A tandem Baylis-Hillman-singlet oxygen oxidation reaction for facile synthesis of γ-substituted γ-hydroxybutenolides

Article abstract of DOI:10.1016/j.tet.2008.09.019

A series of highly functionalised γ-hydroxyacryl γ-hydroxybutenolides, 2, were synthesised in 25-50% overall yields in two or three steps from 2-furfural using a tandem Baylis-Hillman-singlet oxygen oxidation reaction. Crown Copyright

Full text of DOI:10.1016/j.tet.2008.09.019

Tetrahedron 64 (2008) 10831–10836
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
A tandem Baylis–Hillman-singlet oxygen oxidation reaction for facile
synthesis of
g
-substituted
g
-hydroxybutenolides
*
Santoshkumar N. Patil, Benjamin E. Stephens, Fei Liu
Department of Chemistry & Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 26 June 2008
Received in revised form 22 August 2008
Accepted 4 September 2008
Available online 17 September 2008
A series of highly functionalised g-hydroxyacryl g-hydroxybutenolides, 2, were synthesised in 25–50%
overall yields in two or three steps from 2-furfural using a tandem Baylis–Hillman-singlet oxygen oxi-
dation reaction.
Crown Copyright Ó 2008 Published by Elsevier Ltd. All rights reserved.
1. Introduction
2. Results and discussion
The
g
-substituted
g
-hydroxybutenolide core is a common motif
This sequence initiates with the Baylis–Hillman (BH) reaction,
a versatile approach for convergent construction of functionalized
molecules from simple and readily accessible starting materials
such as aldehydes and enones.9
However, the BH reaction can be limitedT:/PGN/ELSEVIER/TET/
web/00018514/ in its scope, as reflected by the moderate yields
observed for many substrates. Nonetheless, this reaction is ame-
nable to preparative scales, which compensates for the yield effi-
ciency. Several known BH reaction conditions were investigated
and optimised for yields of 1 from 2-furfural and various acry-
lates.10 The most general method for this reaction was to use DBU in
neat condition (Scheme 2).
in terpenoid natural products. Some novel examples only recently
discovered are shown in Figure 1. Many of these natural products
exhibit potent biological activities and serve as interesting leads in
drug discovery research.1–6
Biogenetically, it has been suggested that these
g-hydroxy-
butenolide containing natural products may derive from their fur-
anoid precursors by singlet oxygen oxidation.4d Recently, singlet
oxygen has been used extensively in biomimetic synthesis in-
volving furan oxidation for rapid and efficient construction of many
natural products.7 We have also pursued a singlet oxygen based
strategy of efficiently converting functionalised furans derived from
3-furfural and simple acrylates to a- or b-substituted g-hydroxy-
butenolides.8 Herein we report the extension of this tandem
Baylis–Hillman-singlet oxygen oxidation strategy to rapidly convert
2-furfural to highly functionalised
butenolide synthons, 2 (Scheme 1). Currently there are few di-
versity-oriented methods that can rapidly access highly
g-substituted g-hydroxy-
O
O
O
O
RO
H
O
R
functionalised
g-substituted g-hydroxybutenolides from singlet
HO
H
oxygen oxidation of furans. The highly reactive yet chemospecific
nature of singlet oxygen oxidation, along with the cost-effective-
ness of this class of reactions, was envisioned to enhance the
generality of this biomimetic approach and also provide highly
functionalised new
building blocks.
OH
O
O
OH
O
OAc
cassanes
jolkinolides
RO
caribenol A
H
g-substituted g-hydroxybutenolides as useful
H
O
O
HO
RO
O
cespitulactones
O
O
OR'
OR
eremophilanes
O
OH
dayejijiols
* Corresponding author. Tel.: þ61 2 9850 8312; fax: þ61 2 9850 8313.
E-mail address: fliu@alchemist.chem.mq.edu.au (F. Liu).
Figure 1. Examples of natural products with a
core.
g
-substituted -hydroxybutenolide
g
0040-4020/$ – see front matter Crown Copyright Ó 2008 Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.09.019

10832
S.N. Patil et al. / Tetrahedron 64 (2008) 10831–10836
Given the mechanism of the BH reaction, which involves an
O
Baylis–Hillman
OH
O
alkoxide intermediate, various silyl protecting groups were first
examined for in situ trapping of the alkoxide intermediate.
While TMSCl was able to furnish silyl protected BH adducts, the
TMS group was too labile for the subsequent singlet oxygen
oxidation reaction, and as such the reaction only resulted in
complex reaction mixtures. TBSCl was also able to protect the
hydroxy group. With in situ trapping of the alkoxide in-
termediate, this provided 1a in 36% yield from 2-furfural over
two steps in one-pot (Scheme 4a). The hydroxy group could also
be protected separately using TBSOTf after the BH reaction for
a better yield of 50% over two steps (Scheme 4b). The yields of
these two approaches to 1 with various acrylates are summar-
ised in Table 1. For smaller ester substituents, the two-step se-
quence provided slightly higher yields (entries a & b). However,
for larger ester substituents, the much simpler one-pot pro-
cedure gave comparable yields.
The TBS protected series of functionalised furans was then
subjected to singlet oxygen oxidation. Reactions generally pro-
ceeded in very good to excellent yields for all substrates
(Table 2).
Hu¨nig’s base was essential to the formation of butenolides as
its absence resulted in complex mixtures. The rate of this con-
version, compared to that of the series from 3-furfural under
similar conditions,8a was slower, but still complete within a few
hours. The resulting diastereomeric mixtures of butenolides
were in 2:1 ratio. Given the lability of the stereocenter at the
O
TBSO
+
OR
OHC
O
OR
1
O2, hν
O
O
O
TBSO
2
OR
Scheme 1.
O
CH
O
O
DBU
0–25 °C, 1–2 days
O
+
OR
OR
O
OHC
O
B
O
OR
O
O
O
HO
OR
3
B
Scheme 2.
It is well known that an alkyl amine base can be used in
singlet oxygen oxidation to catalyse the disproportionation of the
endoperoxide intermediate (Scheme 3).11 However, initial at-
tempts on using the BH adducts directly in the singlet oxygen
oxidation resulted only in hydroxybutenolide. The presence of
a free hydroxy group led to base-promoted fragmentation of the
side chain during the oxidation reaction.
