Direct chlorination of alcohols with chlorodimethylsilane catalyzed by a gallium trichloride/tartrate system under neutral conditions

Article abstract of DOI:10.1039/b804589e

The reaction of secondary alcohols 1 with chlorodimethylsilane (HSiMe ₂Cl) proceeded in the presence of a catalytic amount of GaCl ₃/diethyl tartrate to give the corresponding organic chlorides 3. In the catalytic cycle, the reaction of diethyl tartrate 4a with HSiMe ₂Cl 2 gives the chlorosilyl ether 5 with generation of H₂. Alcohol-exchange between the formed chlorosilyl ether 5 and the substrate alcohol 1 affords alkoxychlorosilane 6, which reacts with catalytic GaCl ₃ to give the chlorinated product 3. The moderate Lewis acidity of GaCl₃ facilitates chlorination. Strong Lewis acids did not give product due to excessive affinity for the oxy-functionalities. Although tertiary alcohols were chlorinated by this system even in the absence of diethyl tartrate, certain alcohols that are less likely to give carbocationic species were effectively chlorinated using the GaCl₃/diethyl tartrate system. The Royal Society of Chemistry.

Full text of DOI:10.1039/b804589e

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Direct chlorination of alcohols with chlorodimethylsilane catalyzed by a
gallium trichloride/tartrate system under neutral conditions†
Makoto Yasuda, Kenji Shimizu, Satoshi Yamasaki and Akio Baba*
Received 17th March 2008, Accepted 18th April 2008
First published as an Advance Article on the web 28th May 2008
DOI: 10.1039/b804589e
The reaction of secondary alcohols 1 with chlorodimethylsilane (HSiMe2Cl) proceeded in the presence
of a catalytic amount of GaCl3/diethyl tartrate to give the corresponding organic chlorides 3. In the
catalytic cycle, the reaction of diethyl tartrate 4a with HSiMe2Cl 2 gives the chlorosilyl ether 5 with
generation of H2. Alcohol-exchange between the formed chlorosilyl ether 5 and the substrate alcohol 1
affords alkoxychlorosilane 6, which reacts with catalytic GaCl3 to give the chlorinated product 3. The
moderate Lewis acidity of GaCl3 facilitates chlorination. Strong Lewis acids did not give product due to
excessive affinity for the oxy-functionalities. Although tertiary alcohols were chlorinated by this system
even in the absence of diethyl tartrate, certain alcohols that are less likely to give carbocationic species
were effectively chlorinated using the GaCl3/diethyl tartrate system.
over HCl when reacted with chlorohydrosilane would give a route
Introduction
to chlorosilyl ether C, followed by alcohol-exchange to give the
chloride E via B. Moreover, RꢀOH should not give the chloride,
Chlorination of alcohols is an important process in organic
RꢀCl, under these conditions. In this paper, we report GaCl3-
catalyzed direct chlorination of alcohols with chlorohydrosilane
using tartrate as a dummy alcohol.
transformation. There are numerous chlorination systems, but
most of them are employed under acidic conditions.1 Therefore,
substrate selection is severely limited and development of chlori-
nation systems that operate under neutral conditions is required.
Recently, we reported a neutral system for chlorination of alcohols
using dimethylchlorosilane (HSiMe2Cl) and an InCl3 catalyst.2
However, this system requires an equimolar amount of benzil to
avoid background reduction of the alcohol.3 To the best of our
knowledge, a completely catalytic system for direct chlorination
of a wide range of alcohol substrates under neutral conditions has
never been realized.
