Stereoselective synthesis of (2 Z,4 E)-2,4-pentadien-1-ols via sequential 1,4-elimination reaction and [1,2]-wittig rearrangement starting from (E)-4-alkoxy-2-butenyl benzoates

Article abstract of DOI:10.1021/jo402272r

The sequential 1,4-elimination reaction of (E)-4-alkoxy-2-butenyl benzoates and [1,2]-Wittig rearrangement gave (2Z,4E)-2,4-pentadien-1-ols stereoselectively. Z-Selective formation of intermediary vinyl ethers, whose stereochemistry was well elucidated by the "syn-effect", was achieved by treatment of the 2-butenyl benzoates with KOH in the presence of Pd catalyst. The subsequent [1,2]-Wittg rearrangement by use of n-BuLi proceeded with retention of the stereochemistry of the intermediary vinyl ethers.

Full text of DOI:10.1021/jo402272r

Article
pubs.acs.org/joc
Stereoselective Synthesis of (2Z,4E)‑2,4-Pentadien-1-ols via
Sequential 1,4-Elimination Reaction and [1,2]-Wittig Rearrangement
Starting from (E)‑4-Alkoxy-2-butenyl Benzoates
Takeo Nakano, Takahiro Soeta, Kohei Endo, Katsuhiko Inomata, and Yutaka Ukaji*
Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa
920-1192, Japan
S
* Supporting Information
ABSTRACT: The sequential 1,4-elimination reaction of (E)-4-alkoxy-2-butenyl benzoates and [1,2]-Wittig rearrangement gave
(2Z,4E)-2,4-pentadien-1-ols stereoselectively. Z-Selective formation of intermediary vinyl ethers, whose stereochemistry was well
elucidated by the “syn-effect”, was achieved by treatment of the 2-butenyl benzoates with KOH in the presence of Pd catalyst.
The subsequent [1,2]-Wittg rearrangement by use of n-BuLi proceeded with retention of the stereochemistry of the intermediary
vinyl ethers.
Scheme 1. Concept of the “Syn-Effect’’: σ→π* Interaction in
INTRODUCTION
■
the Elimination Reaction of Allylic Sulfones
Stereoselective synthesis of carbon−carbon double bonds as
ubiquitous and versatile two-carbon units is among the most
important and challenging tasks in organic chemistry.1
Consequently, a large number of synthetic methodologies
have been reported, e.g., (1) Wittig reaction, which utilizes the
characteristics of phosphorus;2 (2) Peterson reaction, which
utilizes silicon;3 (3) Julia olefination, which utilizes sulfones;4,5
(4) reduction or carbometalation of alkynes, which takes
advantage of organometallic reagents;6 (5) [3,3]-sigmatoropic
reactions such as Claisen rearrangement;7 and (6) olefin
metathesis, which is realized by the use of Grubbs catalysts.8
However, these reactions depend on new C−C bond formation
or reductive olefin formation from alkynes. On the other hand,
while the elimination reaction is also a powerful method for the
preparation of olefins, the stereochemistry of the products
generally depends on the reaction pathway, i.e., E2 anti-
elimination, syn-elimination, or E1 elimination. Several methods
have been reported for stereoselective synthesis of olefins using
simple elimination reactions.9
In our laboratory, stereoselective formation of sterically
unfavorable (Z)-olefins was investigated with various types of
elimination and isomerization reactions by treatment with a
base.10 We proposed that Z-selectivity was achieved by the “syn-
effect”, namely, a stereoelectronic effect owing to σC−H→π*CC
interaction as depicted in Scheme 1, in which the transition
state of the 1,4-elimination of an allylic sulfone is depicted.10c
Furthermore, it was found that Z-selectivity based on the “syn-
effect” was enhanced when the δ-substituent (R1 in Scheme 1)
was an electron-withdrawing alkoxy or halogen group.
This methodology could then be applied to a stereoselective
synthesis of (Z)-olefins in combination with C−C bond
formation. We have reported a sequential 1,4-elimination
reaction of δ-benzyloxy-substituted allylic sulfones followed by
[1,2]-Wittig rearrangement11 to give (Z)-dienyl alcohols (2,4-
pentadien-1-ols), which are useful synthetic intermediates due
to the presence of both an allylic alcohol moiety and a diene
moiety (Scheme 2a).12 However, the reaction was limited to
only α,α-disubstituted allylic sulfones. When an α-monosub-
stituted allylic sulfone was subjected to the reaction, the
elimination of the benzyloxy group proceeded preferentially via
deprotonation of the more acidic α-proton (Scheme 2b).13 In
this situation, the stereocontrolled preparation of (2Z)-5-
Received: October 11, 2013
Published: November 18, 2013
© 2013 American Chemical Society
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Scheme 2. Z-Selective Synthesis of Dienyl Alcohols
Table 1. Optimization of Reaction Conditions
a
entry
base
DBU
n
yield (%)
Z/E
1
2
3
4
12
7
84
10/1
10/1
NaOt-Bu
NaOt-Bu
<82
b
c
0
c
b
KOt-Bu
0
d
5
d
NaOH
6
6
73
10/1
6
KOH
68
>20/1
a
b
c
1
The ratios were determined by 400 MHz H NMR spectra. Stereochemistries at C4C5 were E. Sublimed NaOt-Bu or KOt-Bu was used. A
d
complex mixture of products was obtained. MS4A were added after the elimination reaction.