Table 1
Preparation of 1 from 2-furfural
Entry
Acrylate
3a–g (%)
1a–g (from 3) (%)
1a–g (one-pot) (%)
a
b
c
d
e
f
Methyl
Ethyl
Butyl
Dodecyl
Benzyl
Cinnamyl
Allyl
52
55
47
36
49
44
33
51
98
97
96
94
86
98
93
84
36
38
43
31
42
40
33
44
OH
O
H
O
O
O
O
O
O
g
h
B
HO
OR
HO
OR
4
Chloroethyl
O2, hν
3
rose bengal
Hünig's base
H
O
O
HO
O
O
B
O
H
O
Table 2
O
OR
Preparation of 2 by singlet oxygen oxidation of 1
Scheme 3.
OH
O2, hv
O
O
O
Hünig's base
rose bengal
–78 °C, CH2Cl2
O
TBSO
O
To circumvent this problem, silyl protection schemes of the
secondary alcohol were investigated using the BH adduct 3a
(Scheme 4).
OR
TBSO
OR
2
1
Entry
R
2a–g (%)
a
b
c
d
e
f
Methyl
Ethyl
Butyl
Dodecyl
Benzyl
Cinnamyl
Allyl
88
91
90
78
80
87
82
78
(a)
O
Si
Cl
DBU, TBSCl
OMe 25 °C
+
O
OHC
OMe
O
O
g
h
O
B
O
Chloroethyl
O
TBSO
OMe
1a
(b)
2,6-lutidine, TBSOTf
25 °C
O
acetal carbon, this may be inherently related to the relative
stability of the two diastereomeric butenolides. The TBS
protection was readily removed under acidic, basic or neutral
conditions but the resulting butenolides decomposed rapidly.
1a
O
HO
3a
OMe
Scheme 4.
However, the TBS protected
g-substituted g-hydroxybutenolides
themselves are stable without any sign of intramolecular

S.N. Patil et al. / Tetrahedron 64 (2008) 10831–10836
10833
cyclisation, even with a free
to an enone ester.
g
-hydroxy group in close proximity
4.2.3. Butyl 2-(furan-2-yl(hydroxy)methyl)acrylate (3c)
Colourless oil. Yield: 47%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3472
(br), 2962 (m), 2935 (m), 2873 (m), 1711 (s), 1632 (m), 1463 (m);
3. Conclusions
1H NMR (400 MHz, CDCl3)
d
0.92 (t, J¼7.4 Hz, 3H, –CH3), 1.25–
1.41 (m, 2H, CH2CH3), 1.54–1.66 (m, 2H, –OCH2CH2–), 3.09 (br s,
1H, –OH), 4.16 (td, J¼6.6, 2.2 Hz, 2H, –OCH2–), 5.58 (s, 1H, H-10),
5.91 (s, 1H, H-3), 6.26 (d, J¼3.2 Hz, 1H, H-300), 6.32–6.33 (m, 1H,
H-400), 6.38 (s, 1H, H-3), 7.37 (dd, J¼1.8, 0.7 Hz, 1H, H-500); 13C
In summary, this sequence allows for the first time the facile
synthesis of highly funtionalised -hydroxyl acryl -hydroxy-
butenolides from readily available starting materials in two or three
steps. These diverse butenolides may be used as building blocks for
natural products with a butenolide core, as well as useful synthons
for butenolide-based diversity-oriented libraries.
g
g
NMR (101 MHz, CDCl3)
d 14.1, 19.6, 31.0, 65.4, 68.1, 107.6, 110.9,
127.0, 140.2, 142.8, 154.7, 166.6; HRMS (ESI) m/z calcd for
C12H16O4Na [MþNa]þ, 247.0946, found 247.0948.
4. Experimental
4.1. General
4.2.4. Dodecyl 2-(furan-2-yl(hydroxy)methyl)acrylate (3d)
Colourless oil. Yield: 36%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3472
(br), 2927 (vs), 2854 (s), 1711 (s), 1632 (w), 1463 (m); 1H NMR
(400 MHz, CDCl3)
d
0.88 (t, J¼6.8 Hz, 3H, –CH3), 1.27 (br s, 18H,
Unless otherwise stated, all chemicals and reagents were used
without further purification. All reactions were performed under
a nitrogen atmosphere and monitored by thin-layer chromatog-
raphy (TLC) using silica gel 60 F254 on aluminium pre-coated
plates (0.25 mm). Visualisation was accomplished using either
a UV lamp (254 nm) or heating with basic KMnO4 solution. Flash
column chromatography was performed on silica gel (60 Å, 40–
–(CH2)9CH3), 1.54–1.67 (m, 2H, –OCH2CH2–), 2.59 (br s, 1H, –OH),
4.10–4.18 (m, 2H, –OCH2–), 5.58 (s, 1H, H-10), 5.92 (s, 1H, H-3),
6.26 (d, J¼3.2 Hz, 1H, H-300), 6.33 (dd, J¼3.1, 1.8 Hz, 1H, H-400), 6.68
(s, 1H, H-3), 7.37 (dd, J¼1.8, 0.9 Hz, 1H, H-500); 13C NMR (101 MHz,
CDCl3)
d 14.6, 23.2, 26.4, 28.9, 29.7, 29.8, 29.9, 30.0, 30.1, 30.1,
32.4, 65.7, 68.1, 107.6, 110.9, 127.0, 140.1, 142.8, 154.7, 166.6; HRMS
(ESI) m/z calcd for C20H32O4Na [MþNa]þ, 359.2198, found
359.2201.
63 m
m, 230–400 mesh). 1H NMR spectra were recorded on Bruker
DPX400 (400 MHz) and DPX600 (600 MHz) spectrometers and
are reported in parts per million using the specified solvent as
internal standard (CDCl3 at 7.26 ppm). 13C NMR spectra were
4.2.5. Benzyl 2-(furan-2-yl(hydroxy)methyl)acrylate (3e)
Colourless oil. Yield: 49%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3465
(br), 1718 (s), 1632 (w), 1454 (w), 1383 (m); 1H NMR (400 MHz,
recorded on
a Bruker DPX400 (101 MHz) spectrometer and
reported in parts per million using the specified solvent as in-
ternal standard (CDCl3 at 77.5 ppm). Infrared spectra were
recorded on a Perkin–Elmer PE1000 FTIR spectrometer. HRMS
was performed at the mass spectrometry laboratory of the Uni-
versity of Illinois at Urbana–Champaign.
CDCl3) d
3.23 (br s,1H, –OH), 5.19 (m, 2H, PhCH2–), 5.62 (s,1H, H-10),
5.98 (s, 1H, H-3), 6.23–6.25 (m, 1H, H-300), 6.31–6.34 (m, 1H, H-400),
6.44 (s, 1H, H-3), 7.20–7.40 (m, 6H, Ar-H, H-500); 13C NMR (101 MHz,
CDCl3) d 67.1, 67.6, 107.7, 110.9, 127.4, 128.1, 128.5, 128.7, 129.0, 135.9,
142.8, 154.6, 166.2; HRMS (ESI) m/z calcd for C15H14O4Na [MþNa]þ,
281.0790, found 281.0778.