Chlorohydrosilane (HSiR2Cl) has interesting structural fea-
tures. In particular, the silicon center has two reactive sites –
hydrogen and chlorine – either of which can be utilized for or-
ganic transformations. Both chlorosilane (R3SiCl) and hydrosilane
(R3SiH) react with alcohols to give silyl ethers in the presence of
either promoters or catalysts.4,5 Both chlorohydrosilane (HSiR2Cl)
sites react with diols to give cyclic silanes.6 The selective reaction
of HSiR2Cl at only the Si–H site prior to reaction with the Si–
Cl site is a difficult problem. The reaction of chlorohydrosilanes
(HSiR2Cl) with alcohols is effectively catalyzed by InCl3to give a
reduced product (alkane) D through hydrosilyl ether A with release
of HCl. In this reaction, Si–Cl reacts prior to reaction with Si–H.3
During chlorination, formation of chlorosilyl ether B necessitates
H2 release, although this phenomenon is rarely observed. Thus,
we were motivated to develop a new, effective catalytic system that
yields B. A dummy alcohol (RꢀOH) that favors production of H2
Results and discussion
Optimization of catalytic chlorination of alcohol
Table 1 summarizes optimization of the catalyst system for
the reaction of 4-phenyl-2-butanol 1a with chlorodimethylsilane
(HSiMe2Cl) 2. After testing many alcohols, diethyl tartrate was
found to be effective in the synthesis of the chlorinated product.
As shown in entry 2, combined use of 10 mol% of diethyl tartrate
4a and 5 mol% of GaCl3 effectively catalyzed the reaction to
give the corresponding chloride 3a.7 As the reaction progressed,
generation of H2 gas was observed. Exclusive use of GaCl3 or
tartrate 4a did not yield the product (entries 1 and 8). GaBr3,
GaI3, or Ga(OTf)3 showed low product yields (entries 4–6). InCl3
also acted as a catalyst, giving 3a, but in lower yield (entry 7). The
amount of 4a, an RꢀOH, was important as loading of 50 mol%
of 4a gave a low yield (entry 3). Other metal halides, such as
AlCl3, ZnCl2, TiCl4, or BiCl3, were examined, but did not yield the
product (entries 9–12). An a-hydroxyl carbonyl unit in the alcohol
(RꢀOH) is indispensable. Both hydroxyl ester 4b and ketone 4c
gave the product when the GaCl3 catalyst was used, although the
yields were low (entries 13 and 14). Neither benzoin ethyl ether 4d
(containing a protected hydroxy carbonyl group) nor the diol 4e
showed catalytic activity.
Department of Applied Chemistry and Center for Atomic and Molecu-
lar Technologies, Graduate School of Engineering, Osaka University, 2-
1 Yamadaoka, Suita, Osaka, 565-0871, Japan. E-mail: yasuda@chem.
eng.osaka-u.ac.jp; Fax: +81 6-6879-7387; Tel: +81 6-6879-7386
† Electronic supplementary information (ESI) available: Experimental
procedures. See DOI: 10.1039/b804589e
Chlorination of secondary alcohols catalyzed by the
GaCl3/tartrate system
Next, we explored the generality of the GaCl3/tartrate-catalyzed
reaction with chlorodimethylsilane by testing different alcohols
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Table 1 Optimization of the catalyst system for chlorination of alcohol
1a
Catalyst system
Entry
RꢀOH (10 mol%)
Metal halide (5 mol%)
Yield (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
None
4a
4a (50 mol%)
GaCl3
GaCl3
GaCl3
GaBr3
GaI3
Ga(OTf)3
InCl3
None
AlCl3
ZnCl2
TiCl4
0
75
19
35
15
4
28
0
0
0
0
0
19
65
0
4a
4a
4a
4a
4a
4a
4a
4a
4a
4b
4c
4d
4e
Scheme 1 Catalytic chlorination mediated by a dummy alcohol (RꢀOH).
BiCl3
GaCl3
GaCl3
GaCl3
GaCl3
0
(Table 2). Various secondary alcohols were effectively converted
to the corresponding chlorides, while primary alcohols did not
yield the product.8 The reaction of 2-octanol 1b afforded the 2-
chlorooctane 3b in moderate yield with some unidentified rear-
ranged chlorides (entry 2). The elemental analysis of the mixture
of the products showed good agreement with chlorooctane. The
ratio of 3b to byproducts is almost 1 : 0.6 by NMR. This result
suggests that our system includes cationic mechanism that often
gives rearranged isomers. Cyclohexanol 1c exclusively gave the
chlorocyclohexane 3c (entry 3). 2-Adamantanol 1d, 3-phenyl-2-
propanol 1e and 2-butanol 1f gave the corresponding chlorides in
high yields (entries 4–6). The acid-sensitive substrate 1g exclusively
gave the corresponding product 3g without any contamination
because the system was employed under neutral conditions
(entry 7). Substrate 1h, bearing both secondary and primary
hydroxyl sites, was chlorinated exclusively at the secondary site
(entry 8). In contrast, conventional chlorination of 1h using a
Ph3P/CCl4 system afforded 13-chloro-2-tridecanol (81% yield)
via reaction at a primary OH group. Our system was selective
for chlorination of polyols. The N-phthaloyl-substituted starting
alcohol 1i was effectively transformed into the chloride form,
while the nitrogen moiety was not involved in the reaction
(entry 9).