monosubstituted-2,4-pentadien-1-ols still remained to be
solved. Previously, we found that (1Z,3E)-1,3-dienes were
produced stereoselectively in the Pd-catalyzed elimination
reaction of acyclic (E)-allylic acetates with a base.10g We
anticipated this protocol would be applicable to the sequential
1,4-elimination reaction and [1,2]-Wittig rearrangement. Here-
in we describe the sequential reaction of stereoselective 1,4-
elimination of (E)-4-alkoxy-2-butenyl benzoates via the π-allylic
palladium complex and subsequent [1,2]-Wittig rearrangement
to afford (2Z,4E)-5-monosubstituted-2,4-pentadien-1-ols
(Scheme 2c).
RESULTS AND DISCUSSION
■
We chose (E)-4-benzyloxy-1-phenyl-2-butenyl benzoate (1a) as
a model substrate for the optimization of the reaction
conditions.14,15 Under our previously reported conditions for
allylic acetates using DBU, the Pd-catalyzed [1,4]-elimination
reaction of 1a did not proceed reproducibly. Deactivation of the
Pd(0) complex by molecular oxygen contamination was
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Table 2. Scope of Substrates
a
entry
Ar
R
yield (%)
Z/E
1
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
a
b
c
d
e
f
68
65
58
63
71
63
68
72
67
53
34
>20/1
18/1
2
2-MeC6H4
3-MeC6H4
4-MeC6H4
4-MeOC6H4
4-ClC6H4
2-Naph
Ph
3
>20/1
>20/1
19/1
4
5
6
15/1
7
g
h
i
>20/1
>20/1
17/1
8
4-MeC6H4
2-Naph
t-Bu
9
Ph
10
11
Ph
j
>20/1
>20/1
Ph
i-Pr
k
a
1
The ratios were determined by 400 MHz H NMR spectra. Stereochemistries at C4C5 were E.
suspected as the cause. In order to prevent this deactivation,
degassed THF was used as the solvent, and the 1,4-elimination
reaction was found to proceed reproducibly. After the 1,4-
elimination by treatment with DBU,16 an excess amount of n-
BuLi was added to the reaction mixture to give the desired
(2Z,4E)-dienyl alcohol 2a in good yield with high Z-selectivity
at the C2−C3 double bond (Table 1, entry 1).17 However, a
large excess (12 equiv) of n-BuLi was required to complete the
[1,2]-Wittig rearrangement.17 The deprotonation of DBU with
excess amounts of n-BuLi was confirmed by deuterium-labeling
experiment (eq 1). After the search for a base that did not react
with n-BuLi, NaOt-Bu could reduce the amount of n-BuLi to 7
equiv for the [1,2]-Wittig rearrangement (entry 2). However,
the desired product 2a was not obtained with NaOt-Bu or KOt-
Bu purified by sublimation (entries 3 and 4). We supposed the
actual base might be NaOH or KOH, which was generated by
partial hydrolysis of NaOt-Bu or KOt-Bu. Therefore, we
employed NaOH and KOH as bases for the initial elimination.
To our delight, elimination proceeded18 reproducibly, and
further treatment with n-BuLi (6 equiv) gave 2a in good yield
with excellent Z-selectivity at the C2−C3 double bond (entries
5 and 6).
group, dienyl alcohol 2k was obtained in low yield, while
excellent Z-selectivity was retained. In this case, byproduct 3,
derived from deprotonation of not Hδ but Hβ′ followed by
[1,2]-Wittig rearrangement, was obtained (Scheme 3).19
Scheme 3. Generation of Byproduct 3 in the Reaction of 2-
Butenyl Benzoate 1k Bearing an Isopropyl Substituent at the
α-Position
Under the optimized conditions, the sequential 1,4-
elimination reaction and [1,2]-Wittig rearrangement of various
substrates were performed (Table 2). Benzyl-type ethers 1b−
1d with o-, m-, and p-methyl groups produced the
corresponding (2Z,4E)-dienyl alcohols 2b−2d (entries 2−4).
When 2-butenyl benzoates 1e and 1f bearing electron-donating
or electron-withdrawing groups on the aromatic ring were
employed, the desired products were also obtained with
excellent Z-selectivities (entries 5 and 6). 4-(2-
Naphthylmethyloxy)butenyl benzoate 1g was also converted
into the corresponding (2Z,4E)-dienyl alcohol 2g (entry 7).
