Montmorillonite K10 clay-catalyzed synthesis of homoallylic silyl ethers: an efficient and environmentally friendly Hosomi-Sakurai reaction

Article abstract of DOI:10.1016/j.tetlet.2009.09.051

Aromatic aldehydes react with allyltrimethylsilane in the presence of activated Montmorillonite K10 clay to give homoallylic silyl ethers in good to excellent yields.

Full text of DOI:10.1016/j.tetlet.2009.09.051

Tetrahedron Letters 50 (2009) 6639–6641
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Tetrahedron Letters
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Montmorillonite K10 clay-catalyzed synthesis of homoallylic silyl ethers: an
efficient and environmentally friendly Hosomi–Sakurai reaction
*
Matthew R. Dintzner , Yawo A. Mondjinou, Barrett Unger
Department of Chemistry, DePaul University, 1110 West Belden Ave., Chicago, IL 60614, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Aromatic aldehydes react with allyltrimethylsilane in the presence of activated Montmorillonite K10 clay
to give homoallylic silyl ethers in good to excellent yields.
Received 22 August 2009
Revised 8 September 2009
Accepted 9 September 2009
Available online 19 September 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Montmorillonite K10 clay
Hosomi–Sakurai reaction
Allyltrimethylsilane
Aromatic aldehydes
Homoallylic silyl ethers
Green chemistry
The Hosomi–Sakurai1 reaction of allylsilanes with aldehydes is
among the most widely utilized carbon–carbon bond-forming
reactions in natural products synthesis.2 The resulting homoallylic
alcohol products are useful platforms for further synthetic elabora-
tion, especially in the event that the allylation reaction proceeds
stereoselectively.3 Although powerful Lewis acids, such as SnCl4,
TiCl4, BF3ÁOEt2, AlCl3, and Sc(OTf)3, have been shown to success-
fully catalyze the Hosomi–Sakurai reaction, the negative impact
of these reagents on the environment has urged the development
of alternative, greener methodologies for effecting this and related
synthetic transformations.4 We have developed a number of appli-
cations for naturally benign Montmorillonite clay, all of which in-
volve the catalysis of carbon–carbon bond-forming reactions.5 In
the course of these ongoing investigations, we have observed that
activated Montmorillonite K10 clay is an extremely efficient cata-
lyst for the addition of allyltrimethylsilane to electron-deficient
benzaldehydes (1) to give homoallylic silyl ethers (2) in good to
excellent yields (Fig. 1).6 In the best-case scenarios, the reaction
proceeds rapidly at room temperature or below in the presence
of minimal solvent, and in quantitative yield with near perfect
atom economy.
interlayer structure and marked increase in its Lewis acidity, as
water is extruded.7 We set out to investigate the clay-catalyzed
addition of allyltrimethylsilane to aromatic aldehydes and ob-
served that the treatment of 3-nitrobenzaldehyde with allyltri-
methylsilane in the presence of activated Montmorilonite K10
(neat) led to a highly exothermic reaction.6 Extraction of the prod-
uct mixture with dichloromethane and analysis by 1H NMR and
GC–MS showed evidence of the desired homoallylic silyl ether
product, along with some unreacted starting materials and a mix-
ture of other unidentified products. We proceeded to effect better
control of the reaction by taking up a mixture of the clay and alde-
hyde in a minimal amount of dichloromethane and cooling the
mixture to 0 °C prior to careful addition of the allyltrimethylsilane.
The reaction mixture was stirred at 0 °C for 5 min, and then al-
lowed to warm to ambient temperature over the course of 1 h. Fil-
tration of the reaction solution and concentration under vacuum
gave a near quantitative yield of the desired product, with no fur-
ther purification necessary. Next, we assayed a variety of aromatic
aldehydes and observed similar results with other electron-deficient
Previous work in our laboratories has shown that Montmoril-
lonite K10 clay is effective in activating aromatic aldehydes toward
nucleophilic attack, particularly when the clay is first activated by
heating (200 °C, 1 h).5 Heating results in the collapse of the clay’s
O
OSi(CH3)3
Si(CH3)3
H
R
R
Montmorillonite-K10
CH2Cl2
2
1
0-23 ºC
* Corresponding author. Tel.: +1 773 325 4726; fax: +1 773 325 7421.
E-mail address: mdintzne@depaul.edu (M.R. Dintzner).
Figure 1. Clay-catalyzed Hosomi–Sakurai reaction.
