Co2(CO)8-catalyzed reactions of acetals or lactones with hydrosilanes and carbon monoxide. A new access to the preparation of 1,2-diol derivatives through siloxymethylation

Article abstract of DOI:10.1246/BCSJ.20200240

The Co2(CO)8-catalyzed reaction of acetals with hydrosilanes and CO under mild reaction conditions (an ambient temperature under an ambient CO pressure), leading to the production of vicinal diols is reported. A siloxymethyl group can be introduced via the cleavage of one of two alkoxy groups in the acetal. The effects of the types of hydrosilanes, acetals, solvents, and reaction temperatures on the yield of siloxymethylation products were examined in detail. The reactivity for hydrosilanes is as follows; HSiMe3 > HSiEtMe2 > HSiEt2Me > HSiEt3. Hemiacetal esters are more reactive than dimethyl acetals. The polarity of the solvent used also has a significant effect on both the course of the reaction as well as the reaction rate. The site-selective siloxymethylation can be achieved in the case of cyclic acetals such as tetrahydrofuran (THF) and tetrahydropyrane (THP) derivatives, depending on the nature of the oxygen substituent attached adjacent to the oxygen atom in the ring. When 2-alkoxy THF or THP derivatives are used as substrates, the siloxymethylation takes place with cleavage of the ring C-O bond. In contrast, the reaction of 2-acetoxy THF or THP derivatives results in siloxymethylation with the cleavage of C-OAc bond. The ring-opening siloxymethylation of lactones was also examined.

Full text of DOI:10.1246/BCSJ.20200240

Advance Publication Cover Page
Co2(CO)8-Catalyzed Reactions of Acetals or Lactones with Hydrosilanes and Carbon
Monoxide. A New Access to the Preparation of 1,2-Diol Derivatives through
Siloxymethylation
Naoto Chatani,* Satoru Fujii, Yoichi Kido, Yasuhide Nakayama, Yasuteru Kajikawa,
Hideo Tokuhisa, Yoshiya Fukumoto, and Shinji Murai*
Advance Publication on the web September 3, 2020
doi:10.1246/bcsj.20200240
© 2020 The Chemical Society of Japan
Advance Publication is a service for online publication of manuscripts prior to releasing fully edited, printed versions. Entire
manuscripts and a portion of the graphical abstract can be released on the web as soon as the submission is accepted. Note that the
Chemical Society of Japan bears no responsibility for issues resulting from the use of information taken from unedited, Advance
Publication manuscripts.

Co2(CO)8-Catalyzed Reactions of Acetals or Lactones with Hydrosilanes and Carbon
Monoxide. A New Access to the Preparation of 1,2-Diol Derivatives through
Siloxymethylation
Naoto Chatani,* Satoru Fujii, Yoichi Kido, Yasuhide Nakayama, Yasuteru Kajikawa, Hideo Tokuhisa,
Yoshiya Fukumoto, and Shinji Murai*†
Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
†The present address: Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
E-mail: chatani@chem.eng.osaka-u.ac.jp, murai@ad.naist.jp
Naoto Chatani
Naoto Chatani received his Ph.D. in 1984 from Osaka University under the guidance of Professors Noboru Sonoda and
Shinji Murai. He subsequently joined the Institute of Scientific and Industrial Research at Osaka University as an Assistant
Professor in Professor Terukiyo Hanafusa’s laboratory. After postdoctoral studies with Professor Scott E. Denmark at the
University of Illinois, Urbana-Champaign (1988-1989), he returned to Osaka University to join Professor Shinji Murai’s
laboratory as an Assistant Professor and was promoted to the rank of Associate Professor in 1992 and then Full Professor
in 2003.
Shinji Murai
Shinji Murai received his Ph.D. in 1966 from Osaka University. He was appointed as an Assistant Professor at Osaka
University in 1966, then Full Professor in 1989. He did a postdoc work in 1967 for Professor Robert West at the University
of Wisconsin. In 2002, he moved to the Japan Science and Technology Agency (JST) as an executive fellow. In 2005, he
was appointed as a Director, a Vice President, and then a Specially Appointed Professor at the Nara Institute of Science
and Technology. Since 2013, he has also served as a Director for the Iwatani Cooperation R&D Center and since 2016 as
an Outside Director.
in many organic synthetic transformations because the reactions
Abstract
The Co2(CO)8-catalyzed reaction of acetals with
afford a variety of valuable synthetic building blocks.1 The
reaction of acetals with organosilicon nucleophiles, such as enol
silyl ethers, allylsilanes, silyl azide, hydrosilanes, and silyl
cyanide has been of particular interest.2 In these reactions, one
of the alkoxide groups in an acetal is replaced by -ketonyl, allyl,
azide, hydride, or cyano groups, respectively. The high affinity
of the silicon atom in these reagents toward the oxygen atom in
an acetal is the driving force for the reaction to proceed.
Although a variety of functional groups can be introduced into
the acetal-carbon, the direct introduction of an oxymethyl group
into an acetal, a conversion that would be of considerable interest
to chemists, does not appear to have been reported. In addition,
the use of oxymethylating reagents or their equivalents3 in
nucleophilic oxymethylation reactions do not appear to be
applicable to acetals, although the oxymethylation of acetals
would be expected to lead to the formation of 1,2-diol
derivatives, which are useful compounds in organic synthesis.4
The commonly employed methods for the synthesis of vicinal
diol units include the hydrolytic ring opening of epoxides, the
dihydroxylation of olefins, and the reduction of -hydroxy
ketones.4 These methods all involve the manipulation of a
functional group on already existing two carbon units. The
oxymethylation of acetals would be expected to provide a new
method for preparing vicinal diol derivatives that involves the
concomitant formation of C-C bonds starting from acetals. Our
methodology for the preparation of vicinal diols by
oxymethylation is based on our previously reported findings that
siloxymethylation with the cleavage of C-O bonds in oxygenated
substrates can be achieved by a Co2(CO)8/HSiR3/CO catalytic
system.5 Although the carbonylation of oxygen-containing
compounds is generally carried out under harsh reaction
hydrosilanes and CO under mild reaction conditions (an ambient
temperature under an ambient CO pressure), leading to the
production of vicinal diols is reported. A siloxymethyl group can
be introduced via the cleavage of one of two alkoxy groups in
the acetal. The effects of the types of hydrosilanes, acetals,
solvents, and reaction temperatures on the yield of
siloxymethylation products were examined in detail. The
reactivity for hydrosilanes is as follows; HSiMe3 > HSiEtMe2 >
HSiEt2Me > HSiEt3. Hemiacetal esters are more reactive than
dimethyl acetals. The polarity of the solvent used also has a
significant effect on both the course of the reaction as well as the
reaction rate. The site-selective siloxymethylation can be
achieved in the case of cyclic acetals such as tetrahydrofuran
(THF) and tetrahydropyrane (THP) derivatives, depending on
the nature of the oxygen substituent attached adjacent to the
oxygen atom in the ring. When 2-alkoxy THF or THP derivatives
are used as substrates, the siloxymethylation takes place with
cleavage of the ring C-O bond. In contrast, the reaction of 2-
acetoxy THF or THP derivatives results in siloxymethylation
with the cleavage of C-OAc bond. The ring-opening
siloxymethylation of lactones was also examined.
