α-β Unsaturated Acylsilanes as Surrogates of Acrolein for Morita–Baylis–Hillman Reactions

Article abstract of DOI:10.1002/ejoc.201801343

α-β-unsaturated acylsilanes are excellent substrates for Morita–Baylis–Hillman (MBH) reactions, affording the expected adducts in good to excellent yields. In these derivatives, as well as the corresponding acetates, the acylsilanes can be smoothly transf

Full text of DOI:10.1002/ejoc.201801343

A Journal of
Accepted Article
Title: α-β Unsaturated Acylsilanes as Surrogates of Acrolein for Morita-
Baylis-Hillman Reactions
Authors: Gangababu Marri, Frederic Justaud, Saibal Das, and Rene
Gree
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10.1002/ejoc.201801343
European Journal of Organic Chemistry
FULL PAPER
α-β Unsaturated Acylsilanes as Surrogates of Acrolein for Morita-
Baylis-Hillman Reactions
Gangababu Marri,[a] Frédéric Justaud,[b] Saibal Das,*[a] and René Grée*[b]
R
R
hν
OH
OH
365 nm
R1
R2
H2O
H
Si
MBH
+ RCHO
O
O
R
R3
R1
Si
R
hν
R2
R3
O
OAc
OAc
R1
R2
R3
365 nm
H2O
H
Si
O
O
synthesis.[4] Since the acylsilane group can be transformed to
aldehydes under very mild and neutral conditions (photolysis in
water/organic solvents mixtures),[5-6] we designed a strategy
where α-β unsaturated acylsilanes could be employed in the MBH
reaction and the adducts could be transformed directly and
efficiently into the target molecules (Scheme 1, Eq. 3 and 4). The
goal of this paper is to demonstrate, for the first time, that α-β
unsaturated acylsilanes can be used in MBH reactions affording
derivatives C and D and to validate this strategy towards type-A
and -B functionalized enals which appear as versatile synthetic
intermediates.
Abstract: α-β unsaturated acylsilanes are excellent substrates for
Morita-Baylis-Hillman (MBH) reactions, affording the expected
adducts in good to excellent yields. In these derivatives, as well as the
corresponding acetates, the acylsilanes can be smoothly transformed
into aldehydes by irradiation at 365 nm in acetone or THF/water
mixtures. Therefore α-β unsaturated acylsilanes are very useful
surrogates for acrolein in MBH reactions, allowing easy preparation of
simple and highly functionalized new building blocks for synthetic
applications.
Morita-Baylis-Hillman reaction
Introduction
HO
DBU or DABCO
R
The Morita-Baylis-Hillman (MBH) reaction has been established
as a major C-C bond forming reaction and the corresponding
adducts proved to be particularly useful for the preparation of a
very large number of molecules (Scheme 1, Eq. 1).[1] Since this
umpolung-type transformation involves the base-mediated
condensation of an electrophilic alkene, such as an acrylate, with
an aldehyde, the use of acrolein in this process is, at best, very
difficult. In fact, only few papers reports such an application and
important limitations have been usually observed.[2] Therefore, in
order to obtain the corresponding target molecules containing
both an allylic alcohol and a vicinal aldehyde (Scheme 1, type-A
and -B), the classical process will be to transform another
function, such as an ester group into the aldehyde by a reduction-
reoxidation process (Scheme 1, Eq. 2).[3]
Z = electron withdrawing groups such as ester,
sulfone, ketone, etc... but very rarely CHO
R = alkyl, aryl, heteroaryl...
(1)
Z
RCHO
Z
Previous work
HO
PGO
PGO
R
R
Reduction
R
MBH
Protection
CO2R1
CO2R1
CO2R1
OH
(2)
(3)
Oxidation
PGO
PGO
This work
H
R
R
[Si]
Protection
H
[Si]
HO
O
O
O
B
D
R
MBH
On the other hand, the acylsilanes are well recognized as highly
versatile functional groups with many applications in organic
[Si]
[Si]
O
HO
C
R
H
[Si]
(4)
PG = protecting group
[Si] = Si(R1)(R2)(R3
C
H
)
A
O
[a]
Dr. G. Marri, Dr. S. Das
CSIR-Indian Institute of Chemical Technology,
Department of Organic Synthesis and Process Chemistry,
Uppal Road, 500007 Hyderabad,
Telangana, India
Scheme 1. Morita-Baylis-Hillman reaction and our working
hypothesis toward the A and B target molecules
E-Mail: saibal@iict.res.in
Results and Discussion
[b]
Dr. F. Justaud, Dr. R. Grée
Univ Rennes, CNRS, ISCR (Institute for Chemical Sciences in
Rennes), UMR 6226, F-35000 Rennes, France.
E-mail: rene.gree@univ-rennes1.fr
To the best of our knowledge, only one method has been reported
to date for the preparation of molecules A. It involves the
condensation of the lithium anion of acrolein acetal with
aldehydes, followed by deprotection of the acetal. (Scheme 2, Eq.
5).[7] To be mentioned also, is the elegant method described
http://blogperso.univ-rennes1/rene.gree/index.php/
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org
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10.1002/ejoc.201801343
European Journal of Organic Chemistry
FULL PAPER
recently which affords highly electrophilic 2-methylene-1,3-
dicarbonyl compounds E (Scheme 2, Eq. 6).[8]
bearing strong electron-withdrawing substituents. When the MBH
reaction becomes slower and more difficult, the dimerization of
the unsaturated starting material becomes competitive and
affords higher yields of the Rauhut-Currier (RC) product.
HO
HO
O
Br
R
R
1) n-BuLi, -70°C
(OEt)2 2) RCHO
H2SO4, 0.25 N
(5)
Table 1. MBH reaction studies with acylsilane 3a as model
H
H
(OEt)2
C
C
C
H
A
Entry
RCHO (equiv.)
Time
(days)
Ratio a
(MBH:RC)
Adduct
(%)
5a(%)
R = alkyl, phenyl
O
O
O
C
R'
R'CCl
cat.
1
2
3
4
5
6
7
8
PhCHO (1.5)
6
72:28
100:00
68:32
80:20
96:4
4a (60)
6a (88)
7a (53)
8a (63)
9a (75)
10a (68)
11a (93)
12a (37)
16
0
(6)
H
H
4-NO2PhCHO (1.2)
4-BrPhCHO (1.5)
2-BrPhCHO (1.5)
3-BrPhCHO (1.5)
3-PyrCHO (1.5)
EtO2CCHO (1.2)
C4H9CHO (2.0)
2
O
DMSO-H2O
7
20
14
9
R' = Me, aryl, thiophene
E
6
Scheme 2. Alternative methods reported for the synthesis of
target molecules A and alkenes E
6
7
82:18
100:00
50:50
13
0
1.5
10
The synthesis of the α-β unsaturated acylsilanes 3 has been
performed by using slight optimizations (see Scheme 3 and
experimental section) of literature procedures. Starting from allylic
alcohol 1, and using retro-Brook reactions, the α-silyl allyl alcohols
2 have been obtained in good yields. The oxidation of alcohols 2
to the desired products 3 was performed efficiently by Swern
method, or by using DMSO activated by 2,4,6-Trichloro-1,3,5-
Triazine (TCT).[9] Latter method proved to be more convenient on
large scale reactions.
26
[a] Ratios between products resulting from Morita-Baylis-Hillman
adducts (MBH, 4a-12a) and Rauhut-Currier (RC, 5a) reaction,
established by 1H NMR analysis on the crude reaction mixtures.
In a next step, the MBH reaction was successfully extended to
other acylsilanes (Scheme 5 and Table 2). On reaction with a few
representative examples of aldehydes, this process could be
developed with acylsilanes bearing five other commonly used
groups: TMS, TIPS, TBDMS, SiMe2Ph and SiPh2Me.
1) n-BuLi
ClSi(R1)(R2)(R3)
Swern
R1
R1
R2
R3
Si
R3
Si
OH
R2 or TCT
2) sec-BuLi
O
HO
R1
O
1
2
R
3
Si
R2
OH
Si
R3
R1
DABCO
a: R1 = R2 = R3 = Et; b: R1 = R2 = Me, R3 = Ph; c: R1 = R2 = R3 = Me;
d: R1 = R2 = R3 = iPr; e: R1 = R2 = Me, R3 = tBu; f: R1 = Me, R2 = R3 = Ph
+
R1
R1
R2
+ RCHO
Si
R2
R3
EtOAc, RT
Si
R2
R3
5b-5f
O
O
R3
O
3b-3f
4b-12f
Scheme 3. Synthesis of the α-β unsaturated acylsilanes
Scheme 5. Extension to other acylsilanes 3b-3f
The α-β unsaturated acylsilane 3a and benzaldehyde were
selected to explore the MBH reaction with a vinylic acylsilane
(Scheme 4).[10]
Table 2. MBH reactions with acylsilanes 3a-3e
O
Entry
RCHO (equiv.)
Si(R1)(R2(R3)
Adduct (%)a
5a-5f
(%)
R
SiEt3
OH
DABCO
+
+ RCHO
1
PhCHO (1.5)
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
Si(Me)3
4b (40)
6b (77)
7b (34)
11b (88)
6c (92)
11c (22)
4d (10)
6d (30)
11d (70)
6e (34)
11e (54)
6f (72)
5b (11)
SiEt3
EtOAc, RT
SiEt3
SiEt3
2
4-NO2PhCHO (1.1)
4-BrPhCHO (1.2)
EtO2CCHO (1.2)
4-NO2PhCHO (1.2)
EtO2CCHO (1.5)
PhCHO (1.5)
0
O
O
O
3
5b (20)
3a
5a
4a-12a
4
0
Scheme 4. Reactivity studies starting from acylsilane 3a
5
0
6
Si(Me)3
0
7
Si(iPr)3
5d (20)
After some experiments it was found that using DABCO as the
nucleophilic catalyst and ethylacetate as the solvent, the desired
adduct 4a was obtained in 60% yield after six days at room
temperature in the dark (Table 1, entry 1). As a byproduct the
dimer 5a was also obtained, through a Rauhut-Currier (RC) type
reaction.[11] The MBH reaction was successfully extended to other
aromatic aldehydes with nitro- and bromo-substituents (entries 2-
5), as well as to the pyridine-3-carboxaldehyde (entry 6). Further,
after two days reaction, the glyoxylate ethylester gave the MBH
adduct only and in excellent yield (entry 7). The less reactive
pentanal afforded the adduct 12a, but in lower yield and as a
mixture with the dimer 5a (entry 8). Clearly, the α-β unsaturated
acylsilane 3a follows the general trends of the MBH reactions: the
reactions are faster, and giving higher yields, with aldehydes
8
4-NO2PhCHO (1.2)
EtO2CCHO (1.5)
4-NO2PhCHO (1.2)
EtO2CCHO (1.5)
4-NO2PhCHO (1.2)
EtO2CCHO (1.5)
Si(iPr)3
5d (25)
9
Si(iPr)3
0
0
0
0
0
10
11
12
13
Si-tBuMe2
Si-tBuMe2
SiPh2Me
SiPh2Me
11f (32)
[a] isolated yields of products resulting from Morita-Baylis-Hillman
adducts (MBH, 4b-11f) and Rauhut-Currier (RC, 5b-5d) reactions.
