, Si Me), 0.87(t, 3H, CH3), 1.5(m, 2H, CH2), 3.5(t, 2H, O CH2),
3.82(s, 3H, OMe-aryl), 6.8–7.5 ppm (m, 4H arylC H) m/z (EI): 296(2%,
[M]+), 281(8%, [M-Me]+), 239(4), 209(6), 223(4), 131(100). (Found: C,
60.5; H, 9.2. C15H28Si2O2), (Mw = 296). (Calculated: C, 60.8; H, 9.4%).
Reaction of TsiSi(C6H4-OMe-p)MeF with NaOiPr/iPrOH
A solution of TsiSi(C6H4-OMe-p)MeF (0.3 g, 0.75 mmol) in 2.5 M
NaOnPr/nPrOH (50 ml) was refluxed for 15 h, then worked up with
a solution of water and petroleum ether. The organic layer was sepa-
rated, washed several times with water, dried (Na2 SO4), filtered, and
the filtrate evaporated. The resulting liquid product mixture was sub-
jected to preparative TLC (silicagel, 60:40 dichloromethane: petroleum
ether as eluent) to give the following products:
i) Me3SiCH2SiMe(An)OiPr FT-1HNMR (CDCl3), −0.0029(s, 9H,
Me3Si), 0.05–0.1(s, 2H, CH2), 0.4(s, 3H, Si Me), 1.0–1.1(d, 6H,
CH(CH3)2), 3.95(m, 1H, O CH ), 3.82(s, 3H, OMe-aryl), 6.9–7.5 ppm
(m, 4H arylC H). m/z (EI): 296(6%, [M]+), 281 (10%, [M-Me]+),
239(24), 223(1), 131(100). (Found: C, 61.1; H, 9.6. C15H28Si2O2),
(Mw = 296). (Calculated: C, 60.8; H, 9.4%).
ii) Me3SiCH2SiMe(An)OH FT-1HNMR (CDCl3), 0.034 (s, 9H, Me3Si),
0.09–0.2(s, 2H, CH2), 0.4(s, 3H, Si Me), 1.6(s, 1H, OH), 3.82(s,
3H, OMe-aryl), 6.9–7.5 ppm (m, 4H aryl C H). m/z (EI): 254(1%,
[M]+), 239(22%, [M-Me]+), 223(2), 167(34). (Found: C, 56.4; H, 8.3.
C12H22Si2O2), (Mw = 254). (Calculated: C, 56.7; H, 8.6%).

Hindered Silyl Ethers
2077
Reaction of TsiSi(C6H4-OMe-p )MeF with NaOnBu/n BuOH
A solution of TsiSi(C6H4-OMe-p)MeF (0.3 g, 0.75 mmol) in 2.5 M
NaOnBu/nBuOH (30 ml) was refluxed for 30 h, then worked up with
a solution of water and petroleum ether. The organic layer was sepa-
rated, washed several times with water, dried (Na2 SO4), filtered, and
the filtrate evaporated. The resulting liquid product mixture was sub-
jected to preparative TLC (silicagel, 60:40 dichloromethane: petroleum
ether as eluent) to give Me3SiCH2SiMe(An)OnBu.
FT-1HNMR (CDCl3), 0.01(s, 9H, Me3Si), −0.009(s, 2H, CH2), 0.4(s,
3H, Si Me), 0.9(t, 3H,CH3), 1.1(m, 2H, CH2), 1.3(m, 2H, CH2), 3.9(t,
2H, O CH2), 3.82(s, 3H, OMe-aryl), 6.9–7.5 ppm (m, 4H, C H aryl).
m/z (EI): 295(6%, [M-Me]+), 279(14), 278(20), 277(72), 205(48), 72(100).
(Found: C, 61.5; H, 9.4. C16H30Si2O2), (Mw = 310). (Calculated: C, 61.9;
H, 9.6%).
Reaction of TsiSi(C6H4-OMe-p )MeF with NaOiBu/iBuOH
TsiSi(C6H4-OMe-p)MeF (0.5 g, 1.25 mmol) was refluxed in 2.5 M
NaOiBu/iBuOH solution (30 ml) for 7 h. The solution was added to
petroleum ether, the organic layer was washed several times with
water, the organic layer was separated, dried (Na2 SO4), filtered,
the solvent evaporated and the residue was purified by TLC (sil-
icagel, 60:40 dichloromethane: petroleum ether as eluent) to give
Me3SiCH2SiMe(An)OiBu.
FT-1HNMR (CDCl3) −0.04(s, 9H, Me3Si), 0.04–0.09(s, 2H, Si CH2),
0.39(s, 3H, Si Me), 0.89(d, 6H,CH(CH3)2), 1.78(m, 1H, CH), 3.3(d, 2H,
O CH2), 3.84(s, 3H, OMe-aryl), 6.9–7.5 ppm (m, 4H, C H aryl). m/z
(EI): 310(4%, [M]+), 295(36%, [M-Me]+), 240(24), 239(98), 131(100).
(Found: C, 61; H, 9.4. C16H30Si2O2), (Mw = 310). (Calculated: C, 61.9;
H, 9.6%).
Reaction of TsiSi(C6H4-OMe-p )MeF
with NaOiAm/iAmOH
A solution of TsiSi(C6H4-OMe-p)MeF (0.2 g, 0.5 mmol) in 2.5 M
NaOiAm/iAmOH (30 ml) was refluxed for 48 h, then worked up with
a solution of water and petroleum ether. The organic layer was sepa-
rated, washed several times with water, dried (Na2 SO4), filtered, and
the filtrate evaporated. The resulting liquid product mixture was sub-
jected to preparative TLC (silicagel, 1:1 dichloromethane: cyclohexane
as eluent) to give Me3SiCH2SiMe(An) OiAm.
FT-1HNMR (CDCl3) −0.05(s, 9H, Me3Si), 0.09(s, 2H, Si CH2), 0.37(s,
3H, Si Me), 0.85(d, 6H,CH(CH3)2), 1.4–1.5 (m, 2H, CH2), 0.9(m, 1H,