Scheme 2 Plausible reaction mechanism.
to give the chlorinated product 3 with siloxane release (path c).
Among paths a–c, path a is crucial. We sought dummy alcohols
(RꢀOH) that favor production of H2 over HCl during generation of
chlorosilyl ethers. In addition, the formed chlorosilyl ether should
not transform into chloride. The tartrate 4a satisfies these require-
ments for the dummy alcohol. Typically, formation of hydrosilyl
ether with generation of HCl is kinetically favored; this was the
only reaction observed during the reaction of benzhydrol with
chlorohydrosilane.3 In the case of tartrate, however, chlorosilyl
ether 5 forms with evolution of H2. Even if the hydrosilyl ether
was generated, transformation into the reduced tartrate would not
take place because the carbocation generated with assistance from
GaCl3 is destabilized by the electron-withdrawing carbonyl group
in 4a. The pathway to the hydorosilyl ether is reversible; therefore,
the irreversible and thermodynamically favorable pathway to the
chlorosilyl ether proceeds, giving H2. The chlorosilyl ether 5 does
not form chlorinated tartrate, also due to destabilization of the
carbocation. Thus, 4a appears to be a suitable dummy alcohol,
although direct evidence is yet to be obtained.
Investigation of reaction mechanism
A plausible reaction mechanism is shown in Scheme 2. Diethyl
tartrate 4a acts as a dummy alcohol (RꢀOH), as shown in Scheme 1,
and gives chlorosilyl ether 5 and H2 as a byproduct (path a).
Compound 5 undergoes alcohol-exchange with the substrate
alcohol 1 to form chlorosilyl alkoxide 6 with regeneration of
4a (path b). The chlorosilyl alkoxide 6 is catalyzed by GaCl3
We confirmed each step for paths a–c of the catalytic cycle
shown in Scheme 2. Path a: A 1 : 2 mixture of 4a and 2 in the
presence of 5 mol% of GaCl3 generated H2 gas and gave the
starting material 4a, after aqueous work-up. The corresponding
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Table 2 Chlorination of secondary alcohols 1a
Entry
1
Alcohol
Time/h
6
Product
Yield (%)
75
2
3
4
36
57
14
4
24
89
5
6
7
1
69
62b
53
4
20
8c
9
24
24
39
84
a All reactions were carried out at room temperature in CH2Cl2 with 1.0 equiv of alcohol 1, 1.3 equiv of HSiMe2Cl 2, 5 mol% of GaCl3, and 10 mol% of
diethyl tartrate 4a. b Direct observation of the product by NMR because of the high volatility of 3f. c HSiMe2Cl (3.0 equiv) was used.
reduced or chlorinated compounds did not form, probably because
the carbocation at the a-position of the carbonyl is unstable.
This result suggests generation of chlorosilyl ether 5. In fact,
NMR analysis of the reaction mixture prior to work-up indicated
generation of 5 (eqn 1, Fig. 1-ii). The OCH2Me signal appeared
as an ABq when irradiated at the Me group, presumably because
of a rigid structure caused by Si-chelation in 5. 29Si NMR showed
1
a reasonable chemical shift at 7.53 ppm without JSiH coupling.
