Acid catalyzed rearrangement of vinyl and ketene acetals

Article abstract of DOI:10.1016/j.tet.2014.01.010

Substituted vinyl and ketene acetals undergo smooth oxygen-to-carbon rearrangement with a catalytic amount of TMSOTf to afford chain-extended ketones or esters, respectively. The developed procedure has been applied to the stereoselective synthesis of C-glycosides from the corresponding anomeric vinyl ethers.

Full text of DOI:10.1016/j.tet.2014.01.010

Tetrahedron 70 (2014) 1651e1658
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Tetrahedron
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Acid catalyzed rearrangement of vinyl and ketene acetals
*
_
Elzbieta Maziarz, Bart1omiej Furman
Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Substituted vinyl and ketene acetals undergo smooth oxygen-to-carbon rearrangement with a catalytic
amount of TMSOTf to afford chain-extended ketones or esters, respectively. The developed procedure has
been applied to the stereoselective synthesis of C-glycosides from the corresponding anomeric vinyl
ethers.
Received 7 November 2013
Received in revised form 19 December 2013
Accepted 6 January 2014
Available online 10 January 2014
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Lewis acids
TMSOTf-catalyzed rearrangement
Vinyl ethers
C-Glycosides
1. Introduction
Interestingly, both (Z) and (E) propenyl ethers furnished a simi-
lar ratio of the corresponding
a-substituted aldehydes. This ob-
Vinyl and ketene acetals belong to a particular class of com-
pounds, which contain both an enol and an acetal moiety within
the same molecule. Their reactivity towards electrophiles origi-
nates from the combination of both structural elements, hence the
servation may suggest that under the reaction conditions, an
asymmetric transformation occurs to provide the thermodynamic
ratio of isomeric products.4
As an extension of our studies we focused on an analogous
transformation of simple vinyl and ketene acetals, which in the
presence of Lewis acid should provide chain-extended ketones or
esters, respectively.
€
reactions, e.g., with Bronsted or Lewis acids, generate in a single
step a carboxonium ion and an enol, which can react further to
produce either aldol ethers or fragmentation products.1 Recently,
Lewis acid promoted oxygen-to-carbon rearrangements of
substituted vinyl ethers,2 or simple anomerically linked tetrahy-
dropyranyl enol ethers,3 have received considerable attention as
a synthetically useful protocol. Earlier, we demonstrated that 4-
vinyloxyazetidin-2-ones, such as 1 also undergo the analogous
Lewis acid catalyst rearrangement into 4-carbonylmethyl-azetidin-
2-ones (2) (Scheme 1).4
2. Results and discussion
The substituted vinyl acetals and unsymmetrical ketene acetals
were readily prepared by the standard methylenation of starting
acetals by treatment with Tebbe reagent (Table 1),5 or through
elimination of b
-iodoacetals,6 respectively (Scheme 2).
As a model for our studies, vinyl acetal 4a was chosen. Initially,
€
the efficiency of various Lewis and Bronsted acids on an oxygen-to-
carbon rearrangement of 4a was evaluated and the obtained results
are summarized in Table 2.
Among the screened catalysts, TMSOTf was most successful. In
the presence of only 1 mol % of TMSOTf in CH2Cl2, vinyl acetal 4a
gave the expected 2-methoxyketone 11a in a 60% yield (entry 7).
Other Lewis acids were less efficient and furnished the desired
product in a lower yield (entries 1 and 2). On the other hand,
Brønsted acids, such as diphenylphosphate, CSA or benzoic acid,
were found to be completely ineffective and their use led to a rapid
degradation of the substrate even at low temperatures (entries
9e11).
Scheme 1.
* Corresponding author. E-mail addresses: furbar@icho.edu.pl, bartlomiej.fur-
man@icho.edu.pl (B. Furman).
0040-4020/$ e see front matter Ó 2014 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2014.01.010

1652
E. Maziarz, B. Furman / Tetrahedron 70 (2014) 1651e1658
Table 1
Table 3
The scope of substrates for methylenation of starting acetals
The scope of substrates for oxygen-to-carbon rearrangement of vinyl and ketene
acetalsa
Entry Starting acetal
R1
R2
Product Yield [%]
Entry
1
R1
R2
Product
Time [h]
0.5
Yield [%]b
60
1
2
3
4
3a
3b
3c
3d
Me
4a
4b
53
59
55
64
Me
11a
Ph
2
3
4
Ph
11b
11c
11d
0.3
0.5
0.5
57
71
50
3,4-Dimethoxybenzyl 4c
3,4-Dimethoxybenzyl
Cyclohexyl
Cyclohexyl
4d
5
6
7
8
5a
5b
5c
5d
Me
6a
6b
6c
6d
50
87
61
69
5
6
7
8
Me
12a
12b
12c
12d
0.6
0.5
1
47
55
56
73
Ph
Ph
4-Methoxyphenyl
3-Chlorophenyl
4-Methoxyphenyl
3-Chlorophenyl
0.5
9
7
Ph
8
74
9
Ph
13
0.5
82
a
Reaction was performed at 0.2 mmol scale.
Isolated yield.
b
Scheme 2.
Table 2
Screening of catalyst for transformation of 4a into ketone 11aa
Scheme 3.
Entry
Catalyst (equiv)
Solvent
Temp [ꢀC]
Time [h]
Yield [%]b
TMSOTf, vinyl ethers 15 were rapidly degraded giving tarry prod-
ucts only. It seems probable that the expected primary reaction
products, in this case the reactive aldehydes, in the presence of acid
undergo further transformations leading to a complex mixture of
products.
Interestingly, the rearrangement of acetal 16 led to the forma-
tion of a mixture of isomeric furans 17a/17b in the ratio of 2:1,
respectively in approximately 30% yield. This transformation can be
described as a cationic rearrangement/intramolecular ene reaction
cascade (Scheme 4).
1
2
3
4
5
6
7
8
BF3$Et2O/1
PhMe
PhMe
CH3CN
CH3CN
PhMe
PhMe
PhMe
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
ꢁ78
ꢁ78
ꢁ10
ꢁ10
ꢁ78
ꢁ78
ꢁ78
ꢁ78
ꢁ78
ꢁ78
ꢁ78
0.3
0.3
1
52
33
35
48
53
51
43
60
BF3$Et2O/0.2
Yb(OTf)3/0.2
Yb(OTf)3/0.02
TMSOTf/1
TMSOTf/0.1
TMSOTf/0.01
TMSOTf/0.01
CSA/0.2
2
0.5
0.5
0.5
0.5
3.5
3
9
10
11
Degr.
Degr.
Degr.
Benzoic acid/0.2
Diphenylphosphate
2
a
Reaction was performed at 0.2 mmol scale.
Isolated yield; degr.¼degradation of the starting material.
b
With the optimized conditions for oxygen-to-carbon rear-
rangement in hand, the scope of the reaction was then examined
and the representative results are summarized in Table 3 and on
Scheme 3.
Under these conditions, the TMSOTf-catalyzed rearrangement
of different vinyl ethers proceeded with a moderate to good yield
and without a noticeable difference when comparing either aro-
matic (entries 1e4) or aliphatic vinyl acetals (entries 5e9). Un-
symmetrical ketene acetals 10a,b with an electron-donating
aromatic ring also provided the desired esters in a good yield
Scheme 4.