4.2. General procedure for the preparation of Baylis–Hillman
adducts 2
4.2.6. Cinnamyl 2-(furan-2-yl(hydroxy)methyl)acrylate (3f)
Colourless oil. Yield: 44%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3468
(br), 1715 (s), 1633 (w), 1496 (w), 1450 (w), 1386 (m), 966 (s); 1H
DBU (3.12 mmol) was added to a stirred solution of an acrylate
(3.75 mmol) and 2-furfural (3.12 mmol) at 0 ꢀC. The reaction mix-
ture was allowed to warm to room temperature and stirred for 1–2
days. Upon completion, ethyl acetate (15 mL) was added to the
reaction and neutralised with 1 N HCl, followed by washing with
water and brine. The organic layer thus obtained was dried over
NaSO4, filtered and concentrated to provide a crude mixture, which
was further purified by column chromatography (petroleum ether/
ethyl acetate 2:1) to afford the Baylis–Hillman adduct as a colour-
less oil.
NMR (400 MHz, CDCl3)
d
3.13 (br s, 1H, –OH), 4.83 (d, J¼6.6 Hz, 2H,
–OCH2–), 5.63 (s, 1H, H-10), 5.98 (s, 1H, H-3), 6.23–6.29 (m, 2H, H-
300, PhCH]CH–), 6.34 (dd, J¼3.1, 1.7 Hz, 1H, H-400), 6.45 (s, 1H, H-3),
6.63 (d, J¼16.1 Hz, 1H, PhCH]CH–), 7.25–7.40 (m, 6H, Ar-H, H-500);
13C NMR (101 MHz, CDCl3)
d 66.0, 67.9, 107.7, 110.9, 123.1, 127.1,
127.4, 128.6, 129.1, 134.9, 136.5, 140.0, 142.8, 154.6, 166.2; HRMS
(ESI) m/z calcd for C17H16O4Na [MþNa]þ, 307.0936, found 307.0934.
4.2.7. Allyl 2-(furan-2-yl(hydroxy)methyl)acrylate (3g)
Colourless oil. Yield: 33%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3438
4.2.1. Methyl-2-(furan-2-yl(hydroxy)methyl)acrylate (3a)10d
Colourless oil. Yield: 52%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3490
(br), 2953 (w), 1719 (s), 1632 (w), 1441 (w); 1H NMR (400 MHz,
(br), 1717 (s), 1631 (w); 1H NMR (400 MHz, CDCl3)
d 3.03 (d,
1H, J¼6.7 Hz, –OH), 4.66 (d, J¼5.5 Hz, 2H, –OCH2–), 5.20–5.34
(m, 2H, –CH]CH2), 5.60 (d, 1H, J¼6.6 Hz, H-10), 5.85–5.90 (m,
1H, –CH]CH2), 5.95 (s, 1H, H-3), 6.27 (d, J¼3.3 Hz, 1H, H-300),
6.34 (dd, J¼3.3, 1.8 Hz, 1H, H-400), 6.43 (s, 1H, H-3), 7.37 (dd,
CDCl3)
d
3.06 (d, J¼6.8 Hz, 1H, –OH), 3.77 (s, 3H, –OCH3), 5.59 (d,
J¼6.8 Hz, 1H, H-10), 5.94 (m, 1H, H-3), 6.26 (ddd, J¼3.2, 0.8, 0.8 Hz,
1H, H-300), 6.33 (dd, J¼3.2, 1.8 Hz, 1H, H-400), 6.38 (s, 1H, H-3), 7.37
(dd, J¼1.8, 0.9 Hz, 1H, H-500); HRMS (ESI) m/z calcd for C9H10O4Na
[MþNa]þ, 205.0468, found 205.0468.
J¼1.8, 0.9 Hz, 1H, H-500); 13C NMR (101 MHz, CDCl3)
d 66.0, 67.9,
107.7, 110.9, 118.9, 127.4, 132.2, 139.9, 142.9, 154.6, 166.1; HRMS
(ESI) m/z calcd for C11H12O4Na [MþNa]þ, 231.0633, found
231.0623.
4.2.2. Ethyl 2-(furan-2-yl(hydroxy)methyl)acrylate (3b)
Colourless oil. Yield: 55%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3456
4.2.8. 2-Chloroethyl 2-(furan-2-yl(hydroxy)methyl)acrylate (3h)
Colourless oil. Yield: 51%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3488
(br), 2953 (w), 1711 (s), 1634 (w), 1438 (w); 1H NMR (400 MHz,
CDCl3)
d
1.26 (t, J¼7.1 Hz, 3H, –CH3), 3.23 (br s, 1H, –OH), 4.20 (q,
(br), 1720 (s), 1632 (w), 1393 (m); 1H NMR (400 MHz, CDCl3)
d 2.92
J¼7.1 Hz, 1H, –OCH2–), 5.57 (s, 1H, H-10), 5.92 (s, 1H, H-3), 6.24 (d,
(d, J¼6.6 Hz, 1H, –OH), 3.68 (t, J¼5.7 Hz, 2H, –CH2Cl), 4.41 (t,
J¼5.7 Hz, 1H, –OCH2–), 5.61 (d, J¼6.4 Hz, 1H, H-10), 6.01 (s, 1H, H-3),
6.28 (s, 1H, H-300), 6.34 (dd, J¼3.3, 1.8 Hz, 1H, H-400), 6.47 (s, 1H, H-3),
J¼3.1 Hz, 1H, H-300), 6.31–6.32 (m, 1H, H-400), 6.37 (s, 1H, H-3), 7.39–
7.41 (m, 1H, H-500); 13C NMR (101 MHz, CDCl3)
d 14.5, 61.5, 67.9,
107.6, 110.9, 127.0, 140.2, 142.7, 154.7, 166.5; HRMS (ESI) m/z calcd
7.37–7.39 (m, 2H, H-500); 13C NMR (101 MHz, CDCl3)
d 41.8, 64.8,
for C10H12O4Na [MþNa]þ, 219.0633, found 219.0626.
67.5, 107.7, 110.9, 127.9, 139.6, 142.9, 154.4, 165.9; MS (ESI) m/z

10834
S.N. Patil et al. / Tetrahedron 64 (2008) 10831–10836
(% relative intensity): 253.0 (100), 255.0 (33); HRMS (ESI) m/z calcd
for C10H11O345ClNa [MþNa]þ, 253.0244, found 253.0237.