Since the use of Et3SiH instead of HSiMe2Cl resulted in slow
generation of H2 under the same conditions, chlorine on Si
must be important for the formation of the silyl ether. GaCl3
is indispensable in this step because a control experiment, in
which the GaCl3-catalyst was not used, did not give 5. Path b:
Addition of 1-octanol to the generated species 5 afforded a mixture
of Me2(OctO)SiCl 7 and 4a by alcohol-exchange (eqn 2).10 The
species formed showed 1H, 13C, and 29Si NMR signals comparable
to those reported for similar compounds (Fig. 1(iii)).11 Path c:
The isolated chlorosilyl ether 9 reacted with catalytic GaCl3
(5 mol%) to give the chloride 3a in 62% yield (eqn 3). These
results provide strong support for the reaction course illustrated
in Scheme 2.
Fig. 1 NMR study for mechanistic investigation (CD2Cl2). Reagents and
conditions: (i) diethyl tartrate 4a. (ii) 2 : 1 mixture of HSiMe2Cl 2 and 4a.
(iii) Mixture of generated 5 with 1-octanol (ROH).
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GaCl3/tartrate system can be applied to chlorination of variety of
tertiary alcohols.
(1)
Conclusions
In summary, the combination of GaCl3 and diethyl tartrate effec-
tively catalyzed the chlorination of secondary alcohols. Tertiary
alcohols that give destabilized carbocations can also be chlorinated
using this combined catalyst system. With this system, we have
developed a completely catalytic reaction for the chlorination of
alcohols under neutral conditions.
(2)
(3)
Experimental
IR spectra were recorded as thin films or as solids in KBr pellets
on a HORIBA FT-720 spectrophotometer. 1H, 13C, and 29Si NMR
spectra were obtained with a 400, 100, and 78.7 MHz spectrometer,
respectively, with TMS as internal standard. Mass spectra were
recorded on a JEOL JMS-DS303 spectrometer. All reactions were
carried out under nitrogen. GLC analyses were performed on a
Shimadzu GC-14A with FID using a 15 m × 3 mm capillary
column packed with TC-WAX, TC-5, or TC-1701 (0.25 lm).
Column chromatography was performed on silica gel (MERK
C60). Bulb-to-bulb distillation (Kugelrohr) was accomplished
in a Sibata GTO-250RS at the oven temperature and pressure
Chlorination of tertiary alcohols
When tertiary alcohols were used as the substrate, diethyl tartrate
4a was not necessary when the GaCl3 catalyst was used (Table 3,
entries 1–3). These reactions proceeded via a mechanism different
from that shown in Schemes 1 and 2, as H2 generation was not
observed during the reaction. The reaction probably proceeded
through an SN1-type chloro-dehydroxylation with the assistance
of a GaCl3 as a Lewis acid, as has been reported for the same type
of reaction using BiCl3.9 However, certain tertiary alcohols that
would not be good substrates for SN1-type reactions showed low
chloride product yields (entries 4 and 6). In fact, BiCl3-catalyzed
reactions of 1l and 1m with 2 for 3 h resulted in low yields (19% and
0%), respectively,9 probably due to destabilization of the tertiary
carbocation either by steric or electronic effects. Interestingly, the
GaCl3/tartrate system significantly improved chlorination of 1l
and 1m, resulting in satisfactory yields (entries 5 and 7). In this
case, generation of H2 was observed. Thus, it was concluded that
the reaction proceeds via the mechanism shown in Scheme 2. The
1
indicated. Yields were determined by GLC or H NMR using
internal standards.
General procedure for chlorination of alcohols catalyzed by the
GaCl3/tartrate system (Table 2)
To a solution of (+)-diethyl tartrate (0.1 mmol) in CH2Cl2 (1 mL)
were added GaCl3 in pentane (0.5 M, 0.1 mL, 0.05 mmol), alcohol
1 (1.0 mmol), and HSiMe2Cl 2 (1.3 mmol) under nitrogen. The
Table 3 Chlorination of tertiary alcohols 1a
Entry
1
Alcohol
Time/h
1.5
Product
Yield (%)
99
2
3
2
3
99
99
4
5b
3
3
6
65
6
2
2
16c
89c
7b
a All entries were carried out at room temperature in CH2Cl2 with 1.0 equiv of alcohol 1, 1.3 equiv of HSiMe2Cl 2, and 5 mol% of GaCl3. b (+)-DET
(10 mol%) 4a was added. c Direct observation of the product by NMR because of the high volatility of 3n.
