A convenient and versatile method for the preparation of α-hydroxymethyl ketone derivatives from the corresponding allyl silyl ethers or allyl carboxylates

Article abstract of DOI:10.1002/jccs.200800134

The ozonolysis of 1-substituted allyl silyl ethers or 1-substituted allyl carboxylates followed by treatment with bases gave the corresponding α-silyloxymethyl- or α-acyloxymethyl-ketones in good yields. It is proposed to proceed via the corresponding α-silyloxy- or α-acyloxyaldehydes intermediates followed by 1,4-group migration. The results of theoretical calculations are applicable to explain the experimental results.

Full text of DOI:10.1002/jccs.200800134

896
Journal of the Chinese Chemical Society, 2008, 55, 896-914
A Convenient and Versatile Method for the Preparation of
a-Hydroxymethyl Ketone Derivatives from the Corresponding Allyl Silyl
Ethers or Allyl Carboxylates
Yung-Son Hona* (
), Ying-Chieh Wonga (
) and Kuo-Jui Wub (
)
aDepartment of Chemistry and Biochemistry, National Chung Cheng University,
Chia-Yi 62102, Taiwan, R.O.C.
bDepartment of Information Management, Toko University, Chia-Yi 61363, Taiwan, R.O.C.
The ozonolysis of 1-substituted allyl silyl ethers or 1-substituted allyl carboxylates followed by treat-
ment with bases gave the corresponding a-silyloxymethyl- or a-acyloxymethyl-ketones in good yields. It
is proposed to proceed via the corresponding a-silyloxy- or a-acyloxyaldehydes intermediates followed
by 1,4-group migration. The results of theoretical calculations are applicable to explain the experimental
results.
Keywords: Ozonides; a-Acyloxyaldehydes; a-Silyloxymethyl ketones; a-Acyloxymethyl ke-
tones; Ene-diol rearrangement.
Different workup reagents react with the
ozonide to give different products
Scheme I
INTRODUCTION
We have earlier reported that ozonides derived from
terminal alkenes when treated with Et3N gave the corre-
sponding aldehydes in good yields.1 The yields of this
workup method are comparable to those with the reducing
agent, such as Ph3P, Me2S or Zn in acetic acid. The use of
the basic workup is superior to conventional reducing agents
in terms of reaction time, ease of byproduct removal, cost
of reagents, and lack of ordor. This methodology has been
commonly utilized in our laboratory for the synthetic de-
signs.2 In our ongoing project, we found that the ozonolysis
of allyl silyl ether 3a-1 followed by treatment with Et3N
gave the a-silyloxymethyl ketone 6a-1 instead of a-silyl-
oxyaldehyde 5a-1. Interestingly, we can only prepare the
a-silyloxyaldehyde 5a-1 by using Ph3P to workup the
ozonolytic reaction (Scheme I).3 The results indicate that
different products will be formed from ozonide 4a-1 de-
rived from alkene 3a-1 depending on the reagents used dur-
ing workup. We can also envisage that it will be a conve-
nient one pot functional group transformation from allyl
silyl ether to a-silyloxymethyl ketone.
1a
PhCHO
1. O , CH Cl ,
3
OTBS
2
2
o
-78 C
H C=CHMgBr
2
Ph
CHO
5a-1
2. 1.0 equiv. Ph P
3
o
THF, -78 C
78%
TBSCl, Et N,
3
cat. DMAP,
CH Cl , 8 h
OH
OTBS
cat. Dibal-H
pentane
Ref. 8
2
2
Ph
2a
Ph
3a-1
78%
O
o
1. O , CH Cl , -78 C
3
2
2
2. 1.2 equiv. Et N
3
Ph
6a-1 OTBS
72%
dehyde 5a-1 was treated with a catalytic amount of diiso-
butylaluminum hydride (Dibal-H) in pentane to give a-
silyloxymethyl ketone 6a-1. The formation 6a-1 was pro-
posed to occur via Oppenauer oxidation. Unfortunately, the
scope of this reaction is not quite broad.8 To the best of our
knowledge, the one-pot transformation of allyl silyl ether
3a-1 to the a-silyloxymethyl ketone 6a-1 is an alternative,
new, mild, and efficient transformation in comparison with
the literature report. In this article, we will describe the
scope and application of this reaction in detail.
The typical methods for the preparation of a-hy-
droxymethyl ketone derivatives are by SN2 displacement of
the corresponding a-bromomethyl ketones with metal hy-
droxides,4 oxidation of the corresponding silyl enol ethers,5
Lewis acid-promoted isomerization of glycidyl silyl ethers,6
or the treatment of diazoketones with a catalytic amount of
rhodium(II) acetate.7 We also reported that a-silyloxyal-
RESULTS AND DISCUSSIONS
Preparation of allyl carboxylates and allyl silyl ethers
The allyl alcohol 2b was prepared from the addition

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 897
of 3-phenylpropylmagnesium bromide to the acrolein (1’).
The other allyl alcohols, such as 2a and 2c-2h, were pre-
pared from the addition of vinylmagnesium bromide to the
corresponding aldehydes 1. These allyl alcohols are usu-
ally formed in good yields so that their crude products
could be used directly for the further transformations, such
as t-butyldimethylsilylation, acetylation, pivalylation and
methoxycarbonylation, respectively (Scheme II). Similar
approach is also applicable to the bisallyl alcohol deriva-
tives, such as 3i-1, 3j-1 and 3i-2, 3j-2, starting from 1,8-
octanedial (1i) and terephthalaldehyde (1j), respectively
(Scheme III). In general, the overall yields for two step se-
quences are good to excellent.
with 1.2 equivalents of Et3N, a-silyloxyaldehyde 5b-1 in-
stead of a-silyloxymethyl ketone 6b-1 was obtained in
good yield. When a stronger base such as 1,8-diazabicyclo-
[5.4.0]undec-7-ene (DBU) was employed to decompose
the ozonide 4b-1, the a-silyloxymethyl ketone 6b-1 was
obtained in 71% yield (Entry 2, Table 1). The results of en-
tries 1 and 2 imply that the tendency of this transformation
is dependent on the substitutent of the substrate. When R is
an aryl group, EtB3N is good enough to achieve the transfor-
mation (i.e. Condition A; Scheme IV). On the other hand,
when R is an alkyl group, DBU is required to achieve the
same purpose (i.e. Condition B; Scheme IV). In addition,
a-silyloxyaldehyde 5b-1 should be the precursor of a-si-
lyloxymethyl ketone 6b-1. By using Condition B, both
a-cyclohexylallyl silyl ether 3c-1 and a-tert-butylallyl
silyl ether 3d-1 gave the rearranged products in high yields
(Entries 3 and 4). In the case of compound 3d-1 which con-
tains bulky tert-butyl group, heating the reaction mixture in
Preparation of a-silyloxymethyl ketones from allyl
silyl ethers
Interestingly, when we carry out the ozonolysis of
3-phenylpropylallyl silyl ether 3b-1 followed by treatment
Scheme II Preparation of allyl carboxylates and allyl silyl ethers
3a-1 78%
3b-1 83%
3c-1 72%
3d-1 68%
3e-1 81%
3f-1 73%
3g-1 83%
3h-1 61%
OSiMe Bu-t
2
3a-2 74%
3b-2 80%
3c-2 78%
3d-2 79%
3e-2 85%
3g-2 83%
3h-2 65%
R
OAc
t-BuMe SiCl, Et N,
Ac O, Et N,
2
2
cat. DMAP, CH Cl , RT
3
3
2
2
cat. DMAP, CH Cl ,
2
2
R
o
0 C-RT
o
Ph(CH ) MgBr, THF, -78 C
2 3
for 2b
H2C=CHCHO
1'
OH
t
OCOBu
3a-3 87%
3c-3 79%
3d-3 54%
t-BuCOCl, Et N,
3
o
H C=CHMgBr, THF, -78 C
2
R
o
CH Cl , 0 C-RT
2
RCHO
1
2
R
for 2a and 2c-2h
2a-2h
OCOPh
PhCOCl, Pyridine,
heat
3a-4 75%
3b-4 81%
R
R = Ph
a
t-Bu-
BnOCH2-
PhOCH2-
d
e
O
MeO
H
Ph(CH2)3-
Cyclohexyl c
b
g
H
O
h
f
O
O
O
Scheme III Preparation of bisallyl silyl ethers and bisallyl acetates
H C=CHMgBr
o
t-BuMe SiCl,
2
Et N, cat. DMAP,
2
THF, -78 C
t-BuMe SiO
2
OSiMe Bu-t
2
HO
OH
M
3
CH Cl , RT
OHC
M CHO
M
2
2
3i-1 78%
3j-1 81%
M = -(CH2)6- 1i
2i -2j
AcO
OAc
Ac O, Et N, cat. DMAP
2
1j
3
3i-2 75%
3j-2 81%
M
o
CH Cl , 0 C-RT
2
2

898 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Hon et al.
Table 1. The ozonolysis of allyl silyl ether or allyl ester followed by treatment with base to give the
corresponding a-hydroxymethyl ketones
Entry
R =
S =
Reactant Product Condition Time (h) Yield (%)a
t-BuMe2Si-
t-BuMe2Si-
t-BuMe2Si-
t-BuMe2Si-
t-BuMe2Si-
t-BuMe2Si-
1
2
3
4
5
6
Ph-
3a-1
3b-1
3c-1
3d-1
3e-1
3f-1
6a-1
6b-1
6c-1
6d-1
6e-1
6f-1
A
B
B
Bb
B
B
8
14
12
60
5
72
71
81
60
84
0c
Ph(CH2)3-
Cyclohexyl
t-Bu-
BnOCH2-
PhOCH2-
1
5
6
O
MeO
5
4
2
7
8
t-BuMe2Si-
3g-1
6g-1
D
7
56d
3
H
H
O
O
7
8'
8
3
4
t-BuMe2Si-
3h-1
6h-1
D
7
54
2
5 O
O
1
6'
6
9
-(CH2)6-
t-BuMe2Si-
t-BuMe2Si-
3i-1
3j-1
6i-1
6j-1
B
C
7
6
72
71
10
11
12
13
14
15
Phenyl
MeCO-
MeCO-
MeCO-
MeCO-
MeCO-
3a-2
3b-2
3c-2
3d-2
3e-2
6a-2
6b-2
6c-2
6d-2
6e-2
A
B
8
12
8
82
70
70
75
69
Ph(CH2)3-
Cyclohexyl
t-Butyl
B
Bb
12
6
BnOCH2-
B
O
MeO
16
MeCO-
3g-2
6g-2
D
D
7
61d
H
H
O
O
17
MeCO-
3h-2
6h-2
7
31
O
O
18
19
-(CH2)6-
MeCO-
MeCO-
3i-2
3j-2
6i-2
6j-2
B
C
6.5
8
67
75
20
21
22
23
24
25
26
Phenyl
t-BuCO-
t-BuCO-
t-BuCO-
PhCO-
PhCO-
H
3c-3
3d-3
3c-3
3a-4
3b-4
2a
6c-3
6d-3
6c-3
6a-4
6b-4
6a
A
B
Bb
A
B
10
12
16
6
81
73
71
74
67
55
46
Cyclohexyl
t-Butyl
Phenyl
Cyclohexyl
Phenyl
8
C
7
Cyclohexyl
H
2b
6b
D
8
a The isolated yields.
b Under refluxing condition.
c Phenol was isolated in almost 62% yield.
d Retention of the chirality a to ketone group.
CH2Cl2 for 60 h is required to give the desired product 6d-1
group, a-silyloxymethyl ketone 6e-1 was obtained in 84%
in good yield (Entry 4). When R is a benzyloxymethyl
yield by exploitation of Condition B (Entry 5). However,