A plausible catalytic cycle, based on the original proposal by
Rovis,7 and Gansauer, is rationalized in Scheme 5. Activation of
8
€
the silyl enol ether with TMSOTf provides a carboxonium cation
and the new enol silyl ether. Next, the latter one being a nucleo-
phile reacts with the electrophilic oxonium ion upon treatment
(Scheme 3). On the other hand, the
b-substituted ethers, such as 15
did not give the expected aldehydes. In the presence of 1 mol % of

E. Maziarz, B. Furman / Tetrahedron 70 (2014) 1651e1658
1653
mass spectra were recorded on ESI-TOF Mariner Spectrometer,
SYNAPT G2-S HDMS or AMD 604 mass spectrometer. Optical ro-
tations were measured with a Jasco P-2000 polarimeter. Melting
points were determined on a Kofler hot-plate microscope and are
uncorrected. Elemental analyses were performed on a Perkin Elmer
240 Analyzer. Thin layer chromatography was performed on Merck
aluminium-backed Silica Gel 60 F254 sheets. Column chromatog-
raphy was carried out using Merck silica gel (230e400 mesh). All
reactions were performed under argon in pre-dried glassware. All
solvents were purified by standard techniques.10
3.1.1. Synthesis of vinyl acetals 3a and b.11 1-Phenyl-1-
methoxychloromethane,12,13 (30 mmol) was cooled to 0 ꢀC and
was added to pulverized sodium acetate/benzoate (40 mmol) at
once. The reaction mixture was allowed to warm to room tem-
perature and stirred vigorously overnight. The solids were filtered
off on a Celite pad and the solvent was removed to obtain the oil
product, which was either used for the next reaction without fur-
ther purification, or was distilled to afford pure product.
Scheme 5.
with the triflate anion to form the corresponding carbonyl
compound.
To demonstrate an extension of the above presented method,
we focused on its use for the synthesis of C-glycosides from the
corresponding anomeric vinyl ethers. To date, several different
approaches for the synthesis of C-glycosides have been explored.9
The most common method for carbonecarbon bond formation at
the anomeric carbon involves the attack of a carbon nucleophile on
the electrophilic anomeric center of a glycosyl donor. We have
found that by treatment with a catalytic amount of TMSOTf, the
readily available anomeric vinyl ethers 19aeb, and 21 can be
rearranged to the desired ketones or esters in a high yield and with
an excellent stereoselectivity (Scheme 6). The structure of C-gly-
cosides 20aeb and 22 was established on the basis of 1D and 2D
NMR experiments. The stereochemistry at the newly formed ster-
eocenters was further confirmed by the appropriate NOE
experiments.
3.1.1.1. Methoxy-(phenyl)methyl acetate (3a).14 Compound 3a
was obtained according to the general procedure starting from 1-
phenyl-1-methoxychloromethane (5.6 g, 36 mmol); obtained
5.6 g (85%) of 3a. 1H NMR (600 MHz, CDCl3)
d
: 7.48e7.43 (m, 2H),
7.39e7.35 (m, 3H), 6.67 (s, 1H), 3.52 (s, 3H), 2.13 (s, 3H); 13C NMR
(150 MHz, CDCl3) : 170.6, 137.2, 129.2, 128.4, 126.3, 98.4, 56.4, 21.2.
d
3.1.1.2. Methoxy-(phenyl)methyl benzoate (3b).15 Compound 3b
was obtained according to the general procedure starting from 1-
phenyl-1-methoxychloromethane (4.7 g, 30 mmol); obtained
5.7 g (78%) of 3b. 1H NMR (400 MHz, CDCl3)
d
: 8.19e8.01 (m, 2H),
7.69e7.51 (m, 3H), 7.50e7.30 (m, 5H), 6.95 (s, 1H), 3.61 (s, 3H); 13
C
O
OEt
OEt
O
O
TMSOTf (10 mol%)
CH2Cl2, -78 oC, 60%
O
OBn
BnO
BnO
OBn
BnO
BnO
21
22
Scheme 6.
In summary, we demonstrated that substituted vinyl acetals and
unsymmetrical ketene acetals undergo smooth TMSOTf-catalyzed
rearrangement to afford chain-extended ketones or esters. This
transformation can also be applied to the sugar-derived anomeric
vinyl ethers to produce C-glycosides. Further work devoted to the
stereoselective synthesis of diverse C-glycosides and related com-
pounds using the presented method is in progress and will be
published in due course.
NMR (100 MHz, CDCl3) d: 166.0, 137.3, 133.3, 130.1, 129.8, 129.2,
128.4 (2ꢂ), 126.3, 99.1, 56.6.
3.1.2. General procedure for compounds 3c, 3d, 5aed, 7a.13 To
a mixture of acid with the corresponding chloride (1.2 equiv), N,N-
diisopropylethylamine or Et3N (1.2 equiv) was added at room
temperature under an argon atmosphere. The reaction progress
was monitored by TLC. The reaction mixture was quenched with
NH4Cl, and the organic materials were extracted with ethyl acetate
and then washed sequentially with water and brine, dried over
MgSO4. Obtained products were either used in the next reaction
without further purification, or were purified by flash-
chromatography (hexane/Et2O 95:5 v/v).
3. Experimental section
3.1. General information
1H NMR and 13C NMR spectra were recorded on Varian Gemini
200, Varian Mercury 400, Varian VNMRS 500 and Varian VNMRS
600 spectrometers, in CDCl3, unless otherwise stated, and with TMS
3.1.2.1. Methoxy-(phenyl)methyl 2-(3,4-dimethoxyphenyl)acetate
(3c). Compound 3c was obtained according to the general pro-
cedure starting from 1-phenyl-1-methoxychloromethane (4.7 g,
used as an internal standard. Chemical shifts (d) were given in parts
30 mmol); obtained 7.9 g (100%) of 3c. 1H NMR (400 MHz, CDCl3)
d:
per million and coupling constants (J) were given in Hertz (Hz).
Infrared spectra were recorded on a FT-IR Jasco 6200 and FT-IR
Spectrum 2000 Perkin Elmer spectrophotometer. High-resolution
7.45e7.40 (m, 2H), 7.39e7.32 (m, 3H), 6.87e6.78 (m, 3H), 6.68 (s,
1H), 3.86 (s, 3H), 3.82 (s, 3H), 3.64 (d, J 0.5 Hz, 2H), 3.46 (s, 3H); 13
C

1654
E. Maziarz, B. Furman / Tetrahedron 70 (2014) 1651e1658
NMR (100 MHz, CDCl3)
d
: 171.4, 148.9, 148.2, 137.1, 129.2, 128.4,
a pad of Celite, washed with hexane and the solvent evaporated.
The residue was chromatographed on silica gel (hexane/Et2O 95:5
v/vþEt3N) to afford ether.
128.2,126.2,121.5, 112.2,111.1, 98.8, 56.5, 55.84, 55.75, 41.1; IR (film)
n
: ; HRMS (ESI) m/z calcd for
2836, 1734, 1516, 1264 cmꢁ1
C
18H20O5Na [MþNa]þ: 339.1208; found: 339.1208.
3.1.3.1. (Methoxy(prop-1-en-2-yloxy)methyl)benzene (4a). Com
pound 4a was obtained according to the general procedure starting
from 3a (1.0 g, 5.6 mmol); obtained 0.7 g (70%) of 4a. 1H NMR
3.1.2.2. Methoxy-(phenyl)methyl
(3d). Compound 3d was obtained according to the general pro-
cyclohexanecarboxylate
cedure starting from 1-phenyl-1-methoxychloromethane (1.6 g,
(500 MHz, CDCl3) d: 7.49e7.44 (m, 2H), 7.41e7.32 (m, 3H), 5.88 (s,
10 mmol); obtained 2.0 g (82%) of 3d. 1H NMR (600 MHz, CDCl3)
d:
1H), 4.06 (d, J 1.8 Hz,1H), 4.04 (dd, J 1.8, 0.8 Hz,1H), 3.36 (s, 3H),1.93
7.45e7.43 (m, 2H), 7.37e7.33 (m, 3H), 6.69 (s, 1H), 3.51 (s, 3H),
2.42e2.36 (m, 1H), 1.95e1.89 (m, 2H), 1.80e1.71 (m, 3H), 1.32e1.21
(d, J 0.8 Hz, 3H); 13C NMR (125 MHz, CDCl3)
128.3, 126.4, 100.6, 86.0, 53.2, 20.9; IR (film)
d: 157.4, 137.9, 128.7,
n
HRMS (EI) m/z calcd for C11H14O2 [M]þ: 178.0994; found: 178.0990.