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reaction mixture was stirred under the conditions noted in text.
H2 gas was generated for the first ca. 15 minutes. The mixture was
quenched by addition of water (10 mL) and extracted with diethyl
ether (3 × 10 mL). The collected organic layer was dried over
MgSO4 and concentrated in vacuo.
HRMS: (CI, 200 eV) calcd for C13H28ClO 235.1829 found m/z
235.1822 (M+ + 1). Anal. Calcd for C13H27ClO: C, 66.50; H, 11.59.
Found: C, 66.42; H, 11.44.
2-(4-Chloropentyl)isoindole-1,3-dione (3i). According to the
general procedure, this compound was prepared from HSiMe2Cl,
1i, GaCl3 and (+)-diethyl tartrate in dichloromethane to give
the product as a colorless liquid after chromatography (hexane–
EtOAc, 80 : 20); further purificati◦on was performed by distillation
under reduced pressure: bp. 175 C/1.0 mmHg; IR: (neat) 1774,
1712 cm−1; 1H NMR: (400 MHz, CDCl3) 7.85 (dd, J = 5.4, 3.2 Hz,
2H, 5-H and 8-H), 7.73 (dd, J = 5.4, 3.2 Hz, 2H, 6-H and 7-H),
4.08 (tq, J = 6.8, 6.8 Hz, 1H, 4ꢀ-H), 3.72 (t, J = 6.8 Hz, 2H, 1ꢀ-H2),
1.92 (m, 1H, 3ꢀ-HA), 1.87–1.72 (m, 3H, 3ꢀ-HB and 2ꢀ-H2), 1.50 (d,
J = 6.8 Hz, 3H, 5ꢀ-H3); 13C NMR: (100 MHz, CDCl3) 168.4 (s,
C-1 and C-3), 134.0 (d, C-6 and C-7), 132.0 (s, C-4 and C-9), 123.2
(d, C-5 and C-8), 57.9 (d, C-7ꢀ), 37.3 (d, C-1ꢀ), 37.3 (d, C-3ꢀ), 25.9
(t, C-2ꢀ), 25.4 (q, C-5ꢀ); MS: (EI, 70 eV) m/z 253 (M+ + 2, 0.82),
251 (M+, 2.5), 160 (M+ − CH2CH2CHClCH3, 100); HRMS: (EI,
70 eV) calcd for C13H14ClNO2 251.0709 found m/z 251.0713 (M+).
Anal. Calcd for C13H14ClNO2: C, 62.03; H, 5.61; N, 5.56. Found:
C, 61.74; H, 5.49; N, 5.60.
General procedure for chlorination of alcohols catalyzed by the
GaCl3 system (Table 3)
To a solution of GaCl3 (0.5 M in pentane, 0.1 mL, 0.05 mmol) in
CH2Cl2 (1 mL) were added alcohol 1 (1.0 mmol) and HSiMe2Cl
2 (1.3 mmol) under nitrogen. The reaction mixture was stirred
under the conditions noted in the text. The mixture was quenched
by addition of water (10 mL) and extracted with diethyl ether (3 ×
10 mL). The collected organic layer was dried over MgSO4 and
concentrated in vacuo.
Product data
The spectral data of 3a,13 3b,14 3d,2a 3e,2a and 3k12 were in an
excellent agreement with the reported data. The spectral data of
3c, 3f, 3m, and 3n were in an excellent agreement with those of
commercially available products.