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.09.051

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M. R. Dintzner et al. / Tetrahedron Letters 50 (2009) 6639–6641
Table 1
Results with aromatic aldehydes
Entry
Aldehyde
Product
Yielda (%)
1
2
3
4
5
6
7
8
9
2-Nitrobenzaldehyde (1a)
3-Nitrobenzaldehyde (1b)
4-Nitrobenzaldehyde (1c)
3-Fluorobenzaldehyde (1d)
4-Chlorobenzaldehyde (1e)
2,6-Dichlorobenzaldehyde (1f)
3-Cyanobenzaldehyde (1g)
Benzaldehyde (1h)
2a
2b
2c
2d
2e
2f
2g
2h
2i
84
99
99
97
99
99
99
75b
0c
4-Anisaldehyde (1i)
10
2-Anisaldehydec (1j)
2j
70b
Figure 2. Suggested mechanism for the clay-catalyzed Hosomi–Sakurai reaction.
a
b
c
Isolated yield.
GC yield.
Based on recovered starting materials.
In summary, we have found that activated Montmorillonite K10
clay efficiently catalyzes the addition of allyltrimethylsilane to
electron-deficient aromatic aldehydes as well as some aliphatic
aldehydes and ketones at room temperature or below in dichloro-
methane to give homoallylic silyl ethers in good to excellent yields.
This methodology constitutes a milder, environmentally friendlier,
and more cost effective alternative to the use of transition metal
halides or oxides for the catalysis of the Hosomi–Sakurai reaction.
A typical procedure for the clay-catalyzed Hosomi–Sakurai
reaction follows: Montmorillonite K10 clay (200 mg) was added
to a glass scintillation vial and heated in an oven at 200 °C for
1 h. The clay was cooled to ambient temperature in a desiccator,
and then treated with 3-nitrobenzaldehyde (200 mg, 1.32 mmol)
and 2 mL dichloromethane. The mixture was cooled to 0 °C in an
ice water bath and stirred gently with a magnetic stir bar. To the
cooled mixture was added allyltrimethylsilane (1.98 mmol) and
the resulting mixture was stirred at 0 °C for 5 min. The ice water
bath was removed and the reaction mixture was allowed to warm
to ambient temperature over the course of 1 h. The reaction mix-
ture was vacuum filtered, washed with an additional 1 mL of
dichloromethane, and concentrated under vacuum to give the de-
sired product (2b) as a pale yellow oil (345 mg, 99%).9
compounds (Table 1, entries 1–8). No reaction was observed with the
more electron-rich 4-anisaldehyde, presumably due to its decreased
electrophilicity. The reaction with 2-anisaldehyde, however, pro-
ceeded to some extent but did not go to completion. As we reported
in a previous study, apparentlyfavorable chelation of theclay’s metal
ions with the oxygen atoms of 2-anisaldehyde may compensate for
its diminished electrophilicity.5a
Control experiments with 3-nitrobenzaldehyde showed that
varying the amount of clay, from 100% to 25% by mass relative to
the mass of the aldehyde, had minimal effect on the yield of the
product. However, no reaction between 3-nitrobenzaldehyde and
allyl trimethylsilane was observed in the absence of clay or in
the presence of unactivated clay.
Although the reaction proceeded fairly with some aliphatic
aldehydes (Table 2, entries 1–4), it was neither as clean nor as high
yielding as with the aromatic systems, presumably due to compet-
itive cyclotrimerization.5a No reaction was observed with
a,b-
unsaturated aldehydes (Table 2, entries 5–7). While treatment of
some aliphatic ketones (Table 2, entries 8 and 9) with allyltrimeth-
ylsilane in the presence of activated K10 gave good yields of the
corresponding 3° homoallylic silyl ethers, no reaction was ob-
served with cyclopentanone or with aromatic ketones (Table 2, en-
tries 10–12).
Acknowledgments
In contrast to the computational and experimental evidence re-
ported for the mechanism of the homogeneous Lewis acid-cata-
We thank DePaul University’s College of Liberal Arts & Science
for funding, and the National Science Foundation CCLI A&I program
(Grant No. DUE-0310624) for support in purchasing our Bruker
Avance 300 MHz NMR spectrometer.
lyzed Hosomi–Sakurai reaction, our results suggest
a closed
transition state model, concerted mechanism for the clay-medi-
ated process (Fig. 2).8 Thus, not only does the reaction generate a
new C–C bond, but it also has the advantage of providing the prod-
ucts in their protected form, as the trimethylsilyl ethers. Deprotec-
tion, if desired, can be effected quantitatively by adding a slight
excess of methanol to the reaction mixture and stirring for
20 min prior to filtering.