2078
M. G. Asadi et al.
CH), 3.54(t, 2H, O CH2), 3.8(s, 3H, OMe-aryl), 6.8–7.4 ppm (m, 4H,
C H aryl). m/z (EI): 309(6%, [M-Me]+), 239(8), 237(4), 207(4), 147(18),
131(100). (Found: C, 62.7; H, 9.6. C17H32Si2O2),(Mw = 324). (Calcu-
lated: C, 62.9; H, 9.8%).
Reaction of TsiSi(C6H4-OMe-p)MeF with
CH2CH CH2ONa/CH2-CHCH2OH
TsiSi(C6H4-OMe-p)MeF (0.37 mmol) was refluxed in 2 M CH2CH
CH2ONa/CH2 CHCH2OH solution (30 ml) for 8 h. The solution was
added to petroleum ether, the organic layer was washed several times
with water, the organic layer was separated, dried (Na2 SO4), filtered,
the solvent evaporated, and the residue was purified by TLC (silicagel,
60:40 dichloromethane: petroleum ether as eluent) to give the following
products:
i) (Me3Si)2CHSiMe(An)OCH2CH CH2 FT-1HNMR (CDCl3) −0.2(s,
1H, CH), −0.04–0.1 (d, 18H, Me3Si), 0.48(s, 3H, Si Me), 3.9(d,
2H, OCH2), 4.9–5.2 (m, 2H, CH2), 5.8(m, 1H, CH), 3.82(s, 3H,
OMe-aryl), 6.9–7.4 ppm (m, 4H, aryl). m/z (EI): 351(12%, [M-Me]+),
309(1), 236(2), 221(2), 203(100). (Found: C, 59.3; H, 9.2. C18H34O2),
(Mw = 366). (Calculated: C, 59; H, 9.3%)
ii) Me3SiCH2SiMe(An)OCH2CH CH2 FT-1HNMR (CDCl3) 0.095(s,
2H, CH2), −0.04(s, 9H, Me3Si), 0.39(s, 3H, Si Me), 4.1(d, 2H, OCH2),
5.1–5.3 (m, 2H, CH2), 5.9(m, 1H, CH), 3.82(s, 3H, OMe-aryl), 6.9–
7.4 ppm (m, 4H, aryl). m/z (EI): 294(4%,[M]+), 279(8%,[M-Me]+),
239(24), 207(10), 131(100). (Found: C, 61.6; H,8.6. C15H26Si2O2),
(Mw = 294). (Calculated: C, 61.2; H, 8.8%).
Reaction of TsiSi(C6H4-OMe-p)MeF with
NaOCH2Ph/PhCH2OH
A solution of TsiSi(C6H4-OMe-p)MeF (0.5 g, 1.25 mmol) in 2.5 M
NaOCH2Ph/PhCH2OH (30 ml) was refluxed for 75 h, then worked up
with a solution of water and petroleum ether. The organic layer was sep-
arated, washed several times with water, dried (Na2 SO4), filtered, and
the filtrate evaporated. The resulting liquid product mixture was sub-
jected to preparative TLC (silicagel, 1:1 dichloromethane: cyclohexane
as eluent) to give Me3Si CH2SiMe(An)OCH2Ph.
FT-1HNMR (CDCl3), −0.01(s, 9H, Me3Si), 0.01–0.2 (s, 2H, Si CH2),
0.4(s, 3H, Si Me), 3.85(s, 3H, OMe-aryl), 4.6(s, 2H, OCH2), 6.9–7.5 ppm
(m, 9H, C H aryl). m/z (EI): 344(1%, [M]+), 329(0.5%, [M-Me]+), 336(6),
257(0.5), 131(68), 91(100). (Found: C, 66.3;H, 8.1.C19H28Si2O2), (Mw
344). (Calculated: C, 66.2; H, 8.1%).
=

Hindered Silyl Ethers
2079
Reaction of TsiSi(C6H4-OMe-p)MeF with Furfuryloxy
Sodium, Furfuryalcohol
TsiSi(C6H4-OMe-p)MeF (0.25 mmol) was refluxed in 1.5 M furfuryloxy
sodium, furfurylalcohol solution (25 ml) for 7 h. The solution was added
to petroleum ether, the organic layer was washed several times with wa-
ter, the organic layer was separated, dried (Na2 SO4), filtered, the sol-
vent evaporated, and the residue was purified by TLC (silicagel, 60:40
dichloromethane: petroleum ether as eluent) to give Anisolemethylfur-
furyloxymethyltrimethylsilylsilane.
FT-1HNMR (CDCl3) −0.03(s, 9H, Me3Si), 0.04–0.2 (s, 2H, CH2),
0.42(s, 3H, Si Me), 3.85(s, 3H, OMe-aryl), 4.6 ppm (s, 2H, OCH2), 6.3(m,
1-αH, Furfuryl alcohol), 6.9–7.5 (m, 4H, aryl), 7.4(m, 2 − βH, Furfuryl
alcohol). m/z (EI): 332(4%, [M-2H]+), 261(4), 247(1), 237(12), 222(6),
165(100). (Found: C, 60.8; H, 7.5. C17H26Si2O3), (Mw = 334). (Calcu-
lated: C, 61.1; H, 7.7%).
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