Keywords: Carbon monoxide, Oxymethylation,
Acetals
1. Introduction
Acetals and ketals are extensively used in organic synthesis,
not only as protecting groups for aldehydes and ketones, but also
1

conditions,6 we demonstrated that our system is effective for the
incorporation of CO into oxygenated compounds, such as
tetrahydrofurans,7 epoxides,8 oxetanes,9 glycosides,10 benzyl
acetates,11 and orthoesters,12 under mild reaction conditions. In
our efforts to expand the scope of the Co2(CO)8/HSiR3/CO
catalytic cleavage of a C-O bond under exceptionally mild
reaction conditions, we found a new type of siloxymethylation
of acetals using a hydrosilane and CO (Scheme 1). In this paper,
our progress in developing a method for introducing a
siloxymethyl group with the cleavage of a C-O bond in acetals
under mild reaction conditions is described. The present reaction
is also applicable to the ring-opening siloxymethylation of
lactones. As will be discussed later, the siloxymethylation
proceeds in multi-step manner, carbonylation followed by
addition of a hydrosilane. The overall process is equivalent to
nucleophilic oxymethylation.
reacted with HSiMe3 and CO in C6H6 at 25 °C for 2 days gave
(2-methoxyethoxy)trimethylsilane (2a) in 70% yield (entry 1).
The use of HSiEtMe2 and HSiEt2Me in place of HSiMe3 resulted
in the need for longer reaction times, and led to lower yields
(entries 2 and 3). Thus, the reactivity of hydrosilane decreases as
follows: HSiMe3 > HSiEtMe2 > HSiEt2Me. It was found that
hemiacetal ester 3 is much more reactive than 1. Thus, the
reaction of 3 with HSiMe3 and CO in C6H6 was complete within
13 h, even at a temperature of 5 °C (entry 4), while the reaction
of 1 required for 2 days at 25 °C (entry 1). The effect of the
solvent used was also examined for the reaction of 3. The use of
CH2Cl2 led to a comparable yield of the product, even in a
shorter reaction time than those obtained by the use of C6H6
(entries 5 vs 6 and 7 vs 8). A higher reactivity of hemiacetal
esters were also shown by the reaction of 3 with HSiEt3, which
gave the corresponding product 2d in 65% yield (entry 9),
although HSiEt3 proved to be unreactive in the reaction of 1. The
phenoxymethyl acetate (4) also reacted with hydrosilanes and
CO to afford the corresponding ethylene glycol derivatives 5 in
good yields (entries 10-13). Although the reaction of trioxane
gave a mixture of numerous products (results not shown), 1,3-
dioxolane (6) reacted with HSiMe3 and CO to give the bis[2-
(trimethylsiloxy)ethyl]ether (7), in which the C(2)-O(1) bond
was selectively cleaved, no products from the cleavage of the
C(4)-O(3) bond were observed (entry 14). There has been great
interest in the synthesis of ethylene glycol from formaldehyde
catalyzed by transition metal complexes. However, the reaction
requires extremely harsh reaction conditions (high reaction
temperatures and high syngas pressures), which limits the
development of this process.13 In contrast, the present reactions
provide a new transformation of formaldehyde derivatives to
ethylene glycol derivatives under extremely mild reaction
conditions, i.e., at ambient temperature and under an ambient CO
pressure. This result would have an impact on the development
of the carbonylation of formaldehyde.
OMe
OMe
cat. Co2(CO)8
HSiR3
+
+ CO
OSiR3
R
R
X
X = OMe, OAc
nucleophilic siloxymethylation
Scheme 1 Co2(CO)8-catalyzed siloxymethylation of acetals
2. Results and Discussion
Reaction of Formaldehyde Acetals. In initial experiments,
we examined the Co2(CO)8-catalyzed reaction of formaldehyde
acetals with hydrosilanes and CO and the results are summarized
in Table 1. The reaction parameters examined include (i) the
acetal structure, (ii) the hydrosilane substitution pattern, (iii) the
solvent, (iv) the reaction temperature, and (v) the reaction time.
To evaluate these reaction parameters, the reaction of various
formaldehyde acetals was examined in detail under varying
reaction conditions. The reaction of dimethoxymethane (1)
Table 1. Co2(CO)8-catalyzed reactions of formaldehyde acetals with hydrosilanes and CO.a
Entry
1
Acetal
Hydrosilane
HSiMe3
Solvent
C6H6
Temp, °C
25
Time
2 d
Product
Yield, %b
70
CH3OCH2OCH3 (1)
CH3OCH2CH2OSiMe3 (2a)
2
1
HSiEtMe2
HSiEt2Me
HSiMe3
C6H6
25
6 d
CH3OCH2CH2OSiEtMe2 (2b)
60
3
1
C6H6
25
7 d
CH3OCH2CH2OSiEt2Me (2c)
10
4
CH3OCH2OAc (3)
C6H6
5
13 h
2a
62
5
3
HSiEtMe2
HSiEtMe2
HSiEt2Me
HSiEt2Me
HSiEt3
C6H6
15
14 h
6 h
2 d
1 d
5 d
2 d
17 h
3 d
1 d
1 d
2b
2b
69
6
3
CH2Cl2
C6H6
15
61
7
3
15
2c
75
8
3
CH2Cl2
C6H6
15
2c
76
9
3
40
CH3OCH2CH2OSiEt3 (2d)
PhOCH2CH2OSiMe3 (5a)
PhOCH2CH2OSiEtMe2 (5b)
PhOCH2CH2OSiEt2Me (5c)
PhOCH2CH2OSiEt2Me (5c)
65
10
11
12
13
14
PhOCH2OAc (4)
HSiMe3
C6H6
15
80
4
4
4
HSiEtMe2
HSiEt2Me
HSiEt2Me
HSiMe3
C6H6
25
86
C6H6
25
82
CH2Cl2
CH2Cl2
25
97
15
85
a Reaction conditions: acetal (2.5 mmol), HSiMe3 (25 mmol, 2.9 mL) or other hydrosilanes (7.5 mmol), Co2(CO)8 (0.1 mmol, 34 mg),
solvent (5 mL) under CO (1 atm). b GC yield.
Reaction of Acetals. To establish the scope and limitations
of the present siloxymethylation reaction, we studied the
Co2(CO)8-catalyzed reaction of acetals derived from both
aliphatic and aromatic aldehydes and the results are summarized
in Table 2. Because of its higher reactivity and the ease of
removing it from the products, HSiMe3 was used as the
hydrosilane throughout this work. Although the only drawback
to the use of HSiMe3 is its high volatility (bp 6.7 °C), we were
able to overcome this drawback by designing a unique type of
syringe for handling volatile liquids.8b Octanal dimethyl acetal
(8a) was reacted with HSiMe3 and CO (1 atm) in C6H6 at 25 °C
for 6 days to give ((2-methoxynonyl)oxy)trimethylsilane (9a), in
2

which one of the methoxy groups in 8a was replaced with a
siloxymethyl group, as a main product, in 86% yield. The major
byproduct was methyl octyl ether (10a), which was produced by
the reduction of 8a by HSiMe3.14 The reaction of octanal
ethylene acetal (8b) also afforded the corresponding
siloxymethylation product 9b in 60% yield. Curiously,
trimethyl(2-(octyloxy)ethoxy)silane (10b) was formed as a sole
product in 78% yield, with no 9b being obtained, when CH3CN
was used as a solvent. This reaction represents a simple method
for the transformation of acetals to ethers. The reaction of the
ester-substituted acetal 8c gave the corresponding diol derivative
9c in good yield. Benzaldehyde acetals 8d and 8e also gave the
corresponding products 9d and 9e, respectively.