: 1268, 1046 cmꢁ1
;
(m, 5H); 13C NMR (150 MHz, CDCl3)
d: 175.6, 137.5, 129.0, 128.4,
126.2, 97.9, 56.3, 43.4, 29.0, 28.8, 25.7, 25.4, 25.3; IR (film)
n
: 2933,
2856, 1731, 1451 cmꢁ1; HRMS (ESI) m/z calcd for C15H20O3Na
[MþNa]þ: 271.1310; found: 271.1312.
3.1.3.2. (Methoxy(1-phenylvinyloxy)methyl)benzene
(4b).18,19 Compound 4b was obtained according to the general
procedure starting from 3b (726 mg, 3 mmol); obtained 212 mg
3.1.2.3. Benzyloxymethyl acetate (5a).16 Compound 5a was ob-
tained according to the general procedure starting from BOMCl
(3.6 g, 23 mmol); obtained 2.5 g (60%) of 5a. 1H NMR (400 MHz,
(29%) of 4b. 1H NMR (400 MHz, CDCl3)
d
: 7.73e7.67 (m, 2H),
7.59e7.53 (m, 2H), 7.46e7.30 (m, 6H), 6.11 (s, 1H), 4.85 (d, J 2.7 Hz,
1H), 4.49 (d, J 2.7 Hz, 1H), 3.41 (s, 3H); 13C NMR (100 MHz, CDCl3)
d
:
CDCl3)
d
: 7.40e7.32 (m, 5H), 5.35 (s, 2H), 4.71 (s, 2H), 2.08 (s, 3H);
157.5, 137.7, 136.1, 128.8, 128.6, 128.4, 128.2, 126.5, 125.4, 101.1, 87.3,
53.0.
13C NMR (100 MHz, CDCl3)
71.8, 21.0.
d: 170.6, 136.9, 128.4, 127.9, 127.8, 88.3,
3.1.3.3. 1,2-Dimethoxy-4-(2-(methoxy(phenyl)methoxy)allyl)ben-
zene (4c). Compound 4c was obtained according to the general
procedure starting from 3c (1.0 g, 3.2 mmol); obtained 450 mg
3.1.2.4. Benzyloxymethyl benzoate (5b).17 Compound 5b was
obtained according to the general procedure starting from BOMCl
(3.9 g, 25 mmol); obtained 6.0 g (100%) of 5b. 1H NMR (600 MHz,
(45%) of 4c. 1H NMR (400 MHz, CDCl3)
d: 7.42e7.30 (m, 5H),
CDCl3)
7.39e7.27 (m, 5H), 5.61 (s, 2H), 4.79 (s, 2H); 13C NMR (150 MHz,
CDCl3)
: 166.0, 137.0, 133.3, 129.8 (2ꢂ), 128.5, 128.4, 128.0, 127.9,
d
: 8.08e8.02 (m, 2H), 7.60e7.55 (m, 1H), 7.48e7.41 (m, 2H),
6.86e6.78 (m, 3H), 5.86 (s, 1H), 4.15 (dd, J 2.0, 0.4 Hz, 1H), 4.09 (d, J
2.0 Hz, 1H), 3.86 (s, 3H), 3.83 (s, 3H), 3.43 (s, 2H), 3.21 (s, 3H); 13C
d
NMR (100 MHz, CDCl3)
128.3, 126.4, 121.0, 112.1, 110.9, 100.6, 86.8, 55.8, 55.7, 53.0, 41.2; IR
(film)
: 1514, 1263, 1029 cmꢁ1; Anal. Calcd for C19H22O4: C, 72.59;
d: 159.9, 148.6, 147.5, 137.7, 130.8, 128.7,
89.0, 72.0; IR (film) n
: 1725, 1270, 1057 cmꢁ1; HRMS (ESI) m/z calcd
for C15H14O3Na [MþNa]þ: 265.0841; found: 265.0844.
n
H, 7.05. Found: C, 72.29; H, 6.89.
3.1.2.5. Benzyloxymethyl 4-methoxybenzoate (5c). Compound 5c
was obtained according to the general procedure starting from
BOMCl (2.1 g, 15 mmol); obtained 3.3 g (98%) of 5c. 1H NMR
3.1.3.4. ((1-Cyclohexylvinyloxy)(methoxy)methyl)benzene
(4d). Compound 4d was obtained according to the general pro-
cedure starting from 3d (1.0 g, 4 mmol); obtained 626 mg (64%) of
(400 MHz, CDCl3)
6.96e6.90 (m, 2H), 5.59 (s, 2H), 4.78 (s, 2H), 3.87 (s, 3H); 13C NMR
(100 MHz, CDCl3) : 165.7, 163.6, 137.1, 131.9, 128.5, 127.92, 127.86,
d: 8.04e7.98 (m, 2H), 7.41e7.27 (m, 5H),
4d. 1H NMR (600 MHz, CDCl3)
d: 7.47e7.44 (m, 2H), 7.40e7.32 (m,
d
3H), 5.89 (s, 1H), 3.99 (dd, J 6.1, 2.1 Hz, 2H), 3.33 (s, 3H), 2.11e2.07
(m, 1H), 1.95e1.90 (m, 2H), 1.81e1.76 (m, 2H), 1.71e1.67 (m, 1H),
122.1, 113.6, 88.7, 71.9, 55.4; IR (film) n ;
: 1719,1606,1258, 1059 cmꢁ1
HRMS (ESI) m/z calcd for C16H16O4Na [MþNa]þ: 295.0946; found:
1.40e1.25 (m, 5H); 13C NMR (150 MHz, CDCl3)
d
: 165.3, 138.1, 128.6,
295.0941.
128.3, 126.5, 100.0, 82.8, 52.9, 43.7, 31.24, 31.19, 26.3 (2ꢂ), 26.2; IR
(film)
C
n ; HRMS (ESI) m/z calcd for
: 2929, 1451, 1103 cmꢁ1
3.1.2.6. Benzyloxymethyl 3-chlorobenzoate (5d). Compound 5d
was obtained according to the general procedure starting from
BOMCl (2.8 g, 20 mmol); obtained 4.5 g (100%) of 5d. 1H NMR
16H22O2Na [MþNa]þ: 269.1517; found: 269.1516.
3.1.3.5. (((Prop-1-en-2-yloxy)methoxy)methyl)benzene
(600 MHz, CDCl3)
7.55e7.52 (m, 1H), 7.40e7.33 (m, 5H), 7.32e7.27 (m, 1H), 5.61 (s,
2H), 4.79 (s, 2H); 13C NMR (150 MHz, CDCl3)
: 164.8, 136.9, 134.6,
133.3, 131.5, 129.8, 129.7, 128.5, 128.1, 127.88, 127.86, 89.4, 72.3; IR
d
: 7.99e7.96 (m, 1H), 7.93e7.90 (m, 1H),
(6a). Compound 6a was obtained according to the general pro-
cedure starting from 5a (1.0 g, 5.6 mmol); obtained 494 mg (50%) of
d
6a. 1H NMR (500 MHz, CDCl3)
d
: 7.37e7.33 (m, 4H), 7.33e7.27 (m,
1H), 5.06 (s, 2H), 4.66 (s, 2H), 4.15 (d, J 1.7 Hz, 1H), 4.01 (s, 1H), 1.85
(s, 3H); 13C NMR (125 MHz, CDCl3)
: 157.5, 137.5, 128.4, 127.9, 127.7,
(film)
n
: 1731, 1253, 1058 cmꢁ1; HRMS (ESI) m/z calcd for
d
C
15H13O3ClNa [MþNa]þ: 299.0451; found: 299.0449.
91.4, 85.1, 70.1, 20.8; IR (film) n
: 1268, 1048 cmꢁ1; HRMS (ESI) m/z
calcd for C11H14O2Na [MþNa]þ: 178.0994; found: 178.1002.