The results obtained show in general a similar tendency to those
obtained with the TES group, and the MBH adducts 4b-12f were
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10.1002/ejoc.201801343
European Journal of Organic Chemistry
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usually isolated in fair to good yields. However, in few cases
(entries 6-8, 10 and 13), lower yields were obtained due to the
lability of corresponding adducts.
were easily obtained from 4a and 6a using conditions A (Table 3,
entries 1 and 2). However, increasing the reaction time afforded
some transposed allylic derivative 14’a (18% of E isomer) (entry
The next step involved the protection of the allylic alcohol function. 3). Therefore, we had to use, in parallel, a method to isolate the
Based on our previous work in acylsilane chemistry,[5] we selected
the acetate group and the results are given in Scheme 6 and
Table 3. The reactions gave the desired acetates 13a-15f in fair
to good yields, although systematic optimization studies had to be
performed and several conditions (A, B and C) were used
depending upon the nature of the R group and the silyl
substituents (see Table 3 and experimental section).
transposed products in order to have authentic samples of such
molecules. Reaction of allylic acetate 14a with potassium acetate
in ionic liquids (conditions D),[12] afforded efficiently the
transposition product 14’a (entry 5, E isomer only). The
stereochemistry of the E isomer of 14’a was established by NoE
experiments. By using these methods, all desired derivatives 13-
15 could be prepared under appropriate conditions (Table 3),
while the regioisomeric derivatives 14’, 15’ were obtained as well
by using conditions D.
KOAc, [bmim][PF6]
R
O
R
O
The, final, key step involved the transformation of the acylsilane
units into aldehydes (Scheme 7). Based on our recent work, we
have employed photolytic conditions in a (1: 2) water: acetone
mixture and classical UV lamps at 365 nm.[13] By using these very
simple conditions the target molecules 16-18, with three
representative R groups (Ph, 4-NO2Ph and EtO2C) were obtained
in excellent yields from derivatives 13a-15f (Table 4). Importantly
this method proved to be successful, independently of the nature
of the silicon protecting groups (TES, TMS, TIPS and SiPhMe2)
and the enals 16-18 were obtained in good to excellent yields (69-
95%, Table 4, entries 1-13).
Ac2O, base, solvent
OH
Si
OAc
R1
R
R1
R2
R1
R2
R3
+
Si
AcO
Si
(see Table 3 and
experimental section)
R2
R3
O
R3
4a-11f
14'a-15'e
13a-15f
Scheme 6. Protection of acylsilanes MBH adducts
Table 3. Protection of MBH adducts
Entry
R
Si(R1)
(R2(R3)
Cond.
[a]
Time
(h)
Adduct
Yield
(%)
1
2
3
Ph
SiEt3
SiEt3
SiEt3
A
A
A
20
6
13a
14a
63
R
R
OAc
ν
h (365nm)
4-NO2Ph
4-NO2Ph
92
OAc
R1
48
14a
81 (18)
Acetone/H2O
Si
R2
H
+(14’a)
O
R3
O
R
4
4-NO2Ph
4-NO2Ph
EtO2C
SiEt3
C
D
A
B
B
B
A
D
A
C
B
B
C
D
C
D
A
C
C
6
2
14a
14’a
15a
13b
14b
15b
14c
14’c
15c
15c
14d
15d
14e
14’e
15e
15’e
14f
82
64
88
76
80
67
72
72
67
75
51
70
68
81
84
64
79[b]
54
77
16-18
13a-15f
5
SiEt3
R
6
SiEt3
40
6
OH
Si
hν (365nm)
OH
H
7
Ph
SiPhMe2
SiPhMe2
SiPhMe2
SiMe3
R1
R2
8
4-NO2Ph
EtO2C
5
THF/H2O: 9/1
O
R3
O
9
5
19-21
4a-11f
10
11
12
13
14
15
16
17
18
19
20
21
22
4-NO2Ph
4-NO2Ph
EtO2C
0.5
2
SiMe3
R1
R2
O
R1
R2
O
SiMe3
5
Si
Si
R3
hν (365nm)
EtO2C
SiMe3
24
5
R3
R1
R2
4-NO2Ph
EtO2C
SiiPr3
H
Acetone/ 2O
Si
H
SiiPr3
3
O
R3
O
4-NO2Ph
4-NO2Ph
EtO2C
SitBuMe2
SitBuMe2
SitBuMe2
SitBuMe2
SiPh2Me
SiPh2Me
SiPh2Me
48
2
22-24
5a-5d
24
2
Scheme 7. Conversion of acylsilanes MBH and RC adducts into
enals
EtO2C
4-NO2Ph
0.2
48
48
4-NO2Ph
14f
Further, it proved to be even possible to perform this
transformation directly on the first, non-protected, MBH adducts
4a-11f. In that case we changed the organic co-solvent from
acetone to THF, for solubility reasons. These reactions afforded
in fair to good yields the target molecules 19-21, with the same
three R groups as before (Table 4, entries 14-22).
EtO2C
15f
[a] Conditions A: Ac2O (2 equiv), Et3N (3 equiv), DMAP (0.1 equiv) DCM, 0 °C
to rt.; B: Ac2O (2 equiv), DMAP (0.1 equiv), DCM, rt; C: Ac2O (5 equiv),
NaHCO3 (2 equiv), DCM, rt ; D: KOAc (1.5 equiv), [bmim]PF6, 50 °C, 2 h.
[b] Temperature of the reaction: -10 °C.
Finally, to complete this study we considered the possibility to
use the same transformation of acylsilanes into aldehydes on the
Rauhut-Currier adducts 5a to 5d (Scheme 7). The reaction
The main reason was that, in several cases, during this
protection step, the products resulting from an allylic transposition
14’-15’ were also obtained. For instance, acetates 13a and 14a
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10.1002/ejoc.201801343
European Journal of Organic Chemistry
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afforded cleanly, and in good to excellent yields, the desired
and distilled prior to use. Anhydrous CH2Cl2 was prepared by
refluxing in the presence of CaH2 and distilled right before use.
We used a Vilber Lourmat VL-6.LC lamp equiped with two 6W
bulbs at 365 nm for the small scale reactions, or a LT5W T8/010
compounds 22 - 24 with both an enal and a remote acylsilane unit.
Table 4. Transformation of acylsilanes MBH adducts into enals.
1
UV Dudexa lamp from Narva for the larger scale reactions. H
NMR spectra were recorded at 300, 400 and 500 MHz, and 13C
NMR spectra were recorded at 75, 101 and 126 MHz, respectively
in CDCl3. The residual peak of CHCl3 was set at 7.26 ppm for 1H
Entry
Starting
Material
Product
R
Time
(h)
Yield
(%)
1
2
3
4
5
6
7
8
13a
14a
15a
13b
14b
15b
15c
14d
15d
14e
15e
14f
15f
4a
6a
11a
6c
11c
6e
11e
6f
16
17
18
16
17
18
18
17
18
17
18
17
18
19
20
21
20
21
20
21
20
21
22
23
24
Ph
48
48
40
24
40
20
40
20
6
20
24
20
24
20
48
48
48
48
48
48
48
48
24
40
8
95
92
53
88
88
83
95
75
80
91
95
69
81
61
78
81
86
53
86
63
93
74
60
90
90
NMR and the central peak of CDCl3 was set at 77.0 ppm for 13
C
4-NO2Ph
EtO2C
Ph
NMR. All products were purified by flash column chromatography
on silica gel (100 – 200 mesh).
4-NO2Ph
EtO2C
EtO2C
4-NO2Ph
EtO2C
4-NO2Ph
EtO2C
4-NO2Ph
EtO2C
Ph
4-NO2Ph
EtO2C
4-NO2Ph
EtO2C
4-NO2Ph
EtO2C
4-NO2Ph
EtO2C
-
General experimental procedure for the preparation of α-
hydroxyallylsilanes (2): to a solution of allyl alcohol 1 (1 equiv)
in anhydrous THF was added n-BuLi (1.2 equiv) at -78 oC. After
30 min stirring at the same temperature, SiR1R2R3Cl (1 equiv) in
dry THF was added in dropwise. Then, the reaction was warmed
to room temperature and stirred for 18 h. Next, sec-BuLi (1.05
equiv) was added in dropwise at -78 oC. After stirring for 2 h at -
50 oC, the reaction mixture was quenched with aqueous NH4Cl at
-78 oC, and then diluted with Et2O. The organic phase was
collected and the aqueous phase was extracted with Et2O for
twice. Combined organic phases were dried with Na2SO4,
concentrated under reduce pressure. The residue was purified by
column chromatography on silica gel to afford (2) as a colourless
oil. With this procedure we prepared all α-hydroxyallylsilanes (2a
to 2f).
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
11f
5a
5b
5d
-
-
This result is in agreement with literature data indicating that
conjugated acylsilanes are more easily cleaved under photolytic
conditions that non conjugated substrates.[6] Similar reactions
have been performed starting from the transposed (E) acylsilane
14’a. However, they did not afford the expected conjugated
aldehyde, and they gave only E-Z equilibration of this molecule,
without hydrolysis of the acylsilane unit.
General experimental procedure for preparation of
acryloylsilanes by Swern protocol (3a-3f): to a solution of
trifluoroacetic anhydride (1.5 equiv) in CH2Cl2 was added DMSO
o
(2 equiv) dropwise at -78 C. After 30 min stirring at the same
temperature, α- hydroxyallylsilanes (2a-2f) (1 equiv) in CH2Cl2
were added in dropwise. Then the reaction was stirred for 1 h at -
78 oC, and followed by adding TEA (3 equiv) slowly. After stirring
for another 1 h at -78 oC, the reaction mixture was quenched with
water and warmed to room temperature. The organic phase was
collected and the aqueous phase was extracted twice with CH2Cl2.
The organic phases were combined, dried with MgSO4 and
concentrated in vacuum. The residue was purified by column
chromatography on silica gel to afford acryloylsilanes (3a-3f) as
bright yellow liquids.
Conclusions
In summary, we have disclosed a short and efficient approach
toward new acrolein-type derivatives, functionalized in position 2.
Taking into account their multiple reactivity profile, these
[14]
molecules appear as versatile building blocks
for the
preparation of natural products, as well as various type of
bioactive compounds.
General experimental procedure for preparation of
acryloylsilanes by using TCT (3a-3f): DMSO (5 equiv) was
added slowly to a solution of 2,4,6-Trichloro-1,3,5-Triazine
(TCT,1.2 equiv) in THF, stirred and maintained at -30 °C for 30
min. Then, a solution of α-hydroxyallylsilane 3 (1.0 equiv) in dry
THF was added dropwise and stirring continued for a further 30
min. Finally Et3N (4 equiv) was added with an additional 30 min of
stirring. The mixture was poored in pentane under vigourous
stirring with appearance of a sticky mass of TEA salt, which was
discarded. The rest of the cloudy solution was stirred with an
excess of MgSO4 while addition of a small amount of water (0.5
to 1.0 ml) permitted the clearance of this solution. Then, it was
filtrated and the volatiles were evaporated at 450 Mbar with a
water bath at 45°C. Additional pentane was added twice to ensure
the total impoverishment of the solvent by azeotropic distillation.
Experimental section
General Information: All anhydrous reactions were performed in
oven-dried round-bottomed flasks under a dry argon atmosphere.
Air and moisture-sensitive compounds were introduced via
syringes or cannulae, using standard inert atmosphere
techniques. Reactions were monitored by thin layer
chromatography (TLC) using E. Merck silica gel plates and
components were visualized by illumination with short-
wavelength UV light and/or staining (p-anisaldehyde or basic
KMnO4). All reagents were used as they were received from
commercial suppliers, unless otherwise noted. THF was dried in
the presence of sodium metal using benzophenone as indicator
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10.1002/ejoc.201801343
European Journal of Organic Chemistry
FULL PAPER
The product was purified by column chromatography on silica gel
to afford acryloylsilanes (3a-3f) as bright yellow liquids.