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 899
yl)allyl silyl ether (3h-1), compound 6h-1 was isolated in
54% yield (Entry 8). Whether the chiral center a- to the
keto group of compound 6h-1 is retained in the reaction
will be discussed later.
Scheme IV Preparation of a-hydroxymethyl ketone
derivatives from the corresponding allyl
silyl ethers or allyl carboxylates
OS
Condition A or C
The allyl silyl ethers tethered with either hexamethyl-
ene or phenylene spacer (i.e. 3i-1 and 3j-1) can also un-
dergo bidirectional reaction to give bis-a-silyloxymethyl
ketones 6i-1 and 6j-1, respectively, in good yields (Entries
9 and 10). When the methallyl silyl ether 7 was treated with
ozone followed by Et3N, a-silyloxymethyl ketone 8 in-
stead of a-silyloxymethyl phenyl ketone 9 was obtained
(Eq. 1). This result is different from those from mono-sub-
stituted alkenes because the silyl group is retained on the
same place of the structure.
O
R = Aromatic
OS
R
R
Condition B or D
R = Aliphatic
6
3 or
2 (when S=H)
S = t-BuMe Si-, MeCO-, t-BuCO, PhCO-, H.
2
Condition A (when R is aromatic):
o
o
(i) O , CH Cl , -78 C; (ii) 1.2 equiv. Et N, -78 C to RT.
3
2
2
3
Condition B (when R is aliphatic):
o
o
(i) O , CH Cl , -78 C; (ii) 1.2 equiv. DBU, -78 C to RT.
3
2
2
Condition C (when R is aromatic):
o
o
(i) O , CH Cl , -78 C; (ii) 0.8 equiv. Ph P, -78 C to RT;
2
3
2
3
o
(iii) 0.5 equiv. Et N, -78 C to RT.
3
1. O , CH Cl ,
3
2
2
OTBS
O
OTBS
Condition D (when R is aliphatic):
o
o
+
-78 C
o
(1)
O
OTBS
not found
Me
(i) O , CH Cl , -78 C; (ii) 0.8 equiv. Ph P, -78 C to RT;
3
2
2
3
Ph
Ph
Ph
o
2. 1.2 equiv. Et N
3
(iii) 0.5 equiv. DBU, -78 C to RT.
7
8
9
o
Me
Me
-78 to RT
when R is a phenyloxymethyl group, no a-silyloxymethyl
ketone 6f-1 but phenol was obtained (Entry 6). Presum-
ably, phenol is formed from the b-elimination of the corre-
sponding aldehyde intermediate 5f-1. The results of entries
5 and 6 imply that the leaving aptitude equal to or better
than phenoxide can not be applied for the purpose of this
transformation.
The preparation of a-carboxylketones from allyl
carboxylates
Similar to allyl tert-butyldimethylsilyl ethers (Entries
1-10, Table 1), the allyl acetates (Entries 11-19), allyl piva-
lates (Entries 20-22) and allyl benzoates (Entries 23-24)
are also applicable to prepare the corresponding a-car-
boxylketones in modest to good yields. When the substrate
with bulky tert-butyl group, such as compounds 3d-2 and
3c-3, higher temperature and longer time are needed to en-
sure the completion of the reaction (Entries 14 and 22). In
other words, the silyl, acetyl, pivalyl and benzoyl groups
work equally well in this reaction system. When Condi-
tions C and D were applied to the allylic alcohols 2a and
2b, respectively, the a-hydroxymethyl ketones 6a and 6b
were formed only in modest yields (Entries 25 and 26). In-
terestingly, the isomerization of a-hydroxyaldehyde to a-
hydroxymethyl ketones is known as the Lobry de Bryn-
Alberda van Ehenstein transformation in carbohydrate
chemistry.9
When Condition B was applied to the a-tetrahydro-
furanyl-allyl silyl ether 3g-1, the yield of the a-silyloxy-
methyl ketone 6g-1 is about 40%. The lower yield by Con-
dition B is probably due to the poor regioselectivity of the
proton abstraction from the corresponding ozonide 4g-1 by
base. In order to improve the reaction yield, Ph3P was em-
ployed to reduce the ozonide intermediate. Without isola-
tion the corresponding aldehyde, the reaction mixture was
directly treated with DBU (i.e. Condition D) to give a-si-
lyloxymethyl ketone 6g-1 in 56% yield (Entry 7). The re-
tention of the C2 configuration of the ribose 6g-1 is evi-
denced by its 1H and 13C NMR spectra. The characteristic
1H NMR chemical shifts of compound 6g-1 are: a doublet
at 4.72 ppm for C2-H, a doublet of doublet at 5.10 ppm for
C3-H and a doublet at 4.56 ppm for C4-H. Its characteristic
13C NMR chemical shifts are: 204.2 ppm for C=O, 80.4
ppm for C2, 84.1 ppm for C3 and 84.3 ppm for C4. The suc-
cess of this reaction may open a new entry for the chain
elongation of the ribose moiety. Similarly, when Condition
D was applied to (4R)-1-(2,2-dimethyl-[1,3]dioxolan-4-
In the case of (4R)-1-(2,2-dimethyl-[1,3]dioxolan-4-
yl)allyl acetate (3h-2), product 6h-2 was isolated in 31%
yield (Entry 17). In order to understand the degree of race-
mization in the formation of compounds 6h-1 (Entry 8) and
6h-2 (Entry 17), (4R)-1-(2,2-dimethyl-[1,3]dioxolan-4-
yl)allyl alcohol (2h) was prepared as a mixture of two di-
astereomers (RS:RR = 56:44) according to the literature

900 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Hon et al.
procedure.10 Reaction of alcohol 2h with (R)-(+)-Mosher
acid (10) mediated by dicyclohexylcarbodiimide (DCC)
gave the Mosher esters 3h-5 in 54% yield as a mixture of
two diastereomers in a ratio of 4:1 and recovered approxi-
mately 40% of the starting alcohol 2h. The ozonolysis of
Mosher ester 3h-5 followed by sequential treatment with
Ph3P and DBU gave equal amount of the inseparable rear-
ranged product 6h-5A and 6h-5B in 44% yield (Scheme
V). The diastereomeric ratio is determined by the integra-
tion of the methoxy peak in 1H NMR at d 3.65 (d, 5JF-H = 1.2
5
Hz) and 3.67 (d, JF-H = 1.1 Hz). It indicates that the a-
chiral center of product 6h-5 racemizes completely during
the reaction.
Proposed mechanism for the formation of a-silyloxy-
methyl ketone from a-silyloxyaldehyde
The functional group transformation in Scheme IV is
useful and convenient in organic synthesis and applicable
to a variety of migratory groups. It is interesting and impor-
tant to understand the possible mechanism of this transfor-
mation. The plausible mechanism is demonstrated by using
tert-butyldimethylsilyl analogue as example shown in Fig.
1. The reaction of ozonide 4a-1 with Et3N does not stop at
the a-silyloxyaldehyde 5a-1, which should be the precur-
sor of the a-silyloxymethyl ketone 6a-1. The a-proton
acidity of the compound 5a-1 is enhanced by phenyl group
so that it is removable with Et3N to give the enolate 5a-1’,
which subsequently undergoes 1,4-silyl group migration to
give the triethylammonium a-silyloxy enolate 5a-1”.11 The
intramolecular proton transfer of the intermediate 5a-1”
gives a-silyloxymethyl ketone 6a-1 and Et3N, which is re-
cycled in the next reaction cylcle (Fig. 1). On the other
hand, the basicity of Ph3P is very weak and it can act only as
a reducing agent to reduce ozonide 4a-1 to give aldehyde
5a-1.
Scheme V The a-chiral center of product 6h-5 race-
mizes completely in the reaction
OH
(R)
O
O
(R)
Ph
DCC, DMAP,
CH Cl , RT, 48 h
(60% conversion)
54% isolated yield
O
2h
O
CF
MeO
3
2
2
(R)
(RS):(RR) = 56:44
+
(4:1)
O
O
O
(R)
3h-5
1. O , CH Cl , -78 C;
Ph
HO
o
3
2
2
6h-5A and 6h-5B
CF
MeO
3
2. 1.2 equiv. DBU,
44%
are inseparable and
10
o
formed in equal amount.
O
0 C, 6.5 h
O
(S)
O
O
(R)
O
O
O
O
(R)
+
(R)
O
MeO
O
Ph
MeO
Ph
F C
3
6h-5B
F C
3
6h-5A
O
o
o
OTBS
1. O , CH Cl , -78 C
3
1. O , CH Cl , -78 C
2
OTBS
CHO
2
2
3
2
Protonation and
tautomerization
2. 1.1 equiv. Ph P
3
2. 1.2 equiv. Et N
3
Ph
Ph
Ph
78%
OTBS
6a-1
72%
5a-1
3a-1
O
3
O
TBS
Ph PO + HCHO
3
Et HN
3
Et N
3
O
OTBS
OTBS
O
5a-1"
Ph
H
O
H
O
Ph
4a-1
1,4-silyl migration
Ph
H
H
O
O
O
Me
Si
Me
Bu-t
Regenerated Et N
3
can be recycled in the
transformation.
4a-1
Ph P
3
Ph P
3
O
Et N
3
deprotonation
O
Ph
Me
Si
Me
Bu-t
Et HN
3
Et N
3
H
OTBS
O
5a-1'
H
O
Et N
3
O
deprotonation
Ph
Ph
H
O
H
5a-1
O
- +
Et N
3
H
HCO
HNEt
3
2
4a-1
Fig. 1. The plausible mechanism for the formations of compounds 5a-1 and 6a-1 from compound 3a-1.

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 901
There are few special features in this mechanism
which are noteworthy. (1) The ring protons and peroxide
bond are two reactive sites on the ozonide 4a-1. The former
can be removed regioselectively with Et3N and the latter is
reduced specifically by Ph3P. Different workup reagents re-
act with the ozonide to give different products. (2) There is
an alternative possibility that the ozonide 4a-1 is reduced
by Et3N to a-silyloxyaldehyde 5a-1 followed by an in situ
base-mediated rearrangement. In this mechanism, 1.2 equiv
of the base were also enough, of which 1 equiv could be
consumed as the reductant. However, in our previous re-
port, we demonstrated that the acid-base mechanism is an
overwhelming pathway.2 Therefore, we could rule out the
possibility that Et3N plays the role as a reductant in this re-
action. (3) The a-proton acidity of compound 5a-1 is en-
hanced by its phenyl group so that Et3N is strong enough to
abstract its a-proton. When the a-substituent of a-silyl-
oxyaldehyde is an alkyl instead of an aryl group, a stronger
base such as DBU is needed to abstract its a-proton. (4)
Once the a-proton of 5a-1 is removed by Et3N, the tandem
1,4-silyl group migration and tautomerization occur to give
a-silyloxymethyl ketone 6a-1. (5) Since the conversion of
intermediate 5a-1” to product 6a-1 involves both the
protonation and tautomerization, which will lead to regen-
erate Et3N. The regenerated Et3N can be further used in the
reaction cycle. Therefore, the reaction needs only 1.2 mol
equivalents of base to give the reaction in high yield, al-
though there are two deprotonations in the whole reaction
sequences (Fig. 1).
OS
O
OS
+ DErxn
(3)
Ph
CHO
Ph
S = -H 5a
S = -SiMe2Bu-t 5a-1
S = -COMe 5a-2
S = -COBu-t 5a-3
6a
6a-1
6a-2
6a-3
O
OAc
OAc
O
O
CHO
5h-2
DErxn (4)
+
O
O
6h-2
OTBS
Me
Me
Me
Me
O
OTBS
(5)
+
DErxn
O
Ph
Ph
8
9
Me
Me
formers (By default, only conformers within 9.6 kcal/mol
of the global minimum will be kept.).12 The equilibrium ge-
ometries and relative conformer energies were calculated
by using the semi-empirical PM3 method based on the low-
est energy geometries of MMFF94 method. Furthermore,
the optimizations of molecular equilibrium geometry and
its relative energies were obtained by using the more reli-
able B3LYP method based on hybrid Density Functional
Theory (DFT) with 6-31+G(d) basis set.
Finally, in order to compare the calculated energy in
gas phase with that of in practical experimental condi-
tions, the single-point energy calculation in CH2Cl2 sol-
vent was performed by using B3LYP method with Polar-
ized Continuum (overlapping spheres) Model (PCM) and
6-31+G(d) basis set. The electronic calculations were per-
formed by implementing the GAUSSIAN 03 program.13
Some MMFF94 molecular mechanics model calculations
were performed by employing the Spartan’06 program.14
The calculated energies of each reaction at various
theoretical levels were summarized in Table 2. The results
by using semi-empirical method PM3 with 6-31+G(d) ba-
sis set are in a reasonable agreement with those of the ex-
perimental results in Table 1 (Entries 1-5, Table 2). The cal-
culated data is also applicable to explain the positive calcu-
lated energies of reactions in Eq. 5 (Entry 6). The data is
consistent with the observation that product 9 is not ob-
served in Eq. 1. The data from Density Functional Theory
(DFT) B3LYP with 6-31+G(d) basis set are also in good
agreement with the experimental results. The calculated
The Theoretical Calculation to Support Our Results
According to the rationale in the Fig. 1, the a-hydroxy-
methyl ketone derivatives are formed from the rearrange-
ment of the corresponding a-hydroxyaldehyde. Presum-
ably, the former isomers are more stable than the latter iso-
mers. In order to understand their relative stabilities and
energy difference, we choose a few examples from Table 1
to carry out their theoretical calculations. These representa-
tive examples are shown in Equations 3-5.
To find the optimal conformers for these compounds,
we need to locate all of their conformers, identify their best
structure and evaluate their energy based on the actual
global minimumvalue. Aconformational distribution search
was carried out by using the MMFF94 molecular mechan-
ics model. It will give rise to a series of low-energy con-