Next, we examined the generality of the sequential reaction for
(E)-2-butenyl benzoates bearing various substituents at the α-
position of the butenyl group. The desired products 2h−2j
were obtained in good yields with excellent Z-selectivities from
2-butenyl benzoates 1h−1j bearing an aryl or t-Bu substituent
on the α-carbon (entries 8−10). However, in the case of a
benzoate 1k with an i-Pr group at the α-position of the butenyl
In conclusion, we achieved a stereoselective synthesis of
(2Z,4E)-2,4-pentadien-1-ols via sequential 1,4-elimination
reaction and [1,2]-Wittig rearrangement starting from (E)-4-
alkoxy-2-butenyl benzoates. The present method would be
applicable in synthetic chemistry, because the stereochemistry
can be predicted correctly by universal stereoelectronic
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effects.20 Development of other Z-selective reactions based on
this strategy is currently underway in our laboratory.
1454, 1353, 1262, 1189, 1121, 1072, 945, 918, 843, 809, 745, 699
cm−1. HRMS (EI): calcd for C18H18O2 [M+] 266.1307, found
266.1313.
4-((3-Methylbenzyl)oxy)-1-phenyl-2-butyn-1-ol (4c). Com-
pound 4c (2.81 g, 86% from 12.3 mmol of 3-methylbenzyl propargyl
ether) was obtained as an oil. 1H NMR (400 MHz, CDCl3): 2.21 (d, J
= 5.9 Hz, 1H), 2.35 (s, 3H), 4.27 (d, J = 1.8 Hz, 2H), 4.57 (s, 2H),
5.53 (d, J = 5.9 Hz, 1H), 7.11−7.17 (m, 3H), 7.23 (d, J = 7.4 Hz, 1H),
7.32−7.42 (m, 3H), 7.55 (d, J = 6.9 Hz, 2H). 13C NMR (100 MHz,
CDCl3): 21.1, 57.0, 64.0, 71.3, 82.0, 86.4, 125.0, 126.4, 128.0, 128.1,
128.3, 128.4, 128.6, 136.8, 137.8, 140.0. IR (neat): 3391, 3029, 2857,
2230, 1609, 1492, 1454, 1380, 1353, 1255, 1192, 1157, 1120, 1078,
1003, 918, 785, 742, 698 cm−1. HRMS (EI): calcd for C18H18O2 [M+]
266.1307, found 266.1305.
4-((4-Methylbenzyl)oxy)-1-phenyl-2-butyn-1-ol (4d). Com-
pound 4d (2.79 g, 92% from 11.4 mmol of 4-methylbenzyl propargyl
ether) was obtained as an oil. 1H NMR (400 MHz, CDCl3): 2.23 (d, J
= 6.0 Hz, 1H), 2.34 (s, 3H), 4.24 (d, J = 1.8 Hz, 2H), 4.57 (s, 2H),
5.53 (d, J = 6.0 Hz, 1H), 7.15 (d, J = 7.8 Hz, 2H), 7.23 (d, J = 7.8 Hz,
2H), 7.32−7.41 (m, 3H), 7.55 (d, J = 6.9 Hz, 2H). 13C NMR (100
MHz, CDCl3): 21.3, 57.3, 64.4, 71.6, 82.5, 86.8, 126.8, 128.4, 128.5,
128.7, 129.3, 134.2, 137.8, 140.7. IR (neat): 3392, 3029, 2857, 2230,
1617, 1515, 1493, 1453, 1382, 1354, 1309, 1262, 1193, 1120, 1077,
1021, 945, 918, 843, 806, 754, 732, 699 cm−1. HRMS (EI): calcd for
C18H18O2 [M+] 266.1307, found 266.1306.
EXPERIMENTAL SECTION
General Method. H NMR spectra were recorded on a 400 MHz
■
1
NMR spectrometer. Chemical shifts δ are reported in ppm using TMS
as an internal standard. Data are reported as follows: chemical shift,
multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, m =
multiplet), coupling constant (J), and integration. 13C NMR spectra
were recorded on a 100 MHz NMR spectrometer. The chemical shifts
are reported relative to CDCl3 (δ = 77.0 ppm). The wavenumbers of
maximum absorption peaks in IR spectra are presented in cm−1.
HRMS (EI positive, ESI-TOF) spectra were measured with quadru-
pole and TOF mass spectrometers. All of the melting points were
measured with a micro melting point apparatus. THF was freshly
distilled from sodium diphenylketyl. THF used for 1,4-elimination was
degassed by three freeze−pump−thaw cycles prior to use. DMF was
distilled and stored over drying agents.