General experimental procedure for the preparation of α-
functional α,β-unsaturated acylsilanes via MBH reactions:
To a solution of acryloylsilane 3 in EtOAc was added the aldehyde,
1-(Triethylsilyl)prop-2-en-1-one (3a): Rf: 0.8 (5:95 EtOAc/n-
Hexane); Yield 88%, as a yellow oil; FT-IR (film) 2954, 2876, 1598, followed by DABCO at 0 oC and reached room temperature with
1180, 1002, 730 cm-1; 1H NMR (500 MHz, CDCl3) δ = 6.44 (dd, J
= 17.9, 10.8 Hz, 1H), 6.03 (dd, J = 17.9, 1.1 Hz 1H), 5.83 (dd, J =
10.8, 1.1 Hz, 1H), 0.93 (t, J = 7.8 Hz, 9H), 0.75 (2 x q, J = 7.8, 1.0
Hz, 6H) ppm; 13C NMR (126 MHz, CDCl3) δ = 237.7, 142.1, 127.2,
7.1, 2.9 ppm; HRMS (ESI +ve) Exact mass calculated for
C9H18ONaSi [M+Na]+: 193.1019, found: 193.1022.
stirring. After consumption of the starting material, water was
added and the organic phase was separated and washed with
water. Aqueous phases were extracted with EtOAc twice and the
organic phases gathered, dried with MgSO4 and concentrated
under reduced pressure. The crude product was purified by
column chromatography.
1-(Dimethyl(phenyl)silyl)prop-2-en-1-one (3b): Rf: 0.6 (5:95
EtOAc/n-Hexane); Yield 80% as a yellow oil; FT-IR (film) 2960,
2871, 1600, 1428, 1250, 1183, 1110, 1024, 955, 815, 783, 697,
653 cm-1; 1H NMR (500 MHz, CDCl3) δ = 7.56-7.51 (m, 2H), 7.43-
7.34 (m, 3H), 6.41 (dd, J = 17.9, 10.8 Hz, 1H), 5.99 (dd, J = 17.9,
0.9 Hz, 1H), 5.86 (dd, J = 10.8, 0.9 Hz, 1H), 0.53 (s, 6H) ppm; 13C
NMR (75 MHz, CDCl3) δ = 235.8, 141.2, 135.1, 133.9, 129.9,
129.4, 128.2, -3.6 ppm; HRMS (ESI +ve) Exact mass calculated
for C11H15OSi [M+H]+; 191.0892, found: 191.0890.
2-(Hydroxy(phenyl)methyl)-1-(triethylsilyl)prop-2-en-1-one
(4a): yield 60% as a yellow oil. FT-IR (film) 3447, 2954, 2875,
1594, 1454, 1019, 734, 697 cm-1; 1H NMR (500 MHz, CDCl3) δ =
7.32 – 7.25 (m, 4H), 7.23-7.19 (m, 1H), 6.14 (d, J = 1.3 Hz, 1H),
6.09 (s, 1H), 5.53 (d, J = 4.6 Hz, 1H), 3.51 (d, J = 4.9 Hz, 1H),
0.90 (t, J = 7.8 Hz, 9H), 0.75-0.77 (2 x q, J = 7.8 Hz, 6H) ppm; 13
C
NMR (126 MHz, CDCl3) δ 239.3, 155.7, 141.9, 128.2, 127.9,
127.4, 126.6, 72.2, 7.2, 3.5 ppm; HRMS (ESI +ve) Exact mass
calculated for C16H24O2NaSi [M+Na]+: 299.1437, found: 299.1438.
1-(Trimethylsilyl)prop-2-en-1-one (3c): Rf : 0.7 (5:95 EtOAc/n-
Hexane); Yield 91% as a yellow oil; FT-IR (film) 2960, 1734, 1460,
1259, 1083, 842, 800 cm-1; 1H NMR (300 MHz, CDCl3) δ 6.43 (dd,
J = 18.0, 10.7 Hz, 1H), 6.12 (dd, J = 18.0, 1.0 Hz, 1H), 5.97 (dd,
J = 10.7, 1.0 Hz, 1H), 0.27 (s, 9H) ppm; 13C NMR (75 MHz,
CDCl3) δ 237.8, 141.4, 128.5, -2.3 ppm; HRMS (ESI +ve) Exact
2-methylene-1,5-bis(triethylsilyl)pentane-1,5-dione (5a): yield
16% as a yellow oil. FT-IR (film) 2954, 2876, 1641, 1595, 1414,
1004, 719 cm-1; 1H NMR (300 MHz, CDCl3) δ = 6.04 (broad s, 1H),
5.95 (s, 1H), 2.68-2.60 (t, J = 7.4 Hz ,2H), 2.39 (tq, J = 7.4, 1.2
Hz, 2H), 0.94 (t, J = 6.5 Hz, 18H), 0.82-0.66 (2 x q, J = 6.5 Hz, 2
x 6H); 13 ppm C NMR (126 MHz, CDCl3) δ = 246.4, 237.5, 154.4,
mass calculated for C6H13OSi [M+H]+; 129.0730, found: 129.0731. 128.6, 48.8, 22.1, 7.4, 7.3, 3.9, 2.2 ppm; HRMS (ESI +ve) Exact
mass calculated for C18H36O2NaSi2 [M+Na]+: 363.2146, found:
1-(Triisopropylsilyl)prop-2-en-1-one (3d): Rf: 0.8 (5:95
EtOAc/n-Hexane); Yield 55% as a yellow oil; FT-IR (film) 2944,
2867, 1637, 1576, 1464, 1390, 1177, 986, 882, 677, 642 cm-1; 1H
NMR (400 MHz, CDCl3) δ = 6.70 (dd, J = 17.4, 10.6 Hz, 1H), 5.96
(dd, J = 17.4, 1.5 Hz, 1H), 5.56 (dd, J = 10.6, 1.5 Hz, 1H), 1.34
(hept, J = 7.5 Hz, 3H), 1.11 (d, J = 7.5 Hz, 18H) ppm; 13C NMR
(101 MHz, CDCl3) δ = 236.7, 141.0, 123.6, 18.5, 11.1 ppm;
HRMS: (ESI -ve) Exact mass calculated for C12H25OSi [M+H]+;
213.1675, found: 213.1678.
363.2150.
2-(Hydroxy(4-nitrophenyl)methyl)-1-(triethylsilyl)prop-2-en-
1-one (6a): yield 88% as a yellow oil. FT-IR (film) 3464, 2956,
2876, 1594, 1519, 1344, 1014, 851, 737 cm-1; 1H NMR (300 MHz,
CDCl3) δ = 8.19 (d, J = 8.7 Hz, 2H), 7.53 (d, J = 8.7 Hz, 2H), 6.21
(s, 1H), 6.17 (d, J = 1.1 Hz, 1H), 5.63 (d, J = 5.5 Hz, 1H), 3.37 (dt,
J = 5.2, 2.7 Hz, 1H), 0.93 (t, J = 7.5 Hz, 9H), 0.83 - 0.75 (3 x q , J
= 7.8 Hz, 6H) ppm; 13C NMR (126 MHz, CDCl3) δ = 239.6, 154.3,
149.1, 147.2, 129.6, 127.2, 123.5, 72.2, 7.2, 3.5 ppm; HRMS (ESI
+ve) Exact mass calculated for C16H23NO4NaSi [M+Na]+:
344.1288, found: 344.1289.
1-(Tert-butyldimethylsilyl)prop-2-en-1-one (3e): Rf : 0.75 (5:95
EtOAc/n-Hexane); Yield: 89% as a yellow oil; FT-IR (film) 2854,
1644, 1463, 1259, 1082, 1018, 800 cm-1; 1H NMR (300 MHz,
CDCl3) δ = 6.59 (dd, J = 17.7, 10.7 Hz, 1H), 6.04 (dd, J = 17.7,
1.3 Hz, 1H), 5.77 (dd, J = 10.7, 1.3 Hz, 1H), 0.95 (s, 9H), 0.25 (s,
6H) ppm; 13C NMR (75 MHz, CDCl3) δ = 236.9, 141.4, 126.4,
26.5, 16.6, -6.2 ppm; HRMS (ESI -ve) Exact mass calculated for
C9H19OSi [M+H]+; 171.1199, found: 171.1202.
2-((4-Bromophenyl)(hydroxy)methyl)-1-(triethylsilyl)prop-2-
en-1-one (7a): yield 53% as a yellow oil. FT-IR (film) 3435, 2954,
2875, 1590, 1486, 1010, 731 cm-1; 1H NMR (500 MHz, CDCl3) δ
= 7.45 (d, J = 7.6 Hz, 2H), 7.22 (d, J = 7.7 Hz, 2H), 6.15 (s, 1H),
6.13 (d, J = 1.2 Hz, 1H), 5.51 (s, 1H), 0.93 (t, J = 7.5 Hz, 9H), 0.79
(q , J = 7.5 Hz, 6H) ppm; 13C NMR (126 MHz, CDCl3) δ = 239.7,
154.9, 140.7, 131.4, 128.8, 128.2, 121.3, 72.1, 7.2, 3.5 ppm;
HRMS (ESI +ve) Exact mass calculated for C16H23O2BrNaSi
[M+Na]+: 377.0542, found: 377.0543.
1-(Methyldiphenylsilyl)prop-2-en-1-one (3f): Rf : 0.6 (5:95
EtOAc/n-Hexane); Yield 73% as a yellow oil; FT-IR (film) 3048,
1638, 1486, 1427, 1251, 1185, 1110, 997, 790, 727, 696 cm-1; 1H
NMR (300 MHz, CDCl3) δ = 7.64-7.58 (m, 4H), 7.50-7.35 (m, 6H),
6.57 (dd, J = 17.8, 10.8 Hz, 1H), 6.02 (dd, J = 17.8, 0.9 Hz, 1H),
5.85 (dd, J = 10.8, 0.9 Hz, 1H), 0.81 (s, 3H) ppm; 13C NMR (75
MHz, CDCl3) δ = 233.7, 141.4, 135.1, 133.2, 130.1, 129.6, 128.2,
-4.3 ppm; HRMS (ESI +ve) Exact mass calculated for
C16H16ONaSi [M+Na]+; 275.0862, found: 275.0864.
2-((2-Bromophenyl)(hydroxy)methyl)-1-(triethylsilyl)prop-2-
en-1-one (8a): yield 63% as a yellow oil. FT-IR (film) 3065, 2960,
2912, 2876, 1596, 1466, 1020, 741 cm-1; 1H NMR (500 MHz,
CDCl3) δ = 7.59 (dd, J = 8.0, 1.7 Hz, 1H), 7.54 (dd, J = 8.0, 1.2
Hz, 1H), 7.37 (td, J = 7.6, 1.2 Hz, 1H), 7.17 (td, J = 7.6, 1.7 Hz,
1H), 6.12 (s, 1H), 5.87 (d, J = 3.3 Hz, 1H), 5.80 (d, J = 1.0 Hz, 1H),
3.52 (d, J = 3.7 Hz, 1H), 0.98 (t, J = 7.2 Hz, 9H), 0.83 - 0.75 (2 x
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201801343
European Journal of Organic Chemistry
FULL PAPER
q , J = 7.8 Hz, 6H) ppm; 13C NMR (126 MHz, CDCl3) δ = 239.8,
153.8, 140.0, 132.6, 129.5, 129.0, 128.5, 127.5, 122.6, 70.8, 7.3,
3.6 ppm; HRMS (ESI +ve) Exact mass calculated for
C16H23O2BrNaSi [M+Na]+: 377.0542, found: 377.0542.