4.3.5. Benzyl 2-((tert-butyldimethylsilyloxy)(furan-2-
yl)methyl)acrylate (1e)
Colourless oil. Yield: 86%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2954
(m), 2931 (m), 2890 (m), 2857 (m), 1717 (s), 1633 (w), 1461 (w),
4.3. General procedure for the preparation of silyl protected
Baylis–Hillman adducts 1
1386 (w); 1H NMR (400 MHz, CDCl3)
d
ꢁ0.02 (s, 3H, –SiCH3), 0.10 (s,
3H, –SiCH3), 0.89 (s, 9H, –C(CH3)3), 5.10 (d, J¼12.6 Hz, 1H, PhCH2–),
5.21 (d, J¼13.1 Hz, 1H, PhCH2–), 5.70 (s, 1H, H-10), 6.13–6.15 (m, 1H,
H-300), 6.17–6.19 (m, 1H, H-3), 6.27–6.29 (m, 1H, H-400), 6.43–6.45
(m, 1H, H-3), 7.20–7.37 (m, 6H, H-500, Ar-H); 13C NMR (101 MHz,
TBS(OTf) (2.0 mmol) was added to a stirred solution of Baylis–
Hillman adduct (1.0 mmol) and 2,6-lutidine (2.0 mmol) in anhy-
drous CH2Cl2 (100 m
L) at 0 ꢀC. The reaction mixture was allowed to
warm to room temperature and monitored by TLC for disappear-
ance of starting material. Reactions were generally complete after
45 min. On completion, the reaction mixture was purified by flash
column chromatography (petroleum ether/ethyl acetate 9:1) to
afford the product as a colourless oil.
CDCl3)
d
ꢁ4.7, 18.7, 26.2, 66.7, 66.8, 107.6, 110.8, 126.2, 128.4, 128.6,
129.0, 136.3, 141.3, 142.4, 155.3, 166.0; HRMS (ESI) m/z calcd for
C21H28O4NaSi [MþNa]þ, 395.1757, found 395.1757.
4.3.6. Cinnamyl 2-((tert-butyldimethylsilyloxy)(furan-2-
yl)methyl)acrylate (1f)
4.3.1. Methyl 2-((tert-butyldimethylsilyloxy)(furan-2-
yl)methyl)acrylate (1a)
Colourless oil. Yield: 98%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2953 (s),
2931 (s), 2888 (s), 2857 (s), 1721 (s), 1635 (m), 1496 (m), 1465 (m),
Colourless oil. Yield: 98%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2954 (s),
963 (s); 1H NMR (400 MHz, CDCl3)
d 0.01 (s, 3H, –SiCH3), 0.14 (s, 3H,
2932 (s), 2890 (m), 2857 (m), 1719 (s), 1633 (m); 1H NMR (400 MHz,
–SiCH3), 0.92 (s, 9H, –C(CH3)3), 4.74 (ddd, J¼13.0, 6.2, 1.3 Hz, 1H,
–OCH2–), 4.84 (ddd, J¼13.0, 6.2, 1.3 Hz, 1H, –OCH2–), 5.74 (s, 1H, H-
10), 6.18–6.32 (m, 4H, H-3, H-300, H-400, PhCH]CH–), 6.40 (t,
J¼1.4 Hz, 1H, H-3), 6.60 (d, J¼15.8 Hz, 1H, PhCH]CH2–), 7.24–7.40
CDCl3)
d
ꢁ0.02 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3), 0.89 (s, 9H,
–C(CH3)3), 3.71 (s, 3H, –OCH3), 5.67 (s, 1H, H-10), 6.13–6.15 (m, 2H,
H-300, H-3), 6.27–6.29 (m, 1H, H-400), 6.38 (s, 1H, H-3), 7.32–7.34 (m,
1H, H-500); 13C NMR (101 MHz, CDCl3)
107.5, 110.7, 125.9, 141.3, 142.4, 155.3, 166.6; HRMS (ESI) m/z calcd
for C15H24O4SiNa [MþNa]þ, 319.1342, found 319.1344.
d
ꢁ4.7, 18.7, 26.2, 52.3, 66.6,
(m, 6H, H-500, Ar-H); 13C NMR (101 MHz, CDCl3)
d
ꢁ4.7, 18.7, 26.2,
65.6, 66.6, 107.6, 110.7, 123.4, 126.1, 127.0, 128.5, 129.0, 134.4, 136.7,
141.3, 142.4, 155.3, 165.8; HRMS (ESI) m/z calcd for C23H30O4SiNa
[MþNa]þ, 421.1811, found 421.1805.
4.3.2. Ethyl 2-((tert-butyldimethylsilyloxy)(furan-2-
yl)methyl)acrylate (1b)
4.3.7. Allyl 2-((tert-butyldimethylsilyloxy)(furan-2-
yl)methyl)acrylate (1g)
Colourless oil. Yield: 97%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2958 (s),
2932 (s), 2859 (m), 1713 (s), 1633 (m), 1466 (m); 1H NMR (400 MHz,
Colourless oil. Yield: 93%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2954 (s),
CDCl3)
d
ꢁ0.02 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3), 0.89 (s, 9H,
2930 (s), 2886 (s), 1715 (s), 1630 (w); 1H NMR (400 MHz, CDCl3)
–C(CH3)3), 1.23 (t, J¼7.1 Hz, 3H, –CH2CH3), 4.23–4.09 (m, 2H,
–OCH2–), 5.67 (s, 1H, H-10), 6.13 (t, J¼1.7 Hz, 1H, H-3), 6.14 (d,
J¼3.3 Hz, 1H, H-300), 6.28 (dd, J¼3.3, 1.8 Hz, 1H, H-400), 6.37 (t,
J¼1.6 Hz, 1H, H-3), 7.33 (dd, J¼1.8, 0.9 Hz, 1H, H-500); 13C NMR
d
ꢁ0.02 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3), 0.86 (s, 9H, –C(CH3)3–),
4.53–4.69 (m, 2H, –OCH2–), 5.15–5.29 (m, 2H, –CH]CH2), 5.68 (m,
1H, H-10), 5.82–5.92 (m, 1H, –CH]CH2), 6.15 (d, J¼3.2 Hz, 1H, H-300),
6.17 (dd, J¼1.6, 1.6 Hz, 1H, H-3), 6.28 (dd, J¼3.2, 1.8 Hz, 1H, H-400),
6.42 (dd, J¼1.4, 1.4 Hz, 1H, H-3), 7.34 (dd, J¼1.8, 0.9 Hz, 1H, H-500);
(101 MHz, CDCl3)
d
ꢁ4.7, 14.6, 18.7, 26.2, 61.1, 66.6, 107.4, 110.7,
125.6, 141.6,142.3, 155.5, 166.1; HRMS (ESI) m/z calcd for C16H27O4Si
[MþH]þ, 333.1679, found 311.1678.