The lower reaction temperatures are desirable in that the
formation of a byproduct 10 can be avoided, which is formed by
the reduction with HSiMe3. The use of a lower temperature,
however, requires much longer reaction times. To overcome this
problem, the use of hemiacetal esters, which were already found
to be much more reactive than the corresponding acetals as
shown in Table 1, would be desirable. Thus, we examined the
reaction of hemiacetal esters which are easily produced by the
reaction of acetals with acid anhydrides.15 The reaction of the
hemiacetal esters, 8f-8h, with HSiMe3 and CO gave the
corresponding siloxymethylation products 9a, 9d, and 9h,
respectively, in good yields. When the reaction was carried out
with HSiMe3 in C6H6 at 15 °C, the hemiacetal ester 8g reacted
much faster (t
= 3 h) than the dimethyl acetal 8d (t
= 30
1/2
1/2
h), as expected. The reaction of the benzaldehyde hemiacetal
acetate 8g was studied under variable reaction conditions, some
of the conditions are summarized in Table 2. The reaction of 8g
was also markedly affected by the reaction conditions, especially
the reaction temperature, the structure of the hydrosilane, and
solvent used. The use of CH2Cl2 as a solvent in the reaction of
8g accelerated the rate of the reaction, however, the undesired
reduction product 10d was produced in higher yield When the
reaction was carried out using HSiEt2Me as a hydrosilane in
place of HSiMe3 in C6H6 at 15 °C, the yield of the reduction
product 10d decreased markedly but the reaction required a
much longer reaction time (data not shown). Generally, a lower
reaction temperature gave a higher yield of 9d and a higher
reaction temperature gave more of the undesired product 10d.
Table 2. Co2(CO)8-catalyzed reactions of acetals with HSiMe3 and CO.a
a Reaction conditions: acetal (2.5 mmol), HSiMe3 (25 mmol, 2.9 mL), Co2(CO)8 (0.1 mmol, 34 mg), solvent (5 mL), under CO (1 atm).
GC yields based on an acetal. Nd refers to not determined.
3

HSiMe3 to give the hydrosilylation product 10. If the complex
15 were formed via 21, the reduction product 10 should be the
major product, as expected from the results for hexanal.
However, this is not the case. A hydrosilane can react with 21 or
22, but not with 14. The use of a polar solvent such as CH2Cl2
resulted in an increase in the yield of 10. In a polar solvent, 14 is
easily converted to an oxocarbenium ion 21 because 21 is
stabilized by a polar solvent.
OMe
OMe
Co2(CO)8
HSiMe3, CO
OSiMe3
8g
+
C6H6
25 °C
20 h (6 d)
9d 7% (7%)
10d 55% (0%)
Co2(CO)8
HSiMe3, CO
Co2(CO)8
HSiMe3, CO
Co2(CO)8
HSiMe3
OSiMe3
OSiMe3
OSiMe3
OMe
+
OMe
SiMe3
14
OMe
Co(CO)4
15
_
13
Co(CO)4
8
R
R
- Me3SiOMe
11 7% (12%)
12 20% (59%)
Scheme 2. The time-course study of 8g.
H
OMe
OMe
OMe
O
HSiMe3
H
Co(CO)3
Co(CO)3
R
R
R
- Me3SiCo(CO)3
SiMe3
O
O
The time-course study of 8g in C6H6 at 25 °C indicated that two
other undesirable side-reaction products were formed, namely,
11 and 12 (Scheme 2). Product 12 is produced by further
reactions, such as the Co2(CO)8-catalyzed siloxymethylation of
10d with HSiMe3 and CO16 or by the reduction of 9d with
HSiMe3. Product 11 appears to be formed by the
siloxymethylation of the initial product 9d through a path similar
to that for the formation of 12 from 10d. After 20 h, the product
yields were as follows; 9d 7% yield, 10d 55%, 11 7%, 12 20%.
When the reaction was run for 6 days, 12 was produced as a main
product in 59% yield, along with 9d (7%) and 11 (12%). In sharp
contrast, 9d was selectively formed in 84% yield when the
reaction was carried out in toluene at -10 °C for 4 days (Table 2).
Thus, a lower reaction temperature is the key to the successful
transformation to siloxymethlation products.
18
16
17
OMe
OMe
13
HSiMe3
- 13
_
Co(CO)4
OSiMe3
19
H
or
Co(CO)4
R
9
R
+
OSiMe3
20
Scheme 3. A proposed mechanism.
(a)
15
10
OMe
+
OMe
+
OMe
H
_
_
Co(CO)4
Co(CO)4
R
- Me3SiOMe
R
21
SiMe3
HSiMe3
13
14
-
Mechanistic Aspects. The silylcobalt complex
Me3SiCo(CO)4 (13), which is known to be formed by the
reaction of Co2(CO)8 with HSiMe3,17 is postulated as the key
catalyst species in the present reaction. A possible reaction
mechanism is shown in Scheme 3 on the basis of the knowledge
obtained from our previous works,7-12 Gladsyz's findings
regarding the stoichiometric reaction of Me3SiMn(CO)5,18 and
some other studies on the stoichiometric reaction using
Me3SiCo(CO)4.19 The interaction of the catalytic active species
13 with the acetal 8 gives an α-alkoxyalkylcobalt complex 1520
via a silyloxonium ion intermediate 14. The complex 15
undergoes a CO migratory insertion to give an acylcobalt
complex 16. The oxidative addition of HSiMe3 to 16 followed
by reductive elimination gives the aldehyde intermediate 18.
Under the reaction conditions used in this study, the aldehyde 18
would be susceptible to hydrosilylation to afford the final
product 9 via 19 or 20.
SiMe3
O
O
OSiMe3
+
13
HSiMe3
_
Co(CO)4
R
H
R
- 13
R
H
10
22
(b)
R
H
H
1,2-H
shift
OMe
1,3-Si
shift
OMe
OMe
Co(CO)3
Co(CO)3
SiMe3
Co(CO)3
R
R
OSiMe3
19
O
OSiMe3
23
17
Scheme 4. Alternative reaction pathways.
The next question is whether or not the reaction proceeds
via an aldehyde 18 as an intermediate. Wegman reported that the
reaction of an acetylcobalt complex, CH3COCo(CO)4(PPh3),
with HSiEt3 gave CH3CHO and Et3SiCo(CO)3(PPh3).19a These
results support our proposed mechanism. However, in a later
study, Markó and coworkers reported that HSiEt3 reacts with
Me2CHCOCo(CO)4 to give, not only the expected Me2CHCHO
and Et3SiCo(CO)4 but also Me2C=CHOSiEt3 and
Me2CHCH2OSiEt3 as the organic products, which were not
formed from Me2CHCHO.19b On the basis of their results, our
reaction mechanism can be reconsidered as shown in Scheme 4b.
Thus, a key step is a 1,3-Si shift from 17 leading to the formation
of the carbenoid complex 23, which undergoes 1,2-H shift to
give the alkyl Co complex 19. This reaction pathway is similar
to that already proposed by Gradysz for analogous Mn
complexes.18 These alternative paths cannot be excluded at this
point.