902 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Hon et al.
Table 2. Calculated relative energiesa (kcal/mol) of related compounds at various theoretical levels
PM3
B3LYP/6-31+G(d) B3LYP/6-31+G(d) Observed
b
Entry Reactant Product
b
c
(DErxn
)
(DErxn
)
(DErxn
)
in Exp.
1
2
3
4
5
6
5a
5a-1
5a-2
5a-3
5h-2
8
6a
6a-1
6a-2
6a-3
6h-2
9
-2.6 (-1.9)
-1.6 (-1.3)
-4.4 (-3.7)
-4.4 (-3.7)
-3.1 (-2.7)
1.0 (1.8)
-7.8 (-7.3)
-5.8 (-5.1)
-7.7 (-7.0)
-7.7 (-7.0)
-4.6 (-4.2)
-1.0 (-0.4)
-7.4
-5.1
-7.3
-7.4
-4.2
-0.6
Yes
Yes
Yes
Yes
Yes
No
a Born-Oppenheimer energies, values in parentheses including vibrational zero-point energies.
b The relative energies DErxn were calculated in gas phase.
c The single point energies were calculated with PCM model in CH2Cl2 solvent.
relative energy (DErxn) of Eq. 5 is -1.0 kcal/mol (Entry 6). It
is not quite consistent with our observation because we do
not isolate compound 9 in Eq. 1. Interestingly, the data us-
ing the B3LYP with 6-31+G(d) in CH2Cl2 are quite consis-
tent with those of the data using the same method/basis set
in gases (Table 2).
(National Chiao-Tung University) by electronic impact at
70 eV (unless otherwise indicated). High Resolution Mass
Spectroscopy (HRMS) was measured on a Finnigan/Ther-
mo Quest MAT 95XL (National Chung Hsing University).
Aldehyde 1g was prepared according to the literature pro-
cedure from D-ribose precursor.15 (R)-Glyceraldehyde
dimethyl acetal (1h)16 was prepared by oxidative cleavage
of the corresponding glycol.
CONCLUSIONS
In summary, the ozonolysis of a-substituted-allyl
silyl ethers or allyl carboxylates followed by treatment with
bases or Ph3P afforded the corresponding a-silyloxyalde-
hydes or a-acyloxyaldehydes intermediates, which could
be converted to the corresponding a-silyloxymethyl ke-
tones or a-acyloxymethyl ketones in good yields by base
(Et3N or DBU) in the same reaction flask. In addition, the
trialkylsilyl, acetyl, pivalyl and benzoyl groups are suitable
for the 1,4-migration in the present study. The energy dif-
ferences predicted by the theoretical calculations also pro-
vide good explanation to our discovery.
General procedure A for the preparation of allylic
alcohol: the addition of vinylmagnesium bromide to
aldehyde (for compounds 2a, 2c, 2e, 2f)
To a solution of cyclohexanecarboxaldehyde (1c)
(572 mg, 5.1 mmol) in 25 mL of anhydrous tetrahydrofuran
(THF) was added vinylmagnesium bromide solution (5.6
mmol, 5.6 mL, 1.0 M in THF) at -78 °C and the solution
was then warmed slowly to rt (room temperature) and stirred
at rt for 4 h. The solution was cooled at 0 °C and quenched
with 10 mL of saturated NH4Cl solution. The solution was
extracted twice with 25 mL of ethyl acetate. The organic
layer was washed with brine and dried over MgSO4. The
organic layer was concentrated by rotary evaporator to give
the oil residue which is pure enough for the next reaction.
The crude product can be purified by silica gel column chro-
matography to give compound 2c (607 mg, 4.33 mmol) in
85% yield as a colorless oil.
EXPERIMENTAL
General Remarks
All reactions were carried out under nitrogen. Unless
otherwise noted, materials were obtained from commercial
suppliers and used without further purification. Melting
points were determined by using a Thomas-Hoover melt-
1-Cyclohexylprop-2-en-1-ol (2c)
1
Rf = 0.52 (Hexane/EtOAc, 5:1); H NMR (CDCl3,
ing point apparatus and were uncorrected. The 1H and 13
C
NMR spectra were recorded on a Bruker Avance DPX400
spectrometer, and chemical shifts were given in ppm down-
field from tetramethylsilane (TMS). IR spectra were taken
with a Perkin-Elmer 682 spectrophotometer and only note-
worthy absorptions were listed. Mass spectra were mea-
sured on a Micromass Trio-2000 GC/MS spectrometer
400 MHz) d 0.95-1.86 (m, 12H), 3.85 (dd, J = 6.4 and 6.4
Hz, 1H), 5.13-5.22 (m, 2H), 5.82-5.91 (m, 1H); 13C NMR
(CDCl3, 100 MHz) d 26.0, 26.1, 26.5, 28.3, 28.7, 43.4,
77.6, 115.3, 139.8; IR (thin film, NaCl): 3378, 3077, 2925,
2852, 1449, 1019, 992, 920 cm-1; MS m/z (relative inten-
sity): 123 (M+-17, 5), 111 (17), 83 (75), 55 (100), 41 (36);

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 903
HRMS Calcd. for C9H16O 140.1201, Found: 140.1206.
1-Phenylprop-2-en-1-ol (2a)
necked flask containing magnesium powder (243 mg, 10
mmol) and a catalytic amount of iodine under nitrogen. Af-
ter the reaction starts, the remaining 1-bromo-3-phenylpro-
pane (0.72 mL, 4.8 mmol) in 6 mL of THF was added drop-
wise and the reaction mixture was then refluxed for 30 min
and then cooled to rt. To a solution of acrolein (280.3 mg,
5.0 mmol) in 10 mL of THF was added the Grignard re-
agent prepared above at -78 °C. The solution was then
warmed slowly to rt and stirred at rt for 4 h. The solution
was cooled at 0 °C and added 10 mL of saturated NH4Cl so-
lution. The solution was extracted twice with 30 mL of
ethyl acetate. The organic layer was washed with brine and
dried over MgSO4. The organic layer was concentrated by
rotary evaporator to give the oil residue. The crude product
2b is pure enough for the next reaction. The crude product
can be purified by silica gel column chromatography to
give alcohol 2b (952 mg, 5.4 mmol) in 90% yield as a col-
Followed the general procedure A to prepare allylic
alcohol 2a from benzaldehyde (1a) in 89% yield; pale yel-
low oil; Rf = 0.41 (Hexane/EtOAc, 5:1); 1H NMR (CDCl3,
400 MHz) d 1.83 (br, 1H), 5.19-5.22 (m, 2H), 5.33-5.38
(m, 1H), 6.02-6.10 (m, 1H), 7.28-7.39 (m, 5H); 13C NMR
(CDCl3, 100 MHz) d 75.2, 115.0, 126.3, 127.6, 128.4,
140.1, 142.5; IR (thin film, NaCl): 3366, 3084, 3063, 3029,
2981, 1454, 1195, 989, 929, 760, 700 cm-1; MS m/z (rela-
tive intensity): 134 (M+, 10), 133 (M+-1, 28), 115 (12), 105
(100), 77 (55).
1-Benzyloxybut-3-en-2-ol (2e)
Followed the general procedure A to prepare allylic
alcohol 2e from 2-benzyloxyacetaldehyde (1e) in 91%
yield; pale yellow oil; Rf = 0.55 (Hexane/EtOAc, 2:1); 1H
NMR (CDCl3, 400 MHz) d 2.41 (d, J = 3.5 Hz, 1H), 3.38
(dd, J = 9.6 and 8.0 Hz, 1H), 3.55 (dd, J = 9.6 and 3.4 Hz,
1H), 4.34-4.37 (m, 1H), 4.58 (s, 2H), 5.20 (ddd, J = 10.6,
1.4, 1.4 Hz, 1H), 5.36 (ddd, J = 17.2, 1.4, 1.4 Hz, 1H), 5.84
(ddd, J = 17.2, 10.6 and 5.6 Hz, 1H), 7.30-7.37 (m, 5H); 13C
NMR (CDCl3, 100 MHz) d 71.3, 73.2, 73.9, 116.2, 127.6,
128.3, 136.6, 137.7; IR (thin film, NaCl): 3430, 3064,
3030, 2898, 2860, 1454, 1105, 993, 928, 739, 698 cm-1; MS
m/z (relative intensity): 178 (M+, 4), 161 (9), 121 (10), 107
(13), 91 (100); HRMS Calcd. for C11H14O2 178.0994,
Found: 178.0991.
1
orless oil. H NMR (CDCl3, 400 MHz) d 1.43-1.73 (m,
5H), 2.64 (t, J = 7.2 Hz, 2H), 4.12-4.13 (m, 1H), 5.10 (d, J =
10.4 Hz, 1H), 5.21 (d, J = 17.2 Hz, 1H), 5.86 (ddd, J = 17.2,
10.4, 6.4 Hz, 1H), 7.16-7.29 (m, 5H); 13C NMR (CDCl3,
100 MHz) d 27.0, 35.7, 36.4, 72.9, 114.5, 125.6, 128.2,
128.3, 141.1, 142.2; IR (thin film, NaCl): 3340, 3025,
2935, 2857, 1602, 1494, 1454, 1425, 1088, 991, 921, 748,
698 cm-1; MS m/z (relative intensity): 176 (M+, 9), 175 (4),
159 (13), 158 (12), 129 (11), 117 (21), 104 (100), 103 (97),
91 (36), 90 (31), 77 (5).
1-Phenoxybut-3-en-2-ol (2f)
General procedure B for the preparation of allyl
tert-butyldimethylsilyl ether: the crude allyl alcohol
prepared by general procedure A was directly used
for the silylation (for compounds 3a-1, 3c-1, 3d-1,
3e-1, 3f-1, 3g-1, 3h-1)
Followed the general procedure A to prepare allylic
alcohol 2f from 2-phenoxyacetaldehyde (1f) in 81% yield;
pale yellow oil; Rf = 0.39 (Hexane/EtOAc, 5:1); 1H NMR
(CDCl3, 400 MHz) d 2.38 (br s, 1H), 3.89 (dd, J = 9.4 and
7.6 Hz, 1H), 4.03 (dd, J = 9.4 and 3.4 Hz, 1H), 4.55 (br s,
1H), 5.29 (ddd, J = 10.6, 1.4 and 1.3 Hz, 1H), 5.46 (ddd, J =
17.2, 1.5 and 1.4 Hz, 1H), 5.95 (ddd, J = 17.2, 10.6 and 5.6
Hz, 1H), 6.91-6.99 (m, 3H), 7.27-7.31 (m, 2H); 13C NMR
(CDCl3, 100 MHz) d 71.1, 71.7, 114.7, 116.9, 121.2,
129.5, 136.2, 158.4; IR (thin film, NaCl): 3379, 3066,
3037, 2925, 2871, 1599, 1495, 1244, 754, 692 cm-1; MS
m/z (relative intensity): 164 (M+, 51), 107 (34), 94 (100),
77 (27); HRMS Calcd. for C10H12O2 164.0837, Found:
164.0832.
The crude product 2c, DMAP (N,N-dimethylamino-
pyridine, 62.3 mg, 0.51 mmol) and Et3N (0.85 mL, 6.12
mmol) in 20 mL of CH2Cl2 was added tert-butyldimethyl-
silyl chloride (846 mg, 5.61 mmol) at rt and stirred it for 4
h. The reaction was quenched with saturated NaHCO3 so-
lution and extracted with ethyl acetate. The organic layer
was dried over MgSO4, concentrated, and chromatographed
on silica gel to give silyl ether 3c-1 (934 mg, 3.67 mmol,
72% yield in two steps from aldehyde 1c) as colorless oil.
1-tert-Butyldimethylsilyloxy-1-cyclohexyl-2-propene
(3c-1)
6-Phenylhex-1-en-3-ol (2b)
Rf = 0.82 (Hexane/EtOAc, 10:1); 1H NMR (CDCl3,
A solution of 1-bromo-3-phenylpropane (0.18 mL,
1.2 mmol) in anhydrous THF (1 mL) was added to a two-
400 MHz) d 0.00 (s, 3H), 0.03 (s, 3H), 0.90 (s, 9H), 0.91-