13C NMR (101 MHz, CDCl3)
d
ꢁ4.7, 18.7, 26.2, 65.7, 66.6, 107.6, 110.7,
118.5, 126.1, 132.4, 141.3, 142.4, 155.3, 165.8; HRMS (ESI) m/z calcd
for C17H26O4SiNa [MþNa]þ, 345.1498, found 345.1499.
4.3.3. Butyl 2-((tert-butyldimethylsilyloxy)(furan-2-
yl)methyl)acrylate (1c)
4.3.8. 2-Chloroethyl 2-((tert-butyldimethylsilyloxy)(furan-2-
yl)methyl)acrylate (1h)
Colourless oil. Yield: 96%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2959 (s),
2933 (s), 2860 (m), 1717 (s), 1635 (m), 1466 (m); 1H NMR (400 MHz,
Colourless oil. Yield: 84%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2954
CDCl3)
d
ꢁ0.02 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3), 0.90–0.92 (m,
(m), 2932 (m), 2889 (m), 2858 (m), 1717 (s), 1635 (w), 1466 (m); 1H
12H, –C(CH3)3, –CH2CH3), 1.28–1.34 (m, 2H, –CH2CH3), 1.55–1.59
(m, 2H, –OCH2CH2–), 4.04–4.16 (m, 2H, –OCH2–), 5.67 (s, 1H, H-10),
6.12–6.13 (m, 2H, H-3, H-300), 6.27 (dd, J¼3.2, 1.9 Hz, 1H, H-400), 6.37
(t, J¼1.4 Hz, 1H, H-3), 7.32 (dd, J¼1.8, 0.7 Hz, 1H, H-500); 13C NMR
NMR (400 MHz, CDCl3)
d
ꢁ0.02 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3),
0.89 (s, 9H, –C(CH3)3), 3.64 (t, J¼5.8 Hz, 2H, –CH2Cl), 4.27–4.43 (m,
2H, –OCH2–), 5.67 (s, 1H, H-10), 6.16 (d, J¼3.3 Hz, 1H, H-300), 6.21 (s,
1H, H-3), 6.29 (dd, J¼3.3, 1.8 Hz, 1H, H-400), 6.45 (s, 1H, H-3), 7.34
(101 MHz, CDCl3)
d
ꢁ4.7, 14.1, 18.7, 19.6, 26.2, 31.0, 65.0, 66.7, 107.4,
(dd, J¼1.8, 0.9 Hz,1H, H-500); 13C NMR (101 MHz, CDCl3)
ꢁ4.7, 26.2,
d
110.7, 125.6, 141.6, 142.3, 155.5, 166.3; HRMS (ESI) m/z calcd for
C18H30O4SiNa [MþNa]þ, 361.1811, found 361.1819.
30.2, 41.8, 64.6, 66.6, 107.6, 110.8, 126.8, 140.9, 142.5, 155.2, 165.7;
MS (ESI) m/z (% relative intensity): 345.1 (100), 347.1 (32); HRMS
(ESI) m/z calcd for C16
345.1287.
35
H
ClO4SiH [MþH]þ, 345.1289, found
25
4.3.4. Dodecyl 2-((tert-butyldimethylsilyloxy)(furan-2-
yl)methyl)acrylate (1d)
Colourless oil. Yield: 94%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2927
4.4. General procedure for the preparation of butenolides 2
(s), 2855 (s), 1717 (s), 1636 (w), 1464 (m); 1H NMR (400 MHz,
CDCl3)
d
ꢁ0.02 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3), 0.86–0.89
To a mixture of a Baylis–Hillman adduct (0.30 mmol) and rose
bengal (0.003 mmol) in methanol or CH2Cl2 (70 mL) was added
Hu¨nig’s base (0.36 mmol). The reaction mixture was then exposed
to singlet oxygen (generated from air with a 150 W flood light) at
ꢁ78 ꢀC. The reaction mixture was then monitored for disappear-
ance of starting material by TLC. Upon completion, solvent was
evaporated under vacuum at room temperature, and the residue
was purified by flash column chromatography (petroleum ether/
ethyl acetate 1:1) to afford the butenolide product as a 2:1 di-
astereomeric mixture.
(m, 12H, –C(CH3)3, –CH2CH3), 1.25–1.30 (m, 18H, –(CH2)9CH3),
1.55–1.59 (m, 2H, –OCH2CH2–), 4.06 (dt, J¼10.8, 6.6 Hz, 1H,
–OCH2–), 4.12 (dt, J¼10.8, 6.6 Hz, 1H, –OCH2–), 5.66 (s, 1H, H-10),
6.12–6.15 (m, 2H, H-3, H-300), 6.28 (dd, J¼3.1, 1.8 Hz, 1H, H-400),
6.38 (t, J¼1.4 Hz, 1H, H-3), 7.32–7.34 (m, 1H, H-500); 13C NMR
(101 MHz, CDCl3)
d
ꢁ4.7, 14.6, 18.8, 23.2, 26.2, 26.3, 29.0, 29.7,
30.0, 30.05, 30.13, 30.15, 30.2, 32.4, 65.3, 66.6, 107.4, 110.7, 125.7,
141.6, 142.3, 155.5, 166.3; HRMS (ESI) m/z calcd for C26H47O4Si
[MþH]þ, 451.3244, found 451.3244.