3.1.2.7. Methoxymethyl benzoate (7).13 Compound 7 was ob-
tained according to a general procedure starting from MOMCl
3.1.3.6. (1-(Benzyloxymethoxy)vinyl)benzene (6b). Compound
6b was obtained according to the general procedure starting from
5b (1.0 g, 4.2 mmol); obtained 873 mg (87%) of 6b. 1H NMR
(2.4 g, 30 mmol); obtained 3.9 g (96%) of 7. 1H NMR (200 MHz,
CDCl3)
3H); 13C NMR (50 MHz, CDCl3)
90.9, 57.7; IR (film)
: 1726, 1272, 1057 cmꢁ1
d: 8.19e8.04 (m, 2H), 7.67e7.39 (m, 3H), 5.49 (s, 2H), 3.55 (s,
d
: 166.0, 133.2, 129.7 (2ꢂ), 128.4,
(600 MHz, CDCl3)
2H), 4.82 (d, J 2.7 Hz,1H), 4.74 (s, 2H), 4.59 (d, J 2.7 Hz, 1H); 13C NMR
(150 MHz, CDCl3) : 157.9, 137.4, 136.1, 128.5, 128.4, 128.2, 128.0,
d: 7.65e7.62 (m, 2H), 7.39e7.28 (m, 8H), 5.28 (s,
n
.
d
3.1.3. General procedure for the preparation of substituted vinyl ac-
etals 4aed, 6aed, 8.5 To a solution of ester (3 mmol) in THF (10 ml),
pyridine (6 equiv) and Tebbe’s reagent (3 equiv) was added drop-
wise at approx. ꢁ50 ꢀC. The reaction progress was monitored by
TLC (hexane/Et2O 9:1 v/v). At the end of the reaction 0.1 M NaOH
was added dropwise and the reaction mixture was stirred vigor-
ously until foaming ceased. Then the mixture was filtrated through
127.8, 125.3, 92.1, 86.2, 70.2; IR (film) n ;
: 1622, 1281, 1018 cmꢁ1
HRMS (ESI) m/z calcd for C16H16O2Na [MþNa]þ: 263.1048; found:
263.1045.
3.1.3.7. 1-(1-(Benzyloxymethoxy)vinyl)-4-methoxybenzene
(6c). Compound 6c was obtained according to the general pro-
cedure starting from 5c (2.0 g, 7.3 mmol); obtained 611 mg (31%) of

E. Maziarz, B. Furman / Tetrahedron 70 (2014) 1651e1658
1655
6c. 1H NMR (400 MHz, CDCl3)
5H), 6.91e6.84 (m, 2H), 5.27 (s, 2H), 4.74 (s, 2H), 4.71 (d, J 2.6 Hz,
1H), 4.50 (d, J 2.6 Hz, 1H), 3.83 (s, 3H); 13C NMR (100 MHz, CDCl3)
159.9, 157.7, 137.4, 130.6, 128.4, 128.0, 127.8, 126.7, 113.5, 92.0, 84.6,
d
: 7.60e7.54 (m, 2H), 7.41e7.28 (m,
(50 MHz, CDCl3)
d
: 163.6, 140.8, 128.4, 127.6, 126.8, 81.2, 63.9, 60.3,
14.4; IR (film) n
: 2981, 1651, 1270, 1024 cmꢁ1; HRMS (ESI) m/z calcd
d:
for C17H18O2Na [MþNa]þ: 277.1204; found: 277.1203.
70.2, 55.3; IR (film)
n
: 1511, 1251, 1021 cmꢁ1; HRMS (ESI) m/z calcd
3.1.4. General procedure for the rearrangement of vinyl ethers using
Lewis acids. To a solution of vinyl ether (0.2 mmol) in CH2Cl2
(1.5 ml) was added Lewis acid (1 mol %) at ꢁ78 ꢀC under argon
atmosphere. The reaction progress was monitored by TLC. After
about 20 min, the reaction mixture was quenched with NaHCO3
satd, and the organic materials were extracted with ethyl acetate,
dried over MgSO4 and then chromatographed on silica gel (hexane/
AcOEt 9:1 to 7:3 v/v) to afford products.
for C17H18O3Na [MþNa]þ: 293.1154; found: 293.1149.
3.1.3.8. 1-(1-(Benzyloxymethoxy)vinyl)-3-chlorobenzene
(6d). Compound 6d was obtained according to the general pro-
cedure starting from 5d (2.0 g, 7.2 mmol); obtained 1.4 g (69%) of
6d. 1H NMR (400 MHz, CDCl3)
d: 7.63e7.59 (m, 1H), 7.52e7.48 (m,
1H), 7.39e7.31 (m, 5H), 7.31e7.27 (m, 2H), 5.28 (s, 2H), 4.84 (d, J
2.9 Hz, 1H), 4.74 (s, 2H), 4.65 (d, J 2.9 Hz, 1H); 13C NMR (100 MHz,
CDCl3)
d
: 156.5, 137.9, 137.2, 134.2, 129.4, 128.5, 128.5, 128.0, 127.9,
3.1.4.1. 4-Methoxy-4-phenylbutan-2-one
(11a).21 Compound
125.5, 123.4, 92.2, 87.2, 70.4; IR (film)
n
: 1566, 1286, 1017 cmꢁ1
;
11a was obtained according to the general procedure starting from
HRMS (ESI) m/z calcd for C16H15O2ClNa [MþNa]þ: 297.0658; found:
4a (36 mg, 0.2 mmol); obtained 21.6 mg (60%) of 11a. 1H NMR
297.0656.
(600 MHz, CDCl3)
3.19 (s, 3H), 2.96 (dd, J 15.9, 9.0 Hz, 1H), 2.57 (dd, J 15.9, 4.3 Hz, 1H),
2.15 (s, 3H); 13C NMR (150 MHz, CDCl3)
: 206.5, 141.0, 128.6, 127.9,
126.5, 79.6, 56.7, 51.9, 31.0; IR (film)
: 1717, 1104 cmꢁ1; HRMS (EI)
m/z calcd for C11H14O2 [M]þ: 178.0994; found: 178.0998.
d: 7.36e7.26 (m, 5H), 4.63 (dd, J 9.0, 4.3 Hz, 1H),
3.1.3.9. (1-(Methoxymethoxy)vinyl)benzene (8).20 Compound 8
was obtained according to the general procedure starting from 7
(1.0 g, 6 mmol); obtained 729 mg (74%) of 8. 1H NMR (600 MHz,
d
n
CDCl3)
2.7 Hz, 1H), 4.50 (d, J 2.7 Hz, 1H), 3.50 (s, 3H); 13C NMR (150 MHz,
CDCl3) : 157.9, 136.1, 128.5, 128.1, 125.3, 94.1, 85.9, 56.3; IR (film)
1281, 1154, 1014 cmꢁ1
d: 7.64e7.61 (m, 2H), 7.36e7.29 (m, 3H), 5.15 (s, 2H), 4.78 (d, J
3.1.4.2. 3-Methoxy-1,3-diphenylpropan-1-one
(11b).22,23 Com
d
n
:
pound 11b was obtained according to the general procedure
starting from 4b (36 mg, 0.2 mmol); obtained 20.5 mg (57%) of 11b.
.
b
-iodoacetals 9aeb and ketene acetals 10aeb were prepared
1H NMR (400 MHz, CDCl3)
d: 7.98e7.91 (m, 2H), 7.59e7.51 (m, 1H),
according literature procedure.6
7.48e7.33 (m, 6H), 7.33e7.27 (m, 1H), 4.89 (dd, J 8.5, 4.4 Hz, 1H),
3.60 (dd, J 16.5, 8.5 Hz, 1H), 3.24 (s, 3H), 3.08 (dd, J 16.5, 4.4 Hz, 1H);
3.1.3.10. 1-((1-Ethoxy-2-iodoethoxy)methyl)-4-methoxybenzene
(9a). Compound 9a was obtained according to the general pro-
cedure starting from (4-methoxyphenyl)methanol (1.4 g,10 mmol);
13C NMR (100 MHz, CDCl3)
d: 197.7, 141.4, 137.1, 133.1, 128.6, 128.5,
128.2, 127.8, 126.6, 79.5, 56.9, 47.1; IR (film)
n: 1687, 1449,
1102 cmꢁ1; HRMS (ESI) m/z calcd for C16H16O2Na [MþNa]þ:
obtained 3.0 g (88%) of 9a. 1H NMR (600 MHz, CDCl3)
d
: 7.30e7.27
263.1043; found: 263.1049.