904 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Hon et al.
1.00 (m, 2H), 1.08-1.24 (m, 3H), 1.28-1.33 (m, 1H), 1.63-
1.82 (m, 5H), 3.79 (t, J = 6.2 Hz, 1H), 5.03-5.11 (m, 2H),
5.72-5.81 (m, 1H); 13C NMR (CDCl3, 100 MHz) d -4.8,
-4.2, 18.3, 26.0, 26.3, 26.4, 26.7, 28.4, 29.0, 44.4, 78.5,
114.4, 140.6; IR (thin film, NaCl): 3077, 2928, 2855, 1253,
1067, 835, 774 cm-1; MS m/z (relative intensity): 253
(M+-1, 4), 239 (M+-15, 22), 197 (100), 171 (34), 115 (11),
55 (4); HRMS Calcd. for C15H30OSi 254.2066, Found:
254.2068.
-4.8, -4.7, 18.3, 25.9, 72.8, 73.3, 75.1, 115.0, 127.4, 127.5,
128.3, 138.5, 138.6; IR (thin film, NaCl): 3066, 3030,
2954, 2931, 2856, 1468, 1254, 1093, 835, 777, 698 cm-1;
MS m/z (relative intensity): 291 (M+-1, 3), 277 (M+-15, 4),
171 (13), 235 (22), 117 (100), 91 (100); HRMS Calcd. for
C17H28O2Si 292.1859, Found: 292.1858.
1-Phenoxy-2-tert-butyldimethylsilyloxybut-3-ene (3f-1)
Followed the general procedure B to give 73% yield
of the allyl silyl ether 3f-1 in two steps from 2-phenoxy-
acetaldehyde (1f); colorless oil; Rf = 0.87 (Hexane/EtOAc,
10:1); 1H NMR (CDCl3, 400 MHz) d 0.101 (s, 3H), 0.105
(s, 3H), 0.92 (s, 9H), 3.87 (d, J = 6.0 Hz, 2H), 4.50-4.54 (m,
1H), 5.19 (ddd, J = 10.6, 1.6 and 1.5 Hz, 1H), 5.39 (ddd, J =
17.1, 1.6 and 1.6 Hz, 1H), 5.93 (ddd, J = 17.2, 10.6 and 5.2
Hz, 1H), 6.88-6.95 (m, 3H), 7.25-7.29 (m, 2H); 13C NMR
(CDCl3, 100 MHz) d -4.7, 18.3, 25.9, 72.18, 72.22, 114.5,
115.7, 120.7, 129.4, 137.8, 158.9; IR (thin film, NaCl):
3066, 3037, 2954, 2929, 2858, 1601, 1496, 1250, 1043,
837, 752, 690 cm-1; MS m/z (relative intensity): 263 (M+-
15, 1), 221 (33), 179 (25), 151 (100), 73 (17); HRMS
Calcd. for C15H23O2Si (M+-15) 263.1467, Found: 263.1470.
Methyl (5RS)-2,3-O-isopropylidene-5-O-tert-butyldi-
methylsilyl-5-vinyl-D-ribofuranoside (3g-1)
1-tert-Butyldimethylsilyloxy-1-phenyl-2-propene (3a-1)
Followed the general procedure B to give 80% yield
of the allyl silyl ether 3a-1 in two steps from benzaldehyde
1
(1a); colorless oil; Rf = 0.89 (Hexane/EtOAc, 10:1); H
NMR (CDCl3, 400 MHz) d 0.00 (s, 3H), 0.08 (s, 3H), 0.92
(s, 9H), 5.07 (ddd, J = 10.2, 1.4 and 1.4 Hz, 1H), 5.17 (d, J
= 5.8 Hz, 1H), 5.28 (ddd, J = 17.0, 1.4 and 1.4 Hz, 1H),
5.88-5.97 (m, 1H), 7.23-7.25 (m, 1H), 7.29-7.35 (m, 4H);
13C NMR (CDCl3, 100 MHz) d -4.8, -4.6, 18.4, 25.9, 75.9,
113.3, 126.0, 127.0, 128.2, 141.8, 143.8; IR (thin film,
NaCl): 3064, 3028, 2956, 2929, 2857, 1471, 1254, 1065,
865, 835, 776, 699 cm-1; MS m/z (relative intensity): 248
(M+, 3), 247 (M+-1, 9), 191 (100), 117 (100), 91 (16);
HRMS Calcd. for C15H24OSi 248.1596, Found: 248.1597.
1-tert-Butyldimethylsilyloxy-tert-butyl-2-propene (3d-1)
Followed the general procedure B to give 68% yield
of the allyl silyl ether 3d-1 in two steps from trimethylacet-
aldehyde (1d); colorless oil; Rf = 0.89 (Hexane/EtOAc,
30:1); 1H NMR (CDCl3, 400 MHz) d 0.01 (s, 3H), 0.03 (s,
3H), 0.86 (s, 9H), 0.91 (s, 9H), 3.66 (d, J = 7.2 Hz, 1H),
5.08-5.12 (m, 2H), 5.76-5.84 (m, 1H); 13C NMR (CDCl3,
100 MHz) d -5.0, -3.9, 18.3, 25.9, 26.0, 35.4, 82.2, 115.6,
139.2; IR (thin film, NaCl): 2955, 2930, 2858, 1254, 1076,
1005, 922, 836 cm-1; MS m/z (relative intensity): 228 (M+,
1), 171 (24), 105 (16), 75 (100), 57 (30), 41 (21); HRMS
Calcd. for C13H28OSi 228.1909, Found: 228.1908.
Followed the general procedure B to give 83% yield
of the allyl silyl ether 3g-1 (as a mixture of two diastereo-
mers, about 4:1) in two steps from aldehyde 1g; colorless
oil; Rf = 0.73 (Hexane/EtOAc, 4:1); 1H NMR (CDCl3, 400
MHz) d 0.00 (s, 0.6H), 0.04 (s, 2.4H), 0.05 (s, 0.6H), 0.08
(s, 2.4H), 0.91 (s, 9H), 1.01 (s, 0.6H), 1.31 (s, 2.4H), 1.47
(s, 3H), 3.33 (s, 2.4H), 3.38 (s, 0.6H), 3.95-4.01 (m, 1.6H),
4.11-4.16 (m, 0.4H), 4.47 (d, J = 6.1 Hz, 0.2H), 4.54 (d, J =
6.1 Hz, 0.8H), 4.62 (dd, J = 6.0 and 1.8 Hz, 0.2H), 4.79 (d, J
= 6.1 Hz, 0.8H), 4.92 (s, 0.8H), 4.99 (s, 0.2H), 5.22-5.33
(m, 2H), 5.82-5.91 (m, 1H); 13C NMR (CDCl3, 100 MHz) d
-4.9, -4.8, -4.2, -3.8, 18.1, 18.2, 25.1, 25.3, 25.77, 25.79,
26.5, 26.8, 55.2, 55.6, 74.2, 75.1, 80.9, 81.7, 85.0, 85.3,
89.9, 90.4, 109.9, 110.1, 112.2, 112.3, 117.0, 137.6, 139.1;
IR (thin film, NaCl): 3078, 2954, 2932, 2858, 1255, 1095,
838 cm-1; MS m/z (relative intensity): 343 (M+-1, 2), 313
(100), 171 (89), 115 (39), 73 (27); HRMS Calcd. for
C16H29O5Si (M+-15) 329.1784, Found: 329.1763.
1-Benzyloxy-2-tert-butyldimethylsilyloxybut-3-ene
(3e-1)
Followed the general procedure B to give 81% yield
of the allyl silyl ether 3e-1 in two steps from 2-benzyloxy-
acetaldehyde (1e); colorless oil; Rf = 0.59 (Hexane/EtOAc,
20:1); 1H NMR (CDCl3, 400 MHz) d 0.06 (s, 3H), 0.07 (s,
3H), 0.90 (s, 9H), 3.42-3.43 (m, 2H), 4.31-4.36 (m, 1H),
4.56 (s, 2H), 5.13 (dd, J = 10.5 and 1.6 Hz, 1H), 5.31 (dd, J
= 17.2 and 1.6 Hz, 1H), 5.88 (ddd, J = 17.2, 10.5 and 5.2
Hz, 1H), 7.26-7.34 (m, 5H); 13C NMR (CDCl3, 100 MHz) d
(1RS,4R)-1-tert-Butyldimethylsilyloxy-1-(2,2-dimethyl-
[1,3]dioxolan-4-yl)-2-propene (3h-1)
Followed the general procedure B to give 61% yield
of the allyl silyl ether 3h-1 (as a mixture of two diastereo-

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 905
mers, about 1:1) in two steps from aldehyde 1h; colorless
oil; Rf = 0.83 (Hexane/EtOAc, 10:1); 1H NMR (CDCl3, 400
MHz) d 0.04 (s), 0.06 (s), 0.075 (s), 0.083 (s), 0.90 (s, 9H),
1.33 (s), 1.34 (s), 1.41 (s), 1.42 (s), 3.76-3.80 (m, 0.5H),
3.89-4.00 (m, 2.5H), 4.10-4.16 (m, 0.5H), 4.20-4.25 (m,
0.5H), 5.16-5.34 (m, 2H), 5.79-5.89 (m, 1H); 13C NMR
(CDCl3, 100 MHz) d -4.9, -4.8, -4.7, -4.3, 18.1, 18.2, 25.1,
25.4, 25.76, 25.78, 26.3, 26.6, 65.2, 66.0, 73.97, 74.02,
78.5, 78.9, 109.2, 109.3, 116.2, 116.3, 136.4, 138.3; IR
(thin film, NaCl): 2986, 2956, 2931, 2858, 1254, 1073,
927, 837, 777 cm-1; MS m/z (relative intensity): 257 (M+-
15, 6), 157 (32), 101 (73), 73 (32), 43 (100); HRMS Calcd.
for C14H28O3Si 272.1808, Found: 272.1809.
rectly for the further reaction. The crude product 2b,
DMAP (61 mg, 0.5 mmol) and Et3N (0.84 mL, 6.0 mmol) in
20 mL of CH2Cl2 was added tert-butyldimethylsilyl chlo-
ride (829 mg, 5.5 mmol) at rt and stirred it for 4 h. The reac-
tion was quenched with saturated NaHCO3 solution and ex-
tracted with ethyl acetate. The organic layer was dried over
MgSO4, concentrated, and chromatographed on silica gel
to give the silyl ether 3b-1 (1205 mg, 4.15 mmol, 83%
yield) as colorless oil in two steps from acrolein (1’). Rf =
0.88 (Hexane/EtOAc, 20:1); 1H NMR (CDCl3, B400 MHz)
d 0.02 (s, 3H), 0.04 (s, 3H), 0.89 (s, 9H), 1.50-1.66 (m, 4H),
2.61 (t, J = 7.2 Hz, 2H), 4.08-4.13 (m, 1H), 4.99-5.14 (m,
2H), 5.74-5.82 (m, 1H), 7.16-7.29 (m, 5H); 13C NMR
(CDCl3, 100 MHz) d -4.8, -4.4, 18.2, 25.9, 26.8, 35.9, 37.6,
73.7, 113.6, 125.6, 128.2, 128.4, 141.7, 142.6; IR (thin
film, NaCl): 3028, 2931, 2858, 1460, 1254, 1088, 837, 742,
698 cm-1; MS m/z (relative intensity): 289 (M+-1, 17), 233
(100), 171 (35), 91 (37), 75 (71); HRMS Calcd. for
C17H27OSi (M+-15) 275.1836, Found: 275.1829.
3,10-Bis-(tert-butyldimethylsilyloxy)dodeca-1,11-diene
(3i-1)
Followed the general procedure B to give 78% yield
of the bis(allyl silyl ether) 3i-1 (as a mixture of two diaster-
eomers) in two steps from octanedial (1i); colorless oil; Rf =
0.87 (Hexane/EtOAc, 4:1); 1H NMR (CDCl3, 400 MHz) d
0.03 (s, 6H), 0.05 (s, 6H), 0.09 (s, 18H), 1.25-1.28 (m, 8H),
1.45-1.47 (m, 4H), 4.04-4.09 (m, 2H), 5.00 (ddd, J = 10.4,
1.6 and 1.6 Hz, 2H), 5.12 (ddd, 17.2, 1.6 and 1.6 Hz, 2H),
5.75-5.83 (m, 2H); 13C NMR (CDCl3, 100 MHz) d -4.8,
-4.4, 18.3, 25.2, 25.9, 29.6, 38.1, 73.9, 113.4, 141.9; IR
(thin film, NaCl): 3077, 2930, 2857, 1472, 1254, 1029,
920, 836 cm-1; MS m/z (relative intensity): 427 (M++1, 4),
425 (M+-1, 11), 369 (74), 279 (31), 171 (50), 75 (100);
HRMS Calcd. for C24H50O2Si2 426.3349, Found: 426.3344.
1,4-Bis-[1-(tert-butyldimethylsilyloxy)allyl]benzene
(3j-1)
General procedure C for the preparation of allyl car-
boxylate: the crude allyl alcohol prepared by general
procedure A was directly used for the acylation (for
compounds 3a-2, 3c-2, 3d-2, 3e-2, 3f-2, 3g-2, 3h-2)
To a mixture of crude product 2c, DMAP (51.6 mg,
0.51 mmol) and Et3N (0.85 mL, 6.12 mmol) in 20 mL of
CH2Cl2 was added acetic anhydride (573 mg, 5.61 mmol) at
rt and stirred it for 3 h. The reaction was quenched with 1 N
HCl and extracted with ethyl acetate. The organic layer was
washed with brine, dried over MgSO4, concentrated, and
chromatographed on silica gel to give the allyl acetate 3c-2
(867 mg, 3.98 mmol, 78% yield in two steps from cyclo-
hexanecarboxaldehyde (1c)) as a pale yellow oil.
Followed the general procedure B to give 81% yield
of the bis(allyl silyl ether) 3j-1 (as a mixture of two diaster-
eomers) in two steps from terephthalaldehyde (1j); color-
less oil; Rf = 0.93 (Hexane/EtOAc, 3:1); 1H NMR (CDCl3,
400 MHz) d 0.01 (s, 6H), 0.06 (s, 6H), 0.91 (s, 18H), 5.06
(d, J = 10.0 Hz, 2H), 5.15 (d, J = 5.6 Hz, 2H), 5.27 (d, J =
17.2 Hz, 2H), 5.91 (ddd, J = 17.2, 10.0 and 5.6 Hz, 2H),
7.27 (s, 4H); 13C NMR (CDCl3, 100 MHz) d -4.8, -4.6,
18.4, 25.9, 75.8, 113.3, 125.9, 141.7, 142.5; IR (thin film,
NaCl): 3016, 2956, 2929, 2857, 1472, 1254, 1077, 865,
836, 776 cm-1; MS m/z (relative intensity): 418 (M+, 3), 417
(M+-1, 5), 403 (M+-15, 6), 361 (100), 170 (39), 154 (43), 73
(59); HRMS Calcd. for C24H42O2Si2 418.2723, Found:
418.2715.
Acetic acid 1-cyclohexylallyl ester (3c-2)
Rf = 0.70 (Hexane/EtOAc, 10:1); 1H NMR (CDCl3,
400 MHz) d 0.93-1.28 (m, 5H), 1.49-1.59 (m, 1H), 1.65-
1.76 (m, 5H), 2.06 (s, 3H), 5.05 (t, J = 6.8 Hz, 1H), 5.17-
5.25 (m, 2H), 5.71-5.79 (m, 1H); 13C NMR (CDCl3, 100
MHz) d 21.0, 25.8, 25.9, 26.3, 28.3, 28.5, 41.4, 78.8, 117.2,
135.1, 170.2; IR (thin film, NaCl): 3084, 2938, 2854, 1739,
1236, 1019, 930 cm-1; MS m/z (relative intensity): 182 (M+,
2), 140 (19), 122 (37), 83 (90), 55 (57), 43 (100); HRMS
Calcd. for C11H18O2 182.1307, Found: 182.1303.
Acetic acid 1-phenylallyl ester (3a-2)
Followed the general procedure C to give 74% yield
of the allyl acetate 3a-2 in two steps from benzaldehyde
(1a); pale yellow oil; Rf = 0.74 (Hexane/EtOAc, 5:1); 1H
6-Phenyl-3-tert-butyldimethylsilyloxy-1-hexene (3b-1)
The crude product 2b prepared above was used di-