S.N. Patil et al. / Tetrahedron 64 (2008) 10831–10836
10835
4.4.1. Methyl 2-((tert-butyldimethylsilyloxy)(2-hydroxy-5-oxo-2,5-
dihydrofuran-2-yl)methyl)acrylate (2a)
(m, 1H, H-300), 6.48 (d, J¼1.1 Hz, 1H, H-3), 7.09 (d, J¼5.7 Hz, 1H,
H-400); 13C NMR (101 MHz, CDCl3)
d
ꢁ4.9, ꢁ4.5, 14.6, 18.5, 23.2,
Colourless oil. Yield: 88%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2954 (s),
26.07, 26.37, 28.9, 29.7, 29.8, 29.99, 30.04, 30.1 (br), 32.4, 66.6,
72.8, 107.9, 125.6, 129.9, 139.2, 151.2, 168.4, 170.6; minor dia-
2933 (s), 2856 (s), 1764 (s), 1721 (s); major diastereomer: 1H NMR
(400 MHz, CDCl3)
d
0.00 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3), 0.86 (s,
stereomer: 1H NMR
d 0.05 (s, 3H, –SiCH3), 0.15 (s, 3H, –SiCH3),
9H, –C(CH3)3), 3.82 (s, 3H, –OCH3), 4.89 (s, 1H, H-10), 5.27 (br s, 1H,
0.88 (m, 3H, –(CH2)9CH3), 0.90 (s, 9H, C(CH3)3), 1.19–1.43 (m,
18H, –(CH2)9CH3), 1.63–1.75 (m, 2H, –OCH2CH2–), 4.15–4.24 (m,
2H, –OCH2–), 4.81 (d, J¼0.7 Hz, 1H, H-10), 5.33 (br s, 1H, –OH),
6.11–6.15 (m, 2H, H-3, H-30), 6.51 (d, J¼1.2 Hz, 1H, H-3), 6.93 (d,
–OH), 6.11 (br s, 1H, H-3), 6.14 (br s, 1H, H-300), 6.50 (br s, 1H, H-3),
7.09 (d, J¼5.1 Hz,1H, H-400); 13C NMR (101 MHz, CDCl3)
ꢁ4.9, ꢁ4.5,
d
18.5, 26.1, 53.2, 72.7, 107.9, 125.6, 130.2, 138.9, 151.2, 167.6, 170.6;
minor diastereomer: 1H NMR
d
0.04 (s, 3H, –SiCH3), 0.15 (s, 3H,
J¼5.7 Hz, 1H, H-400); 13C NMR
d
ꢁ4.6, ꢁ4.4, 14.6, 18.6, 23.2, 26.12,
–SiCH3), 0.89 (s, 9H, –C(CH3)3), 3.80 (s, 3H, –OCH3), 4.83 (s, 1H, H-
10), 5.27 (br s,1H, –OH), 6.11 (br s,1H, H-3), 6.13 (br s,1H, H-300), 6.50
26.39, 28.98, 29.7, 29.8, 29.99, 30.04, 30.1 (br), 32.4, 66.3, 72.9,
107.5, 125.0, 130.5, 138.8, 152.2, 167.4, 170.5; HRMS (ESI) m/z
calcd for C26H47O6Si [MþH]þ, 483.3142, found 483.3139.
(br s, 1H, H-3), 6.93 (d, J¼5.1 Hz, 1H, H-400); 13C NMR
d
ꢁ4.6, ꢁ4.4,
18.6, 26.1, 53.0, 73.0, 107.5, 125.1, 130.7, 138.5, 152.1, 167.6, 170.5;
HRMS (ESI) m/z calcd for C15H24O6SiNa [MþNa]þ, 351.1240, found
351.1241.
4.4.5. Benzyl 2-((tert-butyldimethylsilyloxy)(2-hydroxy-5-oxo-2,5-
dihydrofuran-2-yl)methyl)acrylate (2e)
Colourless oil. Yield: 80%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2955
(m), 2932 (m), 2890 (m), 2859 (m), 1775 (s), 1711 (s), 1629 (w),
1461 (w), 1391 (m), 1100 (s), 1082 (s); major diastereomer: 1H
4.4.2. Ethyl 2-((tert-butyldimethylsilyloxy)(2-hydroxy-5-oxo-2,5-
dihydrofuran-2-yl)methyl)acrylate (2b)
Colourless oil. Yield: 91%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2958
(s), 2935 (s), 2854 (s), 1762 (s), 1711 (s); major diastereomer: 1H
NMR (400 MHz, CDCl3)
d
ꢁ0.01 (s, 3H, –SiCH3), 0.10 (s, 3H,
–SiCH3), 0.86 (s, 9H, –C(CH3)3), 4.91 (s, 1H, H-10), 5.25 (s, 2H,
PhCH2–), 6.07 (d, J¼5.7 Hz, 1H, H-300), 6.11 (m, 1H, H-3), 6.53 (s,
1H, H-3), 7.06 (d, J¼5.7 Hz, 1H, H-400), 7.31–7.42 (m, 5H, Ar-H);
NMR (400 MHz, CDCl3)
d 0.00 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3),
0.87 (s, 9H, –C(CH3)3), 1.34 (t, J¼7.2 Hz, 3H, –CH3), 4.24–4.29 (m,
2H, –OCH2–), 4.87 (d, J¼1.1 Hz, 1H, H-10), 5.37 (br s, 1H, –OH),
6.09 (t, J¼1.2 Hz, 1H, H-3), 6.12–6.15 (m, 1H, H-300), 6.49 (d,
J¼1.1 Hz, 1H, H-3), 7.09 (d, J¼6.8 Hz, 1H, H-400); 13C NMR
13C NMR (101 MHz, CDCl3)
d
ꢁ4.5 (br), 18.5 (br), 26.1 (br), 68.0,
72.9, 107.8, 125.5, 128.8 (br), 129.2, 130.3, 135.6 (br), 139.0, 151.2,
167.9, 170.5; minor diastereomer: 1H NMR
d 0.04 (s, 3H, –SiCH3),
(101 MHz, CDCl3)
d
ꢁ4.9, ꢁ4.5, 14.55, 18.5, 26.1, 62.5, 72.8, 107.9,
0.15 (s, 3H, –SiCH3), 0.90 (s, 9H, –C(CH3)3), 4.85 (s, 1H, H-10),
5.23 (s, 2H, PhCH2–), 6.01 (d, J¼5.6 Hz, 1H, H-300), 6.14 (m, 1H,
H-3), 6.55 (m, 1H, H-3), 6.83 (d, J¼5.6 Hz, 1H, H-400), 7.31–7.42
125.6, 129.9, 139.2, 151.3, 168.4, 170.5; minor diastereomer: 1H
NMR 0.05 (s, 3H, –SiCH3), 0.15 (s, 3H, –SiCH3), 0.90 (s, 9H,
d
–C(CH3)), 1.32 (t, J¼7.4 Hz, 3H, –CH3), 4.24–4.29 (m, 2H, –OCH2–),
4.82 (d, J¼1.1 Hz, 1H, H-10), 5.31 (br s, 1H, –OH), 6.12–6.15 (m, 2H,
H-3, H-300), 6.51 (d, J¼1.1 Hz, 1H, H-3), 6.93 (d, J¼5.7 Hz, 1H, H-
(m, 5H, Ar–H); 13C NMR (101 MHz, CDCl3)
d
ꢁ4.9 (br), 18.5 (br),
26.1 (br), 67.8, 73.0, 107.5, 125.1, 128.8 (br), 129.1, 130.7, 135.6
(br), 138.7, 152.0, 166.8, 170.5; HRMS (ESI) m/z calcd for
C21H29O6Si [MþH]þ, 405.1733, found 405.1735.