An alternative pathway to the alkylcobalt complex 15
involves the direct loss of methyl trimethysilyl ether from 14
leading to the formation of the oxocarbenium ion 21, followed
-
by the attack of Co(CO)4 (Scheme 4a). We disfavor this
pathway on the basis of the following experimental results. The
Co2(CO)8-catalyzed reaction of hexanal with HSiMe3 and CO
under reaction conditions that are identical to those in the
dimethylacetal of hexanal 8a gave the predominant formation of
a hydrosilylation product along with a small amount of the
siloxymethylation product.21 In the case of acetals, the
generation of the alkylcobalt complex 15 would proceed via an
-
S
N
2 type reaction, where Co(CO)4 attacks at 14 prior to the
liberation of methyl silyl ether. In contrast, the reaction of
aldehydes involves the initial interaction of 13 with an aldehyde
leading to a silyloxonium ion 22, which is easily reduced by
Reaction of Cyclic Acetals. The siloxymethylation
reported herein is promising as a synthetic method for
4

introducing an siloxymethyl group into an organic molecule. It
was found that the site-selective siloxymethylation can be
achieved by taking advantage of differences in reactivity
between a cyclic acetal and a cyclic hemiacetal ester (Scheme 6).
In the case of 2-alkoxy tetrahydrofuran derivatives 24, the
siloxymethylation occurred with the site-selective cleavage of a
ring C-O bond. Thus, 24 catalytically reacted with HSiMe3 and
CO (1 atm) to afford the 1,2,5-triol derivatives 25a-25c (Scheme
6a).22 In contrast, the reaction of 2-acetoxy tetrahydrofuran 26
gave the diethylmethylsilyl ether of the tetrahydrofurfuryl
alcohol 27, with the ring remaining intact (Scheme 6b). The
difference in the reaction site between 24 and 26 is due to the
difference between the ability of leaving groups. Thus, an
acetoxy group in 26 acts a good leaving group as a silyl acetate.
The reaction of tetrahydropyrane derivatives 28 and 30 also
resulted in the same site-selective reaction (Scheme 6c and d).
BzO
OSiMe3
BzO
Co2(CO)8
OAc
O
O
HSiEt2Me, CO
CH2Cl2
25 °C, 40 h
Bz = COPh
BzO
33
OBz
75%
OBz
32
BzO
OAc
O
Co2(CO)8
OAc
O
AcO
HSiMe3, CO
AcO
AcO
AcO
C6H6
OSiMe3
OAc
OAc
a-34
OAc
40 °C, 20 h
35
78% (from
)
34
75% (from ß-34)
Scheme 7. Siloxymethylation of glycosyl acetates.
Reaction of Lactones. As described above, the reaction of
cyclic acetals or hemiacetal esters with hydrosilanes and CO
proceeded smoothly to yield siloxymethylation products in a
site-selective manner. In a further extension of the present
siloxymethylation, the reaction of lactones with hydrosilanes
and CO was examined. As a result, two types of the products,
1,2,ω-triols 37 and ω-siloxy acids 38, were obtained, the ratio
being dependent on the structure of lactones being used. The
results are summarized in Table 3. The reaction of the γ-
butyrolactone (36a) with HSiMe3 and CO in C6H6 at 15 °C for 7
days gave 37a in 60% yield along with 6% of 38a. The product
distribution was influenced by the reaction temperature
employed. Higher temperatures favored the formation of 38a.
The reaction at 40 °C gave 38a in 31% yield as the main product,
although the total yield was not high. The course of the reaction
is rationalized by the consideration as shown in Scheme 8. The
product 37a is apparently formed via the intermediacy of 2-
siloxytetrahydrofuran 40a which is formed by the
hydrosilylation of the carbonyl group in 36a via path a.23 Ring-
opening siloxymethylation then takes place from 40a via steps
similar to the formation of 25 from 24 (Scheme 6a). The attack
of Co(CO)4- at the -carbon in 39 (path b) gives the alkylcobalt
intermediate 41, which subsequently produces 38a. At lower
temperatures, path a is faster than path b.
(a)
Co2(CO)8
HSiMe3, CO
Me3SiO
OR'
OSiMe3
OR'
O
CH2Cl2, 10 °C, 7 d 25a
87%
25b 92%
25c
24a
R' = Me (
)
R' = PhCH2 (24b)
C6H6, 10 °C, 5 d
24c C6H6, 15 °C, 4 d
R' = Me3SiCH2CH2
(
)
59%
(b)
(c)
Co2(CO)8
HSiEt2Me, CO
OSiEt2Me
27 66%
O
OAc
O
C6H6
25 °C, 20 h
26
Co2(CO)8
HSiMe3, CO
Me3SiO
OMe
OSiMe3
29 70%
CH2Cl2
O
OMe
OAc
15 °C, 4 d
28
(d)
Co2(CO)8
HSiMe3, CO
OSiMe3
31 68%
C6H6
O
O
_
25 °C, 20 h
Co(CO)4
_
path a
path b
30
37a
a
H
OSiMe3
O
b
40a
Scheme 6. Site-selective siloxymethylation.
+
O
O
The siloxymethylation reactions of cyclic acetals shown in
Scheme 6b and 6d were applicable to the preparation of C-
nucleocide (Scheme 7).10 The acetoxy group at the anomeric
center of a sugar can be selectively replaced with a siloxymethyl
group. The stereoselective substitution of an acetoxy group at the
C-1 position of a furanose ring by a siloxymethyl group upon the
reaction of 32 with HSiEt2Me and CO gave 33 in a
stereoselective manner indicative of participation by the
neighboring 3-benzoyl group. In the reaction of glucosyl acetate
34, the siloxymethyl group is introduced predominantly from the
β-face regardless the stereochemistry of the starting materials.
The reaction of the α-isomer of 34 gave β-35 in 78% yield and
the -isomer also gave -35 in 75% yield. The stereochemistry
of the formation of glucose derivative 35 is consistent with
participation by the neighboring 3-acetoxy group.
38a
SiMe3
O
(OC)4Co
O
39
SiMe3
41
Scheme 8. The reaction paths to 37a and 38a.
In contrast to the parent -butyrolactone 36a, the reaction
of -substituted γ-lactones 36b and 36c selectively gave 1,2,5-
triol derivatives 37b and 37c, and no 4-siloxy acids 38b and 38c
were obtained. This can be attributed to the steric hindrance of
the γ-carbon of the lactones, which inhibits path b. The reaction
of the δ-valerolactone (36d) with HSiMe3 and CO gave the
corresponding 1,2,6-triol 37d in 60% yield. It should be noted
that 2-(trimethylsiloxy)tetrahydropyrane (40d) was formed as
the main product in 66% yield when hexane was used as the
solvent at 25 °C. This result provides strong evidence that
supports our mechanistic proposal that 40a and 40d are
intermediates in the production of 37a and 37d. In contrast to the
reaction of a δ-lactone, a 2-siloxytetrahydrofuran, such as 40a,
could not be detected in the reaction of γ-lactones, indicating that
5

the ring-opening of the five-membered ether 40a is much easier
than that for the six-membered ether 40d.
ring strain, cannot compete with path b where the ring strain is
released.
_
Co(CO)4
O
OSiMe3
path a
X
_
O
H
a
40d
O
SiEt2Me
b
+
O
40e
Curiously, in the reaction of β-lactones 36e, 4-siloxy-
butyric acid derivative 38e was obtained as a single product, with
no evidence for the formation of 37e. The difference in the
product distribution between γ-lactones and β-lactones is due to
their ring strain (Scheme 9). The hydrosilylation of a carbonyl
group leading to 2-siloxyoxetane 40e (path a), which still has
O
(OC)4Co
path b
SiEt2Me
38e
O
O
SiEt2Me
Scheme 9. The reaction paths in β-lactone 36e.