1,5-Bis(dimethyl(phenyl)silyl)-2-methylenepentane-1,5-dione
(5b): yield 11% as a yellow oil. FT-IR (film) 2960, 1642, 1596,
1
1427, 1251, 1109, 812, 781, 730, 697, 649 cm-1; H NMR (300
MHz, CDCl3) δ = 7.50 (m, 4H), 7.36 (m, 6H), 5.81 (d, J = 2.3 Hz,
2H), 2.63 (t, J = 7.2 Hz, 2H), 2.34 (t, J = 7.2 Hz, 2H), 0.49 and
0.45 (s, 6H) ppm; 13C NMR (75 MHz, CDCl3) δ = 244.5, 235.2,
152.5, 136.0, 134.3, 133.9, 133.8, 130.0, 129.9, 129.7, 128.2,
47.2, 22.2, -2.7, -4.7 ppm; HRMS (ESI +ve) Exact mass
calculated for C22H28O2NaSi2 [M+Na]+: 403.1526, found:
403.1522.
2-((3-Bromophenyl)(hydroxy)methyl)-1-(triethylsilyl)prop-2-
en-1-one (9a): yield 75% as a yellow oil. FT-IR (film) 3435, 2954,
1875, 1590, 1486, 1403, 1234, 1070, 815, 731 cm-1; 1H NMR (400
MHz, CDCl3) δ = 7.47 (s, 1H), 7.40-7.33 (dd, J = 7.8, 1.5 Hz, 1H,
1H), 7.24 (dd, J = 7.8, 1.5 Hz, 1H), 7.17 (td, J = 7.8, 1.0 Hz, 1H),
6.15-6.12 (m, 2H), 5.49 (d, J = 4.2 Hz, 1H), 3.49-3.42 (m, 1H),
0.91 (t, J = 7.8 Hz, 9H), 0.77 (q , J = 7.8 Hz, 6H) ppm; 13C NMR
(101 MHz, CDCl3) δ = 239.7, 154.8, 144.1, 130.5, 129.8, 129.5,
128.8, 125.2, 122.4, 71.9, 7.2, 3.5 ppm; HRMS (ESI +ve) Exact
mass calculated for C16H23O2BrNaSi [M+Na]+: 377.0542, found:
377.0542.
1-(Dimethyl(phenyl)silyl)-2-(hydroxy(4-nitrophenyl)methyl)
prop-2-en-1-one (6b): yield 77% as a yellow oil. FT-IR (film) 3486,
2959, 1688, 1596, 1518, 1344, 1252, 1109, 1066, 818, 786, 735,
652 cm-1; 1H NMR (300 MHz, CDCl3) δ = 7.95 (d, J = 8.7 Hz, 2H),
7.29 - 7.24 (m, 4H), 7.23 - 7.13 (m, 3H), 5.92 (s, 1H), 5.89 (s, 1H),
5.39 (d, J = 5.4 Hz, 1H), 3.15 (d, J = 5.4, 1H), 0.33 (s, 6H) ppm;
13C NMR (75 MHz, CDCl3) δ = 237.3, 152.9, 148.9, 147.2, 134.7,
133.7, 130.9, 130.1, 128.3, 127.2, 123.5, 72.0 -3.2 ppm; HRMS
(ESI +ve) Exact mass calculated for C18H19NO4NaSi [M+Na]+:
364.0981, found: 364.0981.
2-(Hydroxy(pyridin-3-yl)methyl)-1-(triethylsilyl)prop-2-en-1-
one (10a): yield 68% as a yellow oil. FT-IR (film) 3170, 2954,
2875, 1593, 1424, 948, 711 cm-1; 1H NMR (300 MHz, CDCl3) δ =
8.46 (d, 0.9 Hz, 1H), 8.38 (dd, J = 4.8, 1.9 Hz, 1H), 7.68 (ddt, J =
7.8, 1.9, 0.9 Hz, 1H), 7.21 (dd, J = 7.8, 4.8, Hz, 1H), 6.27 (s, 1H),
6.18 (s, 1H), 5.58 (s, 1H), 0.88 (t, J = 6.9, 9H), 0.77 (m, 6H) ppm;
13C NMR (126 MHz, CDCl3) δ = 238.2, 155.5, 148.1, 147.9, 138.4,
134.7, 128.1, 123.2, 68.9, 7.1, 3.5 ppm; HRMS (ESI +ve) Exact
mass calculated for C15H23NO2NaSi [M+Na]+: 300.1390, found:
300.1390.
2-((4-Bromophenyl)(hydroxy)methyl)-1-(dimethyl(phenyl)
silyl)prop-2-en-1-one (7b): yield 34% as a yellow oil. FT-IR (film)
3449, 2959, 1690, 1593, 1485, 1252, 1112, 1069, 1009, 818, 734,
652 cm-1; 1H NMR (300 MHz, CDCl3) δ = 7.49-7.30 (m, 7H), 7.17-
7.10 (d, J = 8.7 Hz, 2H), 6.03 (s, 1H), 6.00 (d, J = 1.2 Hz, 1H),
5.45 (s, 1H), 3.18 (s, 1H), 0.50 (s, 3H), 0.49 (s, 3H) ppm; 13C NMR
(75 MHz, CDCl3) δ = 234.8, 150.9, 137.9, 132.5, 131.2, 128.8,
127.7, 127.4, 125.7, 125.7, 118.9, 69.4, -5.6, -5.7 ppm; HRMS
(ESI +ve) Exact mass calculated for C18H19O2NaSiBr [M+Na]+:
397.0235, found: 397.0241.
Ethyl 2-hydroxy-3-((triethylsilyl)carbonyl)but-3-enoate (11a):
yield 93% as a yellow oil. FT-IR (film) 3492, 2956, 2877, 1736,
1598, 1234, 1086, 1019, 735 cm-1; 1H NMR (400 MHz, CDCl3) δ
= 6.31 (s, 1H), 6.19 (s, 1H), 4.79 (d, J = 6.3 Hz, 1H), 4.19 (q, J =
7.0 Hz, 2H), 3.38 (d, J = 6.3 Hz, 1H), 1.21 (t, J = 7.0 Hz, 3H), 0.97
(t, J = 8.2, 9H), 0.81 (q, J = 8.2 Hz, 6H) ppm; 13C NMR (101 MHz,
CDCl3) δ = 236.2, 172.6, 151.3, 129.9, 69.9, 61.7, 13.9, 7.1, 3.4
ppm; HRMS (ESI +ve) Exact mass calculated for C13H24O4NaSi
[M+Na]+: 295.1336, found: 295.1335.
Ethyl-3-((dimethyl(phenyl)silyl)carbonyl)-2-hydroxybut-3-
enoate (11b): yield 88% as a yellow oil. FT-IR (film) 3491, 2853,
1608, 1428, 1249, 1029, 827, 733, 647 cm-1; 1H NMR (300 MHz,
CDCl3) δ = 7.59-7.49 (m, 2H), 7.45-7.33 (m, 3H), 6.20 (s, 1H),
6.06, (s, 1H), 4.79 (d, J = 4.2 Hz, 1H), 4.29-4.05 (m, 2H), 3.43 (d,
J = 5.8 Hz, 1H), 1.20 (t, J = 7.1 Hz, 3H), 0.56 (s, 3H), 0.54 (s, 3H)
ppm; 13C NMR (75 MHz, CDCl3) δ = 234.4, 172.6, 149.9, 135.2,
133.8, 131.5, 129.9, 128.3, 70.1, 61.9, 14.0, -3.1, -3.2 ppm;
HRMS (ESI +ve) Exact mass calculated for C15H20O4NaSi
[M+Na]+: 315.1029, found: 315.1032.
3-Hydroxy-2-methylene-1-(triethylsilyl)heptan-1-one
(12a):
yield 37% as a yellow oil. FT-IR (film) 3435, 2955, 2875, 1592,
1414, 1017, 731 cm-1; 1H NMR (300 MHz, CDCl3) δ = 6.20 (s, 1H),
6.05 (s, 1H), 4.39 (q, J = 6.4 Hz, 1H), 1.60-1.53(m, 2H), 1.42-1.23
(m, 4H), 0.98 (t, J = 8.2 Hz, 9H), 0.90 (t, J = 7.0 Hz, 3H), 0.81 (q,
J = 8.2 Hz, 6H) ppm; 13C NMR (126 MHz, CDCl3) δ = 240.1, 155.9,
127.7, 71.2, 35.9, 28.0, 22.5, 14.0, 7.3, 3.7 ppm; HRMS (ESI +ve)
Exact mass calculated for C14H28O2NaSi [M+Na]+: 279.1750,
found: 279.1753.
2-(Hydroxy(4-nitrophenyl)methyl)-1-(trimethylsilyl)prop-2-
en-1-one (6c): yield 92% as a yellow oil. FT-IR (film) 2960, 1596,
1518, 1410, 1343, 1249, 1014, 986, 839, 755, 700, 624 cm-1; 1H
NMR (300 MHz, CDCl3) δ = 8.17 (d, J = 8.8 Hz, 2H), 7.48 (d, J =
8.8 Hz, 2H), 6.24 (s, 1H), 6.18 (d, J = 1.1 Hz, 1H), 5.59 (d, J =
4.50 Hz, 1H), 0.26 (s, 9H) ppm; 13C NMR (75 MHz, CDCl3) δ =
239.2, 153.0, 149.0, 147.2, 130.2, 127.2, 123.5, 71.9, -1.5 ppm;
HRMS (ESI +ve) Exact mass calculated for C13H17NO4NaSi
[M+H]+: 302.0819, found: 302.0818.
1-(Dimethyl(phenyl)silyl)-2-(hydroxy(phenyl)methyl)prop-2-
en-1-one (4b): yield 40% as a yellow oil. FT-IR (film) 3493, 2959,
1597, 1427, 1251, 1112, 1058, 814, 781, 695, 650 cm-1; 1H NMR
(300 MHz, CDCl3) δ = 7.51-7.46 (m, 2H), 7.44-7.37 (m, 3H), 7.34-
7.26 (m, 5H), 6.05 (s, 1H), 6.02 (d, J = 1.2 Hz, 1H), 5.55 (d, J =
4.7 Hz, 1H), 3.08 (d, J = 5.0 Hz, 1H), 0.53 and 0.51 (s, 3H) ppm;
13C NMR (75 MHz, CDCl3) δ 237.4, 153.9, 141.4, 135.3, 133.8,
130.2, 129.9, 128.3, 128.2, 127.5, 126.5, 72.5, -3.1, -3.2 ppm;
HRMS (ESI +ve) Exact mass calculated for C18H20O2NaSi
[M+Na]+: 319.1130, found: 319.1134.
Ethyl-2-hydroxy-3-((trimethylsilyl)carbonyl)but-3-enoate
(11c): yield 22% as a yellow oil. FT-IR (film) 3451, 2982, 2930,
1742, 1701, 1451, 1372, 1207, 1020, 759, 691 cm-1; 1H NMR (300
MHz, CDCl3) δ = 6.27 (d, J = 0.9 Hz, 1H), 6.16 (s, 1H), 4.78 (d, J
= 5.2 Hz, 1H), 4.29 – 3.99 (m, 2H), 3.44 (d, J = 6.2 Hz, 1H), 1.18
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201801343
European Journal of Organic Chemistry
FULL PAPER
(t, J = 7.1 Hz, 3H), 0.25 (s, 9H) ppm; 13C NMR (75 MHz, CDCl3) δ
= 236.3, 172.6, 150.1, 129.9, 70.1, 61.7, 14.0, -1.7 ppm; HRMS
(ESI +ve) Exact mass calculated for C10H18O4Na Si [M+H]+:
253.0866, found: 253.0866.