12-Chlorotetradecyl acetate (3g). According to the general
procedure, this compound was prepared from HSiMe2Cl, 1g,
GaCl3 and (+)-diethyl tartrate in dichloromethane to give the
product as a colorless liquid after chromatography (hexane–
EtOAc, 97 : 3). Further purification was performed by distillation
under reduced pressure, to give the product (including some
rearrangement products): bp. 165 ◦C/0.4 mmHg; IR: (neat) 2927
2-Chloro-2-methylhexane (3j). According to the general proce-
dure, this compound was prepared from HSiMe2Cl, 1j and GaCl3
in dichloromethane to give the product as a colorless liquid after
chromatography (hexane–EtOAc, 90 : 10); further purification
was performed by distillation under reduced pressure: bp. 58 ◦C/
1
−1
1
50 mmHg; IR: (neat) 2962, 1466 cm−1; H NMR: (400 MHz,
=
(C–H), 1743 (C O), 1242 cm ; H NMR: (400 MHz, CDCl3)
4.05 (t, J = 6.8 Hz, 2H, 1-H2), 3.85 (m, 1H, 12-H), 2.05 (s, 3H,
COCH3), 1.03 (t, J = 7.4 Hz, 3H, 14-H3) (other signals could
not be identified due to overlap with those of rearrangement by-
products); 13C NMR: (100 MHz, CDCl3) 171.3 (C, CO), 65.9
(CH, C-12), 64.5 (CH2, C-1), 31.5 (CH2, C-13), 10.9 (CH3, C-
14) (other signals could not be identified due to overlap with
those of rearrangement by-products); MS: (CI, 200 eV) m/z 293
(M+ + 3, 31), 291 (M+ + 1, 100), 255 (M+ + 1 − HCl, 65), 195
(M+ + 1 − HCl − CH3COOH, 47); HRMS: (CI, 200 eV) calcd for
C16H32ClO2 291.2091 found m/z 291.2086 (M+ + 1). Anal. Calcd
for C16H31ClO2: C, 66.07; H, 10.74. Found: C, 66.36; H, 10.59.
CDCl3) 1.74 (m, 2H, 3-H2), 1.57 (s, 3H, 1-H3 or 2-Me), 1.57 (s,
3H, 2-Me or 1-H3), 1.46 (m, 2H, 4-H2), 1.33 (tq, J = 7.4, 7.4 Hz,
2H, 5-H2), 0.93 (t, J = 7.4 Hz, 3H, 6-H3); 13C NMR: (100 MHz,
CDCl3) 71.3 (s, C-2), 45.8 (t, C-3), 32.4 (q, C-1 and 2-Me), 27.3
(t, C-4), 22.8 (t, C-5), 14.0 (q, C-6); MS: (EI, 70 eV) m/z 121
(M+ + 2 − CH3, 0.75), 119 (M+ − CH3, 2.2), 99 (M+ − Cl, 17), 77
(C(CH3)2Cl, 65), 56 (100), 41 (55); HRMS: (EI, 70 eV) calcd for
C6H12Cl 119.0628 found m/z 119.0630 (M+ − CH3). Anal. Calcd
for C7H15Cl: C, 62.44; H, 11.23. Found: C, 62.59; H, 11.05.
2-(7-Chloro-3,7-dimethyloctyl)isoindole-1,3-dione (3l). Accor-
ding to the general procedure, this compound was prepared from
HSiMe2Cl, 1l and GaCl3 in dichloromethane to give the product
as a solid after recrystallization (hexane–ether): mp. 88–90 ◦C; IR:
12-Chloro-1-tridecanol (3h). According to the general proce-
dure, this compound was prepared from HSiMe2Cl, 1h, GaCl3
and (+)-diethyl tartrate in dichloromethane to give the product
as a colorless liquid after chromatography (hexane–EtOAc, 90 :
10). Further purification was performed by distillation under
reduced pressure and GPC, to give the product (including some
rearrangement products): bp. 175 ◦C/0.5 mmHg; IR: (neat) 3309
(OH) cm−1; 1H NMR: (400 MHz, CDCl3) 4.02 (tq, J = 6.6, 6.6 Hz,
1H, 12-H), 1.50 (d, J = 6.6 Hz, 3H, 13-H3) (other signals could
not be identified due to overlap with those of rearrangement by-
products); 13C NMR: (100 MHz, CDCl3) 63.1 (CH2, C-1), 59.0