Table 3. Co2(CO)8-catalyzed reactions of lactones with hydrosilanes and CO.a
a Reaction conditions: lactone (2.5 mmol), HSiMe3 (25 mmol, 2.9 mL) or HSiEt2Me (12.5 mmol), Co2(CO)8 (0.1 mmol, 34 mg), C6H6
(5 mL), under CO (1 atm). GC yields based on a lactone. NR refers to no reaction.
performed on a Sibata glass tube oven GTO-250R; boiling points
4. Conclusion
(bp) refer to air bath temperature and are uncorrected. 1H NMR
spectra were recorded on a JEOL JNM-PS-100 spectrometer in
CCl4 or a JEOL GSX-270 spectrometer in CDCl3 with
tetramethylsilane as an internal standard. Data are reported as
follows: chemical shift in ppm (δ), multiplicity (s = singlet, d =
doublet, t = triplet, m = multiplet, c = complex, and br = broad),
coupling constant (Hz), integration, and interpretation. Infrared
spectra (IR) were obtained on a Shimadzu IR-400 spectrometer;
absorptions are reported in reciprocal centimeters. Mass spectra
were obtained on a Hitachi Model RMU-6E spectrometer with
ionization voltages of 70 eV. Elemental analyses were performed
by the Elemental Analyses Section of Osaka University.
Analytical GLC was carried out on a Shimadzu GC-3BF gas
chromatograph, equipped with a flame ionization detector, using
a 6-m x 3-mm stainless steel column packed with 5% Silicone
The incorporation of one molecule of CO into acetals and
lactones proceeds under exceptionally mild reaction conditions
(ambient CO pressure and ambient temperature) with the site-
selective cleavage of the C-O bonds in acetals and lactones. In
the view of organic synthesis, the present reaction provides a
new and convenient method for nucleophilic introduction of a
siloxymethyl group at an acetal-carbon and for the preparation
of vicinal diol derivatives. The introduced siloxymethyl group
can easily be converted into useful functional groups, such as
hydroxymethyl,24 acetoxymethyl,25 halomethyl,26 aldehyde,27
and ester groups.28
4. Experimental
General Procedures. Bulb-to-bulb distillations were
6

OV-1 on 60-80-mesh Chromosorb W. Benzene and toluene were
distilled from sodium-lead alloy. CH2Cl2 and CH3CN were
distilled from CaH2. Co2(CO)8 was obtained from Strem
Chemicals, Inc., and purified by low-temperature
recrystallization from hexane. The acetals 8a, 8c, and 8d were
prepared by the acetalization of the corresponding aldehydes
with trimethyl orthoformate.18b The acetals 8b and 8e was
prepared from the corresponding aldehydes and ethylene
glycol.29 The hemiacetal esters 3 and 8f-8h were prepared by the
treatment of corresponding dimethyl acetals with Ac2O in the
presence of p-TsOH.15 Compound 4 was prepared according to
a literature method.30 Tetrahydrofuran derivatives 24b and 24c
were prepared according to a literature method.31 Compounds 26
and 30 were according to a literature method.32 Compounds 1, 6,
24a, 28, and 36a-36e were commercially available. HSiMe3 was
prepared from Me3SiCl and LiAlH4 following a literature
procedure.33 We designed a special apparatus shown in Figure 1
for handling HSiMe3, which has low boiling point (bp 6.7 °C).
This apparatus may be conveniently used for any other low
boiling compounds that have a vapor pressure below 20 atm at
room temperature. It is composed of a stainless steel reservoir A
in sizes from 50 to 200 mL, a needle valve B, a thick-walled
calibrated glass barrel of 10 mm x 150 mm C, a needle bulb
having a needle locking tip (Luer-Lok) D, and a Luer-Lok
syringe needle E. The HSiMe3 is transferred into A through B
and an appropriate connector by trap-to-trap distillation.
(container A should not be more than 80% filled for trap-to-trap
distillation for safety issues.). C, D, and E are then connected to
A, but B is closed. Positioning the apparatus with E in an upward
direction, the needle valves D and B are opened in this order and
remain open until the glass tube C is filled with HSiMe3 vapor.
After D is closed, the entire assembly is held upside down to
allow the HSiMe3 to be transferred into C as a liquid. Slightly
cooling C can be helpful. When the desired amount of HSiMe3
is collected in C, valve B is closed. The needle E is then inserted
through the septum of the reaction vessel, and the liquid HSiMe3
can be injected by opening the bulb D similar to the operation
when a normal syringe technique is used. The entire apparatus
(A-E) can be conveniently disassembled for use in a subsequent
procedure.
(52), 103 (14), 73 (100); Anal. Calcd for C10H26O3Si2: C, 47.95;
H, 10.46. Found: C, 47.60; H, 10.59.
((2-Methoxynonyl)oxy)trimethylsilane (9a). Bp 110-
120 °C (10 Torr); 1H NMR δ 0.08 (s, 9 H), 0.86 (t, J = 6 Hz, 3
H), 1.09-1.45 (m, 12 H), 2.87-3.17 (m, 1 H), 3.29 (s, 3 H), 3.35-
3.55 (m, 2 H); IR (neat) 2920, 2850, 1470, 1460, 1250, 1110,
1080, 870, 840, 750; MS, m/z (relative intensity) 246 (M+, 0),
231 (9), 143 (100), 111 (37), 89 (29), 73 (37), 69 (57); Anal.
Calcd for C13H30O2Si: C, 63.35; H, 12.27. Found: C, 63.21; H,
12.44.
5-Heptyl-2,2,10,10-tetramethyl-3,6,9-trioxa-2,10-
disilaundecane (9b). Bp 140-150 °C (2 Torr); 1H NMR δ 0.10
(s, 18 H), 0.90 (t, J = 6 Hz, 3 H), 1.14-1.64 (m, 12 H), 3.04-3.70
(m, 7 H, CH); IR (neat) 2930, 2870, 1470, 1260, 1110, 950, 850,
760, 690; MS, m/z (rel intensity) 348 (M+, 0), 245 (49), 201 (34),
117 (100), 103 (10), 73 (7); Anal. Calcd for C17H40O3Si2: C,
58.56; H, 11.56. Found: C, 58.62; H, 11.72.
Trimethyl(undecyloxy)silane (10b). Bp 120-130 °C (10
Torr); 1H NMR δ 0.08 (s, 9 H), 0.88 (t, J = 6 Hz, 3 H), 1.12-1.58
(m, 12 H), 3.33 (t, J = 6 Hz, 4 H), 3.60 (t, J = 6 Hz, 2 H); IR
(neat) 2920, 2850, 1460, 1250, 1100, 940, 840, 750; MS, m/z (rel
intensity) 246 (M+, 0), 231 (30), 119 (100), 103 (49), 75 (61), 73
(62), 57 (48); Anal. Calcd for C13H20O2Si: C, 63.35; H, 12.27.
Found: C, 63.26; H, 12.42.
Methyl
3-methoxy-4-((trimethylsilyl)oxy)butanoate
(9c). Bp 100-120 °C (20 Torr); 1H NMR δ 0.11 (s, 9 H), 2.50-
2.60 (m, 2 H), 3.41 (s, 3 H), 3.69 (s, 3 H), 3.56-3.71 (m, 3 H); IR
(neat) 2960, 2836, 1744, 1442, 1374, 1202, 1254, 1200, 1166,
1116, 1032, 1004, 956, 876, 844, 752, 690; MS, m/z 205 (M+-
15); Anal. Calcd for C9H20O4Si: C, 49.06; H, 9.15. Found: C,
48.78; H, 9.22.