2857, 1743, 1253, 1089, 1040, 840, 779 cm-1; 1H NMR (300 MHz,
CDCl3) δ = 6.33 (s, 1H), 6.22 (s, 1H), 4.76 (d, J = 6.1 Hz, 1H),
4.21 (q, J = 7.1 Hz, 2H), 3.37 (d, J = 6.0 Hz, 1H), 1.24 (t, J = 7.1
Hz, 3H), 0.94 (s, 9H), 0.30 (s, 3H), 0.29 (s, 3H) ppm; 13C NMR (75
MHz, CDCl3) δ = 235.9, 172.8, 151.4, 131.1, 70.6, 61.9, 26.5, 16.8,
14.0, -4.9 ppm; HRMS (ESI +ve) Exact mass calculated for
C13H24O4NaSi [M+Na]+: 295.1341, found: 295.1339.
2-(Hydroxy(phenyl)methyl)-1-(triisopropylsilyl)prop-2-en-1-
one (4d): yield 10% as a yellow oil. FT-IR (film) 3493, 2944, 2894,
1659, 1465, 1113, 992, 882, 751 cm-1; 1H NMR (500 MHz, CDCl3)
δ = 7.35-7.30 (m, 3H), 7.27-7.23 (m, 2H), 6.10 (d, J = 1.0 Hz, 1H),
6.05 (s, 1H), 5.58 (s, 1H), 3.34-3.01 (m, 1H), 1.30-1.20 (m, 3H),
095 (s, J = 6.2 Hz, 9H), 0.98 (s, J = 6.2 Hz, 9H) ppm; 13C NMR
(75 MHz, CDCl3) δ = 239.6, 156.3, 141.5, 128.2, 127.5, 126.6,
73.0, 29.7, 18.5, 12.2 ppm; HRMS (ESI +ve) Exact mass
calculated for C19H31O2Si [M+H]+: 319.2093, found: 319.2086.
2-(Hydroxy(phenyl)methyl)-1-(methyldiphenylsilyl)prop-2-
en-1-one (6f): yield 72% as a yellow oil. FT-IR (film) 3070, 1688,
1596, 1518, 1428, 1344, 1109, 792, 728, 696 cm-1; 1H NMR (300
MHz, CDCl3) δ = 8.13 (d, J = 8.7 Hz, 2H), 7.55 – 7.31 (m, 12H),
6.15 (s, 1H), 6.11 (s, 1H), 5.67 (s, 1H), 3.60 (s, 1H), 0.80 (s, 3H)
ppm; 13C NMR (75 MHz, CDCl3) δ = 235.3, 153.7, 149.2, 147.2,
135.0, 134.9, 134.0, 133.0, 132.9, 131.7, 130.3, 128.4, 128.3,
127.3, 123.5, 71.7, -3.6 ppm; HRMS (ESI +ve) Exact mass
calculated for C23H21NO4NaSi [M+Na]+: 426.1132, found:
426.1129.
2-methylene-1,5-bis(triisopropylsilyl)pentane-1,5-dione (5d):
yield 20% as a yellow oil. FT-IR (film) 2944, 2867, 1639, 1594,
1464, 1256, 1168, 922, 882, 675 cm-1; 1H NMR (300 MHz, CDCl3)
δ = 6.02 (s, 1H), 5.82 (s, 1H), 2.60 (t, J = 7.1 Hz, 2H), 2.36 (t, J =
7.1 Hz, 2H), 1.41-1.18 (m, 6H), 1.07 (d, J = 2.6 Hz, 18H), 1.04 (d,
J = 2.6 Hz, 18H) ppm; 13C NMR (75 MHz, CDCl3) δ = 245.5, 236.8,
155.2, 128.1, 50.1, 22.1, 18.7, 18.5, 12.3, 10.7 ppm; HRMS: (ESI
Ethyl-2-hydroxy-3-((methyldiphenylsilyl)carbonyl)but-3-
enoate (11f): yield 32% as a yellow oil. FT-IR (film) 3450, 3070,
2981, 1734, 1694, 1428, 1254, 1112, 1024, 790, 724, 697 cm-1;
+ve) Exact mass calculated for C24H48O2NaSi2 [M+Na]+: 447.3091, 1H NMR (300 MHz, CDCl3) δ = 7.62-7.56 (m, 4H), 7.48 – 7.32 (m,
found: 447.3084.
6H), 6.24 (s, 1H), 6.10 (s, 1H), 4.86 (s, 1H), 4.20 (m, 2H), 3.55
(d, J = 5.6 Hz, 1H), 1.19 (t, J = 7.1 Hz, 3H), 0.81 (s, 3H) ppm; 13C
NMR (75 MHz, CDCl3) δ = 232.7, 172.6, 150.5, 135.0, 133.3,
133.2, 132.7, 130.2, 128.3, 70.2, 62.0, 14.0, -3.6 ppm; HRMS
(ESI +ve) Exact mass calculated for C20H22O4NaSi [M+Na]+:
377.1179, found: 377.1177.
2-(Hydroxy(4-nitrophenyl)methyl)-1-(triisopropylsilyl)prop-2-
en-1-one (6d): yield 30% as a yellow oil. FT-IR (film) 3486, 2944,
2892, 1600, 1465, 1250, 1177, 1015, 920, 882, 677, 642 cm-1; 1H
NMR (300 MHz, CDCl3) δ = 8.02 (d, J = 8.8 Hz, 2H), 7.37 (d, J =
8.8 Hz, 2H), 6.0 (s, 1H), 5.97 (s, 1H), 5.47 (d, J = 5.5 Hz, 1H),
3.21 (d, J = 5.6 Hz, 1H), 1.22-1.11 (m, 3H), 0.88 (d, J = 7.5Hz,
9H), 0.86 (d, J = 7.5Hz, 9H) ppm; 13C NMR (75 MHz, CDCl3) δ =
236.8, 152.5, 146.6, 144.6, 126.8, 124.7, 120.9, 69.8, 16.0, 9.6
ppm; HRMS (ESI -ve) Exact mass calculated for C19H30NO4Si
[M+H]+: 364.1944, found: 364.1947.
General experimental procedure for the protection of MBH
adducts as acetates:
Three methods have to been employed to protect the previous
MBH products. After some time we found that the use of TEA was
not necessary and induced the formation of transposed product.
Finally NaHCO3 was found to be more efficient for sensitive
substrates. We described the three methods which were used:
Ethyl -2-hydroxy-3-((triisopropylsilyl)carbonyl)but-3-enoate
(11d): yield 70% as a yellow oil. FT-IR (film) 3491, 2944, 1602,
1371, 1190, 1026, 857, 741, 635 cm-1; 1H NMR (300 MHz, CDCl3)
δ = 6.33 (s, 1H), 6.16 (s, 1H), 4.77 (d, J = 6.4 Hz, 1H), 4.18 (q, J
= 7.2 Hz, 2H), 3.41 (d, J = 6.5 Hz, 1H), 1.44-1.27 (m, 3H), 1.20 (t,
J = 7.2 Hz, 3H), 1.10 (dd, J = 7.5, 1.2 Hz, 18H) ppm; 13C NMR
(75 MHz, CDCl3) δ = 235.8, 172.8, 151.9, 130.3, 70.5, 61.8, 18.6,
13.9, 12.2 ppm; HRMS (ESI +ve) Exact mass calculated for
C16H30O4NaSi [M+Na]+: 337.1811, found: 337.1811.
Method A:
a round bottom flask was charged with β-
hydroxyacryloylsilane (1 equiv), acetic anhydride (2 equiv), in dry
DCM under nitrogen flush at 0 °C. Then DMAP (0.1 equiv) and
TEA (3 equiv) were added to the solution and stirring was
continued at room temperature and monitored by TLC using 10%
EtOAc/pentane. After aqueous workup and concentration, the
compound was purified by column chromatography.
1-(Tert-butyldimethylsilyl)-2-(hydroxy(4-nitrophenyl)methyl)
Method B: a round bottom flask was charged with β-
prop-2-en-1-one (6e): yield 34% as a yellow oil. FT-IR (film) 3480, hydroxyacryloylsilane (1 equiv), acetic anhydride (1,2 – 1,5 equiv)
1
2930, 28602, 1590, 1520, 1345, 1250, 821, 778 cm-1; H NMR
(300 MHz, CDCl3) δ = 8.18 (d, J = 8.8 Hz, 2H), 7.53 (d, J = 8.8 Hz,
2H), 6.22 (d, J = 0.5 Hz, 1H), 6.18 (d, J = 1.1 Hz, 1H), 5.63 (d, J
= 4.1 Hz, 1H), 3.42 (d, J = 5.2 Hz, 1H), 0.86 (s, 9H), 0.26 (s, 3H),
0.25 (s, 3H) ppm; 13C NMR (75 MHz, CDCl3) δ = 247.5, 238.9,
154.6, 149.1, 147.2, 130.3, 127.2, 123.49, 72.1, 16.7, -4.8 ppm;
HRMS (ESI +ve) Exact mass calculated for C16H23NO4NaSi
[M+Na]+: 344.1288, found: 344.1289.
in dry DCM under nitrogen flush at 0 °C. Then DMAP (0.2 equiv)
was added to the solution and stirring was continued at room
temperature and monitored by TLC using 10 % EtOAc/pentane.
After aqueous workup and concentration, the compound was
purified by column chromatography.
Method C:
a round bottom flask was charged with β-
hydroxyacryloylsilane (1 equiv), acetic anhydride (5 equiv) in
dried DCM under nitrogen flush at 0°C. Then, NaHCO3 (2.0 equiv)
was added to the solution and stirring was continued at room
temperature and the reaction monitored by TLC using 10 %
Ethyl-3-((tert-butyldimethylsilyl)carbonyl)-2-hydroxybut-3-
enoate (11e): yield 54% as a yellow oil. FT-IR (film) 3445, 2929,
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201801343
European Journal of Organic Chemistry
FULL PAPER
EtOAc/pentane. After aqueous workup and concentration, the
compound was purified by column chromatography.
(m, 2H), 7.42-7.25 (m, 7H), 6.60 (s, 1H), 6.13 (d, J = 1.3 Hz, 1H),
6.04 (s, 1H), 2.10 (s, 3H), 0.46 (s, 3H), 0.39 (s, 3H) ppm; 13C NMR
(75 MHz, CDCl3) δ = 233.3, 169.1, 150.7, 147.5, 145.6, 134.9,
133.7, 130.0, 129.3, 128.3, 128.2, 123.6, 71.0, 20.9, -3.1, -3.3
ppm; HRMS (ESI +ve) Exact mass calculated for C20H21NO5NaSi
[M+Na]+: 406.1087, found: 406.1071.