400); 13C NMR
d
ꢁ4.6, ꢁ4.4, 14.58, 18.6, 26.1, 62.2, 73.0, 107.5,
125.0, 130.5, 138.8, 152.2, 167.3, 170.6; HRMS (ESI) m/z calcd for
C16H27O6Si [MþH]þ, 343.1577, found 343.1574.
4.4.6. Cinnamyl 2-((tert-butyldimethylsilyloxy)(2-hydroxy-5-oxo-
2,5-dihydrofuran-2-yl)methyl)acrylate (2f)
4.4.3. Butyl 2-((tert-butyldimethylsilyloxy)(2-hydroxy-5-oxo-2,5-
dihydrofuran-2-yl)methyl)acrylate (2c)
Colourless oil. Yield: 87%; IR (CHCl3/NaCl) nmax (cmꢁ1): 3365
(br), 2955 (m), 2932 (m), 2889 (m), 2858 (m), 1771 (s), 1712 (s),
1628 (w), 1466 (m), 1097 (s), 967 (m), 840 (s); major di-
Colourless oil. Yield: 90%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2958 (s),
2931 (s), 1764 (s), 1708 (s); major diastereomer: 1H NMR (400 MHz,
astereomer: 1H NMR (600 MHz, CDCl3)
d 0.02 (br s, 3H, –SiCH3),
CDCl3)
d
0.00 (s, 3H, –SiCH3), 0.10 (s, 3H, –SiCH3), 0.86 (s, 9H, –
0.12 (br s, 3H, –SiCH3), 0.87 (br s, 9H, –C(CH3)3), 4.86 (d,
J¼6.3 Hz, 2H, –OCH2–), 4.91 (br s, 1H, H-10), 5.36 (br s, 1H, –OH),
6.06–6.18 (m, 2H, H-3, H-300), 6.30 (dt, J¼15.8, 6.6 Hz, 1H,
PhCH]CH–), 6.56 (s, 1H, H-3), 6.69 (d, J¼15.7 Hz, 1H,
PhCH]CH–), 7.10 (br s, 1H, H-400), 7.27–7.43 (m, 5H, Ar–H); 13C
C(CH3)3), 0.96 (t, J¼7.3 Hz, 3H, –CH2CH3), 1.34–1.48 (m, 2H,
–CH2CH3), 1.61–1.73 (m, 2H, –OCH2CH2–), 4.14–4.24 (m, 2H,
–OCH2–), 4.87 (s, 1H, H-10), 5.41 (br s, 1H, –OH), 6.08 (br s, 1H, H-3),
6.10–6.14 (m, 1H, H-300), 6.48 (d, J¼0.9 Hz, 1H, H-3), 7.09 (d,
J¼5.6 Hz, 1H, H-400); 13C NMR (101 MHz, CDCl3)
d
ꢁ4.9, ꢁ4.5, 14.2,
NMR (101 MHz, CDCl3)
108.0, 122.6, 125.5, 127.1, 128.8, 129.1, 130.0 (br), 135.5, 139.2,
151.3, 167.9, 170.6 (br); minor diastereomer: 1H NMR
0.02 (br s,
d
ꢁ4.5 (br), 18.4 (br), 26.0 (br), 66.8, 72.6,
18.5, 19.6, 26.07, 31.0, 66.3, 72.85, 107.9, 125.5, 129.8, 139.2, 151.3,
168.4, 170.6; minor diastereomer: 1H NMR
d
0.05 (s, 3H, –SiCH3),
d
0.15 (s, 3H, –SiCH3), 0.90 (s, 9H, –C(CH3)3), 0.95 (t, J¼7.3 Hz, 3H,
–CH2CH3), 1.34–1.48 (m, 2H, –CH2CH3), 1.61–1.73 (m, 2H,
–OCH2CH2–), 4.14–4.24 (m, 2H, –OCH2–), 4.82 (s, 1H, H-10), 5.34 (br
s,1H, –OH), 6.06–6.14 (m, 2H, H-3, H-300), 6.51 (d, J¼0.7 Hz,1H, H-3),
3H, –SiCH3), 0.12 (br s, 3H, –SiCH3), 0.88 (br s, 9H, –C(CH3)3),
4.86 (d, 2H, J¼6.3 Hz, –OCH2–), 4.91 (br s, 1H, H-10), 5.36 (br s,
1H, –OH), 6.06–6.18 (m, 2H, H-3, H-300), 6.30 (dt, J¼15.8, 6.6 Hz,
1H, PhCH]CH–), 6.56 (s, 1H, H-3), 6.69 (d, J¼15.7 Hz, 1H,
PhCH]CH–), 6.94 (br s, 1H, H-400), 7.27–7.43 (m, 5H, Ar–H); 13C
6.93 (d, J¼5.6 Hz, 1H, H-400); 13C NMR
d
ꢁ4.6, ꢁ4.4, 14.2, 18.6, 19.6,
26.12, 31.0, 66.0, 72.94, 107.5, 125.0, 130.5, 138.8, 152.2, 167.4, 170.5;
HRMS (ESI) m/z calcd for C18H31O6Si [MþH]þ, 371.1890, found
371.1898.
NMR
d
ꢁ5.0 (br), 18.4 (br), 26.0 (br), 66.6, 72.8, 107.6, 122.6,
125.0, 127.1, 128.8, 129.1, 130.6 (br), 136.3, 138.7, 152.2, 166.9,
170.6; HRMS (ESI) m/z calcd for C23H30O6SiNa [MþNa]þ,
453.1709, found 453.1707.