(E)-4-Alkoxy-2-butenyl benzoates 1 were prepared from the
corresponding propargyl ethers and aldehydes according to the
following scheme:
4-((4-Methoxybenzyl)oxy)-1-phenyl-2-butyn-1-ol (4e). Com-
pound 4e (1.36 g, 89% from 5.4 mmol of 4-methoxybenzyl propargyl
ether) was obtained as an oil. 1H NMR (400 MHz, CDCl3): 2.21 (br,
1H), 3.80 (s, 3H), 4.23 (d, J = 1.2 Hz, 2H), 4.54 (s, 2H), 5.53 (s, 1H),
6.87 (d, J = 8.7 Hz, 2H), 7.27 (d, J = 8.7 Hz, 2H) 7.32−7.41 (m, 3H),
7.55 (d, J = 6.9 Hz, 2H). 13C NMR (100 MHz, CDCl3): 55.3, 57.1,
64.4, 71.3, 82.5, 86.7, 113.9, 126.7, 128.4, 128.7, 129.3, 130.0, 140.7,
159.4. IR (neat): 3401, 3062, 3031, 2837, 2226, 1612, 1585, 1512,
1493, 1455, 1354, 1302, 1249, 1175, 1118, 1074, 1032, 918, 818, 759,
700 cm−1. HRMS (EI): calcd for C18H18O3 [M+] 282.1256, found
282.1253.
4-((4-Chlorobenzyl)oxy)-1-phenyl-2-butyn-1-ol (4f). Com-
pound 4f (2.67 g, 85% from 11.0 mmol of 4-chlorobenzyl propargyl
ether) was obtained as an oil. 1H NMR (400 MHz, CDCl3): 2.18 (br,
1H), 4.27 (d, J = 1.8 Hz, 2H), 4.57 (s, 2H), 5.54 (s, 1H), 7.27−7.42
(m, 7H), 7.54 (d, J = 6.4 Hz, 2H). 13C NMR (100 MHz, CDCl3):
57.4, 64.2, 70.7, 82.0, 86.6, 126.4, 128.0, 128.2, 128.4, 129.2, 133.5,
135.5, 140.3. IR (neat): 3378, 3031, 2861, 1598, 1540, 1491, 1455,
1408, 1354, 1262, 1193, 1120, 1086, 1015, 918, 841, 806, 733, 699,
674 cm−1. HRMS (EI): calcd for C17H15ClO2 [M+] 286.0761, found
286.0765.
4-(2-Naphthalenylmethoxy)-1-phenyl-2-butyn-1-ol (4g).
Compound 4e (1.86 g, 73% from 8.4 mmol of 2-naphthalenylmethoxy
propargyl ether) was obtained as an oil. 1H NMR (400 MHz, CDCl3):
2.23 (br, 1H), 4.31 (d, J = 1.8 Hz, 2H), 4.78 (s, 2H), 5.54 (s, 1H),
7.33−7.42 (m, 3H), 7.46−7.49 (m, 3H), 7.55−7.57 (m, 2H), 7.80−
7.84 (m, 4H). 13C NMR (100 MHz, CDCl3): 57.2, 64.3, 71.6, 82.3,
86.5, 125.8, 125.9, 126.0, 126.5, 126.9, 127.5, 127.8, 128.1, 128.2,
128.5, 132.9, 133.0, 134.5, 140.3. IR (neat): 3381, 3057, 2854, 2230,
1601, 1509, 1492, 1454, 1355, 1271, 1173, 1123, 1078, 1003, 918, 856,
818, 754, 699 cm−1. HRMS (EI): calcd for C21H18O2 [M+] 302.1307,
found 302.1305.
4-(Benzyloxy)-1-(4-tolyl)-2-butyn-1-ol (4h). Compound 4h
(2.13 g, 76% from 10.5 mmol of benzyl propargyl ether) was obtained
as an oil. 1H NMR (400 MHz, CDCl3): 2.15 (d, J = 6.0 Hz, 1H), 2.36
(s, 3H), 4.27 (d, J = 1.8 Hz, 2H), 4.61 (s, 2H), 5.49 (d, J = 6.0 Hz,
1H), 7.20 (d, J = 7.8 Hz, 2H), 7.29−7.38 (m, 5H), 7.43 (d, J = 7.8 Hz,
2H). 13C NMR (100 MHz, CDCl3): 20.9, 57.1, 63.8, 71.3, 81.7, 86.7,
126.3, 127.6, 127.9, 128.2, 128.9, 136.9, 137.5, 137.7. IR (neat): 3396,
3029, 2858, 2235, 1605, 1511, 1496, 1454, 1354, 1264, 1196, 1178,
1114, 1071, 1026, 942, 821, 742, 699 cm−1. HRMS (EI): calcd for
C18H18O2 [M+] 266.1307, found 266.1300.
Representative Procedure for Preparation of 4-Alkoxy-2-
butyn-1-ol 4a. To a solution of benzyl propargyl ether (4.00 g, 27.4
mmol) in THF (45 mL) was added n-BuLi (16.9 mL of 1.62 M
solution in hexane, 27.4 mmol) dropwise at −78 °C. After 20 min of
stirring, benzaldehyde (3.19 g, 30.1 mmol) was added, and the
resulting solution was stirred for 30 min at −78 °C, warmed to room
temperature, and stirred for 3 h.21 The reaction mixture was quenched
with a satd aq solution of NH4Cl. After the solvent was evaporated, the
aqueous layer was separated and extracted with Et2O. The combined
organic extracts were washed with H2O and brine and dried over
Na2SO4. The crude product was purified by silica gel column
chromatography (hexane/AcOEt = 5/1) to give 4a (6.01 g, 87%) as an
oil.