1-Phenyl-2-((triethylsilyl)carbonyl)allylacetate (13a): method
A: yield 63% as a yellow oil. FT-IR (film) 2955, 2876, 1740, 1599,
1369, 1223, 1026, 696 cm-1; 1H NMR (500 MHz, CDCl3) δ = 7.38-
7.24 (m, 5H), 6.69 (s, 1H), 6.23 (d, J = 1.5 Hz, 1H), 6.16 (s, 1H),
2.10 (s, 3H), 0.92 (t, J = 7.8 Hz, 9H), 0.78 (q, J = 7.7 Hz, 6H) ppm;
13C NMR (126 MHz, CDCl3) δ = 235.5, 169.3, 153.4, 138.4, 128.3,
128.0, 127.5, 126.6, 72.1, 21.1, 7.2, 3.5 ppm; HRMS (ESI +ve)
Exact mass calculated for C18H26O3NaSi [M+Na]+: 341.1543,
found: 341.1545.
Ethyl-2-acetoxy-3-((dimethyl(phenyl)silyl)carbonyl)but-3-
enoate (15b): method B: yield 67% as a yellow liquid.FT-IR (film)
2924, 2853, 1745, 1608, 1372, 1217, 1115, 1060, 827, 788, 701
cm-1; 1H NMR (400 MHz, CDCl3) δ = 7.46-7.41 (m, 2H), 7.33-7.25
(m, 3H), 6.14 (d, J = 0.8 Hz, 1H), 6.03 (s, 1H), 5.85 (d, J = 0.8 Hz,
1H), 4.06 (q, J = 7.0 , 2H), 2.01 (s, 3H), 1.11 (t, J = 7.1 Hz, 3H),
0.47 (s, 3H), 0,46 (s, 3H) ppm; 13C NMR (101 MHz, CDCl3) δ =
231.7, 169.7, 168.3, 146.7, 135.1, 133.8, 132.2, 130.0, 128.3,
68.6, 61.6, 20.6, 13.9, -3.1, -3.2 ppm; HRMS (ESI +ve) Exact
mass calculated for C17H22O5NaSi [M+Na]+: 357.1134, found:
357.1134.
1-(4-Nitrophenyl)-2-((triethylsilyl)carbonyl)allyl acetate (14a):
method A: yield 92% as a yellow thick oil. When time was
prolonged from 6 h to 48 h isomerisation of 14a to 14’a took place
and this compound (14’a, E isomer) was obtained in 18% yield
together with compound (14a) in 81%. Method C: yield: 82% as a
yellow solid. FT-IR (film) 2596, 2876, 1745, 1598, 1521, 1345,
1220, 735, 698 cm-1; 1H NMR (300 MHz, CDCl3) δ 8.18 (d, J = 8.7
Hz, 2H), 7.53 (d, J = 8.7 Hz, 2H), 6.69 (s, 1H), 6.34 (d, J = 1.4 Hz,
1H), 6.25 (s, 1H), 2.12 (s, 3H), 0.96 – 0.84 (m, 9H), 0.81 – 0.71
(m, 6H) ppm; 13C NMR (75 MHz, CDCl3) δ 235.3, 169.1, 152.3,
147.4, 145.8, 128.2, 127.9, 123.6, 71.1, 21.0, 7.2, 3.5 ppm; HRMS
(ESI +ve) Exact mass calculated for C18H25NO5NaSi [M+Na]+:
386.1394, found: 386.1390.
1-(4-Nitrophenyl)-2-((trimethylsilyl)carbonyl)allylacetate
(14c): method A: yield 72% as a yellow liquid. FT-IR (film) 1741,
1598, 1519, 1370, 1345, 1221, 1108, 992, 839, 750, 698, 622,
530 cm-1; 1H NMR (300 MHz, CDCl3) δ = 8.16 (d, J = 8.7 Hz, 2H),
7.53 (d, J = 8.7 Hz, 2H, 2H), 6.67 (s, 1H), 6.36 (d, J = 1.3 Hz, 1H),
6.28 (d, J = 0.7 Hz, 1H), 2.12 (s, 3H), 0.25 (s, 9H) ppm; 13C NMR
(75 MHz, CDCl3) δ = 235.1, 169.1, 150.9, 147.5, 145.8, 128.5,
123.6, 70.9, 20.9, -1.5 ppm; HRMS (ESI +ve) Exact mass
calculated for C15H19NO5NaSi [M+Na]+: 344.0924, found:
344.0928.
(E)-3-(4-Nitrophenyl)-2-((triethylsilyl)carbonyl)allyl
acetate
1
(14a’): H NMR (300 MHz, CDCl3) δ = 8.30 (d, J = 8.7 Hz, 2H),
7.59 (d, J = 8.6 Hz, 3H), 4.86 (s, 2H), 2.03 (s, 3H), 1.04 (t, J = 7.0
Hz, 9H), 0.90 (q, J = 7.0 Hz, 6H) ppm; 13C NMR (75 MHz, CDCl3)
δ = 235.3, 170.3, 148.0, 144.0, 143.0, 140.8, 130.0, 123.9, 57.0,
20.7, 7.4, 3.9 ppm; HRMS (ESI +ve) Exact mass calculated for
C18H25NO5NaSi [M+Na]+: 386.1394, found: 386.1392.
Ethyl-2-acetoxy-3-((trimethylsilyl)carbonyl)but-3-enoate
(15c): method A: yield 67%, method C: yield: 75% as a yellow
liquid. FT-IR (film) 1742, 1608, 1371, 842, 620 cm-1; 1H NMR (300
MHz, CDCl3) δ = 6.38 (s, 1H), 6.30 (s, 1H), 5.97 (s, 1H), 4.21 (q,
J = 7.6 Hz, 2H), 2.15 (s, 3H), 1.25 (t, J = 7.6 Hz, 3H), 0.33 (s, 9H)
ppm; 13C NMR (75 MHz, CDCl3) δ = 233.4, 169.7, 168.4, 146.9,
130.9, 68.6, 61.6, 20.6, 13.9, -1.5 ppm; HRMS (ESI +ve) Exact
mass calculated for C12H20O5NaSi [M+Na]+: 295.0972, found:
295.0971.
Ethyl 2-acetoxy-3-((triethylsilyl)carbonyl)but-3-enoate (15a):
method A: yield 88% as a yellow liquid. FT-IR (film): 2956, 2877,
1746, 1606, 1371, 12118, 736 cm-1; 1H NMR (300 MHz, CDCl3) δ
= 6.39 (d, J = 0.8 Hz, 1H), 6.28 (s, 1H), 5.97 (d, J = 0.8 Hz, 1H),
4.28 – 4.04 (m, 2H), 2.14 (s, 3H), 1.16 (t, J = 7.2 Hz, 3H), 0.92 (t,
J = 7.0 Hz, 9H, 6H), 0.77 (q, J = 7.0 Hz, 9H) ppm; 13C NMR (75
MHz, CDCl3) δ = 233.4, 169.6, 168.3, 148.2, 130.5, 68.6, 61.4,
20.5, 13.8, 7.2, 3.5 ppm; HRMS (ESI +ve) Exact mass calculated
for C15H26O5NaSi [M+Na]+: 337.1441, found: 337.1446.
1-(4-Nitrophenyl)-2-((triisopropylsilyl)carbonyl)allyl acetate
(14d): method B: yield 51% as a yellow liquid. FT-IR (film) 2945,
2867, 1748, 1600, 1524, 1347, 1226, 1113, 1048, 849, 751, 684
cm-1; 1H NMR (300 MHz, CDCl3) δ = 8.02 (d, J = 8.8 Hz, 2H), 7.37
(d, J = 8.8 Hz, 2H), 6.66 (s, 1H), 6.24 (s, 1H), 6.11 (s, 1H), 2.05
(s, 3H), 1.31-1.20 (m, 3H), 0.97 (d, J = 7.4 Hz, 9H), 0.94 (d, J =
7.4 Hz, 9H) ppm; 13C NMR (75 MHz, CDCl3) δ = 234.9, 169.1,
153.2, 147.4, 145.9, 128.3, 127.6, 123.6, 71.3, 21.0, 18.6, 12.2
ppm; HRMS: (ESI +ve) Exact mass calculated for C21H31NO5NaSi
[M+Na]+: 428.1869, found: 428.1869.
2-((Dimethyl(phenyl)silyl)carbonyl)-1-phenylallyl
acetate
(13b): method B: yield 76%. FT-IR (film) 2955, 2911, 2876, 1740,
1
1599, 1369, 1223, 10226, 735, 696 cm-1; H NMR (500 MHz,
CDCl3) δ = 7.46-7.42 (m, 2H), 7.41-7.32 (m, 3H), 7.31-7.23(m,
5H), 6.60 (s, 1H), 6.10 (s, 1H), 6.02 (s, 1H), 2.04 (s, 3H), 0.51 (s,
3H), 0.45 (s, 3H) ppm; 13C NMR (126 MHz, CDCl3) δ = 233.5,
169.3, 151.8, 138.2, 135.4, 133.8, 129.8, 128.4, 128.3, 128.2,
128.1, 127.5, 71.9, 21.1, -3.0, -3.2 ppm; HRMS (ESI +ve) Exact
mass calculated for C20H22O3NaSi [M+Na]+: 361.1236, found:
361.1238.
Ethyl-2-acetoxy-3-((triisopropylsilyl)carbonyl)but-3-enoate
(15d): method B: yield 70% as a yellow liquid. FT-IR (film) 2944,
2867, 1748, 1602, 1464, 1371, 1216, 1062, 982, 882, 676 cm-1;
1H NMR (400 MHz, CDCl3) δ = 6.31 (d, J = 0.8 Hz, 1H), 6.15 (s,
1H), 5.89 (s, 1H), 4.10 (q, J = 7.1 Hz, 2H), 2.05 (s, 3H), 1.30 (m,
3H), 1.14 (t, J = 7.1 Hz, 3H), 1.04 (d, J = 7.5 Hz, 9H), 1.03 (d, J =
7.5 Hz, 9H) ppm; 13C NMR (101 MHz, CDCl3) δ = 233.0, 169.7,
2-((Dimethyl(phenyl)silyl)carbonyl)-1-(4-nitrophenyl)allyl
acetate (14b): method B: yield 80% as a yellow liquid. FT-IR (film)
2919, 2850, 1745, 1600, 1521, 1371, 1346, 1223, 1110, 1039,
834, 787, 734, 700 cm-1; 1H NMR (300 MHz, CDCl3) δ = 8.09-8.02
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201801343
European Journal of Organic Chemistry
FULL PAPER
168.4, 148.9, 130.6, 69.0, 61.5, 20.6, 18.6, 18.6, 13.9, 12.2 ppm;
HRMS (ESI +ve) Exact mass calculated for C18H32O5NaSi
[M+Na]+: 379.1917, found: 379.1915.
J= 8.8 Hz, 2H), 7.59 (d, J = 8.8 Hz, 2H), 7.57 (s, 1H), 4.86 (s, 2H),
2.03 (s, 3H), 1.04 (t, J= 6.7 Hz, 9H), 0.90 (q, J= 6.7 Hz, 6H) ppm;
13C NMR (75 MHz, CDCl3) δ = 235.3, 170.3, 148.0, 144.0, 143.0,
140.8, 130.0, 123.9, 57.0, 20.7, 7.4, 3.9 ppm; HRMS (ESI +ve)
Exact mass calculated for C18H25NO5NaSi [M+Na]+: 386.13942
found: 386.1392.