(2-Methoxy-2-phenylethoxy)trimethylsilane (9d). Bp
1
100-120 °C (10 Torr); H NMR δ 0.07 (s, 9 H), 3.29 (s, 3 H),
3.64 (dd, J = 10.5, 4 Hz, 2 H), 3.75 (dd, J = 10.5, 7.5 Hz, 2 H),
4.25 (dd, J = 7.5, 4 Hz, 1 H), 7.29-7.35 (m, 5 H, Ph); IR (neat)
3060, 3030, 2950, 2870, 2825, 1500, 1460, 1360, 1250, 1210,
1180, 1100, 1060, 1040, 840, 760, 700; MS, m/z (rel intensity)
224 (M+, 1), 209 (1), 121 (100), 89 (14), 73 (13). Anal. Calcd for
C12H20O2Si: C, 64.24; H, 8.98. Found: C, 64.22; H, 9.10.
2,2,10,10-Tetramethyl-5-phenyl-3,9-dioxa-2,10-
1
disilaundecane (9e). Bp 100-120 °C (2 Torr); H NMR δ 0.02
when a normal syringe technique is used. The entire
apparatus (A-E) can be conveniently disassembled for use in a
(s, 9 H, Me3Si), 0.08 (s, 9 H), 3.26-3.80 (m, 6 H), 4.18-4.36 (m,
1 H); IR (neat) 3070, 3030, 2950, 2860, 1495, 1455, 1250, 1100,
840, 750, 700; MS, m/z (rel intensity) 326 (M+, 0), 223 (61), 189
(30), 147 (25), 117 (54), 73 (100); Anal. Calcd for C16H30O3Si:
C, 58.84; H, 9.26. Found: C, 59.04; H, 9.09.
subsequent
procedure.
Fig. 1. An apparatus for handling HSiMe3.
(2-(4-Chlorophenyl)-2-methoxyethoxy)trimethylsilane
(9h). Bp 100-120 °C (2 Torr); 1H NMR δ 0.04 (s, 9 H), 3.24 (s,
3 H), 3.44 (dd, J = 11, 6 Hz, 2 H), 3.64 (dd, J = 11, 7 Hz, 2 H),
4.10 (dd, J = 7, 6 Hz, 1 H), 7.29-7.35 (m, 4 H, Ph); IR (neat)
2950, 1600, 1490, 1410, 1255, 1210, 1100, 850; MS, m/z (rel
intensity) 258 (M+), 155 (100), 103(10), 89 (28), 73 (30).
5-Methoxy-2,2,10,10-tetramethyl-3,9-dioxa-2,10-
disilaundecane (25a). Bp 100-120 °C (10 Torr); 1H NMR δ 0.08
(s, 18 H), 1.28-1.64 (m, 4 H), 2.96-3.20 (m, 1 H), 3.32 (s, 3 H),
3.36-3.64 (m, 4 H): IR (neat) 2950, 2900, 2870, 2830, 1450,
1390, 1250, 1090, 940, 840, 750, 690; MS, m/z (rel intensity)
278 (M+, 0), 175 (20), 85 (100), 73 (35), 71 (91); Anal. Calcd for
C12H30O3Si2: C, 51.75; H, 10.86. Found: C, 51.70; H, 10.83.
5-(Benzyloxy)-2,2,10,10-tetramethyl-3,9-dioxa-2,10-
disilaundecane (25b). Bp 140-150 °C (1 Torr); 1H NMR δ 0.08
(s, 18 H), 1.28-1.68 (m, 4 H), 3.24-3.70 (m, 5 H), 4.52 (m, 2 H),
7.19 (s, 5 H); IR (neat) 3070, 3040, 2950, 2860, 1945, 1870,
1810, 1500, 1460, 1390, 1355, 1250, 1210, 1100, 840, 750; MS,
m/z (rel intensity) 354 (M+, 0), 251 (4), 158 (13), 143 (10), 103
(10), 91 (100), 73 (21); Anal. Calcd for C18H34O3Si2: C, 60.96;
General Procedure for the Co2(CO)8-Catalyzed
Reaction of Acetals with Hydrosilane and Carbon Monoxide.
In a 10-mL reaction flask with an efficient condensed (dry-ice-
CH3OH) was placed Co2(CO)8 (0.1 mmol, 34 mg), after the flask
was flashed with CO (1 atm from a stock balloon), HSiMe3 (25
mmol, 2.9 mL) was added using a pressure syringe at 25 °C.34
After 5 min, benzene (5 mL) and octanal dimethylacetal (8a) (2.5
mmol, 435 mg) were added and the mixture was stirred at 25 °C
(bath temperature, under reflux of HSiMe3) for 6 days under CO
(1
atm).
GC
analysis
showed
that
[(2-
methoxynonyl)oxy]trimethylsilane (9a) was formed in 86%
yield. Kugel rohr distillation (110-120 °C/10 Torr) gave
essentially pure 9a (410 mg, 67% yield). An analytical sample
was obtained by preparative GC purification (Silicone OV-1).
2,2,10,10-Tetramethyl-3,6,9-trioxa-2,10-disilaundecane
(7). Bp 100-110 °C (11 Torr); 1H NMR δ 0.12 (s, 18 H), 3.44
(dd, J = 4, 6 Hz, 4 H), 3.68 (dd, J = 4, 6 Hz, 4 H); IR (neat) 2950,
2850, 1460, 1250, 1140, 1100, 940, 840, 750, 680; MS, m/z
(relative intensity) 250 (M+, 0), 235 (4), 191 (5), 147 (14), 117
7

H, 9.6.
Found: C, 60.82; H, 9.78.
Acknowledgements
This work was supported, in part, by grants from Ministry
of Education, Culture, Sports, Science and Technology, Japan
(MEXT). Thanks are also given to the Instrumental Analysis
Center, Faculty of Engineering, Osaka University, for assistance
in obtaining MS and elemental analyses.
2,2,11,11-Tetramethyl-7-(((trimethylsilyl)oxy)methyl)-
3,8-dioxa-2,11-disiladodecane (25c). Bp 130-140 °C (2 Torr);
1H NMR δ 0.01 (s, 9 H), 0.09 (s, 9 H), 0.82 (t, J = 7 Hz, 2 H),
1.29-1.65 (m, 4 H), 3.01-3.67 (m, 7 H); IR (neat) 2960, 2900,
2870, 1250, 1000, 940, 850, 750, 690; MS, m/z (rel intensity)
364 (M+, 0), 233 (12), 143 (94), 101 (13), 73 (100); Anal. Calcd
for C16H40O3Si3: C, 52.69; H, 11.05. Found: C, 52.76; H, 11.24.
5-Methoxy-2,2,11,11-tetramethyl-3,10-dioxa-2,11-
disiladodecane (29). Bp 110-120 °C (10 Torr); 1H NMR δ 0.06
(s, 18 H), 1.20-1.56 (m, 6 H), 2.88-3.12 (m, 1 H), 3.26 (s, 3 H),
3.32-3.60 (m, 4 H); IR (neat) 2950, 2900, 2850, 2820, 1470,
1440, 1390, 1250, 1100, 840, 750, 660; MS, m/z (rel intensity)
293 (M+, 0), 189 (13), 103 (14), 99 (14), 85 (100), 73 (54); Anal.
Calcd for C13H32O3Si2: C, 53.37; H, 11.02. Found: C, 53.60; H,
11.18.