In a similar manner, 4-alkoxy-2-butyn-1-ols 4b−4k were prepared
from the corresponding propargyl ethers.
4-(Benzyloxy)-1-phenyl-2-butyn-1-ol (4a).21 1H NMR (400
MHz, CDCl3): 2.25 (d, J = 5.9 Hz, 1H), 4.27 (d, J = 1.8 Hz, 2H), 4.61
(s, 2H), 5.53 (d, J = 5.9 Hz, 1H), 7.28−7.41 (m, 8H), 7.55 (d, J = 7.3
Hz, 2H). 13C NMR (100 MHz, CDCl3): 57.0, 63.9, 71.3, 81.8, 86.3,
126.3, 127.6, 127.8, 128.0, 128.1, 128.2, 136.8, 140.2. IR (neat): 3390,
3062, 3030, 2857, 2227, 1644, 1494, 1454, 1387, 1354, 1313, 1264,
1193, 1120, 1071, 1026, 918, 738, 698 cm−1. HRMS (EI): calcd for
C17H16O2 [M+] 252.1150, found 252.1155.
4-((2-Methylbenzyl)oxy)-1-phenyl-2-butyn-1-ol (4b). Com-
pound 4b (3.63 g, 91% from 15.0 mmol of 2-methylbenzyl propargyl
ether) was obtained as an oil. 1H NMR (400 MHz, CDCl3): 2.25 (d, J
= 6.0 Hz, 1H), 2.34 (s, 3H), 4.28 (d, J = 1.8 Hz, 2H), 4.60 (s, 2H),
5.53 (d, J = 6.0 Hz, 1H), 7.15−7.24 (m, 3H), 7.25−7.43 (m, 4H), 7.54
(d, J = 6.9 Hz, 2H). 13C NMR (100 MHz, CDCl3): 18.6, 57.3, 64.2,
69.8, 82.2, 86.4, 125.6, 126.4, 128.0, 128.1, 128.4, 129.0, 130.1, 134.9,
136.9, 140.3. IR (neat): 3391, 3063, 3029, 2864, 2235, 1604, 1493,
4-(Benzyloxy)-1-(2-naphthalenyl)-2-butyn-1-ol (4i). Com-
pound 4i (1.44 g, 81% from 5.8 mmol of benzyl propargyl ether)
1
was obtained as an oil. H NMR (400 MHz, CDCl3): 2.34 (br, 1H),
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4.30 (d, J = 0.9 Hz, 2H), 4.63 (s, 2H), 5.69 (s, 1H), 7.28−7.35 (m,
5H), 7.47−7.52 (m, 2H), 7.66 (d, J = 8.2 Hz, 1H), 7.82−7.89 (m,
3H), 8.00 (s, 1H). 13C NMR (100 MHz, CDCl3): 57.1, 64.2, 71.4,
82.3, 86.4, 124.4, 125.1, 126.0, 127.4, 127.7, 127.9, 128.0, 128.2, 128.3,
132.9, 133.0, 136.9, 137.7. IR (neat): 3375, 3057, 2857, 2225, 1601,
1507, 1495, 1455, 1355, 1269, 1167, 1113, 1071, 1025, 951, 903, 861,
821, 748, 699 cm−1. HRMS (EI): calcd for C21H18O2 [M+] 302.1307,
found 302.1306.
(E)-4-((3-Methylbenzyl)oxy)-1-phenyl-2-buten-1-yl Benzoate
(1c). Starting from 5.5 mmol of 4c, almost pure 5c (1.33 g) was
obtained. Then 707 mg of the intermediary 5c was used to give 1c
1
(678 mg, 69% for 2 steps) as an oil. H NMR (400 MHz, CDCl3):
2.33 (s, 3H), 4.06 (d, J = 5.5 Hz, 2H), 4.47 (s, 2H), 5.97 (dt, J = 15.5,
5.5 Hz, 1H), 6.05 (dd, J = 15.5, 5.9 Hz, 1H), 6.54 (d, J = 5.9 Hz, 1H),
7.09−7.58 (m, 12H), 8.09 (d, J = 7.3 Hz, 2H). 13C NMR (100 MHz,
CDCl3): 21.3, 69.7, 72.4, 75.9, 124.9, 127.0, 128.1, 128.2, 128.3, 128.4,
128.6, 129.6, 129.7, 130.1, 130.7, 133.0, 137.8, 137.9, 139.0, 165.4. IR
(neat): 3061, 3031, 2919, 2855, 1718, 1601, 1585, 1492, 1451, 1314,
1266, 1176, 1158, 1107, 1069, 1025, 968, 907, 780, 757, 712 cm−1.