2-((Tert-butyldimethylsilyl)carbonyl)-1-(4-nitrophenyl)allyl
acetate (14e): method C: yield 68% as a yellow liquid. FT-IR (film)
1
2930, 2858, 1746, 1522, 1346, 1224, 1041, 836, 780 cm-1; H
NMR (300 MHz, CDCl3) δ = 8.16 (d, J = 8.8 Hz, 2H), 7.53 (d, J =
8.8 Hz, 2H), 6.69 (d, J = 1.1 Hz, 1H), 6.32 (d, J = 1.3 Hz, 1H), 6.25
(d, J = 0.7 Hz, ), 2.12 (s, 3H), 0.84 (s, 9H), 0.25 (s, 3H), 0.24 (s,
3H) ppm; 13C NMR (75 MHz, CDCl3) δ = 234.7, 217.1, 210.3,
169.1, 152.6, 147.4, 145.8, 128.6, 128.2, 123.5, 71.1, 26.5, 20.9,
16.7, -4.8, -4.9 ppm; HRMS (ESI +ve) Exact mass calculated for
C18H25NO5NaSi [M+Na]+: 386.1394, found: 386.1397.
(E)-3-(4-nitrophenyl)-2-((trimethylsilyl)carbonyl)allylacetate
(14’c): yield 72% as a yellow thick oil. FT-IR (Film) 2960, 1738,
1597, 1517, 1350, 1229, 1028, 838 cm-1; 1H NMR (300 MHz,
CDCl3) δ = 8.25 (d, J= 8.8 Hz, 2H), 7.60 (d, J= 8.8 Hz, 2H), 7.56
(s, 1H), 4.81(s, 2H), 2.03 (s, 3H), 0.31 (s, 9H) ppm; 13C NMR (75
MHz, CDCl3) δ = 235.0, 170.3, 147.9, 143.7, 142.6, 140.7, 130.1,
123.8, 57.0, 20.7, -1.2 ppm; HRMS (ESI +ve) Exact mass
calculated for C15H19NO5NaSi [M+Na]+: 344.1924, found:
344.0925.
Ethyl-2-acetoxy-3-((tert-butyldimethylsilyl)carbonyl)but-3-
enoate (15e): method C: yield 84% as a yellow liquid. FT-IR (film)
2928, 2857, 1749, 1602, 1465, 1370, 1248, 1220, 839, 778 cm-1;
1H NMR (300 MHz, CDCl3) δ = 6.35 (d, J = 0.7 Hz, 1H), 6.27 (s,
1H), 5.94 (d, J = 0.7 Hz, 1H), 4.17 (q, J = 7.1 Hz, 2H), 2.11 (s, 3H),
1.22 (t, J = 7.1 Hz, 3H), 0.92 (s, 9H), 0.28 (d, J = 2.9 Hz, 3H), 0.27
ppm; 13C NMR (75 MHz, CDCl3) δ = 233.0, 169.6, 168.4, 148.4,
131.4, 68.9, 61.5, 26.5, 20.6, 16.8, 13.9, -5.0 ppm; HRMS (ESI
+ve) Exact mass calculated for C15H26O5NaSi [M+Na]+: 337.1441,
found: 337.1440.
(E)-2-((tert-butyldimethylsilyl)carbonyl)but-2-en-1-ylacetate
(14’e): yield 81% as a yellow thick oil. FT-IR (Film) 2960, 2931,
2855, 1739, 1512, 1345, 1227, 735cm-1; 1H NMR (300 MHz,
CDCl3) δ = 8.29 (d, J= 8.8 Hz, 2H), 7.59 (d, J= 8.8 Hz, 2H ), 7.56
(d, J = 2.1 Hz, 1H), 4.85 (s, 2H), 2.04 (s, 3H), 1.00 (s, 9H), 0.38
(s, 6H) ppm; 13C NMR (75 MHz, CDCl3) δ = 234.9, 170.4, 148.0,
144.2, 143.7, 140.8, 129.9, 123.9, 57.2, 26.7, 20.8, 17.0, -4.5
ppm; HRMS (ESI +ve) Exact mass calculated for C18H25NO5NaSi
[M+Na]+: 386.1394, found: 386.1392.
2-((Methyldiphenylsilyl)carbonyl)-1-(4-nitrophenyl)allyl
acetate (14f): method A: yield: 79%, method C: yield 54% as a
yellow liquid. FT-IR (film) 2953, 2923, 2878, 17448, 1599, 1522,
Ethyl-(E)-4-acetoxy-3-((tert-butyldimethylsilyl)carbonyl)pent-
2-enoate (15’e): yield 64% as a yellow thick oil. FT-IR (Film) 2945,
2932, 2859, 1751, 1226, 1202, 1032, 838, 779 cm-1;1H NMR (300
MHz, CDCl3) δ = 6.35 (s, 1H), 5.19 (s, 2H), 4.27 (q, J = 7.1 Hz,
2H), 2.01 (s, 3H), 1.34 (t, J = 7.1 Hz, 3H), 0.96 (s, 9H), 0.31 (s,
6H) ppm;13C NMR (75 MHz, CDCl3) δ = 237.5, 170.2, 165.3,
153.1, 128.2, 61.3, 58.0, 26.5, 20.7, 17.0, 14.1, -5.3 ppm; HRMS
(ESI +ve) Exact mass calculated for C15H26O5NaSi [M+Na]+:
337.14417, found: 337.1438.
1
1343, 1218, 851, 742, 684 cm-1; H NMR (300 MHz, CDCl3) δ =
8.34 – 7.90 (m, 2H), 7.71 – 7.14 (m, 10H), 6.78 (s, 1H), 6.27 (d, J
= 1.4 Hz, 1H), 6.19 (s, 1H), 2.12 (s, 3H), 0.78 (s, 3H) ppm; 13C
NMR (75 MHz, CDCl3): δ = 231.7, 169.1, 151.3, 147.5, 145.6,
134.9, 134.9 (2C), 133.1, 132.9, 130.3, 130.2, 128.3(3C), 123.6,
71.1, 21.0, -3.6 ppm; HRMS (ESI +ve) Exact mass calculated for
C25H23NO5NaSi [M+Na]+: 468.1237, found: 468.1237.
Ethyl-2-acetoxy-3-((methyldiphenylsilyl)carbonyl)but-3-
enoate (15f): method C: yield 77% as a yellow liquid. FT-IR (film)
2959, 2925, 2853, 1746, 1020, 800, 722, 700 cm-1; 1H NMR (300
MHz, CDCl3) δ = 7.67 – 7.56 (m, 4H), 7.51 – 7.29 (m, 6H), 6.29
(s, 1H), 6.19 (s, 1H), 6.03 (s, 1H), 4.18 (q, J = 7.1 Hz, 2H), 2.14
(s, 3H), 1.21 (t, J = 7.1 Hz, 3H), 0.83 (s, 3H) ppm; 13C NMR (75
MHz, CDCl3) δ = 230.1, 169.7, 168.3, 147.4, 135.0, 133.3, 133.2,
133.1, 130.3, 128.3, 128.3, 68.7, 61.7, 20.7, 14.0, -3.5 ppm;
HRMS (ESI +ve) Exact mass calculated for C22H24O5NaSi
[M+Na]+: 419.12852, found: 419.1282.
General experimental procedure for the transformation of
MBH adducts into aldehydes:
A round bottom flask was charged with an acetyl protected β-
hydroxyacryloylsilane dissolved in acetone/water 2:1 or
THF/water 9:1. The solution was degasified then enlightened at
365 nm under stirring at room temperature. After completion of
the reaction as monitored by TLC, solvents were removed in
vacuum. The residue was dissolved in DCM and an aqueous
workup done. The organic layer was dried with MgSO4 and after
concentration under reduced pressure the corresponding
aldehyde was obtained.
(E)-3-(4-Nitrophenyl)-2-((triethylsilyl)carbonyl)allylacetate
(14’a): in a 10 mL round bottomed was added compound (14a)
(610 mg, 1.67 mmol) and 1.5 ml of [BMiM],PF6 followed by
addition of KOAc (214 mg, 2.2 mmol, 1.5 equiv) at 50 °C.The
reaction mixture was kept for 2 hours at this temperature. The
product was extracted with diethyl ether and purified by column
chromatography with 20% diethyl ether/cyclohexane as eluent to
afford pure product (14’a) (386 mg, 64% yield) as a yellow solid.
FT-IR (Film) 2956, 2876, 1738, 1597, 1522, 1339, 1222, 1097,
1020, 856, 724, 702 cm- 1; 1H NMR (300 MHz, CDCl3) δ = 8.30 (d,
2-Formyl-1-phenylallyl acetate (16): from compound (13a):
yield 95%; from compound (13b): yield 88% as colourless oil. FT-
1
IR (film) 2960, 1737, 1688, 1222, 1025, 697 cm-1; H NMR (500
MHz, CDCl3) δ = 9.56 (s, 1H), 7.44 – 7.27 (m, 5H), 6.68 (s, 1H),
6.51 (d, J = 1.4 Hz, 1H), 6.22 (s, 1H), 2.13 (s, 3H) ppm; 13C NMR
(125 MHz, CDCl3) δ = 191.7, 169.3, 148.7, 137.4, 133.6, 128.5,
128.4, 127.4, 71.4, 21.0 ppm; HRMS (ESI +ve) Exact mass
calculated for C12H12O3Na [M+Na]+: 227.0678, found: 227.0681.
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10.1002/ejoc.201801343
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2-Formyl-1-(4-nitrophenyl)allyl acetate (17): from compound
(14a): yield 92%; (14b): yield 88%; (14d): yield 75%; (14e): yield
91%; (14f): yield 69% as a colourless oil. FT-IR (film) 3088, 2935,
2858, 1741, 1687, 1602, 1518, 1335, 1225, 967, 848, 747, 695
cm-1; 1H NMR (300 MHz, CDCl3) δ = 9.54 (s, 1H), 8.17 (d, J = 8.8
Hz, 2H), 7.56 (d, J = 8.8 Hz, 2H), 6.69 (s, 1H), 6.60 (d, J = 1.3 Hz,
1H), 6.29 (s, 1H), 2.15 (s, 3H) ppm; 13C NMR (75 MHz, CDCl3) δ
= 191.4, 169.1, 147.7, 144.7, 134.5, 128.2, 123.7, 70.4, 20.8 ppm;
HRMS (ESI +ve) Exact mass calculated for C12H11NO5Na
[M+Na]+: 272.05294, found: 272.0528.
149.6, 134.9, 47.9, 20.7, 7.2, 2.0 ppm; HRMS (ESI +ve) Exact
mass calculated for C12H22O2NaSi [M+Na]+: 249.1281, found:
249.1281.
5-(Dimethyl(phenyl)silyl)-2-methylene-5-oxopentanal
(23):
from compound 5b: 90% yield as a colourless oil. FT-IR (film)
2924, 2859, 1690, 1642, 1428, 1252, 1112, 950, 815, 783, 736,
649 cm-1; 1H NMR (300 MHz, CDCl3) δ = 9.43 (s, 1H), 7.57-7.46
(m, 2H), 7.46-7.29 (m, 3H), 6.13 (s, 1H), 5.91 (s, 1H), 2.75 (t, J =
7.0 Hz, 2H), 2.42 (t, J = 7.0 Hz, 2H), 0.49 (s, 6H) ppm; 13C NMR
(75 MHz, CDCl3) δ = 244.2, 194.3, 149.0, 134.8, 133.9, 133.0,
129.9, 128.2, 46.3, 20.8, -4.9 ppm; HRMS (ESI +ve) Exact mass
calculated for C14H18O2NaSi [M+Na]+: 269.0974, found: 269.0977.