Trimethyl((tetrahydro-2H-pyran-2-yl)methoxy)silane
(31). 1H NMR δ 0.10 (s, 3 H), 0.61 (q, J = 7.8 Hz, 4 H), 0.96 (t,
J = 7.8 Hz, 6 H), 1.48-1.92 (m, 6 H), 3.43-3.51 (m, 1 H), 2.92-
3.97 (m, 1 H), 4.88 (dd, J = 6, 3 Hz, 1 H); IR (neat) 2956, 2884,
1462, 1446, 1418, 1397, 1352, 1324, 1273, 1254, 1202, 1166,
1134, 1118, 1089, 1030, 1024, 992, 934, 910, 874, 846, 828, 802,
770, 690; MS, m/z (rel intensity) 202 (M+, 0), 174 (30), 117 (10),
99 (100); Anal. Calcd for C10H22O2Si: C, 59.35; H, 10.96.
Found: C, 59.55; H, 11.14.
References
1.
For reviews on acetals in organic synthesis, see: A. D.
Dilman, S. L. Ioffe, Chem. Rev. 2003, 103, 733-772. J.
Janssens, M. D. P. Risseeuw, J. Van der Eycken, S. Van
Calenbergh, Eur. J. Org. Chem. 2018, 6405-6431.
2.
E. Colvin, Silicon in Organic Synthesis; Butterworths:
London, 1981. W. P. Weber, Silicon Reagents for Organic
Synthesis; Springer-Verlag: Berlin, 1983. P. Magnus, T. S.
Sarkar, Comprehensive Organometallic Chemistry;
Wilkinson, G., Ed.; Pergamon: New York, 1984; Vol. 7.
Using various synthetic equivalents of -CH2OR, vicinal
diol derivatives have been prepared from aldehydes with
the formation of the two carbon units at the same time. W.
C. Still, J. Am. Chem. Soc. 1978, 100, 1481. N. Meyer, D,
Seebach, Chem. Ber. 1980, 113, 1290. W. C. Still, C.
Sreekumar, J. Am. Chem. Soc. 1980, 102, 1201. T. Cohen,
J R. Matz, J. Am. Chem. Soc. 1980, 102, 6900. E. J. Corey,
T. M. Eckrich, Tetrahedron Lett. 1983, 24, 3163. E. J.
Corey, T. M. Eckrich, Tetrahedron Lett. 1983, 24, 3165. K.
Tamao, N. Ishida, M. Kumada, J. Org. Chem. 1983, 48,
2120. T. Imamoto, T. Takayama, M. Yokoyama,
Tetrahedron Lett. 1984, 25, 3225. K. Tamao. N. Ishida,
Tetrahedron Lett. 1984, 25, 4245. J. S. Sawyer, A.
Kucerovy, T. L. MacDonald, G. J. McGarvey, J. Am. Chem.
Soc. 1988, 110, 842. C. R. Johnson, J. R. Medich, J. Org.
Chem. 1988, 53, 4131. T. Hiiro, Y. Atarashi, N. Kambe, S.
Fujiwara, A. Ogawa, I. Ryu, N. Sonoda, Organometallics
1990, 9, 1355. J. Park, S. F. Pedersen, Tetrahedron 1992,
48, 2069. A. Guijarro, M. Yus, Tetrahedron Lett. 1996, 37,
5593. K. Itami, K. Mitsudo, J.-i. Yoshida, Tetrahedron Lett.
1999, 40, 5537. R. P. Smyj, J. M. Chong, Org. Lett. 2001,
3, 2903. S. Nakamura, Y. Ito, L. Wang, T. Toru, J. Org.
Chem. 2004, 69, 1581. L. Ma, D. Zhao, L. Chen, X. Wang,
Y.-L. Chen, J. Shen, Tetrahedron 2012, 68, 8704.
3.
2,2,10,10-tetramethyl-5-((trimethylsilyl)oxy)-3,9-dioxa-
2,10-disilaundecane (37a). Bp 90-100 °C (3 Torr); H NMR δ
1
0.08 (s, 27 H), 1.16-1.76 (m, 4 H), 3.34 (d, J = 6 Hz, 2 H), 3.42-
3.76 (m, 3 H); IR (neat) 2950, 2890, 2850, 1440, 1390, 1250,
1100, 840, 750, 680; MS, m/z (rel intensity) 336 (M+, 0), 233
(17), 147 (17), 143 (100), 85 (13), 73 (63); Anal. Calcd for
C19H36O3Si3: C, 49.94; H, 10.78. Found: C, 49.96; H, 10.87.
2,2,4,10,10-Pentamethyl-7-((trimethylsilyl)oxy)-3,9-
1
dioxa-2,10-disilaundecane (37b). Bp 90-100 °C (2 Torr); H
NMR δ 0.00 (s, 27 H), 1.00 (d, J = 6 Hz, 3H), 1.16-1.44 (m, 4
H), 3.25 (d, J = 5 Hz, 2 H), 3.36-3.72 (m, 2 H); IR (neat) 2950,
2900, 2860, 1450, 1380, 1250, 1080, 840, 750, 680; MS, m/z (rel
intensity) 348 (M+, 0), 247 (15), 157 (100), 147 (14), 117 (15),
73 (49); Anal. Calcd for C20H38O3Si3: C, 51.37; H, 10.92. Found:
C, 51.41; H, 11.20.
2,2,10,10-Tetramethyl-4-pentyl-7-((trimethylsilyl)oxy)-
3,9-dioxa-2,10-disilaundecane (37c). Bp 100-120 °C (1 Torr);
1H NMR δ 0.08 (s, 27 H), 0.87 (t, J = 5 Hz, 3 H), 1.12-1.56 (m,
12 H), 3.30 (d, J = 5 Hz, 2 H), 3.38-3.68 (m, 2 H); IR (neat) 2950,
2860, 1450, 1380, 1250, 1080, 840, 750, 680; MS, m/z (rel
intensity) 406 (M+, 0), 303 (23), 213 (100), 173 (25), 129 (44),
73 (47); Anal. Calcd for C19H46O3Si3: C, 56.09; H, 11.40. Found:
C, 56.27; H, 11.61.
2,2,11,11-Tetramethyl-5-((trimethylsilyl)oxy)-3,10-
dioxa-2,11-disiladodecane (37d). Bp 100-110 °C (10 Torr); 1H
NMR δ 0.06 (s, 27 H), 1.16-1.56 (m, 6 H), 3.22-3.34 (m, 2 H),
3.34-3.58 (m, 3 H); IR (neat) 2950, 2870, 1460, 1440, 1390,
1250, 1100, 860, 750, 690; MS, m/z (rel intensity) 350 (M+, 0),
247 (15), 157 (16), 147 (31), 129 (21), 85 (100), 73 (72); Anal.
Calcd for C20H38O3Si3: C, 51.37, H, 10.92. Found: C, 51.60; H,
11.19.
4.
5.
For reviews on the construction of vicinal diols, see: C.
Wang, Asian J. Org. Chem. 2018, 7, 509-521.
Our review on transition metal/HSiR3/CO, see: Chatani,
N.; Murai, S. Synlett 1996, 414. See also: W. Yao, M.-j.
Xia, X.-b. Meng, Q. Li, Z.-j. Li, Org. Biomol. Chem. 2014,
12, 8180. J. E. R. Pena, E. J. Alexanian, Org. Lett. 2017,
19, 4413. G. Albano, M. Morelli, L. A. Aronica, Eur. J. Org.