(CH, C-12), 40.4 (CH2, C-11), 25.7 (CH3, C-13) (other signals
could not be identified due to overlap with those of rearrangement
by-products); MS: (CI, 200 eV) m/z 237 (M+ + 3, 3.47), 235 (M+ +
1, 12.3), 217 (M+ + 1 − H2O, 41.0), 199 (M+ + 1 − HCl, 100), 181
(M+ + 1 − HCl − H2O, 22.1), 125 (24.0), 111 (26.6), 97 (21.1);
1
(KBr) 1770, 1712 cm−1; H NMR: (400 MHz, CDCl3) 7.84 (dd,
J = 5.6, 3.2 Hz, 2H, 5-H and 8-H), 7.71 (dd, J = 5.6, 3.2 Hz, 2H,
6-H and 7-H), 3.71 (m, 2H, 1ꢀ-H2), 1.70 (m, 3H), 1.56 (s, 6H, 8ꢀ-H3
and 7ꢀ-Me), 1.59–1.21 (m, 5H), 1.21 (m, 1H), 0.99 (d, J = 6.3 Hz,
3H, 3ꢀ-Me); 13C NMR: (100 MHz, CDCl3) 168.4 (C, C-1 and C-3),
133.8 (CH, C-6 and C-7), 132.2 (C, C-4 and C-9), 123.1 (CH, C-5
and C-8), 71.2 (C, C-7ꢀ), 46.2 (CH2), 36.7 (CH2), 36.2 (CH2), 35.5
(CH2), 32.4 (CH3, 7ꢀ-Me), 32.4 (CH3, C-8ꢀ), 30.6 (CH, C-3ꢀ), 22.3
(CH2), 19.3 (CH3, 3ꢀ–Me); MS: (EI, 70 eV) m/z 323 (M+ + 2, 2.41),
321 (M+, 6.94), 200 (23.0), 161 (47.2), 160 (PhthNCH2, 100), 148
(28.2); HRMS: (EI, 70 eV) calcd for C18H24ClNO2 321.1496 found
m/z 321.1502 (M+). Anal. Calcd for C18H24ClNO2: C, 67.17; H,
7.52; N, 4.35. Found: C, 67.15; H, 7.38; N, 4.47.
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5 Example for employing Si–H bond:H. Ito, K. Takagi, T. Miyahara
and M. Sawamura, Org. Lett., 2005, 7, 3001–3004 and references cited
therein.
6 K. Tanino, T. Shimizu, M. Kuwahara and I. Kuwajima, J. Org. Chem.,
1998, 63, 2422–2423.
Acknowledgements
Financial support from a Grant-in-Aid for Scientific Research
from the Ministry of Education, Culture, Sports, Science and
Technology, Japan, is gratefully acknowledged.
7 No asymmetric induction was observed even when optically active
diethyl tartrate was used.
8 In the reaction of 1-octanol with 2 using the GaCl3/tartarate catalyst
system, H2 gas was generated and the starting alcohol was quantita-
tively recovered.
9 M. Labrouille`re, C. Le Roux, H. Gaspard-Iloughmane, and J. Dubac,
Synlett, 1994, 723-724.
10 Primary alcohol was used to observe the intermediate because sec-
ondary alcohols might not stay at the corresponding intermediate and
would give the chlorinated product. The oversubstituted compound
(OctO)2SiMe2 8 was formed as a side product.
References and notes
1 (a) Comprehensive Organic Transformations, 2nd edn, ed. R. C. Larock,
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2 (a) M. Yasuda, S. Yamasaki, Y. Onishi and A. Baba, J. Am. Chem. Soc.,
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Baba, Org. Synth., 2006, 83, 38–44.
3 M. Yasuda, Y. Onishi, M. Ueba, T. Miyai and A. Baba, J. Org. Chem.,
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4 Example for employing Si–Cl bond:E. J. Corey and A. Venkateswarlu,
J. Am. Chem. Soc., 1972, 94, 6190–6191.
11 E. Liepins, I. Zicmane and E. Lukevics, J. Organomet. Chem., 1986,
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12 Y. Nishimoto, M. Yasuda and A. Baba, Org. Lett., 2007, 9, 4931–4934.
13 A. G. M. Barrett, D. C. Braddock, R. A. James, N. Koike and P. A.
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