906 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Hon et al.
NMR (CDCl3, 400 MHz) d 2.11 (s, 3H), 5.24 (ddd, J =
10.4, 1.2 and 1.2 Hz, 1H), 5.28 (ddd, J = 17.2, 1.2 and 1.2
Hz, 1H), 5.97-6.05 (m, 1H), 6.25-6.27 (m, 1H, -CHOAc),
7.30-7.36 (m, 5H); 13C NMR (CDCl3, 100 MHz) d 21.0,
76.0, 116.7, 127.0, 128.0, 128.4, 136.2, 138.8, 169.7; IR
(thin film, NaCl): 3088, 3065, 3033, 2988, 1741, 1371,
1234, 1021, 760, 700 cm-1; MS m/z (relative intensity): 176
(M+, 17), 134 (64), 115 (100), 77 (15); HRMS Calcd. for
C11H12O2 176.0837, Found: 176.0840.
0.8H), 5.00 (s, 0.2H), 5.29-5.46 (m, 3H), 5.74-5.91 (m,
1H); 13C NMR (CDCl3, 100 MHz) d 21.0, 24.9, 25.0, 26.4,
54.8, 55.5, 73.7, 75.5, 81.0, 85.0, 85.4, 87.3, 87.7, 109.2,
110.2, 112.3, 112.5, 118.5, 120.8, 132.5, 133.4, 169.6; IR
(thin film, NaCl): 3089, 2990, 2939, 2837, 1747, 1373,
1234, 1093 cm-1; MS m/z (relative intensity): 271 (M+-1,
1), 257 (M+-15, 14), 173 (100), 115 (16), 87 (41), 59 (62),
43 (78); HRMS Calcd. for C12H17O6 (M+-15) 257.1027,
Found: 257.1025.
Acetic acid 1-tert-butylallyl ester (3d-2)
(2R,3RS)-3-Acetoxy-1,2-O-isopropylidene-4-pentene
(3h-2)
Followed the general procedure C to give 79% yield
of the allyl acetate 3d-2 in two steps from trimethylacet-
aldehyde (1d); pale yellow oil; Rf = 0.67 (Hexane/EtOAc,
10:1); 1H NMR (CDCl3, 400 MHz) d 0.92 (s, 9H), 2.08 (s,
3H), 4.98 (d, J = 6.8 Hz, 1H), 5.20 (br s, 1H), 5.23 (br d, J =
3.9 Hz, 1H), 5.75-5.83 (m, 1H); 13C NMR (CDCl3, 100
MHz) d 21.0, 25.7, 34.1, 81.7, 118.0, 133.6, 170.2; IR (thin
film, NaCl): 2962, 2872, 1741, 1241, 1019, 933 cm-1; MS
m/z (relative intensity): 157 (M++1, 4), 105 (11), 57 (43),
43 (100); HRMS Calcd. for C9H16O2 156.1150, Found:
156.1154.
Followed the general procedure C to give 65% yield
of the allyl acetate 3h-2 (as a mixture of two diastereomers)
in two steps from aldehyde 1h; pale yellow oil; Rf = 0.67
(Hexane/EtOAc, 3:1); 1H NMR (CDCl3, 400 MHz) d 1.36
(s, 3H), 1.42 and 1.43 (br s, 3H), 2.11 (s, 3H), 3.76-3.83 (m,
1H), 3.98-4.06 (m, 1H), 4.18-4.25 (m, 1H), 5.30-5.39 (m,
3H), 5.73-5.88 (m, 1H); 13C NMR (CDCl3, 100 MHz) d
20.9, 21.0, 25.2, 25.3, 26.20, 26.24, 65.5, 65.6, 73.9, 74.8,
76.2, 76.7, 109.8, 109.9, 118.8, 119.4, 132.2, 132.3, 169.7,
169.8; IR (thin film, NaCl): 3089, 2988, 2937, 2888, 1746,
1372, 1235, 1072, 850 cm-1; MS m/z (relative intensity):
201 (M++1, 4), 143 (11), 101 (32), 43 (100); HRMS Calcd.
for C10H16O4 200.1049, Found: 200.1046.
2-Acetoxy-1-benzyloxybut-3-ene (3e-2)
Followed the general procedure C to give 85% yield
of the allyl acetate 3e-2 in two steps from 2-benzyloxyacet-
aldehyde (1e); pale yellow oil; Rf = 0.22 (Hexane/EtOAc,
10:1); 1H NMR (CDCl3, 400 MHz) d 2.10 (s, 3H), 3.54-
3.61 (m, 2H), 4.54 (1/2 ABq, J = 12.2 Hz, 1H), 4.60 (1/2
ABq, J = 12.2 Hz, 1H), 5.25 (ddd, J = 10.6, 1.2 and 1.2 Hz,
1H), 5.33 (ddd, J = 17.3, 1.2 and 1.2 Hz, 1H), 5.46-5.51 (m,
1H), 5.84 (ddd, J = 17.3, 10.6 and 6.0 Hz, 1H), 7.29-7.35
(m, 5H); 13C NMR (CDCl3, 100 MHz) d 21.1, 71.3, 73.1,
117.9, 127.57, 127.60, 128.3, 133.4, 137.9, 170.1; IR (thin
film, NaCl): 3086, 3064, 3032, 2862, 1741, 1371, 1238,
1021, 741, 698 cm-1; MS m/z (relative intensity): 220 (M+,
2), 134 (7), 91 (58), 43 (100); HRMS Calcd. for C13H16O3
220.1099, Found: 220.1011.
3,10-Diacetoxy-1,11-dodecadiene (3i-2)
Followed the general procedure C to give 75% yield
of the allyl acetate 3i-2 (as a mixture of two diastereomers)
in two steps from octanedial (1i); pale yellow oil; Rf = 0.87
1
(Hexane/EtOAc, 5:1); H NMR (CDCl3, 400 MHz) d
1.28-1.29 (m, 8H), 1.55-1.62 (m, 4H), 2.06 (s, 6H), 5.14-
5.25 (m, 6H), 5.72-5.81 (m, 2H); 13C NMR (CDCl3, 100
MHz) d 21.1, 24.8, 29.0, 34.0, 74.6, 116.4, 136.5, 170.1; IR
(thin film, NaCl): 3087, 2936, 2860, 1739, 1239, 1020,
1068, 930 cm-1; MS m/z (relative intensity): 282 (M+, 6),
222 (16), 164 (100), 121 (32), 42 (69); HRMS Calcd. for
C16H26O4 282.1831, Found: 282.1832.
1,4-Bis-(1-acetoxyallyl)benzene (3j-2)
Methyl (5RS)-5-O-acetyl-2,3-O-isopropylidene-5-vinyl-
D-ribofuranoside (3g-2)
Followed the general procedure C to give 81% yield
of the allyl acetate 3j-2 (as a mixture of two diastereomers)
in two steps from terephthalaldehyde (1j); pale yellow oil;
Followed the general procedure C to give 83% yield
of the allyl acetate 3g-2 (as a mixture of two diastereomers,
4:1) in two steps from aldehyde 1g; pale yellow oil; Rf =
0.66 (Hexane/EtOAc, 5:1); 1H NMR (CDCl3, 400 MHz) d
1.31 (s, 0.6H), 1.32 (s, 2.4H), 1.48 (s, 3H), 2.10 (s, 3H),
3.30 (s, 0.6H), 3.31 (s, 2.4H), 4.21-4.25 (m, 1H), 4.57-4.59
(m, 1H), 4.64-4.66 (m, 0.2H), 4.68-4.69 (m, 0.8H), 4.96 (s,
1
Rf = 0.85 (Hexane/EtOAc, 2.5:1); H NMR (CDCl3, 400
MHz) d 2.11 (s, 3H), 5.25 (ddd, J = 10.5, 1.2 and 1.1 Hz,
2H), 5.30 (ddd, J = 17.2, 1.2 and 1.0 Hz, 2H), 5.94-6.02 (m,
2H), 6.25 (dd, J = 6.0 and 0.8 Hz, 2H), 7.35 (s, 4H); 13C
NMR (CDCl3, 100 MHz) d 21.1, 75.7, 116.9, 127.3, 136.0,

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 907
138.8, 169.8; IR (thin film, NaCl): 3089, 3020, 2989, 2933,
1741, 1371, 1230, 1020, 939, 822 cm-1; MS m/z (relative
intensity): 274 (M+, 1), 172 (100), 155 (26), 115 (36), 43
(98); HRMS Calcd. for C16H18O4 274.1205, Found:
274.1211.
1H), 6.23 (br dt, J = 5.8 and 1.2 Hz, 1H), 7.29-7.35 (m, 5H);
13C NMR (CDCl3, 100 MHz) d 27.1, 38.8, 75.7, 116.4,
126.8, 127.9, 128.43, 136.6, 139.3, 177.1; IR (thin film,
NaCl): 3065, 3033, 2975, 2934, 2872, 1732, 1479, 1279,
1151, 983, 934, 740, 700 cm-1; MS m/z (relative intensity):
218 (M+, 6), 115 (74), 91 (12), 57 (100); HRMS Calcd. for
C14H18O2 218.1312, Found: 218.1307.
Acetic acid 1-(3-phenylpropyl)allyl ester (3b-2)
Followed the general procedure to give 80% yield of
the allyl acetate 3b-2 in two steps (via 2b) from acrolein
Trimethylacetic acid 1-tert-butylallyl ester (3d-3)
Followed the general procedure for the preparation of
compound 3c-3, the allyl trimethylacetate 3d-3 was pre-
pared in 54% yield for two steps from trimethylacetalde-
hyde (1d); pale yellow oil; Rf = 0.77 (Hexane/EtOAc, 5:1);
1H NMR (CDCl3, 400 MHz) d 0.93 (s, 9H), 1.23 (s, 9H),
4.94 (d, J = 6.4 Hz, 1H), 5.18 (br s, 1H), 5.20-5.22 (m, 1H),
5.75-5.84 (m, 1H); 13C NMR (CDCl3, 100 MHz) d 25.8,
27.2, 34.4, 39.0, 81.2, 177.7, 133.7, 177.3; IR (thin film,
NaCl): 2968, 2932, 2871, 1731, 1281, 1157 cm-1; MS m/z
(relative intensity): 197 (M+-1, 3), 105 (7), 85 (19), 57 (100),
41 (72); HRMS Calcd. for C12H22O2 198.1620, Found:
198.1625.
1
(1’); colorless oil; Rf = 0.56 (Hexane/EtOAc, 10:1); H
NMR (CDCl3, 400 MHz) d 1.62-1.71 (m, 4H), 2.05 (s, 3H),
2.63 (t, J = 7.4 Hz, 2H), 5.14-5.28 (m, 3H), 5.71-5.80 (m,
1H), 7.16-7.23 (m, 3H), 7.28-7.31 (m, 2H); 13C NMR
(CDCl3, 100 MHz) d 21.0, 26.7, 33.6, 35.4, 74.4, 116.5,
125.7, 128.18, 128.21, 136.4, 141.8, 170.0; IR (thin film,
NaCl): 3085, 3026, 2943, 2861, 1737, 1454, 1240, 749,
700 cm-1; MS m/z (relative intensity): 218 (M+, 1), 217
(M+-1, 4), 159 (70), 104 (91), 91 (100), 43 (76); HRMS
Calcd. for C14H18O2 218.1307, Found: 218.1310.
Trimethylacetic acid 1-cyclohexylallyl ester (3c-3)
The crude product 2c prepared from the general pro-
cedure A was used directly for the further reaction. To a
mixture of crude product 2c and Et3N (0.85 mL, 6.12
mmol) in 20 mL of CH2Cl2 was added trimethylacetyl chlo-
ride (676 mg, 5.61 mmol) at rt and stirred it for 8 h. The re-
action was quenched with 1 N HCl and extracted with ethyl
acetate. The organic layer was washed with brine, dried
over MgSO4, concentrated, and chromatographed on silica
gel to give the allyl trimethylacetate 3c-3 (902 mg, 4.0
mmol, 79% yield in two steps from aldehyde 1c) as a pale
yellow oil. colorless oil; Rf = 0.89 (Hexane/EtOAc, 10:1);
1H NMR (CDCl3, 400 MHz) d 0.99-1.06 (m, 2H), 1.22 (s,
9H), 1.51-1.61 (m, 3H), 1.64-1.76 (m, 6H), 5.03 (br t, J =
6.3 Hz, 1H), 5.14-5.22 (m, 2H), 5.71-5.77 (m, 1H); 13C
NMR (CDCl3, 100 MHz) d 25.96, 26.0, 26.4, 27.2, 28.1,
28.8, 38.9, 41.7, 78.1, 116.7, 135.4, 177.5; IR (thin film,
NaCl): 2929, 2854, 1731, 1281, 1159 cm-1; MS m/z (rela-
tive intensity): 224 (M+, 2), 223 (M+-1, 9), 139 (5), 85 (36),
57 (100); HRMS Calcd. for C14H24O2 224.1776, Found:
224.1177.
Benzoic acid 1-phenylallyl ester (3a-4)
To a solution of benzaldehyde (1a) (552 mg, 5.2
mmol) in 25 mL of anhydrous THF was added vinylmag-
nesium bromide solution (5.7 mmol, 5.7 mL, 1.0 M in
THF) at -78 °C and the solution was then warmed slowly to
rt and stirred at rt for 4 h. The solution was cooled at 0 °C
and added 10 mL of saturated NH4Cl solution. The solution
was extracted twice with 30 mL of ethyl acetate. The or-
ganic layer was washed with brine and dried over MgSO4.
The organic layer was concentrated by rotary evaporator to
give the oil residue. The crude product 2a is pure enough
for the next reaction. Asolution of the crude product 2a in 5
mL of pyridine was added benzoyl chloride (845 mg, 5.61
mmol) at rt and heated up to reflux for 4 h. The reaction was
quenched with 1 N HCl at 0 °C and extracted with ethyl ac-
etate. The organic layer was dried over MgSO4, concen-
trated, and chromatographed on silica gel to give allyl ben-
zoate 3a-4 (928 mg, 3.95 mmol) as pale yellow oil in 75%
1
yield. Rf = 0.87 (Hexane/EtOAc, 5:1); H NMR (CDCl3,
Trimethylacetic acid 1-phenylallyl ester (3a-3)
400 MHz) d 5.30 (d, J = 10.4 Hz, 1H), 5.40 (d, J = 17.2 Hz,
1H), 6.09-6.17 (m, 1H), 6.52 (br d, J = 5.6 Hz, 1H), 7.32-
7.58 (m, 8H), 8.10-8.12 (m, 2H); 13C NMR (CDCl3, 100
MHz) d 76.6, 117.0, 127.0, 128.1, 128.3, 128.5, 129.6,
130.2, 133.0, 136.2, 138.9, 165.4; IR (thin film, NaCl):
3064, 3033, 2932, 1719, 1451, 1267, 1123, 760, 700 cm-1;
MS m/z (relative intensity): 238 (M+, 3), 237 (M+-1, 3), 211
Followed the general procedure for the preparation of
compound 3c-3, the allyl trimethylacetate 3a-3 was pre-
pared in 87% yield for two steps from benzaldehyde (1a);
1
colorless oil; Rf = 0.89 (Hexane/EtOAc, 10:1); H NMR
(CDCl3, 400 MHz) d 1.23 (s, 9H), 5.22 (dt, J = 10.5 and 1.2
Hz, 1H), 5.29 (dt, J = 17.1 and 1.2 Hz, 1H), 5.95-6.03 (m,