HRMS (EI): calcd for C25H24O3 [M+] 372.1725, found 372.1721.
(E)-4-((4-Methylbenzyl)oxy)-1-phenyl-2-buten-1-yl Benzoate
(1d). Starting from 6.4 mmol of 4d, almost pure 5d (1.45 g) was
obtained. Then 570 mg of the intermediary 5d was used to give 1d
6-(Benzyloxy)-2,2-dimethyl-4-hexyn-3-ol (4j).22 Compound 4j
(1.16 g, 42% from 11.9 mmol of benzyl propargyl ether) was obtained
1
as an oil. H NMR (400 MHz, CDCl3): 1.01 (s, 9H), 1.72 (br, 1H),
4.07 (s, 1H), 4.23 (d, J = 1.8 Hz, 2H), 4.60 (s, 2H), 7.26−7.36 (m,
5H). 13C NMR (100 MHz, CDCl3): 25.2, 35.6, 57.2, 71.1, 71.3, 81.2,
86.3, 127.7, 128.0, 128.3, 137.2. IR (neat): 3446, 3030, 2956, 2867,
2215, 1606, 1540, 1478, 1455, 1363, 1321, 1240, 1123, 1072, 1008,
936, 743, 698 cm−1. HRMS (EI): calcd for C15H20O2 [M+] 232.1463,
found 232.1464.
1
(546 mg, 58% for 2 steps) as an oil. H NMR (400 MHz, CDCl3):
2.33 (s, 3H), 4.04 (d, J = 5.5 Hz, 2H), 4.46 (s, 2H), 5.95 (dt, J = 15.5,
5.5 Hz, 1H), 6.02 (dd, J = 15.5, 6.0 Hz, 1H), 6.53 (d, J = 6.0 Hz, 1H),
7.10−7.58 (m, 12H), 8.10 (d, J = 7.3 Hz, 2H). 13C NMR (100 MHz,
CDCl3): 21.1, 69.5, 72.2, 75.9, 127.0, 127.9, 128.1, 128.3, 128.6, 129.0,
129.7, 130.2, 130.6, 133.0, 133.5, 134.9, 137.3, 139.1, 165.5. IR (neat):
3031, 2921, 2856, 1719, 1601, 1515, 1493, 1451, 1315, 1267, 1176,
1107, 1070, 1025, 969, 806, 756, 712 cm−1. HRMS (EI): calcd for
C25H24O3 [M+] 372.1725, found 372.1726.
6-(Benzyloxy)-2-methyl-4-hexyn-3-ol (4k).22 Compound 4k
(2.53 g, 94% from 12.3 mmol of benzyl propargyl ether) was obtained
as an oil. 1H NMR (400 MHz, CDCl3): 1.01 (d, J = 7.3 Hz, 3H), 1.03
(d, J = 7.3 Hz, 3H), 1.60 (br, 1H), 1.87−1.93 (m, 1H), 4.23 (s, 2H),
4.23−4.25 (m, 1H), 4.60 (s, 2H), 7.28−7.36 (m, 5H). 13C NMR (100
MHz, CDCl3): 17.3, 18.0, 34.2, 57.2, 67.6, 71.3, 81.1, 86.4, 127.7,
128.0, 128.3, 137.1. IR (neat): 3402, 3031, 2962, 2872, 2215, 1620,
1496, 1455, 1384, 1352, 1261, 1207, 1144, 1073, 1027, 936, 743, 699
cm−1. HRMS (EI): calcd for C14H18O2 [M+] 218.1307, found
218.1311.
(E)-4-((4-Methoxybenzyl)oxy)-1-phenyl-2-buten-1-yl Ben-
zoate (1e). Starting from 3.6 mmol of 4e, almost pure 5e (986
mg) was obtained. Then 781 mg of the intermediary 5e was used to
1
give 1e (619 mg, 56% for 2 steps) as an oil. H NMR (400 MHz,
Representative Procedure for Preparation of (E)-4-Alkoxy-2-
butenyl Benzoate 1a. To a solution of compound 4a (2.52 g, 10
mmol) in THF (20 mL) was added Red-Al (5.6 mL of 3.6 M solution
in toluene, 20 mmol) dropwise at −40 °C. The reaction mixture was
warmed to room temperature, stirred for 3 h, and quenched with a
satd aq solution of Na2SO4. After insoluble substance was filtered off
through a bed of Celite, the solvent was evaporated. The residue was
passed through a short silica gel column (hexane/AcOEt = 2/1) to
afford the almost pure (E)-2-buten-1-ol 5a23 (2.53 g). This material
was used for the conversion to the corresponding benzoate 1a without
further purification. To a solution of the obtained 5a (2.53 g) in DMF
(40 mL) were added Et3N (2.02 g, 20 mmol), benzoyl chloride (1.40
g, 10 mmol), and DMAP (610 mg, 5 mmol) at room temperature, and
the resulting solution was stirred overnight. The reaction mixture was
quenched with a satd aq solution of NH4Cl. The aqueous layer was
separated and extracted with AcOEt. The combined organic extracts
were washed with H2O and brine and dried over Na2SO4. The crude
product was purified by silica gel column chromatography (hexane/
AcOEt = 15/1) to give 1a (2.51 g, 70% for 2 steps) as an oil.