(m, 2H), 6.90e6.86 (m, 2H), 4.69 (t, J 5.5 Hz, 1H), 4.61 (d, J 11.3 Hz,
1H), 4.50 (d, J 11.3 Hz, 1H), 3.80 (s, 3H), 3.66 (dq, J 9.3, 7.0 Hz, 1H),
3.56 (dq, J 9.3, 7.0 Hz, 1H), 3.24 (d, J 5.5 Hz, 2H), 1.23 (t, J 7.0 Hz, 3H);
3.1.4.3. 1-(3,4-Dimethoxyphenyl)-4-methoxy-4-phenylbutan-2-
one (11c). Compound 11c was obtained according to the general
procedure starting from 4c (63 mg, 0.2 mmol); obtained 45 mg
13C NMR (150 MHz, CDCl3)
d: 159.3, 129.54, 129.49, 113.8, 100.9,
68.0, 62.0, 55.3, 15.2, 5.4; IR (film)
n
: 2974, 1613, 1514, 1249,
(71%) of 11c. 1H NMR (400 MHz, CDCl3)
d: 7.37e7.24 (m, 5H),
1033 cmꢁ1; HRMS (ESI) m/z calcd for C12H17O3NaI [MþNa]þ:
6.86e6.73 (m, 1H), 6.72e6.66 (m, 1H), 6.64e6.61 (m, 1H), 4.64 (dd, J
8.7, 4.6 Hz, 1H), 3.86 (s, 3H), 3.84 (s, 3H), 3.68e3.56 (m, 2H), 3.19 (s,
3H), 2.99 (dd, J 15.9, 8.7 Hz, 1H), 2.61 (dd, J 15.9, 4.6 Hz, 1H); 13C
359.0120; found: 359.0117.
3.1.3.11. ((1-Ethoxy-2-iodoethoxy)methylene)dibenzene
(9b). Compound 9b was obtained according to the general pro-
cedure starting from diphenylmethanol (3.7 g, 20 mmol); obtained
NMR (100 MHz, CDCl3)
126.5, 126.2, 121.7, 112.4, 111.3, 79.6, 56.8, 55.8, 55.8, 50.7, 50.0; IR
(film)
: 1713, 1516, 1262, 1238, 1028 cmꢁ1; Anal. Calcd for
19H22O4: C, 72.59; H, 7.05. Found: C, 72.36; H, 6.98.
d: 206.3, 148.9, 148.0, 140.9, 128.5, 127.9,
n
5.6 g (73%) of 9b. 1H NMR (600 MHz, CDCl3)
d
: 7.41e7.21 (m, 10H),
5.72 (s, 1H), 4.67 (t, J 5.4 Hz, 1H), 3.58e3.46 (m, 2H), 3.27e3.21 (m,
2H), 1.17 (t, J 7.0 Hz, 3H); 13C NMR (150 MHz, CDCl3)
: 142.2, 141.1,
128.5, 128.3, 127.8, 127.5, 127.4, 126.8, 99.7, 79.5, 61.6, 15.1, 5.7; IR
C
d
3.1.4.4. 1-Cyclohexyl-3-methoxy-3-phenylpropan-1-one
(11d). Compound 11d was obtained according to the general pro-
cedure starting from 4d (49 mg, 0.2 mmol); obtained 24.5 mg (50%)
(film) n
: 2975, 1494, 1454, 1107, 1019 cmꢁ1; HRMS (ESI) m/z calcd for
C
17H19O2NaI [MþNa]þ: 405.0327; found: 405.0323.
of 11d. 1H NMR (400 MHz, CDCl3)
d: 7.30e7.18 (m, 5H), 4.61 (dd, J
8.6, 4.5 Hz, 1H), 3.12 (s, 3H), 2.93 (dd, J 16.2, 8.6 Hz, 1H), 2.51 (dd, J
16.2, 4.5 Hz, 1H), 2.26e2.17 (m, 1H), 1.83e1.61 (m, 4H), 1.30e1.04
3.1.3.12. 1-((1-Ethoxyvinyloxy)methyl)-4-methoxybenzene
(10a). Compound 10a was obtained according to the general
procedure starting from 9a (1.0 g, 3 mmol); obtained 573 mg (91%)
(m, 6H); 13C NMR (100 MHz, CDCl3)
d: 211.4, 141.4, 128.5, 127.7,
126.5, 79.5, 56.8, 51.4, 49.1, 28.0, 27.9, 25.8, 25.6, 25.5; IR (film) n:
of 10a. 1H NMR (400 MHz, CDCl3)
d
: 7.34e7.27 (m, 2H), 6.91e6.86
2930, 1710, 1450, 1103 cmꢁ1; HRMS (ESI) m/z calcd for C16H22O2Na
[MþNa]þ: 269.1517; found: 269.1515.
(m, 2H), 4.77 (s, 2H), 3.84 (q, J 7.0 Hz, 2H), 3.80 (s, 3H), 3.21 (d, J
3.8 Hz, 1H), 3.17 (d, J 3.8 Hz, 1H), 1.33 (t, J 7.0 Hz, 3H); 13C NMR
(100 MHz, CDCl3)
55.2, 14.4; IR (film)
(ESI) m/z calcd for
231.1004.
d
: 164.8, 159.4, 129.5, 128.4, 113.8, 69.7, 63.7, 56.8,
3.1.4.5. 4-(Benzyloxy)butan-2-one (12a).24,25 Compound 12a
was obtained according to the general procedure starting from 6a
(36 mg, 0.2 mmol); obtained 17 mg (47%) of 12a. 1H NMR (600 MHz,
n
: 2981, 1647, 1515, 1248, 1031 cmꢁ1; HRMS
C
12H16O3Na [MþNa]þ: 231.0997; found:
CDCl3)
d
: 7.35e7.25 (m, 5H), 4.50 (s, 2H), 3.73 (t, J 6.3 Hz, 2H), 2.71 (t,
: 207.1, 138.0,
J 6.3 Hz, 2H), 2.17 (s, 3H); 13C NMR (150 MHz, CDCl3)
d
3.1.3.13. ((1-Ethoxyvinyloxy)methylene)dibenzene
(10b). Com
128.4, 127.67, 127.65, 73.2, 65.2, 43.8, 30.5; HRMS (EI) m/z calcd for
C
pound 10b was obtained according to the general procedure
11H14O2 [M]þ: 178.0994; found: 178.0991.
starting from 9b (1.0 g, 2.6 mmol); obtained 574 mg (87%) of 10b. 1H
NMR (200 MHz, CDCl3)
d
: 7.51e7.31 (m, 10H), 6.16 (s, 1H), 3.88 (q, J
3.1.4.6. 3-(Benzyloxy)-1-phenylpropan-1-one
(12b).26 Com
7.0 Hz, 2H), 3.28 (dd, J 8.4, 3.7 Hz, 2H), 1.38 (t, J 7.0 Hz, 3H); 13C NMR
pound 12b was obtained according to the general procedure

1656
E. Maziarz, B. Furman / Tetrahedron 70 (2014) 1651e1658
starting from 6b (48 mg, 0.2 mmol); obtained 26.5 mg (55%) of 12b.
1H NMR (600 MHz, CDCl3)
: 7.98e7.95 (m, 2H), 7.58e7.54 (m, 1H),
113.8, 101.3, 19.7, 15.3; IR (film) n ;
: 1692, 1154, 1110, 1025 cmꢁ1
d
HRMS (ESI) m/z calcd for C15H20O2Ag [MþAg]þ: 339.0514; found:
7.48e7.43 (m, 2H), 7.36e7.31 (m, 4H), 7.29e7.25 (m, 1H), 4.56 (s,
339.0505.
2H), 3.93 (t, J 6.6 Hz, 2H), 3.29 (t, J 6.6 Hz, 2H); 13C NMR (150 MHz,
Rearrangement of 16 was performed analogously to the pro-
cedure described for 11a to afford compounds 17a (14%) and 17b
(8%).