908 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Hon et al.
(1), 115 (91), 104 (100), 77 (38); HRMS Calcd. for
C16H14O2 238.0994, Found: 238.0097.
added Et3N (0.5n mmol) at -78 °C and warmed slowly to rt.
After the completion of reaction, it was concentrated, chro-
matographed on silica gel column to give the desired prod-
uct.
Benzoic acid 1-cyclohexylallyl ester (3b-4)
The crude product 2b prepared above was used di-
rectly for the further reaction. Followed the procedure for
the preparation of compound 3a-4, the allyl benzoate 3b-4
was prepared in 81% yield for two steps from 3-phenylpro-
panal (1b); pale yellow oil; Rf = 0.91 (Hexane/EtOAc, 5:1);
1H NMR (CDCl3, 400 MHz) d 1.09-1.27 (m, 5H), 1.69-
1.86 (m, 5H), 5.23 (d, J = 10.4 Hz, 1H), 5.23-5.33 (m, 2H),
5.83-5.92 (m, 1H), 7.42-7.47 (m, 2H), 7.54-7.58 (m, 1H),
8.04-8.10 (m, 2H); 13C NMR (CDCl3, 100 MHz) d 25.9,
26.3, 28.3, 28.6, 41.7, 79.2, 117.3, 128.2, 129.5, 130.6,
132.7, 135.0, 165.7; IR (thin film, NaCl): 3069, 2928,
2853, 1719, 1450, 1272, 1113, 712 cm-1; MS m/z (relative
intensity): 244 (M+, 3), 243 (M+-1, 3), 227 (11), 123 (52),
105 (100), 77 (17), 55 (7); HRMS Calcd. for C16H20O2
244.1463, Found: 244.1460.
Type D condition for the a-hydroxymethyl ketone de-
rivative formation
To the ozonide solution, Ph3P (0.8n mmol) was added
at -78 °C and the reaction mixture was warmed slowly to rt
and stirred it for 6 h. To the resulted reaction mixture was
added DBU (0.5n mmol) at -78 °C and warmed slowly to rt.
After the completion of reaction, it was quenched with 1 N
HCl at 0 °C and extracted with ethyl acetate. The organic
layer was dried over MgSO4, concentrated, and chromato-
graphed on silica gel column to give the desired product.
2-(tert-Butyldimethylsilyloxy)-1-phenylethanone (6a-1)
Followed the general procedure for the ozonolysis of
compound 3a-1 and the Type A condition for the ene-diol
rearrangement, compound 6a-1 was obtained in 72% yield;
1
colorless oil; Rf = 0.61 (Hexane/EtOAc, 10:1); H NMR
General procedure for the ozonolysis of alkene
A two-necked flask fitted with a glass tube to admit
ozone, a CaCl2 drying tube and a magnetic stirring bar was
charged with terminal alkene (n mmol) in CH2Cl2 (5n mL).
The flask was cooled to -78 °C and ozone was bubbled
through the solution. When the solution turned blue, ozone
addition was stopped. Nitrogen was passed through the so-
lution until the blue color was discharged.
(CDCl3, 400 MHz) d 0.13 (s, 6H), 0.94 (s, 9H), 4.92 (s,
2H), 7.44-7.57 (m, 5H); 13C NMR (CDCl3, 100 MHz) d
-5.4, 18.4, 25.8, 67.4, 127.9, 128.5, 133.2, 134.9, 197.4; IR
(thin film, NaCl): 3063, 2953, 2929, 1707, 1471, 1155,
838, 779, 690 cm-1; MS m/z (relative intensity): 235 (M+-
15, 4), 221 (63), 193 (41), 105 (100), 77 (38); HRMS
Calcd. for C13H19O2Si (M+-CH3) 235.1151, Found:
235.1154.
Type A condition for the a-hydroxymethyl ketone de-
rivative formation
1-(tert-Butyldimethylsilyloxy)-5-phenylpentan-2-one
(6b-1)
To the ozonide solution was added Et3N (1.2n mmol)
at -78 °C and the reaction was warmed slowly to rt and
stirred it for 6-8 h. The reaction mixture was concentrated,
chromatographed on silica gel column to give the desired
product.
Followed the general procedure for the ozonolysis of
compound 3b-1 and the Type B condition for the ene-diol
rearrangement, compound 6b-1 was obtained in 71% yield;
1
colorless oil; Rf = 0.49 (Hexane/EtOAc, 20:1); H NMR
Type B condition for the a-hydroxymethyl ketone de-
rivative formation
(CDCl3, 400 MHz) d 0.08 (s, 6H), 0.92 (s, 9H), 1.93 (quin,
J = 7.4 Hz, 2H), 2.51 (t, J = 7.4 Hz, 2H), 2.64 (t, J = 7.4 Hz,
2H), 4.41 (s, 2H), 7.17-7.28 (m, 5H); 13C NMR (CDCl3,
100 MHz) d -5.6, 18.2, 24.7, 25.7, 35.1, 37.5, 69.2, 125.9,
128.3, 128.4, 141.5, 210.7; IR (thin film, NaCl plates):
3026, 2929, 2857, 1719, 1471, 1105, 839, 779, 699 cm-1;
MS m/z (relative intensity): 293 (M++1, 15), 235 (63), 143
(68), 117 (100), 105 (37), 91 (37); HRMS Calcd. for
C17H28O2Si 292.1859, Found: 292.1858.
To the ozonide solution was added DBU (1.2n mmol)
at -78 °C and the reaction was warmed slowly to rt and
stirred it for 6-8 h. The reaction was quenched with 1 N HCl
at 0 °C and extracted with ethyl acetate. The organic layer
was dried over MgSO4, concentrated, and chromatographed
on silica gel to give the desired product.
Type C condition for the a-hydroxymethyl ketone de-
rivative formation
2-(tert-Butyldimethylsilyloxy)-1-cyclohexylethanone
(6c-1)
To the ozonide solution was added Ph3P (0.8n mmol)
at -78 °C and the reaction mixture was warmed slowly to rt
and stirred it for 6 h. To the resulted reaction mixture was
Followed the general procedure for the ozonolysis of
compound 3c-1 and the Type B condition for the ene-diol

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
rearrangement, compound 6c-1 was obtained in 81% yield;
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 909
1H NMR (CDCl3, 400 MHz) d 0.10 (s, 3H), 0.12 (s, 3H),
0.93 (s, 9H), 1.27 (s, 3H), 1.40 (s, 3H), 3.35 (s, 3H), 4.40
(1/2 ABq, J = 18.0 Hz, 2H) , 4.45 (1/2 ABq, J = 18.0 Hz,
2H), 4.56 (d, J = 5.8 Hz, 1H), 4.72 (d, J = 4.2 Hz, 1H), 5.04
(s, 1H), 5.10 (dd, J = 5.8 and 4.3 Hz, 1H); 13C NMR (CDCl3,
100 MHz) d -5.7, -5.5, 18.4, 24.6, 25.78, 25.79, 54.9, 68.6,
80.4, 84.1, 84.3, 107.2, 113.0, 204.2; [a] 3D3 = +63.1 (c =
0.081, CHCl3); IR (thin film, NaCl): 2952, 2932, 2898,
2857, 1742, 1110, 1039, 840 cm-1; MS m/z (relative inten-
sity): 347 (M++1, 2), 331 (11), 315 (9), 257 (20), 115 (36),
73 (100), 59 (26); HRMS Calcd. for C16H30O6Si 346.1812,
Found: 346.1810.
1
colorless oil; Rf = 0.51 (Hexane/EtOAc, 30:1); H NMR
(CDCl3, 400 MHz) d 0.08 (s, 6H), 0.92 (s, 9H), 1.26-1.33
(m, 6H), 1.77-1.81 (m, 4H), 2.62 (br t, J = 8.0 Hz, 1H), 4.24
(s, 2H); 13C NMR (CDCl3, 100 MHz) d -5.6, 18.3, 25.6,
25.7, 25.8, 28.2, 46.1, 68.1, 212.9; IR (thin film, NaCl
plates): 2930, 2856, 1716, 1105, 838, 778 cm-1; MS m/z
(relative intensity): 257 (M++1, 8), 241 (M+-15, 22), 199
(100), 198 (70), 118 (18), 83 (16), 55 (24); HRMS Calcd.
for C14H28O2Si 256.1859, Found: 256.1853.
1-(tert-Butyldimethylsilyloxy)-3,3-dimethylbutan-2-one
(6d-1)
Followed the general procedure of the ozonolysis of
compound 3d-1 and the Type B condition (except the reac-
tion was carried out under refluxing condition) for the
ene-diol rearrangement, compound 6d-1 was obtained in
60% yield; colorless oil; Rf = 0.44 (Hexane/EtOAc, 20:1);
1H NMR (CDCl3, 400 MHz) d 0.09 (s, 6H), 0.92 (s, 9H),
1.16 (s, 9H), 4.51 (s, 2H); 13C NMR (CDCl3, 100 MHz) d
-5.5, 18.5, 25.8, 26.4, 42.6, 65.5, 212.7; IR (thin film,
NaCl): 2956, 2930, 2859, 1717, 1090, 838, 780 cm-1; MS
m/z (relative intensity): 231 (M++1, 9), 201 (4), 105 (7), 75
(36), 57 (100), 41 (89); HRMS Calcd. for C12H26O2Si
230.1702, Found: 230.1700.
(RS)-2-(tert-Butyldimethylsilyloxy)-1-(2,2-dimethyl[1,3]-
dioxolan-4-yl)ethanone (6h-1)
Followed the general procedure for the ozonolysis of
compound 3h-1 and the Type D condition for the ene-diol
rearrangement, compound 6h-1 was obtained in 54% yield;
1
colorless oil; Rf = 0.56 (Hexane/EtOAc, 4:1); H NMR
(CDCl3, 400 MHz) d 0.10 (s, 6H), 0.92 (s, 9H), 1.40 (s,
3H), 1.48 (s, 3H), 4.02 (dd, J = 8.6 and 5.7 Hz, 1H), 4.27 (t,
J = 8.4 Hz, 1H), 4.50 (s, 2H), 4.69 (dd, J = 8.0 and 5.7 Hz,
1H); 13C NMR (CDCl3, 100 MHz) d -5.58, -5.56, 18.4,
25.0, 25.7, 25.9, 66.4, 67.6, 78.9, 110.9, 207.8; IR (thin
film, NaCl): 2954, 2931, 2887, 2858, 1738, 1256, 840, 780
cm-1; MS m/z (relative intensity): 273 (M+-1, 6), 217 (10),
117 (31), 101 (41), 73 (37), 57 (100), 43 (100); HRMS
Calcd. for C13H26O4Si 274.1600, Found: 274.1592.
1,10-Bis-(tert-butyldimethylsilyloxy)decan-2,9-dione
(6i-1)
1-Benzyloxy-3-(tert-butyldimethylsilyloxy)propan-2-
one (6e-1)
Followed the general procedure for the ozonolysis of
compound 3e-1 and the Type B condition for the ene-diol
rearrangement, compound 6e-1 was obtained in 84% yield;
1
colorless oil; Rf = 0.42 (Hexane/EtOAc, 10:1); H NMR
Followed the general procedure for the ozonolysis of
compound 3i-1 and the Type B condition for the ene-diol
rearrangement, compound 6i-1 was obtained in 72% yield;
white solid, mp, 46-47 °C; Rf = 0.44 (Hexane/EtOAc,
10:1); 1H NMR (CDCl3, 400 MHz) d 0.09 (s, 12H), 0.92 (s,
18H), 1.29-1.32 (m, 4H), 1.56-1.59 (m, 4H), 2.48 (t, J = 7.2
Hz, 4H), 4.16 (s, 4H); 13C NMR (CDCl3, 100 MHz) d -5.6,
18.2, 23.0, 25.7, 28.9, 38.0, 69.2, 210.8; IR (thin film,
NaCl): 2952, 2930, 2860, 1720, 1255, 1108, 839, 779 cm-1;
MS m/z (relative intensity): 431 (M++1, 18), 415 (23), 222
(39), 148 (25), 73 (100); HRMS Calcd. for C22H46O4Si2
430.2935, Found: 430.2931.
(CDCl3, 400 MHz) d 0.07 (s, 6H), 0.90 (s, 9H), 4.32 (s, 2H),
4.33 (s, 2H), 4.60 (s, 2H), 7.26-7.36 (m, 5H); 13C NMR
(CDCl3, 100 MHz) d -5.7, 18.1, 25.6, 68.0, 73.1, 73.3,
127.86, 127.88, 128.4, 137.0, 207.1; IR (thin film, NaCl):
3062, 3032, 2952, 2931, 2887, 1732, 1456, 1255, 1099,
839, 746, 698 cm-1; MS m/z (relative intensity): 295 (M++1,
4), 237 (16), 207 (7), 163 (2), 107 (16), 91 (100); HRMS
Calcd. for C16H26O3 Si 294.1651, Found: 294.1649.
(2S,3S,4R,5R)-2-(tert-Butyldimethylsilyloxy)-1-(3,4-O-
isopropylidene-5-methoxytetrahydrofuran-2-yl)eth-
anone (6g-1)
Followed the general procedure for the ozonolysis of
compound 3g-1 and the Type D condition for the ene-diol
rearrangement, optical pure compound 6g-1 was obtained
in 56% yield; colorless oil; Rf = 0.50 (Hexane/EtOAc, 5:1);
1,4-Bis(tert-butyldimethylsilyloxyacetyl)benzene (6j-1)
Followed the general procedure for the ozonolysis of
compound 3j-1 and the Type C condition for the ene-diol
rearrangement, compound 6j-1 was obtained in 71% yield;