In similar manner, (E)-4-alkoxy-2-butenyl benzoates 1b−1k were
prepared from the corresponding 4-alkoxy-2-butyn-1-ols 4b−4k.
(E)-4-(Benzyloxy)-1-phenyl-2-buten-1-yl Benzoate (1a). 1H
NMR (400 MHz, CDCl3): 4.07 (d, J = 5.5 Hz, 2H), 4.52 (s, 2H), 5.96
(dt, J = 15.6, 5.5 Hz, 1H), 6.04 (dd, J = 15.6, 6.0 Hz, 1H), 6.54 (d, J =
6.0 Hz, 1H), 7.26−7.58 (m, 13H), 8.09 (d, J = 6.8 Hz, 2H). 13C NMR
(100 MHz, CDCl3): 69.6, 72.3, 75.9, 127.0, 127.6, 127.7, 128.1, 128.3,
128.5, 128.6, 129.5, 129.6, 130.1, 130.6, 133.0, 137.9, 139.0, 165.4. IR
(neat): 3063, 3031, 2855, 1717, 1600, 1584, 1494, 1452, 1315, 1267,
1176, 1107, 1069, 1025, 968, 751, 712 cm−1. HRMS (EI): calcd for
C24H22O3 [M+] 358.1569, found 358.1573.
CDCl3): 3.80 (s, 3H), 4.03 (d, J = 5.5 Hz, 2H), 4.44 (s, 2H), 5.95 (dt,
J = 15.6, 5.5 Hz, 1H), 6.03 (dd, J = 15.6, 5.5 Hz, 1H), 6.54 (d, J = 5.5
Hz, 1H), 6.86 (d, J = 8.7 Hz, 2H), 7.22−7.58 (m, 10H), 8.09 (d, J =
8.2 Hz, 2H). 13C NMR (100 MHz, CDCl3): 55.2, 69.4, 72.0, 75.9,
113.7, 127.0, 128.1, 128.3, 128.6, 129.4, 129.7, 130.0, 130.2, 130.6,
133.0, 139.1, 159.2, 165.4. IR (neat): 3062, 3032, 2934, 2836, 1718,
1612, 1585, 1512, 1493, 1452, 1361, 1314, 1266, 1175, 1107, 1026,
968, 820, 756, 713 cm−1. HRMS (EI): calcd for C25H24O4 [M+]
388.1675, found 388.1683.
(E)-4-((4-Chlorobenzyl)oxy)-1-phenyl-2-buten-1-yl Benzoate
(1f). Starting from 7.0 mmol of 4f, almost pure 5f (1.87 g) was
obtained. Then 800 mg of the intermediary 5f was used to give 1f (783
mg, 67% for 2 steps) as an oil. 1H NMR (400 MHz, CDCl3): 4.05 (d, J
= 5.5 Hz, 2H), 4.46 (s, 2H), 5.95 (dt, J = 16.4, 5.5 Hz, 1H), 6.03 (dd, J
= 16.4, 5.9 Hz, 1H), 6.53 (d, J = 5.9 Hz, 1H), 7.25−7.59 (m, 12H),
8.09 (d, J = 8.9 Hz, 2H). 13C NMR (100 MHz, CDCl3): 69.8, 71.5,
75.8, 126.9, 128.1, 128.3, 128.4, 128.6, 129.0, 129.3, 129.6, 130.1,
130.8, 133.0, 133.3, 136.5, 138.9, 165.4. IR (neat): 3062, 3032, 2854,
1718, 1600, 1584, 1491, 1451, 1396, 1314, 1267, 1200, 1176, 1108,
1025, 1015, 968, 841, 807, 757, 712 cm−1. HRMS (EI): calcd for
C24H21ClO3 [M+] 392.1179, found 392.1175.
(E)-4-(2-Naphthalenylmethoxy)-1-phenyl-2-buten-1-yl Ben-
zoate (1g). Starting from 5.5 mmol of 4g, almost pure 5g (1.35 g)
was obtained. Then 802 mg of the intermediary 5g was used to give 1g
1
(463 mg, 35% for 2 steps) as an oil. H NMR (400 MHz, CDCl3):
4.11 (d, J = 5.5 Hz, 2H), 4.67 (s, 2H), 5.98 (dt, J = 15.5, 5.5 Hz, 1H),
6.06 (dd, J = 15.5, 5.5 Hz, 1H), 6.55 (d, J = 5.5 Hz, 1H), 7.30−7.58
(m, 11H), 7.75−7.84 (m, 4H), 8.09 (d, J = 8.2 Hz, 2H). 13C NMR
(100 MHz, CDCl3): 69.7, 72.4, 75.9, 125.7, 125.8, 126.0, 126.5, 127.0,
127.6, 127.8, 128.1, 128.3, 128.6, 129.5, 129.6, 130.1, 130.7, 132.8,
132.9, 133.1, 135.4, 139.0, 165.4. IR (neat): 3058, 2852, 1716, 1601,
1508, 1492, 1451, 1314, 1267, 1175, 1107, 1069, 1025, 966, 856, 818,
753, 712 cm−1. HRMS (EI): calcd for C28H24O3 [M+] 408.1725, found
408.1729.