CDCl3)
73.3, 65.6, 38.9; IR (film)
d
: 198.3, 138.2, 137.0, 133.1, 128.6, 128.4, 128.1, 127.7, 127.6,
: 1685, 1450, 1104 cmꢁ1
n
.
3.1.4.7. 3-(Benzyloxy)-1-(4-methoxyphenyl)propan-1-one
(12c). Compound 12c was obtained according to the general pro-
cedure starting from 6c (54 mg, 0.2 mmol); obtained 30 mg (56%) of
3.1.5.1. (2S*,3R*,5S*)-2,3,4,4,5-Pentamethyl-5-phenyl-2-(prop-1-
en-2-yl)tetrahydrofuran-3-ol (17a). Compound 17a was obtained
according to the general procedure starting from 16 (46 mg,
0.2 mmol); obtained 6.5 mg (14%) of 17a. 1H NMR (600 MHz,
12c. 1H NMR (400 MHz, CDCl3)
d
: 7.99e7.92 (m, 2H), 7.38e7.27 (m,
5H), 6.98e6.91 (m, 2H), 4.56 (s, 2H), 3.92 (t, J 6.7 Hz, 2H), 3.87 (s,
3H), 3.25 (t, J 6.7 Hz, 2H); 13C NMR (100 MHz, CDCl3)
: 196.8, 163.5,
138.2, 130.4, 130.1, 128.4, 127.7, 127.6, 113.7, 73.3, 65.8, 55.4, 38.5; IR
CDCl3)
4.73 (s, 1H), 4.26 (d, J 8.2 Hz, 1H), 3.87 (d, J 8.2 Hz, 1H), 1.83 (s,
3H), 1.08 (s, 3H), 0.63 (s, 3H); 13C NMR (125 MHz, CDCl3)
: 144.6,
138.4, 127.8, 127.4, 126.3, 111.9, 87.6, 84.9, 82.7, 45.2, 22.8, 17.2,
d: 7.35e7.25 (m, 5H), 5.10 (d, J 0.8 Hz, 1H), 4.91 (s, 1H),
d
d
(film) n
: 1675, 1601, 1259, 1171 cmꢁ1; HRMS (ESI) m/z calcd for
C
17H18O3Na [MþNa]þ: 293.1154; found: 239.1162.
15.0; IR (film) n
: 3439, 2971, 1465, 1452, 1044 cmꢁ1; HRMS (ESI-
TOF) m/z calcd for
339.0508.
C
15H20O2Ag [MþAg]þ: 339.0514; found:
3.1.4.8. 3-(Benzyloxy)-1-(3-chlorophenyl)propan-1-one
(12d). Compound 12d was obtained according to the general pro-
cedure starting from 6d (55 mg, 0.2 mmol); obtained 40 mg (73%)
3.1.5.2. (2S*,3S*,5S*)-2,3,4,4,5-Pentamethyl-5-phenyl-2-(prop-1-
en-2-yl)tetrahydrofuran-3-ol (17b). Compound 17b was obtained
according to the general procedure starting from 16 (46 mg,
0.2 mmol); obtained 3.8 mg (8%) of 17b. 1H NMR (600 MHz, CDCl3)
of 12d. 1H NMR (500 MHz, CDCl3)
d: 7.94e7.92 (m, 1H), 7.84e7.81
(m, 1H), 7.54e7.50 (m, 1H), 7.41e7.37 (m, 1H), 7.35e7.25 (m, 5H),
4.55 (s, 2H), 3.91 (t, J 6.4 Hz, 2H), 3.24 (t, J 6.4 Hz, 2H); 13C NMR
(125 MHz, CDCl3)
d
: 197.0, 138.5, 138.0, 134.9, 133.0, 129.9, 128.4,
d
: 7.37e7.24 (m, 5H), 5.34 (d, J 0.5 Hz, 1H), 5.16 (dd, J 1.7, 1.1 Hz, 1H),
4.93 (s, 1H), 4.87 (d, J 3.5 Hz, 1H), 3.87 (d, J 3.5 Hz, 1H), 1.78 (d, J
0.5 Hz, 3H), 1.14 (s, 3H), 0.66 (s, 3H); 13C NMR (150 MHz, CDCl3)
128.2, 127.6 (2ꢂ), 126.2, 73.3, 65.4, 39.0; IR (film)
n: 1689, 1571,
1208, 1103 cmꢁ1; HRMS (ESI) m/z calcd for C16H15O2ClNa [MþNa]þ:
d:
297.0658; found: 297.0665.
141.8, 138.7, 127.8, 127.3, 126.4, 113.0, 86.7, 83.7, 79.2, 47.5, 21.0, 20.0,
19.3; HRMS (ESI-TOF) m/z calcd for
339.0514; found: 339.0501.
C
15H20O2Ag [MþAg]þ:
3.1.4.9. 3-Methoxy-1-phenylpropan-1-one (13).27 Compound 13
was obtained according to the general procedure starting from 8
(33 mg, 0.2 mmol); obtained 27 mg (82%) of 13. 1H NMR (600 MHz,
Compounds 18a,b were obtained according to standard pro-
cedures for acylation and benzoylation of commercially available
CDCl3)
3.81 (t, J 6.5 Hz, 2H), 3.36 (s, 3H), 3.23 (t, J 6.5 Hz, 2H); 13C NMR
(150 MHz, CDCl3) : 198.3, 136.9, 133.1, 128.6, 128.1, 67.8, 58.9, 38.6;
IR (film)
: 1683, 1449, 1118 cmꢁ1
d
: 7.96e7.93 (m, 2H), 7.56e7.52 (m, 1H), 7.46e7.42 (m, 2H),
2,3,5-tri-O-benzyl-
zyl-
-arabinofuranoside (18a);31 obtained according to the general
procedure starting from 2,3,5-tri-O-benzyl- -arabinofuranose
(1.26 g, 3 mmol); obtained 1.33 g (96%) of 18a. Product was afforded
as a 1:0.5 anomeric mixture. 1H NMR (600 MHz, CDCl3)
: 7.37e7.24
D-arabinofuranose. 1-O-Acetyl-2,3,5-tri-O-ben-
D
d
D
n
.
d
3.1.4.10. Ethyl 3-(4-methoxyphenyl)propanoate (14a).28 Compound
14a was obtained according to the general procedure starting from
10a (100 mg, 0.48 mmol); obtained 69 mg (69%) of 14a. 1H NMR
(m, 22.5H), 6.29 (d, J 4.2 Hz, 0.5H), 6.25* (s, 1H), 4.69 (d, J 11.8 Hz,
0.5H), 4.64* (d, J 11.9 Hz, 1H), 4.61 (d, J 11.8 Hz, 1H), 4.56* (s, 2H),
4.56e4.54 (m, 1.5H), 4.52* (s, 1H), 4.50* (s, 1H), 4.37* (dd, J 10.6,
5.2 Hz, 1H), 4.23e4.19 (m, 0.5H), 4.19e4.14 (m, 1H), 4.08* (d, J
2.2 Hz, 1H), 3.98* (dd, J 5.7, 2.2 Hz, 1H), 3.65e3.60* (m, 2H),
3.59e3.56 (m, 1H), 2.08* (s, 3H), 1.98 (s, 1.5H) *refer to major
(600 MHz, CDCl3) d: 7.12e7.09 (m, 2H), 6.83e6.80 (m, 2H), 4.11 (q, J
7.1 Hz, 2H), 3.77 (s, 3H), 2.88 (t, J 7.8 Hz, 2H), 2.57 (t, J 7.8 Hz, 2H), 1.22
(t, J 7.1 Hz, 3H); 13C NMR (150 MHz, CDCl3)
113.8, 60.3, 55.2, 36.2, 30.1, 14.2; IR (film)
d
: 173.0, 158.0, 132.6, 129.2,
: 2981, 2936, 1734, 1514,
n
anomer; 13C NMR (150 MHz, CDCl3)
d: 170.0*, 169.9, 137.99, 137.95*,
1247, 1037 cmꢁ1
.