4.4.4. Dodecyl 2-((tert-butyldimethylsilyloxy)(2-hydroxy-5-oxo-
2,5-dihydrofuran-2-yl)methyl)acrylate (2d)
4.4.7. Allyl 2-((tert-butyldimethylsilyloxy)(2-hydroxy-5-oxo-2,5-
dihydrofuran-2-yl)methyl)acrylate (2g)
Colourless oil. Yield: 78%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2928
(vs), 2856 (s), 1772 (s), 1705 (m), 1462 (m), 1103 (s), 1080 (s);
Colourless oil. Yield: 78%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2956
(m), 2932 (m), 2891 (m), 2858 (m), 1773 (s), 1711 (s), 1630 (w),
1463 (m), 1389 (s), 1100 (s), 840 (s); major diastereomer: 1H
major diastereomer: 1H NMR (400 MHz, CDCl3)
d 0.0 (s, 3H,
–SiCH3), 0.10 (s, 3H, –SiCH3), 0.87 (s, 9H, –C(CH3)3), 0.88 (m,
3H, –(CH2)9CH3), 1.19–1.43 (m, 18H, –(CH2)9CH3), 1.63–1.75 (m,
2H, –OCH2CH2–), 4.15–4.24 (m, 2H, –OCH2–), 4.87 (d, J¼0.7 Hz,
1H, H-10), 5.41 (br s, 1H, –OH), 6.08 (m, 1H, H-3), 6.11–6.15
NMR (400 MHz, CDCl3)
d 0.00 (s, 3H, –SiCH3), 0.11 (s, 3H,
–SiCH3), 0.86 (s, 9H, –C(CH3)3), 4.67–4.73 (m, 2H, –OCH2–),
4.90 (d, 1H, J¼0.9 Hz, H-10), 5.18 (br s, 1H, –OH), 5.26–5.39 (m,

10836
S.N. Patil et al. / Tetrahedron 64 (2008) 10831–10836
2H, –CHg]CH2), 5.88–6.02 (m, 1H, –CH]CH2), 6.11–6.13 (m, 2H,
H-3, H-300), 6.54 (d, J¼1.1 Hz, 1H, H-3), 7.09 (d, J¼5.7 Hz, 1H, H-
by a pre-doctoral scholarship from Macquarie University, and
B.E.S. is the recipient of an Australian Postgraduate Award
scholarship.
400); 13C NMR (101 MHz, CDCl3)
d
ꢁ4.9, ꢁ4.5, 18.5, 26.1, 66.8,
72.8, 107.8, 119.6, 125.6, 130.3, 131.8, 139.0, 151.2, 167.8, 170.6;
minor diastereomer: 1H NMR
d
0.05 (s, 3H, –SiCH3), 0.16 (s, 3H,
Supplementary data
–SiCH3), 0.90 (s, 9H, –C(CH3)3), 4.67–4.73 (m, 2H, –OCH2–), 4.83
(d, J¼0.9 Hz, 1H, H-10), 5.18 (br s, 1H, –OH), 5.27–5.39 (m, 2H,
–CH]CH2), 5.88–6.02 (m, 1H, –CH]CH2), 6.13–6.16 (m, 2H, H-3,
H-30), 6.55 (d, J¼0.9 Hz, 1H, H-3), 6.92 (d, J¼5.7 Hz, 1H); 13C
Supplementary data for this article (1H and 13C NMR spectra of
compounds 1a–h and 2a–h) can be found online. Supplementary
data associated with this article can be found in the online version,
at doi:10.1016/j.tet.2008.09.019.
NMR
d
ꢁ4.6, ꢁ4.4, 18.6, 26.1, 66.6, 73.0, 107.5, 119.5, 125.1, 130.8,
131.9, 138.6, 152.1, 166.8, 170.5; HRMS (ESI) m/z calcd for
C17H27O6Si [MþH]þ, 355.1577, found 355.1575.
References and notes
4.4.8. Chloroethyl 2-((tert-butyldimethylsilyloxy)(2-hydroxy-5-
oxo-2,5-dihydrofuran-2-yl)methyl)acrylate (2h)
1. Yadav, P. P.; Arora, A.; Bid, H. K.; Konwar, R. R.; Kanojiya, S. Tetrahedron Lett.
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Colourless oil. Yield: 82%; IR (CHCl3/NaCl) nmax (cmꢁ1): 2957
(m), 2859 (m), 1766 (s), 1725 (s), 1633 (w), 1395 (w), 1103 (s); major
diastereomer: 1H NMR (400 MHz, CDCl3)
d 0.01 (s, 3H, –SiCH3), 0.11
(s, 3H, –SiCH3), 0.87 (s, 9H, –C(CH3)3), 3.71–3.77 (m, 2H, –CH2Cl),
4.32–4.55 (m, 2H, –OCH2–), 4.91 (s, 1H, H-10), 4.96 (br s, 1H, –OH),
6.13–6.18 (m, 2H, H-3, H-300), 6.55–6.57 (m, 1H, H-3), 7.11 (d,
J¼5.7 Hz, 1H, H-400); 13C NMR (101 MHz, CDCl3)
d
ꢁ4.9, ꢁ4.5, 18.5,
26.06, 41.8, 65.5, 72.6, 107.7, 125.7, 130.8, 138.7, 151.2, 167.4, 170.5;
minor diastereomer: 1H NMR
d 0.06 (s, 3H, –SiCH3), 0.16 (s, 3H,
–SiCH3), 0.91 (s, 9H, –C(CH3)3), 3.71–3.77 (m, 2H, –CH2Cl), 4.32–
4.55 (m, 2H, –OCH2–), 4.86 (s, 1H, H-10), 4.99 (br s, 1H, –OH), 6.13–
6.18 (m, 2H, H-3, H-300), 6.55–6.57 (m, 1H, H-3), 6.96 (d, J¼5.7 Hz,
1H, H-400); 13C NMR
125.4, 131.1, 138.4, 151.9, 166.4, 170.4; MS (ESI) m/z (% relative in-
d
ꢁ4.6, ꢁ4.4, 18.6, 26.11, 41.9, 65.3, 73.0, 107.5,
tensity): 377.1 (100), 379.1 (32); HRMS (ESI) m/z calcd for
35
10. (a) Yu, C.; Liu, B.; Hu, L. J. Org. Chem. 2001, 66, 5413–5418; (b) Cai, J.; Zhou, Z.;
Zhao, G.; Tang, C. Org. Lett. 2002, 4, 4723–4725; (c) Chandrasekhar, S.; Nar-
sihmulu, C.; Saritha, B.; ShameemSultana, S. Tetrahedron Lett. 2004, 45, 5865–
5867; (d) Basavaiah, D.; Krishnamacharyulu, M.; Rao, A. J. Synth. Commun.
2000, 30, 2061–2069.
C16
H
ClO6Si [MþH]þ, 377.1187, found 377.1187.
26
Acknowledgements
11. (a) Kernan, M. R.; Faulkner, J. D. J. Org. Chem.1988, 53, 2773–2776; (b) Teijeira, M.;
Suarez, P. L.; Gomez, G.; Teran, C.; Fall, Y. Tetrahedron Lett. 2005, 46,
5889–5892.
This work is supported by an Australian Research Council
Discovery Grant to F.L. (ARC-DP0558754). S.N.P. was supported