Chem. 2017, 3473. F. Zhu, A. Spannenberg, X.-F. Wu,
Chem. Commun. 2017, 53, 13149. S. Zhao, N. P. Mankad,
Angew. Chem., Int. Ed. 2018, 57, 5867. B. Chen, X.-F. Wu,
Org. Lett. 2019, 21, 2899. B. Cho, X.-F. Wu, Adv. Synth.
Catal. 2019, 361, 3441.
6.
F. Piacenti, M. Bianchi, Organic Syntheses via Metal
Carbonyls; Wiley-Interscience: I. Wender, P. Pino, Eds.
New York, 1977, Vol 2 pp 1-42.
Diethyl(methyl)silyl
4-
7.
8.
T. Murai, Y. Hatayama, S. Murai, N. Sonoda,
Organometallics 1983, 2, 1883.
((diethyl(methyl)silyl)oxy)butanoate (38e). Bp 110-120 °C
(2.2 Torr); 1H NMR δ 0.02 (s, 3 H, Me3Si), 0.19 (s, 3 H), 0.37-
1.19 (m, 20 H), 1.69 (quit, J = 7 Hz, 2 H), 2.27 (t, J = 7 Hz, 2 H),
3.54 (t, J = 7 Hz, 2 H); IR (neat) 2950, 2870, 1720, 1465, 1420,
1260, 1190, 1100, 1010, 800, 760; MS, m/z (rel intensity) 304
(M+, 0), 289 (6), 275 (100), 189 (71), 161 (71), 101 (29), 73 (43);
Anal. Calcd for C14H32O3Si2: C, 55.21; H, 10.59. Found: C,
55.25; H, 10.65.
(a) T. Murai, S. Kato, S. Murai, T. Toki, S. Suzuki, N.
Sonoda, N. J. Am. Chem. Soc. 1984, 106, 6093. (b) T.
Murai, E. Yasui, S. Kato, Y. Hatayama, S. Suzuki, Y.
Yamasaki, N. Sonoda, H. Kurosawa, Y. Kawasaki, S.
Murai, J. Am. Chem. Soc. 1989, 111, 7938.
9.
T. Murai, K. Furuta, S. Kato, S. Murai, N. Sonoda, J.
Organomet. Chem. 1986, 302, 249.
10. N. Chatani, T. Ikeda, T. Sano, N. Sonoda, H. Kurosawa, Y.
8

Kawasaki, S. Murai, J. Org. Chem. 1988, 53, 3387.
11. N. Chatani, T. Sano, K. Ohe, Y. Kawasaki, S. Murai, J. Org.
Chem. 1990, 55, 5923.
2246.
32. S. Lee, P. S. J. Kaib, B. List, J. Am. Chem. Soc. 2017, 139,
2156.
12. N. Chatani, Y. Kajikawa, H. Nishimura, S. Murai,
Organometallics 1991, 10, 21.
33. O. W. Steward, O. R. Pierce, J. Am. Chem. Soc. 1961, 83,
1916.
13. For the synthesis of ethylene glycol or glycolaldehyde
from formaldehyde derivatives and CO, see: K. Murata, A.
Matsuda, T. Masuda, T. Bull. Chem. Soc. Jpn. 1985, 58,
2141. Marchionna, M.; Longoni, G. Gazz. Chim. Ital. 1986,
116, 453. M. Marchionna, G. Longoni, Organometallics
1987, 6, 606. Z. B. Wang, T. Shimada, H. Takagi, C.-H.
Ahn, T. Sano, K. Soga, I. Takahashi, T. Masuda, Bull.
Chem. Soc. Jpn. 1999, 72, 1935. T. Li, Y. Souma, Q. Xu,
Catal. Today 2006, 111, 288.
34. We have designed a special syringe for handling HSiMe3,
which has a low boiling point (bp 6.7 °C). See ref 8b and
the experimental section for details.
14. For papers on the transformation of acetals to ethers by the
reduction with a hydrosilane, see: (a) T. Tsunoda, M.
Suzuki, R. Noyori, Tetrahedron Lett. 1979, 4679. (b) T.
Ohta, T. Michibata, K. Yamada, R. Omoria, I. Furukawa,
Chem. Commun. 2003, 1192.
15. W. B. Hughes, R. D. Kleene, J. Am. Chem. Soc. 1954, 76,
5161.
16. We previously reported on the siloxymethylation of benzyl
methyl ether with HSiMe3 and CO in the presence of
Co2(CO)8. See ref 11.
17. (a) A. J. Chalk, J. F. Harrod, J. Am. Chem. Soc. 1967, 89,
1640. (b) Y. L. Baay, A. G. MacDiarmid, Inorg. Chem.
1969, 8, 986.
18. D. L. Johnson, J. A. Gladysz, Inorg. Chem. 1981, 20, 2508.
M. Marsi, J. A. Gladysz, Organometallics 1982, 1, 1467.
19. (a) R. W. Wegman, Organometallics 1986, 5, 707. (b) I.
Kovacs, A. Sisak, F. Ungvary, L. Marko, Organometallics
1988, 7, 1025.
20. α-Alkoxy-substituted methyl- and acetylcobalt complexs
are known compounds, see: A. Sisak, E. Sampar-
Szerencses, V. Galamb, L. Nemeth, F. Ungvary, G. Palyi,
Organometallics 1989, 8, 1096.
21. N. Chatani, H. Tokuhisa, I. Kokubu, S. Fujii, S. Murai, J.
Organomet. Chem. 1995, 499, 193.
22. A similar site-selectivity has been observed in the reaction
of 24a with Me3SiCN. K. Utimoto, Y. Wakabayashi, T.
Horiie, M. Inoue, Y. Shishiyama, M. Obayashi, H. Nozaki,
Tetrahedron 1983, 39, 967. J. Koller, R. G. Bergman,
Organometallics 2012, 31, 2530.
23. For a paper on reduction of lactones to lactols with a
hydrosilane, see: X. Verdaguer, M. C. Hansen, S. C. Berk,
S. L. Buchwald, J. Org. Chem. 1997, 62, 8522. See also:
A. P. Davis, S. C. Hegarty, J. Am. Chem. Soc. 1992, 114,
2745.
24. T. W. Greene, Protective Groups in Organic Synthesis;
John Wiley & Sons, Inc.: New York, 1991. A. S. Pilcher,
D. K. Hill, S. J. Shimshock, R. E. Waltermire, P. Deshong,
J. Org. Chem. 1992, 52, 2492.
25. K. L. Chandra, C. P. Saravanan, V. K. Singh, V.
Tetrahedron Lett. 2001, 42, 5309.
26. Compound 35 was treated with SOBr2 in CDCl3 at 40 °C
for 1 day and then with pyridine for 2 days gave the
corresponding bromide in 63 % yield.
27. M. M. Heravi, D. Ajami, K. Tabar-Heydar, M. M.
Mojtahedi, J. Chem. Res. (S), 1998, 620.
28. I. E. Marko, A. Mekhalfia, W. D. Ollis, Synlett 1990, 345.
J. Muzart, A. N. Ajjou, Synlett 1991, 497.
29. Mukai, W. J. Cho, I. J. Kim, M. Kido, M. Hanaoka,
Tetrahedron 1991, 47, 3007.
30. R. A. McClelland, R. O. C. Norman, C. B. Thomas, J.
Chem. Soc., Perkin I 1972, 562.
31. G. F. Woods, D. N. Kramer, J. Am. Chem. Soc. 1947, 69,
9