137.6* (2ꢂ), 137.31, 137.26*, 128.5e128.3, 128.0e127.6 (aromatic
overlap), 100.5*, 94.3, 87.1*, 83.74, 83.73*, 83.3*, 81.6, 81.2, 73.4*,
3.1.4.11. Ethyl 3,3-diphenylpropanoate (14b).29 Compound 14b
was obtained according to the general procedure starting from 10b
(102 mg, 0.4 mmol); obtained 87 mg (85%) of 14b. 1H NMR
73.3, 73.1, 72.5, 72.1*, 72.0*, 71.1, 69.6*, 21.3* (2ꢂ); IR (film)
n: 2865,
1747, 1229, 1098 cmꢁ1
.
(600 MHz, CDCl3)
d
: 7.30e7.23 (m, 8H), 7.20e7.16 (m, 2H), 4.55 (t, J
3.1.5.3. 1-O-Benzoyl-2,3,5-tri-O-benzyl-
(18b). Compound 18b was obtained according to the general pro-
cedure starting from 2,3,5-tri-O-benzyl- -arabinofuranose (1.1 g,
2.6 mmol); obtained 1.36 g (100%) of 18b. Product was afforded as
a 1:0.3 anomeric mixture. 1H NMR (600 MHz, CDCl3)
: 8.18e8.14
D-arabinofuranoside
8.1 Hz, 1H), 4.03 (q, J 7.1 Hz, 2H), 3.05 (d, J 8.1 Hz, 2H), 1.10 (t, J
7.1 Hz, 3H); 13C NMR (150 MHz, CDCl3)
d: 171.8, 143.5, 128.5, 127.7,
D
126.5, 60.4, 47.1, 40.8, 14.0; IR (film) n ;
: 2981, 1733, 1151 cmꢁ1
HRMS (ESI) m/z calcd for C17H18O2Na [MþNa]þ: 277.1204; found:
d
277.1204.
(m, 1.3H), 8.06e8.03 (m, 0.6H), 8.00e7.95 (m, 2H), 7.70e7.65 (m,
1H), 7.58e7.51 (m, 3H), 7.43e7.22 (m, 19H), 6.55e6.54* (m, 1H),
6.52 (s, 0.3H), 4.72* (d, J 11.7 Hz, 1.3H), 4.67* (d, J 11.6 Hz, 1H), 4.64*
(d, J 11.7 Hz, 1H), 4.58 (s, 0.6H), 4.57* (d, J 11.6 Hz, 1H), 4.54e4.51*
(m, 2.3H), 4.49 (dd, J 9.9, 4.7 Hz, 0.3H), 4.34e4.29* (m, 2H),
4.26e4.20* (m, 1.3H), 4.06 (dd, J 5.2, 1.8 Hz, 0.3H), 3.70e3.60* (m,
3.1.5. Synthesis of (bis(2-methylprop-1-enyloxy)methyl)benzene
(16). The vinyl ether 16 was obtained by isomerization of the allyl
ether prepared according to a literature procedure,30 from 1-
phenyl-1-methoxychloromethane,12,13 and allyl alcohol. To a solu-
tion of allyl ether (150 mg, 0.6 mmol) in THF (1.2 ml) the activated
(by hydrogenation) Crabtree’s catalyst (6.5 mg) in THF (1.2 mL) was
added dropwise under an argon atmosphere. The reaction progress
of was monitored by TLC. Then, solvent was removed to provide 16
2.6H) *refer to major anomer signals; 13C NMR (150 MHz, CDCl3)
d:
165.4*, 162.3, 138.01*, 138.0, 137.9*, 137.6, 137.3*, 137.2, 134.5*, 133.3,
133.1*, 130.6e127.6 (aromatic overlap), 100.8, 95.0*, 86.8, 84.0*,
83.78, 83.76, 81.8*, 81.3*, 73.5, 73.3*, 73.1*, 72.6*, 72.09, 72.05, 71.0*,
(94 mg, 63%). 1H NMR (400 MHz, CDCl3)
7.41e7.31 (m, 3H), 6.07e6.04 (m, 2H), 5.83 (s, 1H), 1.66 (s, 6H), 1.55
(s, 6H); 13C NMR (100 MHz, CDCl3)
: 137.8,135.1,128.6,128.2,126.6,
d
: 7.53e7.47 (m, 2H),
69.70; IR (film) n
: 2865, 1788, 1724, 1452, 1268 cmꢁ1; HRMS (ESI-
TOF) m/z calcd for
547.2108.
C
33H32O6Na [MþNa]þ: 547.2097; found:
d

E. Maziarz, B. Furman / Tetrahedron 70 (2014) 1651e1658
1657
3.1.5.4. 1-O-(Prop-1-en-2-yl)-2,3,5-tri-O-benzyl-
D
-arabinofur-
3.1.5.8. 1-O-(1-Ethoxyvinyl)-2,3,5-tri-O-benzyl-
D
-arabinofurano-
anoside (19a). Compound 19a was obtained according to the
general procedure starting from 18a (0.5 g, 1 mmol); obtained
446 mg (90%) of 18a. Product was afforded as a 1:0.5 anomeric
side (21). Was performed analogously to the procedure described
for 10a.
Obtained according to the general procedure starting from
corresponding iodoacetal (1.0 g, 1.6 mmol); obtained 690 mg (88%)
of 21. Product was afforded as a 1:0.2 anomeric mixture. 1H NMR
mixture. 1H NMR (600 MHz, CDCl3)
d: 7.37e7.25 (m, 22.5H), 5.53*
(s, 1H), 5.39 (d, J 4.1 Hz, 0.5H), 4.69 (d, J 11.8 Hz, 0.5H), 4.63 (d, J
11.4 Hz, 0.5H), 4.61e4.49 (m, 8H), 4.27* (dt, J 6.5, 4.4 Hz, 1H), 4.21
(d, J 1.7 Hz, 0.5H), 4.19e4.13 (m, 3.5H), 4.05* (dd, J 6.5, 3.3 Hz, 1H),
4.03 (s, 1.5H), 3.66* (dd, J 10.9, 4.1 Hz, 1H), 3.61* (dd, J 10.9, 4.7 Hz,
1H), 3.57e3.51 (m, 1H), 1.83* (s, 3H), 1.79 (s, 1H); *refer to major
(600 MHz, CDCl3) d: 7.38e7.25 (m, 18H), 5.63 (s, 0.2H), 5.51* (d, J
4.3 Hz, 1H), 4.67* (d, J 11.8 Hz, 2H), 4.64e4.53* (m, 4.8H), 4.52e4.48
(m, 0.4H), 4.35e4.31 (m, 0.2H), 4.22e4.12* (m, 3.2H), 4.05e4.02 (m,
0.2H), 3.84e3.78* (m, 2.4H), 3.67e3.56* (m, 2.4H), 3.50 (d, J 3.6 Hz,
0.2H), 3.47* (d, J 3.4 Hz,1H), 3.27 (d, J 3.6 Hz, 0.2H), 3.24* (d, J 3.4 Hz,
anomer signals; 13C NMR (150 MHz, CDCl3)
d: 157.3, 157.1*, 138.2,
138.2, 138.1*, 137.9*, 137.6, 137.4*, 128.4e128.3, 128.0e127.5 (aro-
matic overlap), 103.3*, 97.2, 88.2*, 86.5, 86.0*, 83.8, 83.04, 83.01*,
81.6*, 81.0, 73.4* (2ꢂ), 72.5, 72.4, 72.2, 72.1*, 71.9*, 69.3*, 21.0,
1H),1.31* (dt, J 11.5, 7.0 Hz, 3.6H) *refer to major anomer signals; 13
C
NMR (150 MHz, CDCl3)
137.6*, 137.4, 128.4e127.5 (aromatic overlap), 103.7, 98.1*, 88.0,
d
: 163.0*, 162.6, 138.2*, 138.1* (2ꢂ), 137.8,
20.9*; IR (film)
n
: 2921, 2865, 1662, 1636, 1454, 1266, 1101 cmꢁ1
;
83.6*, 83.1, 82.8*, 81.9, 81.2*, 73.4*, 73.3, 72.41*, 72.38*, 72.3*, 72.1,
HRMS (ESI) m/z calcd for C29H32O5Na [MþNa]þ: 483.2147; found:
72.0, 69.2, 64.0, 63.9*, 61.9*, 61.3, 14.4, 14.3*; IR (film) n: 2869, 1652,
483.2150.