References and notes
1. (a) Hosomi, A.; Sakurai, H. Tetrahedron Lett. 1976, 16, 1295; (b) Denmark, S. E.;
Almstead, N. G. In Modern Carbonyl Chemistry; Otera, J., Ed.; Wiley-VCH:
Weinheim, Germany, 2000; p 403. Chapter 11.
2. For selected examples of the Hosomi–Sakurai reaction used in natural products
synthesis, see: (a) Troast, D. M.; Yuan, J.; Porco, J. A., Jr. Adv. Synth. Catal. 2008,
350, 1701; (b) Spangenber, T.; Airiau, E.; Thuong, M. B. T.; Donnard, M.; Billet,
M.; Mann, A. Synlett 2008, 18, 2859; (c) Kalidindi, S.; Jeong, W. B.; Schall, A.;
Bandichhor, R.; Nosse, B.; Reiser, O. Natl. Prod. 2007, 46, 6361; (d) Pospisil, J.;
Marko, I. E. J. Am. Chem. Soc. 2007, 129, 3516; (e) van Innis, L.; Plancher, J. M.;
Marko, I. E. Org. Lett. 2006, 8, 6111; (f) Crimmins, M. T.; Zuccarello, J. L.; Cleary, P.
A.; Parrish, J. D. Org. Lett. 2005, 8, 159; (g) Wender, P. A.; Hegde, S. G.; Hubbard,
R. D.; Zhang, L. J. Am. Chem. Soc. 2002, 124, 4956; (h) Williams, D. R.; Myers, B. J.;
Mi, L. Org. Lett. 2000, 7, 945; (i) Bonjoch, J.; Cuesta, J.; Diaz, S.; Gonzalez, A.
Tetrahedron Lett. 2000, 41, 5669; (j) Davis, C. E.; Duffy, B. C.; Coates, R. M. Org.
Lett. 2000, 2, 2717; (k) Marko, I. E.; Mekhalfia, A.; Murphy, F.; Bayston, D.; Bailey,
M.; Janousek, Z.; Dolan, S. Pure Appl. Chem. 1997, 69, 565.
3. (a) Judd, W. R.; Ban, S.; Aube, J. J. Am. Chem. Soc. 2006, 128, 13736; (b) Pospisil, J.;
Kumamoto, T.; Marko, I. E. Angew. Chem., Int. Ed. 2006, 45, 3357; (c) Wadamoto,
M.; Yamamoto, H. J. Am. Chem. Soc. 2005, 127, 14556; (e) Bonini, B. F.; Comes-
Franchini, M.; Fochi, M.; Mazzanti, G.; Ricci, A.; Varchi, G. Tetrahedron:
Asymmetry 1998, 9, 2979; (f) Shing, T. K. M.; Li, L.-H. J. Org Chem. 1997, 62,
1230; (g) Matsumoto, K.; Oshima, K.; Utimoto, K. J. Org. Chem. 1994, 59, 7152;
(h) Hayashi, T.; Kabeta, K.; Hamachi, I.; Kumada, M. Tetrahedron Lett. 1983, 24,
2865.
Table 2
Results with aliphatic and
a,b-unsaturated aldehydes, and ketones
Entry
Carbonyl compound
Yielda (%)
1
2
3
4
5
6
7
8
9
Propionaldehyde
Butyraldehyde
16
47
61
25
0b
0b
0b
70
90
0b
0b
0b
Isobutyraldehyde
Cyclohexancarboxaldehyde
3-Methyl-2-butenal
Crotonaldehyde
trans-Cinnamaldehyde
Acetone
2-Butanone
Cyclopentanone
Acetophenone
10
11
12
Benzophenone
a
GC yield.
b
Based on recovered starting material.

M. R. Dintzner et al. / Tetrahedron Letters 50 (2009) 6639–6641
6641
4. (a) Kawabata, T.; Kato, M.; Mizugaki, T.; Ebitani, K.; Kaneda, K. Chem. Eur. J. 2005,
11, 288; (b) Jin, Y. Z.; Yasuda, N.; Furuno, H.; Inanaga, J. Tetrahedron Lett. 2003,
44, 8765; (c) Sasidharan, M.; Tatsumi, T. Chem. Lett. 2003, 32, 624.