910 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Hon et al.
white solid, mp, 115-116 °C; Rf = 0.21 (Hexane/EtOAc,
10:1); 1H NMR (CDCl3, 400 MHz) d 0.12 (s, 12H), 0.93 (s,
18H), 4.90 (s, 4H), 8.01 (s, 4H); 13C NMR (CDCl3, 100
MHz) d -5.4, 18.4, 25.8, 67.7, 128.2, 138.2, 197.2; IR (thin
film, NaCl): 3098, 2949, 2928, 2856, 1698, 1472, 1249,
1163, 839, 780 cm-1; MS m/z (relative intensity): 407 (M+-
15, 6), 365 (100), 308 (19), 221 (2), 89 (4), 73 (100); HRMS
Calcd. for C22H38O4Si2 422.2309, Found: 422.2310.
Acetic acid 2-oxo-2-phenylethyl ester (6a-2)
(100), 83 (100), 55 (29); HRMS Calcd. for C10H16O3
184.1099, Found: 184.1099.
Acetic acid 3,3-dimethyl-2-oxobutyl ester (6d-2)
Followed the general procedure for the ozonolysis of
compound 3d-2 and the Type B condition for the ene-diol
rearrangement, compound 6d-2 was obtained in 75% yield;
pale yellow oil; Rf = 0.35 (Hexane/EtOAc, 5:1); 1H NMR
(CDCl3, 400 MHz) d 1.20 (s, 9H), 2.16 (s, 3H), 4.88 (s,
2H); 13C NMR (CDCl3, 100 MHz) d 20.3, 26.0, 42.7, 64.3,
170.1, 207.6; IR (thin film, NaCl): 2969, 2874, 1752, 1726,
1234, 1050 cm-1; MS m/z (relative intensity): 157 (M+-1,
3), 101 (6), 85 (15), 71 (5), 57 (100), 41 (35); HRMS Calcd.
for C8H14O3 158.0943, Found: 158.0946.
Followed the general procedure for the ozonolysis of
compound 3a-2 and the Type A condition for the ene-diol
rearrangement, compound 6a-2 was obtained in 82% yield;
colorless solid, mp, 41-42 °C; Rf = 0.38 (Hexane/EtOAc,
5:1); 1H NMR (CDCl3, 400 MHz) d 2.23 (s, 3H), 5.34 (s,
2H), 7.46-7.50 (m, 2H), 7.59-7.61 (m, 1H), 7.90-7.93 (m,
2H); 13C NMR (CDCl3, 100 MHz) d 20.3, 65.8, 127.6,
128.7, 133.6, 134.1, 170.1, 192.0; IR (thin film, NaCl):
3065, 3033, 2988, 1741, 1455, 1234, 1021, 760, 700 cm-1;
MS m/z (relative intensity): 178 (M+, 2), 136 (6), 119 (6),
105 (100), 77 (51), 51 (21); HRMS Calcd. for C10H10O3
178.0630, Found: 178.0632.
1-Benzyloxy-3-acetoxypropan-2-one (6e-2)
Followed the general procedure for the ozonolysis of
compound 3e-2 and the Type B condition for the ene-diol
rearrangement, compound 6e-2 was obtained in 69% yield;
pale yellow oil; Rf = 0.48 (Hexane/EtOAc, 2:1); 1H NMR
(CDCl3, 400 MHz) d 2.16 (s, 3H), 4.15 (s, 2H), 4.60 (s,
2H), 4.90 (s, 2H), 7.26-7.40 (m, 5H); 13C NMR (CDCl3,
100 MHz) d 20.2, 66.7, 73.55, 73.61, 127.8, 128.0, 128.5,
136.7, 170.0, 201.8; IR (thin film, NaCl): 3062, 3032,
2935, 2867, 1741, 1411, 1234, 1105, 1070, 742, 700 cm-1;
MS m/z (relative intensity): 223 (M++1, 3), 181 (20), 107
(19), 91 (100), 43 (36); HRMS Calcd. for C12H14O4
222.0892, Found: 222.0894.
Acetic acid 2-oxo-5-phenylpentyl ester (6b-2)
Followed the general procedure for the ozonolysis of
compound 3b-2 and the Type B condition for the ene-diol
rearrangement, compound 6b-2 was obtained in 70% yield;
pale yellow oil; Rf = 0.49 (Hexane/EtOAc, 10:1); 1H NMR
(CDCl3, 400 MHz) d 1.95 (quin, J = 7.4 Hz, 2H), 2.15 (s,
3H), 2.41 (t, J = 7.4 Hz, 2H), 2.64 (t, J = 7.6 Hz, 2H), 4.61
(s, 2H), 7.16-7.30 (m, 5H); 13C NMR (CDCl3, 100 MHz) d
20.30, 24.5, 34.8, 37.6, 67.8, 125.9, 128.3, 128.33, 141.1,
170.0, 203.4; IR (thin film, NaCl): 3027, 2934, 2862, 1751,
1732, 1455, 1417, 1232, 747, 701 cm-1; MS m/z (relative
intensity): 221 (M++1, 2), 178 (4), 147 (40), 104 (100), 91
(51), 43 (26); HRMS Calcd. for C13H16O3 220.1099, Found:
220.1097.
(RS)-2-Acetoxy-1-(2,2-dimethyl[1,3]dioxolan-4-yl)eth-
anone (6h-2)
Followed the general procedure for the ozonolysis of
compound 3h-2 and the Type D condition for the ene-diol
rearrangement, compound 6h-2 was obtained in 31% yield;
pale yellow oil; Rf = 0.51 (Hexane/EtOAc, 3:1); 1H NMR
(CDCl3, 400 MHz) d 1.39 (s, 3H), 1.51 (s, 3H), 2.17 (s,
3H), 4.11 (dd, J = 8.8 and 5.2 Hz, 1H), 4.23 (t, J = 8.8 Hz,
1H), 4.55 (dd, J = 8.8 and 5.2 Hz, 1H), 4.92 (1/2 ABq, J =
17.9 Hz, 2H), 4.99 (1/2 ABq, J = 17.9 Hz, 2H); 13C NMR
(CDCl3, 100 MHz) d 20.3, 24.6, 25.8, 66.3, 66.4, 79.0,
111.2, 170.1, 203.3; IR (thin film, NaCl): 2990, 2939,
1753, 1737, 1376, 1232, 1073, 842 cm-1; MS m/z (relative
intensity): 202 (M+, 3), 187 (13), 145 (6), 117 (31), 100
(43), 72 (23), 59 (16), 43 (100); HRMS Calcd. for C9H14O5
202.0841, Found: 202.0843.
Acetic acid 2-cyclohexyl-2-oxoethyl ester (6c-2)
Followed the general procedure for the ozonolysis
of compound 3c-2 and the Type B condition for the ene-
diol rearrangement, compound 6c-2 was obtained in 70%
yield; white solid, mp, 48-49 °C; Rf = 0.49 (Hexane/
1
EtOAc, 10:1); H NMR (CDCl3, 400 MHz) d 1.23-1.31
(m, 5H), 1.78-1.86 (m, 5H), 2.16 (s, 3H), 2.38-2.45 (m,
1H), 4.73 (s, 2H); 13C NMR (CDCl3, 100 MHz) d 20.3,
25.3, 25.5, 28.0, 47.2, 66.5, 170.0, 206.1; IR (thin film,
NaCl): 2930, 2855, 2862, 1753, 1725, 1449, 1229 cm-1;
MS m/z (relative intensity): 184 (M+, 2), 124 (20), 111
(2S,3S,4R,5R)-2-Acetoxy-1-(3,4-O-isopropylidene-5-
methoxytetrahydrofuran-2-yl)ethanone (6g-2)
Followed the general procedure for the ozonolysis of
compound 3g-2 and the Type D condition for the ene-diol

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 911
rearrangement, compound 6g-2 was obtained in 61% yield;
yellow oil; Rf = 0.67 (Hexane/EtOAc, 2:1); 1H NMR (CDCl3,
400 MHz) d 1.28 (s, 3H), 1.46 (s, 3H), 2.18 (s, 3H), 3.36 (s,
3H), 4.54 (d, J = 4.1 Hz, 1H), 4.57 (d, J = 5.8 Hz, 1H), 4.86
(1/2 ABq, J = 17.8 Hz, 1H), 5.00 (dd, J = 5.6 and 4.2 Hz,
1H), 5.04 (s, 1H), 5.08 (1/2 ABq, J = 17.8 Hz, 1H); 13C
NMR (CDCl3, 100 MHz) d 20.3, 24.1, 25.7, 54.9, 67.6,
80.8, 83.8, 84.0, 107.7, 113.0, 167.0, 199.6; [a] 3D3 = +17.9
(c = 0.143, CHCl3); IR (thin film, NaCl): 2991, 2941, 2839,
1758, 1741, 1230, 1095, 1041 cm-1; MS m/z (relative inten-
sity): 275 (M++1, 4), 259 (20), 185 (47), 143 (19), 115 (29),
85 (53), 59 (34), 43 (100); HRMS Calcd. for C12H18O7
274.1053, Found: 274.1055.
(CDCl3, 100 MHz) d 27.1, 38.6, 65.7, 127.6, 128.6, 133.5,
134.3, 177.7, 192.3; IR (thin film, NaCl): 3036, 2975,
2935, 2873, 1739, 1704, 1480, 1151, 751, 689 cm-1; MS
m/z (relative intensity): 220 (M+, 2), 105 (100), 77 (17), 57
(22); HRMS Calcd. for C13H16O3 200.1099, Found:
200.1104.
Trimethylacetic acid 2-cyclohexyl-2-oxoethyl ester
(6c-3)
Followed the general procedure for the ozonolysis of
compound 3c-3 and the Type B condition for the ene-diol
rearrangement, compound 6c-3 was obtained in 73% yield;
pale yellow oil; Rf = 0.49 (Hexane/EtOAc, 10:1); 1H NMR
(CDCl3, 400 MHz) d 1.22-1.41 (m, 5H), 1.27 (s, 9H),
1.60-1.85 (m, 5H), 2.39-2.43 (m, 1H), 5.30 (s, 2H); 13C
NMR (CDCl3, 100 MHz) d 25.4, 25.6, 27.0, 28.0, 38.5,
47.1, 66.5, 177.6, 206.4; IR (thin film, NaCl): 2932, 2856,
1726, 1283, 1142 cm-1; MS m/z (relative intensity): 226
(M+, 7), 143 (3), 111 (28), 105 (29), 83 (43), 55 (43), 41
(100); HRMS Calcd. for C13H22O3 226.1569, Found:
226.1569.
1,10-Diacetoxydecan-2,9-dione (6i-2)
Followed the general procedure for the ozonolysis of
compound 3i-2 and the Type B condition for the ene-diol
rearrangement, compound 6i-2 was obtained in 67% yield;
white solid; mp, 99-100 °C; Rf = 0.41 (Hexane/EtOAc,
1
2:1); H NMR (CDCl3, 400 MHz) d 1.29-1.33 (m, 4H),
1.59-1.63 (m, 4H), 2.17 (s, 6H), 2.41 (t, J = 7.3 Hz, 4H),
4.64 (s, 4H); 13C NMR (CDCl3, 100 MHz) d 20.4, 22.8,
28.6, 38.4, 67.9, 170.1, 203.7; IR (thin film, NaCl): 2987,
2936, 2870, 1754, 1723, 1234, 1219, 1068, 726 cm-1; MS
m/z (relative intensity): 287 (M++1, 4), 213 (8), 171 (19),
153 (8), 43 (100); HRMS Calcd. for C14H22O6 286.1416;
Found: 286.1413.
Trimethylacetic acid 3,3-dimethyl-2-oxobutyl ester
(6d-3)
Followed the general procedure for the ozonolysis of
compound 3d-3 and the Type B condition for the ene-diol
rearrangement, compound 6d-3 was obtained in 71% yield;
pale yellow oil; Rf = 0.52 (Hexane/EtOAc, 10:1); 1H NMR
(CDCl3, 400 MHz) d 1.21 (s, 9H), 1.27 (s, 9H), 4.87 (s,
2H); 13C NMR (CDCl3, 100 MHz) d 26.1, 27.1, 38.6, 42.7,
64.2, 177.8, 207.7; IR (thin film, NaCl): 2970, 2873, 1752,
1724, 1286, 1158 cm-1.
1,4-Bis(acetoxyacetyl)benzene (6j-2)
Followed the general procedure for the ozonolysis of
compound 3j-2 and the Type C condition for the ene-diol
rearrangement, compound 6j-2 was obtained in 75% yield;
white solid; mp, 146-147 °C; Rf = 0.62 (Hexane/EtOAc,
1:2); 1H NMR (CDCl3, 400 MHz) d 2.24 (s, 6H), 5.34 (s,
4H), 8.02 (s, 4H); 13C NMR (CDCl3, 100 MHz) d 20.4,
66.0, 128.1, 137.7, 170.2, 191.7; IR (thin film, NaCl):
2985, 2949, 1745, 1697, 1431, 1080, 820 cm-1; MS m/z
(relative intensity): 279 (M++1, 6), 237 (25), 205 (100),
163 (30), 43 (40); HRMS Calcd. for C14H14O6 278.0790,
Found: 278.0787.
Benzoic acid 2-oxo-2-phenylethyl ester (6a-4)
Followed the general procedure for the ozonolysis of
compound 3a-4 and the Type A condition for the ene-diol
rearrangement, compound 6a-4 was obtained in 74% yield;
white solid; mp, 121-122 °C; Rf = 0.56 (Hexane/EtOAc,
10:1); 1H NMR (CDCl3, 400 MHz) d 5.59 (s, 2H), 7.46-
7.65 (m, 6H), 7.98 (d, J = 7.6 Hz, 2H), 8.15 (d, J = 7.2 Hz,
2H); 13C NMR (CDCl3, 100 MHz) d 66.4, 127.8, 128.4,
128.8, 129.4, 129.9, 133.3, 133.8, 166.0, 192.1; IR (thin
film, NaCl): 3057, 2985, 2943, 1726, 1702, 1450, 1266,
1123, 740, 690 cm-1; MS m/z (relative intensity): 240 (M+,
2), 151 (7), 117 (17), 104 (100), 77 (61), 51 (19); HRMS
Calcd. for C15H12O3 240.0786, Found: 240.0784.
Benzoic acid 2-cyclohexyl-2-oxoethyl ester (6b-4)
Followed the general procedure for the ozonolysis of
Trimethylacetic acid 2-oxo-2-phenylethyl ester (6a-3)
Followed the general procedure for the ozonolysis of
compound 3a-3 and the Type A condition for the ene-diol
rearrangement, compound 6a-3 was obtained in 81% yield;
white solid, mp, 59-60 °C; Rf = 0.67 (Hexane/EtOAc,
10:1); 1H NMR (CDCl3, 400 MHz) d 1.30 (s, 9H), 5.30 (s,
2H), 7.42-7.58 (m, 3H), 7.87-7.89 (m, 2H); 13C NMR