Ethyl 2-acetoxy-3-formylbut-3-enoate (18): from compound
(15a): yield 53%; (15b): yield 83%; (15c): yield 95%; (15d): yield
80%; (15e): yield 95%; (15f): yield 81% as a colourless oil. FT-
IR (film) 2924, 2852, 1723, 1450, 1370, 1210, 1158, 1030, 883
cm-1; 1H NMR (400 MHz, CDCl3) δ = 9.52 (s, 1H), 6.55 (s, 1H),
6.29 (s, 1H), 5.89 (d, J = 1.0 Hz, 1H), 4.15 (q, J = 7.2 Hz, 2H),
2.09 (s, 3H), 1.20-1.16 (t, J = 7.2 Hz, 3H) ppm; 13C NMR (101
MHz, CDCl3) δ = 190.6, 169.6, 167.6, 143.5, 137.3, 67.5, 62.0,
20.6, 13.9 ppm; HRMS (ESI +ve) Exact mass calculated for
C9H12O5Na [M+Na]+: 223.0582, found: 223.0584.
2-Methylene-5-oxo-5-(triisopropylsilyl)pentanal (24): from
compound 5d: yield 90% as a colourless oil. FT-IR (film) 2942,
2866, 1692, 1636, 1464, 1251, 881, 828, 674 cm-1; 1H NMR (300
MHz, CDCl3) δ = 9.44 (s, 1H), 6.22 (s, 1H), 5.93 (s, 1H), 2.68 (t, J
= 7.1 Hz, 2H), 2.42 (t, J = 7.1 Hz, 2H), 1.28-1.14 (m, 3H), 1.02 (s,
9H), 0.98 (s, 9H) ppm; 13C NMR (75 MHz, CDCl3) δ = 245.3, 194.4,
149.4, 134.9, 49.1, 20.6, 18.5, 17.6, 10.7 ppm; HRMS (ESI +ve)
Exact mass calculated for C15H28O2NaSi [M+Na]+: 291.1756,
found: 291.1756.
2-(Hydroxy(phenyl)methyl)acrylaldehyde
(19):
from
Acknowledgments
compound (4a): yield 61% as a colourless oil. FT-IR (film) 3412,
2922, 1682, 1453, 958, 698 cm-1; 1H NMR (400 MHz, CDCl3) δ =
9.59 (s, 1H), 7.41-7.27 (m, 5H), 6.47 (d, J = 1.4 Hz, 1H), 6.18 (s,
1H), 5.64 (s, 1H), 2.88 (d, J = 3.5 Hz, 1H) ppm; 13C NMR (101
MHz, CDCl3) δ = 193.9, 151.3, 140.8, 134.5, 128.5, 128.0, 126.6,
71.1 ppm; HRMS (ESI +ve) Exact mass calculated for
C10H10O2Na [M+Na]+: 185.0573, found: 185.0574.
This research has been performed as part of the Indo-French
"Joint Laboratory for Natural Products and Synthesis toward
Affordable Health". We thank CNRS, CSIR and University of
Rennes 1 for support of this research. G. M. thanks to CSIR for
financial assistance. We thank CRMPO (Rennes) for MS
analyses. We thank a reviewer for useful comments on literature
dealing with MBH reactions on acrolein.
2-(Hydroxy(4-nitrophenyl)methyl) acrylaldehyde (20): from
compound (6a): yield 78%; (6c): yield 86%; (6e): yield 86%; (6f):
yield 93% as a colourless oil. FT-IR (film) 3071, 2958, 2855, 1688,
1600, 1515, 1428, 1343, 1255, 1111, 850, 691 cm-1; 1H NMR (300
MHz, CDCl3) δ = 9.56 (s, 1H), 8.16 (d, J = 8.8 Hz, 2H), 7.56 (d, J
= 8.8 Hz, 2H), 6.52 (d, J = 1.3 Hz, 1H), 6.23 (d, J = 0.7 Hz, 1H),
5.71 (s, 1H) ppm; 13C NMR (75 MHz, CDCl3) δ = 193.6, 150.5,
148.4, 147.4, 135.3, 127.4, 123.6, 69.9 ppm; HRMS (ESI +ve)
Exact mass calculated for C10H8NO3 [M-H2O+H]+: 190.0498,
found: 191.0498.
Keywords: Morita-Baylis-Hillman • Rauhut-Currier • Acylsilanes
• Photolysis • Enals
[1]
For comprehensive reviews on MBH reactions see: (a) V. Singh, S. Batra,
Tetrahedron 2008, 64, 4511-4574; (b) D. Basavaiah, B. S. Reddy, S. S.
Batsara, Chem. Rev. 2010, 110, 5447-5674; (c) D. Basavaiah, G.
Veerraraghavaiah, Chem. Soc. Rev. 2012, 41, 68-78; (d) Y. Wei, M. Shi,
Chem. Rev. 2013, 113, 6659-6690; (e) H. Pelissier, Tetrahedron 2017,
73, 2831-2861; (f) T. N. Reddy, V. J. Rao, Tetrahedron Lett. 2018, 59,
2859-2875 and references cited therein
Ethyl 3-formyl-2-hydroxybut-3-enoate (21): from compound
(11a): yield 81%; (11c): yield 53%; (11e): yield 63%; (11f): yield
74% as a colourless oil. FT-IR (film) 3458, 2982, 2936, 1734,
1687, 1446, 1200, 1022, 969 cm-1; 1H NMR (300 MHz, CDCl3) δ
9.60 (s, 1H), 6.58 (d, J = 0.9 Hz, 1H), 6.27 (s, 1H), 4.94 (s, 1H),
4.25 (q, J = 7.2 Hz, 2H), 1.26 (t, J = 7.2 Hz, 3H) ppm; 13C NMR
(75 MHz, CDCl3) δ 192.1, 172.2, 146.7, 136.3, 68.2, 62.4, 13.9
ppm; HRMS: (ESI +ve) Exact mass calculated for C7H10O4Na
[M+Na]+: 181.04713, found: 181.0474.
[2]
(a) J. S. Hill, N. S. Isaacs, Tetrahedron Lett. 1986, 27, 5007-5010; (b) G.
M. Strunz, R. Bethell, G. Sampson, P. White, Can. J. Chem. 1995, 73,
1666-1674; (c) D. Basavaiah, A. J. Rao, M. Krishnamacharyulu, Arkivoc
2002, vii, 136-145; (d) Y-M. Xu, M. Shi, J. Org. Chem. 2004, 69, 417-
425; (e) X. Tang, B. Zhang, Z. He, R. Gao, Z. He, Adv. Synth. Cat. 2007,
349, 2007-2017; (f) X. Zeng, Y. Liu, C. Ji, J. Zhou Chin. J. Chem. 2012,
30, 2631-2635.
[3]
[4]
P. Rada Krishna, R. R. Kadiyala, Tetrahedron Lett. 2010, 51, 4981-4983.
For excellent reviews on acylsilanes and α-β unsaturated acylsilanes
see: (a) A. F. Patrocinio, P. J. S. Moran, J. Braz. Chem. Soc. 2001, 12,
7-31; (b) P. C. B. Page, M. J. McKenzie, Product Subclass 25:
Acylsilanes. In Science of Synthesis; I. Fleming, Ed.; Thieme: Stuttgart,
2001; Vol. 4, pp 513-568; (c) M. N. Garrett, J. S. Johnson, Product
Subclass 4: Silicon compound. In Science of Synthesis; I. Fleming, Ed.;
Thieme: Stuttgart, Knowledge update 2012/2; Vol. 4, pp 1-85; (d) G. R.
Boyce, S. N. Grezler, J. S. Johnson, X. Linghu, J. T. Malinovski, D. A.
Nicewicz, A. D. Satterfield, D. C. Schmitt, K. M. Steward, J. Org. Chem.
2-Methylene-5-oxo-5-(triethylsilyl)pentanal
(22):
from
compound 5a: yield 60% as a colourless oil. FT-IR (film) 2954,
2876, 1689, 1639, 1414, 1016, 945, 719 cm-1; 1H NMR (500 MHz,
CDCl3) δ = 9.51 (s, 1H), 6.26 (s, 1H), 5.99 (s, 1H), 2.75 (t, J = 7.2
Hz, 2H), 2.48 (t, J = 7.2 Hz, 2H), 0.96 (t, J = 8.0 Hz, 9H), 0.73 (q,
J = 8.0 Hz, 6H) ppm; 13C NMR (126 MHz, CDCl3) δ = 245.7, 194.7,
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10.1002/ejoc.201801343
European Journal of Organic Chemistry
FULL PAPER
2012, 77, 4503-4515; (e) H.-J. Zhang, D. L. Pribbenow, C. Bolm, Chem.
Soc. Rev. 2013, 42, 8540-8571 and references cited therein.
[11] For a review article on Rauhut-Currier reactions see: C. E. Aroyan, A.
Dermenci, S. J. Miller, Tetrahedron 2009, 65, 4069-4084.
[5]
J. Ruiz, A. S. Murthy, T. Roisnel, S. Chandrasekhar, R. Grée, J. Org.
Chem. 2015, 80, 2364-2375.
[12] G. W. Kabalka, B. Venkataiah, G. Dong, Tetrahedron Lett. 2003, 44,
4673-4675.
[6]
[7]
S. Denmark, M. Xie, J. Org. Chem. 2007, 72, 7050-7053.
a) J. C. Depezay, Y. Le Merrer, Tetrahedron Lett. 1974, 32, 2751-2754;
b) J. C. Depezay, Y. Le Merrer, Bull. Soc. Chim. Fr. 1981, 7-8 (Pt. II),
306-312.
[13] We used a Vilber Lourmat VL-6.LC lamp equiped with two 6W bulbs at
365 nm for the small scale reactions, or a LT5W T8/010 UV Dudexa lamp
from Narva for the larger scale reactions (see supplementary
information).
[8]
[9]
P. Singh, A. Kumar, S. Kaur, J. Kaur, H. Singh, Chem. Commun., 2016,
52, 2936-2939.
[14] For instance, very few derivatives with an α-methylene-1,3- diol structure
have been reported to date. All of them are symmetrical and only a few
synthetic uses have been described for them: a) C. M. König, K. Harms,
U. Koert, Org. Lett. 2007, 9, 4777-4779; b) Y. Lu, I. S. Kim, A. Hassan,
D. J. Del Valle, M. J. Krische, Ang. Chem. 2009, 121, 5118-5121; Ang.
Chem. Int. Ed. 2009, 48, 5018-5021; c) A. F. G. Goldberg, R. A. Craig II,
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L. De Luca, G. Giocomelli, A. Porcheddu, J. Org. Chem. 2001, 66, 7907-
7909.
[10] Elegant uses of α-β-unsaturated acylsilanes in synthesis have been
already described, see for instance: A. Degl’Innocenti, P. Ulivi, A.
Capperucci, G. Reginato, A. Mordini, A. Ricci, Synlett, 1992, 883-886,
and references cited therein.
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Entry for the Table of Contents (Please choose one layout)
Layout 2:
FULL PAPER
Key Topic: Synthetic Methodology
Gangababu Marri, Frédéric Justaud,
Saibal Das and René Grée
Page No. – Page No.
α-β Unsaturated Acylsilanes as
Surrogates of Acrolein for Morita-
Baylis-Hillman Reactions
Text for Table of Contents
A short approach toward new acrolein-type derivatives, functionalized in position 2 is described. It involves as the key step, a smooth
transformation of acylsilanes into aldehydes by irradiation in water-organic solvent mixtures. The functionalized enals obtained by this
new route appear as versatile building blocks for the preparation of natural products and/or bioactive compounds.
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