147.12, 133.96, 131.99, 129.06, 122.12, 120.89, 117.88, 73.75, 44.88, 0.05; GC–
MS (70 eV), tR = 18.158 min, m/z 265 (<1%); 250 [MÀ15]+ (2%); 224 [MÀ41]+
(50%); 73 [MÀ192]+ (100%). 1-Nitro-4-[1-[(trimethylsilyl)oxy]-3-buten-1-yl]benzene
(2c): IR (CDCl3) 3079, 2958, 2903, 1641, 1607, 1522, 1492, 1432, 1416, 1350,
5. (a) Dintzner, M. R.; Little, A. J.; Pacilli, M.; Pileggi, D.; Osner, Z. R.; Lyons, T. W.
Tetrahedron Lett. 2007, 48, 1577; (b) Dintzner, M. R.; Wucka, P.; Lyons, T. W. J.
Chem. Educ. 2006, 83, 270; (c) Dintzner, M. R.; Lyons, T. W.; Akroush, M. H.;
Wucka, P.; Rzepka, A. T. Synlett 2005, 5, 785; (d) Dintzner, M. R.; McClelland, K.
M.; Morse, K. M.; Akroush, M. H. Synlett 2004, 11, 2028; (e) Dintzner, M. R.;
Morse, K. M.; McClelland, K. M.; Coligado, D. M. Tetrahedron Lett. 2004, 45, 79.
6. Dintzner, M. R.; Pacilli, M.; Pileggi, D. J.; Zuziak, M. M. From Abstracts of Papers,
235th National Meeting of the American Chemical Society, New Orleans, LA;
American Chemical Society: Washington, DC, 2008; CHED 551.
1316, 1292, 1253 cmÀ1 1H NMR (300 MHz, CDCl3) d 8.19 (d, J = 8.29 Hz, 2H),
;
7.49 (d, J = 8.29 Hz, 2H), 5.74 (m, 1H), 5.03 (m, 2H), 4.80 (dd, J = 5.65, 6.78 Hz,
1H)2.45 (m, 2H), 0.08 (s, 9H); 13C NMR (75 MHz, CDCl3) d 152.37, 147.06,
133.93, 126.63, 123.43, 117.85, 73.85, 44.79, 0.02; GC–MS (70 eV),
tR = 20.424 min, m/z 265 M+ (<1%); 224 [MÀ41]+ (70%); 73 [MÀ192]+ (100%).
1-Fluoro-3-[1-[(trimethylsilyl)oxy]-3-buten-1-yl]benzene (2d): IR (CDCl3) 3078,
2957, 2903, 1704, 1642, 1616, 1593, 1489, 1450, 1359, 1252 cmÀ1 1H NMR
;
(300 MHz, CDCl3) d 7.30 (m, 1H), 7.10 (m, 2H), 6.95 (m, 1H), 5.80 (m, 1H), 5.06
(m, 2H), 4.72 (dd, J = 5.46, 7.16 Hz, 1H), 2.48 (m, 2H), 0.11 (s, 9H); 13C NMR
(75 MHz, CDCl3) d 147.73, 146.57, 134.77, 130.20, 121.4, 118.94, 113.97, 112.61,
72.56, 43.82, 0.06; GC–MS (70 eV), tR = 8.711 min, m/z 238 M+ (<1%); 223
[MÀ15]+ (5%); 197 [MÀ41]+ (100%); 73 [MÀ165]+ (95%). 1-Chloro-4-[1-
[(trimethylsilyl)oxy]-3-buten-1-yl]benzene (2e): IR (CDCl3) 3078, 2958, 2903,
7. Yahiaoui, A.; Belbachir, M.; Hachemaoui, A. Int. J. Mol. Sci. 2003, 4, 458.
8. Bottoni, A.; Costa, A. L.; Di Tommaso, D.; Rossi, I.; Tagliavini, E. J. Am. Chem. Soc.
1997, 119, 12131.
9. Analytical data for compounds 2a–g: Proton nuclear magnetic resonance (1H)
spectra and carbon-13
(
13C) spectra were recorded at 400 and 100 MHz,
respectively. The proton signal of residual, non-deuterated solvent (d 7.26 ppm
for CHCl3) was used as an internal reference for 1H spectra. For 13C spectra,
chemical shifts are reported relative to the d 77.23 ppm resonance of CDCl3.
Coupling constants are reported in Hz. Infrared spectra were recorded as thin
films on a Nicolet Avatar 360. Gas chromatographic analysis was performed on a
Hewlett–Packard 5890 Series II gas chromatograph with a 5971 Series mass
selective detector. 1-Nitro-2-[1-[(trimethylsilyl)oxy]-3-buten-1-yl]benzene (2a):
IR (CDCl3) 3077, 2958, 1701, 1641, 1610, 1577, 1527, 1445, 1346, 1298.