1454, 1271, 1014 cmꢁ1; HRMS (ESI) m/z calcd for C30H34O6Na
[MþNa]þ: 513.2253; found: 513.2253.
3.1.5.5. 1-O-(1-Phenylvinyl)-2,3,5-tri-O-benzyl-D-arabinofurano-
side (19b). Compound 19b was obtained according to the general
procedure starting from 18b (524 mg, 1 mmol); obtained 318 mg
(61%) of 19b. Product was afforded as a 1:0.3 anomeric mixture.
3.1.5.9. Ethyl
2-(2,3,5-tri-O-benzyl-D-arabinofuranosyl)acetate
(22).32 Was performed analogously to the procedure described for
11a.
1H NMR* (500 MHz, C6D6)
d
: 7.77e7.73 (m, 2H), 7.27e7.22 (m,
Obtained according to the general procedure starting from 21
3H), 7.15e6.97 (m, 15H), 5.47 (d, J 4.4 Hz, 1H), 4.84 (dd, J 9.1,
2.4 Hz, 2H), 4.64 (d, J 12.1 Hz, 1H), 4.59 (d, J 12.1 Hz, 1H),
4.47e4.42 (m, 1H), 4.39 (d, J 11.7 Hz, 1H), 4.37e4.32 (m, 1H),
4.32e4.29 (m, 1H), 4.20 (d, J 6.0 Hz, 2H), 4.12 (dd, J 7.1, 4.4 Hz, 1H),
(98 mg, 0.2 mmol); obtained 55 mg (60%) of 22. 1H NMR (600 MHz,
C6D6) d: 7.26e7.05 (m, 15H), 4.73 (td, J 7.0, 3.9 Hz, 1H), 4.41 (s, 2H),
4.35e4.29 (m, 3H), 4.27 (d, J 12.1 Hz, 1H), 4.19 (d, J 11.8 Hz, 1H), 4.10
(d, J 2.3 Hz, 1H), 4.06 (d, J 3.9 Hz, 1H), 3.96e3.89 (m, 2H), 3.63 (dd, J
9.8, 5.2 Hz, 1H), 3.56 (dd, J 9.8, 7.3 Hz, 1H), 2.90 (qd, J 16.2, 7.0 Hz,
3.52 (dd, J 6.0, 2.6 Hz, 2H); 13C NMR* (125 MHz, C6D6)
d: 158.2,
138.7, 138.5, 138.0, 136.2, 128.2e127.2 (aromatic overlap), 125.4,
98.5, 86.8, 84.7, 83.3, 81.5, 73.0, 72.13 (2ꢂ), 72.09; *refer to major
2H), 0.91 (t, J 7.1 Hz, 3H); 13C NMR (150 MHz, CDCl3)
d: 171.2, 138.2,
137.78, 137.76, 128.4, 128.34, 128.30, 127.77, 127.75, 127.71, 127.65,
anomer; IR (film)
n
:
2929, 2865, 1623, 1495, 1454, 1280,
127.6 (2ꢂ), 83.7, 83.0, 82.6, 77.4, 73.3, 71.49, 71.46, 70.5, 60.4, 34.2,
1120 cmꢁ1; HRMS (ESI) m/z calcd for C34H34O5Na [MþNa]þ:
14.2; IR (film)
n
: 2864, 1731, 1454, 1092 cmꢁ1; HRMS (ESI) m/z calcd
25
545.2304; found: 545.2310.
for
C
30H34O6Na [MþNa]þ: 513.2253; found: 513.2254;
[a]
D
þ30.30 (c 0.98, CHCl3).
3.1.5.6. 1-(2,3,5-Tri-O-benzyl-D-arabinofuranosyl)propan-2-one
(20a). Was performed analogously to the procedure described for
11a.
Acknowledgements
Obtained according to the general procedure starting from 19a
Financial support by the European Union within European Re-
gional Development Fund, Project POIG.01.01.02.-14-102/09 is
gratefully acknowledged.
(46 mg, 0.1 mmol); obtained 43 mg (94%) of 20a. 1H NMR (600 MHz,
CDCl3) d: 7.35e7.23 (m, 13H), 7.21e7.18 (m, 2H), 4.58e4.40 (m, 6H),
4.30 (d, J 11.6 Hz,1H), 4.06 (td, J 6.0, 3.4 Hz,1H), 4.02 (d, J 3.9 Hz,1H),
3.91 (d, J 3.0 Hz, 1H), 3.58 (dd, J 9.9, 6.0 Hz, 1H), 3.51 (dd, J 9.9,
6.2 Hz, 1H), 2.92e2.79 (m, 2H), 2.11 (s, 3H); 13C NMR (150 MHz,
Supplementary data
1H and 13C NMR spectra of 3ae22. Supplementary data related
to this article can be found at http://dx.doi.org/10.1016/
j.tet.2014.01.010.
CDCl3)
d: 206.8, 138.2, 137.78, 137.77, 128.44, 128.39, 128.3, 127.79,
127.76, 127.73, 127.68, 127.66, 127.6, 83.7, 83.1, 82.5, 77.1, 73.3, 71.6,
71.5, 70.5, 43.1, 30.6; IR (film) n ;
: 2909, 2864, 1713, 1454, 1097 cmꢁ1
HRMS (ESI) m/z calcd for C29H32O5Na [MþNa]þ: 483.2147; found:
25
483.2158; [
a
]
D
þ27.18 (c 1.03, CHCl3).
References and notes
3.1.5.7. 2-(2,3,5-Tri-O-benzyl-
phenylethanone (20b). Was performed analogously to the pro-
cedure described for 11a.
D
-arabinofuranosyl)-1-
1. (a) Frauenrath, H. Synthesis 1989, 721e734; (b) Frauenrath, H. In Selectivities in
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Obtained according to the general procedure starting from 19b
(52 g, 0.1 mmol); obtained 34 mg (65%) of 20b. 1H NMR (600 MHz,
CDCl3) d: 7.97e7.92 (m, 2H), 7.58e7.53 (m, 1H), 7.46e7.41 (m, 2H),
7.36e7.25 (m, 10H), 7.23e7.16 (m, 3H), 7.11e7.07 (m, 2H), 4.67e4.63
(m, 1H), 4.61e4.55 (m, 2H), 4.52 (dd, J 12.0, 5.5 Hz, 2H), 4.43 (d, J
11.6 Hz,1H), 4.30 (d, J 11.6 Hz,1H), 4.18 (d, J 3.9 Hz,1H), 4.11 (td, J 6.0,
3.4 Hz, 1H), 3.94 (d, J 3.2 Hz, 1H), 3.63 (dd, J 10.0, 6.0 Hz, 1H), 3.55
(dd, J 10.0, 6.0 Hz, 1H), 3.51 (dd, J 17.4, 8.3 Hz, 1H), 3.41 (dd, J 17.4,
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9720e9721.
5.2 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d: 198.1, 138.2, 137.8, 137.7,
€
8. Gansauer, A.; Fielenbach, D.; Stock, C.; Geich-Gimbel, D. Adv. Synth. Catal. 2003,
136.9,133.1,128.5,128.4,128.32,128.25,128.1,127.77,127.76,127.70,
127.66, 127.65,127.6, 84.0, 82.9, 82.5, 77.8, 73.3, 71.7, 71.5, 70.6, 38.1;
345, 1017e1030.
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IR (film)
n
: 2913, 2863, 1683, 1451, 1094 cmꢁ1; HRMS (ESI) m/z calcd
for C34H34O5Na [MþNa]þ: 545.2304; found: 545.2321; [
þ14.00 (c 1.23, CHCl3).
a]
25
D

1658
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