912 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Hon et al.
compound 3b-4 and the Type B condition for the ene-diol
rearrangement, compound 6b-4 was obtained in 67% yield;
white solid, mp, 49-50 °C; Rf = 0.58 (Hexane/EtOAc,
10:1); 1H NMR (CDCl3, 400 MHz) d 1.22-1.50 (m, 5H),
1.67-1.93 (m, 5H), 2.48-2.55 (m, 1H), 4.97 (s, 2H), 7.44-
7.48 (m, 2H), 7.57-7.61 (m, 1H), 8.08-8.10 (m, 2H); 13C
NMR (CDCl3, 100 MHz) d 25.3, 25.5, 28.0, 47.1, 66.9,
128.2, 129.2, 129.6, 133.1, 165.6, 206.0; IR (thin film,
NaCl): 3060, 2933, 2856, 1719, 1451, 1277, 1126, 739,
710 cm-1; MS m/z (relative intensity): 246 (M+, 3), 162
(13), 111 (51), 83 (100), 55 (53), 41 (21); HRMS Calcd. for
C15H18O3 246.1256, Found: 246.1265.
(10 mL) was added DCC (680.8 mg, 3.3 mmol) at rt and
stirred it for 48 h. The reaction was quenched with 1 N HCl
at 0 °C and extracted with ethyl acetate. The organic layer
was dried over MgSO4, concentrated and chromatographed
on silica gel to give product 3h-5 (606.4 mg, 1.62 mmol) in
54% yield (as a mixture of two diastereomers, 4 :1) and re-
covered 194.5 mg of compound 2h. Inseparable products
6h-5A and 6h-5B (1:1 ratio) were obtained in 44% yield
from compound 3h-5 by Type D condition; colorless oil; Rf
= 0.72 (hexane/EtOAc, 5:1); 1H NMR (CDCl3, 400 MHz) d
1.40 (s, 3H), 1.52 (s, 1.5H), 1.53 (s, 1.5H), 3.65 (d, 5JH-F
=
1.2 Hz, 1.5H), 3.67 (d, 5JH-F = 1.1 Hz, 1.5H), 4.13-4.18 (m,
1H), 4.24 (dd, J = 8.9 and 7.9 Hz, 0.5H), 4.25 (dd, J = 9.1
and 7.7 Hz, 0.5H), 4.56 (dd, J = 5.1 and 5.1 Hz, 0.5H), 4.58
(dd, J = 5.0 and 5.0 Hz, 0.5H), 5.05 (1/2 ABq, J = 17.6 Hz,
0.5H), 5.26 (1/2 ABq, J = 17.5 Hz, 0.5H), 5.12 (1/2 ABq, J
= 17.6 Hz, 0.5H), 5.22 (1/2 ABq, J = 16.9 Hz, 0.5H),
7.42-7.43 (m, 3H), 7.63-7.66 (m, 2H); 13C NMR (CDCl3,
100 MHz) d 24.6, 25.92, 25.93, 55.7, 66.47, 66.51, 67.80,
67.84, 79.0, 79.1, 84.64 (q, J = 24.0 Hz, -CCF3), 84.60 (q, J
= 24.0 Hz, -CCF3), 111.48, 111.52, 123.1 (q, J = 287 Hz,
-CF3), 127.53, 127.54, 128.38, 128.39, 129.73, 131.86,
131.93, 166.17, 166.18, 202.1; [a] 2D8.4 = +5.57 (c = 0.068,
CHCl3); IR (thin film, NaCl): 3066, 2990, 2937, 2853,
1759, 1740, 1376, 1269, 1171 cm-1; MS m/z (relative inten-
sity): 376 (M+, 3); HRMS Calcd. for C17H19F3O6 376.1134,
Found: 376.1135.
2-Hydroxy-1-phenylethanone (6a)
Followed the general procedure for the ozonolysis
of compound 2a and the Type C condition for the ene-diol
rearrangement, compound 6a was obtained in 55% yield;
white solid; mp, 86-87 °C; Rf = 0.41 (Hexane/EtOAc,
5:1); 1H NMR (CDCl3, 400 MHz) d 3.51 (br s, 1H, -OH),
4.89 (br s, 2H), 7.27-7.54 (m, 2H), 7.62-7.66 (m, 1H),
7.92-7.94 (m, 2H); 13C NMR (CDCl3, 100 MHz) d 65.4,
127.6, 128.9, 133.3, 134.2, 198.4; IR (thin film, NaCl):
3481, 3057, 2986, 2906, 1687, 1450, 1266, 739, 704 cm-1;
MS m/z (relative intensity): 136 (M+, 7), 104 (81), 77
(100), 50 (58); HRMS Calcd. for C8H8O2 136.0524,
Found: 136.0522.
1-Cyclohexyl-2-hydroxyethanone (6b)
Followed the general procedure for the ozonolysis
of compound 2b and the Type D condition for the ene-diol
rearrangement, compound 6b was obtained in 46% yield;
1-tert-Butyldimethylsilyloxy-1-phenyl-2-methylprop-2-
ene (7)
1
colorless oil; Rf = 0.59 (Hexane/EtOAc, 5:1); H NMR
Followed the general procedure A to prepare allylic
alcohol from benzaldehyde (1a) (329 mg, 3.1 mmol) and
2-methylvinylmagnesium bromide (3.41 mmol) in THF.
The crude product, DMAP (37.9 mg, 0.31 mmol) and
imidazole (222 mg, 3.25 mmol) in CH2Cl2 (20 mL) was
added t-butyldimethylsilyl chloride (489.8 mg, 3.25 mmol)
at rt and stirred it for 2 h. The reaction was quenched with
saturated NaHCO3 solution and extracted with ethyl ace-
tate. The organic layer was dried over MgSO4, concen-
trated and chromatographed on silica gel to give the silyl
ether 7 (619 mg, 2.36 mmol) as a colorless oil in 76% yield
(CDCl3, 400 MHz) d 1.24-1.43 (m, 5H), 1.71-1.86 (m,
5H), 2.35-2.41 (m, 1H), 3.15 (t, J = 4.6 Hz, 1H), 4.22 (d, J
= 4.6 Hz, 2H); 13C NMR (CDCl3, 100 MHz) d 25.4, 25.6,
28.3, 47.1, 66.4, 212.6; IR (thin film, NaCl): 3418, 2925,
2852, 1713, 1449, 1097 cm-1; MS m/z (relative intensity):
143 (M++1, 5), 142 (M+, 5), 111 (39), 83 (100), 55 (33), 41
(22); HRMS Calcd. for C8H14O2 142.0994, Found:
142.0996.
6h-5A and 6h-5B
Compound 2h was prepared in 70% yield from (R)-
aldehyde 1h (650.7 mg, 5.0 mmol) and vinylmagnesium
bromide (5.5 mmol, 5.5 mL, 1.0 M in THF) according to
general procedure A. To a solution of alcohol 2h (474.5
mg, 3.0 mmol), (R)-Mosher acid (10) (737.6 mg, 3.15
mmol), DMAP (36.6 mg, 0.3 mmol) in dichloromethane
1
from aldehyde 1a. Rf = 0.91 (hexane/EtOAc, 20:1); H
NMR (400 MHz, CDCl3) d -0.02 (s, 3H), 0.07 (s, 3H), 0.92
(s, 9H), 1.53 (s, 3H), 4.82-4.83 (m, 1H), 5.10-5.11 (m, 2H),
7.26-7.33 (m, 5H); 13C NMR (100 MHz, CDCl3) d -5.0,
-4.9, 17.2, 18.3, 25.9, 78.6, 110.9, 126.1, 126.9, 127.9,

a-Hydroxyketone Derivatives from Ene-diol Rearrangement
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 913
4. Moore, J. A.; Wanger, R. B. J. Am. Chem. Soc. 1950, 72,
2884-2887.
143.3, 147.9; IR (thin film, NaCl): 3068, 3028, 2955, 2929,
2857, 1471, 1256, 1092, 875, 837, 776, 698 cm-1; MS m/z
(relative intensity): 261 (M+-1, 6), 206 (100), 131 (28), 91
(6), 75 (53); HRMS: m/z calcd. for C16H26OSi: 262.1753;
Found: 262.1750.
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1599-1602. (b) Chenault, H. K.; Danishefsky, S. J. J. Org.
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1-(tert-Butyldimethylsilyloxy)-1-phenylpropan-2-one
(8)
Compound 7 (301 mg, 1.15 mmol) was treated with
ozone in dichloromethane followed by addition of Et3N
(0.19 mL, 1.38 mmol) at -78 °C. The reaction was warmed
slowly to rt and stirred it for 4 h. The reaction mixture was
concentrated, chromatographed on silica gel column to
give the corresponding ketone 8 (243 mg, 0.92 mmol) in
80% yield as a pale yellow oil; Rf = 0.56 (hexane/EtOAc,
10:1); 1H NMR (400 MHz, CDCl3) d 0.00 (s, 3H), 0.09 (s,
3H), 0.95 (s, 9H), 2.11 (s, 3H), 5.04 (s, 1H), 7.26-7.44 (m,
5H); 13C NMR (100 MHz, CDCl3) d -5.2, -5.0, 18.1, 23.8,
25.7, 81.2, 125.7, 128.4, 138.6, 208.8; IR (thin film, NaCl):
3064, 3032, 2986, 2932, 1720, 1451, 1268, 1109, 933, 712,
700 cm-1; MS m/z (relative intensity): 249 (M+-15, 6), 221
(100), 207 (77), 105 (7), 73 (84); HRMS: m/z calcd. for
C15H24O2Si: 264.1546; Found: 264.1547.
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ACKNOWLEDGEMENTS
We are grateful to the National Science Council and
National Chung Cheng University for the financial sup-
port, to the Prof. Wei-Ping Hu of National Chung Cheng
University for providing computation resources.
10. Jager, V.; Schrother, D.; Koppenhoefer, B. Tetrahedron
1991, 47, 2195-2210.
Received March 12, 2008.
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