1641, 1598, 1491, 1432, 1409, 1360, 1295, 1262, 1252 cmÀ1 1H NMR (300 MHz,
;
CDCl3) d 7.30 (m, 4H), 5.77 (m, 1H), 5.05 (m, 2H), 4.68 (dd, J = 5.46, 7.35 Hz, 1H),
2.43 (m, 2H), 0.07 (s, 9H); 13C NMR (75 MHz, CDCl3) d 143.41, 134.77, 132.62,
128.06, 127.28, 117.20, 74.17, 45.04, 0.10; GC–MS (70 eV), tR = 11.263 min, m/z
254/256 M+/M+2 (<1%); 213/215 [MÀ41]+ (98%); 73 [MÀ181]+ (100%). 1,3-
Dichloro-2-[1-[(trimethylsilyl)oxy]-3-buten-1-yl]benzene (2f): IR (CDCl3) 3078,
2958, 1642, 1581, 1562, 1437, 1251 cmÀ1 1H NMR (300 MHz, CDCl3) d 7.29
;
(m, 2H), 7.11 (m, 1H), 5.81 (m, 1H), 5.50 (m, 1H), 5.05 (dd, J = 6.40, 8.10 Hz, 1H),
2.86 (m, 1H), 2.68 (m, 1H), 0.04 (s, 9H); 13C NMR (75 MHz, CDCl3) d 137.92,
134.73, 129.38, 128.93, 128.60, 117.16, 71.45, 40.00, 0.12; GC–MS (70 eV),
tR = 13.209 min, m/z 288/290/292 M+/M+2/M+4 (<1%); 247/249/251 [MÀ41]+
(93%); 73 [MÀ215]+ (100%). 3-[1-[(Trimethylsilyl)oxy]-3-buten-1-yl]benzonitrile
(2g): IR (CDCl3) 3078, 2958, 2902, 2230, 1641, 1602, 1584, 1482, 1434, 1359,
1252 cmÀ1 1H NMR (300 MHz, CDCl3) d 7.89 (m, 2H), 7.63 (m, 1H), 7.40 (m, 1H),
;
5.86 (m, 1H), 5.38 (dd, J = 4.05, 7.63 Hz), 5.07 (m, 2H), 2.52, (m, 1H), 2.41 (m,
1H), 0.05 (s, 9H); 13C NMR (75 MHz, CDCl3) d 147.17, 140.64, 139.31, 134.46,
133.12, 128.63, 127.72, 123.98, 117.59, 69.63, 44.24, 0.27; GC–MS (70 eV),
tR = 11.843 min, m/z 265 M+ (<1%); 224 [MÀ41]+ (60%); 73 [MÀ192]+ (100%). 1-
Nitro-3-[1-[(trimethylsilyl)oxy]-3-buten-1-yl]benzene (2b): IR (CDCl3) 3077, 2958,
1285, 1252 cmÀ1 1H NMR (300 MHz, CDCl3) d 7.62 (m, 1H), 7.53 (m, 2H), 7.42
;
2902, 1641, 1432, 1479, 1437, 1351, 1310, 1252 cmÀ1
;
1H NMR (300 MHz,
(m, 1H), 5.73 (m, 1H), 5.01 (m, 2H), 4.72 (dd, J = 5.65, 6.78 Hz, 1H), 2.41 (m, 2H),
0.06 (s, 9H); 13C NMR (75 MHz, CDCl3) d 146.41, 134.01, 130.76, 130.33, 129.55,
119.00, 117.79, 112.16, 73.73, 44.89, 0.04; GC–MS (70 eV), tR = 14.267, m/z 245
M+ (<1%); 230 [MÀ15]+ (10%); 204 [MÀ41]+ (98%); 73 [MÀ172]+ (100%).
CDCl3) d 8.19 (s, 1H), 8.10 (ddd, J = 1.13, 2.26, 8.1 Hz, 1H), 7.66 (d, J = 7.72 Hz,
1H), 7.49 (t, J = 7.91 Hz, 1H), 5.75 (m, 1H), 5.02 (m, 2H), 4.81 (dd, J = 5.56,
6.88 Hz, 1H), 2.45 (m, 2H), 0.07 (s, 9H); 13C NMR (75 MHz, CDCl3) d 148.21,