(E)-4-((2-Methylbenzyl)oxy)-1-phenyl-2-buten-1-yl Benzoate
(1b). Starting from 5.0 mmol of 4b, almost pure 5b (1.22 g) was
obtained. Then 708 mg of the intermediary 5b was used to give 1b
1
(644 mg, 61% for 2 steps) as an oil. H NMR (400 MHz, CDCl3):
2.30 (s, 3H), 4.08 (d, J = 5.0 Hz, 2H), 4.50 (s, 2H), 5.97 (dt, J = 15.6,
5.0 Hz, 1H), 6.05 (dd, J = 15.6, 5.5 Hz, 1H), 6.54 (d, J = 5.5 Hz, 1H),
7.15−7.58 (m, 12H), 8.09 (d, J = 9.6 Hz, 2H). 13C NMR (100 MHz,
CDCl3): 18.7, 69.7, 70.5, 75.8, 125.6, 126.9, 127.7, 128.1, 128.3, 128.5,
129.6, 130.1, 130.6, 132.9, 135.8, 136.6, 139.0, 165.3. IR (neat): 3063,
3031, 2855, 1719, 1601, 1493, 1452, 1314, 1266, 1176, 1107, 1070,
1025, 968, 746, 712 cm−1. HRMS (EI): calcd for C25H24O3 [M+]
372.1725, found 372.1728.
(E)-4-(Benzyloxy)-1-(4-tolyl)-2-buten-1-yl Benzoate (1h).
Starting from 5.2 mmol of 4h, almost pure 5h (1.32 g) was obtained.
Then 715 mg of the intermediary 5h was used to give 1h (615 mg,
58% for 2 steps) as an oil. 1H NMR (400 MHz, CDCl3): 2.34 (s, 3H),
4.06 (d, J = 5.0 Hz, 2H), 4.50 (s, 2H), 5.95 (dt, J = 15.5, 5.0 Hz, 1H),
6.03 (dd, J = 15.5, 5.5 Hz, 1H), 6.50 (d, J = 5.5 Hz, 1H), 7.16−7.57
(m, 12H), 8.08 (d, J = 6.8 Hz, 2H). 13C NMR (100 MHz, CDCl3):
21.2, 69.8, 72.3, 75.9, 127.1, 127.6, 127.8, 128.3, 128.4, 128.6, 129.2,
12658
dx.doi.org/10.1021/jo402272r | J. Org. Chem. 2013, 78, 12654−12661

The Journal of Organic Chemistry
Article
129.3, 129.7, 130.2, 130.9, 133.0, 136.0, 138.0, 165.5. IR (neat): 3030,
2921, 2857, 1717, 1601, 1514, 1495, 1452, 1315, 1267, 1176, 1108,
1069, 1025, 968, 816, 737, 711 cm−1. HRMS (EI): calcd for C25H24O3
[M+] 372.1725, found 372.1730.
1H), 6.00 (dd, J = 15.1, 6.4 Hz, 1H), 6.47 (dd, J = 15.1, 10.5 Hz, 1H),
6.58 (d, J = 15.6 Hz, 1H), 6.78 (dd, J = 15.6, 10.5 Hz, 1H).
(2Z,4E)-1-(2-Methylphenyl)-5-phenyl-2,4-pentadien-1-ol
(2b). Compound 2b (56 mg, 65% from 0.35 mmol 1b) was obtained
1
as an oil. H NMR (400 MHz, CDCl3): 1.92 (br, 1H), 2.36 (s, 3H),
(E)-4-(Benzyloxy)-1-(2-naphthalenyl)-2-buten-1-yl Benzoate
(1i). Starting from 4.8 mmol of 4i, almost pure 5i (1.29 g) was
obtained. Then 667 mg of the intermediary 5i was used to give 1i (528
mg, 53% for 2 steps) as an oil. 1H NMR (400 MHz, CDCl3): 4.08 (d, J
= 5.5 Hz, 2H), 4.51 (s, 2H), 5.99 (dt, J = 15.5, 5.5 Hz, 1H), 6.13 (dd, J
= 15.5, 5.9 Hz, 1H), 6.71 (d, J = 5.9 Hz, 1H), 7.24−7.61 (m, 11H),
7.80−7.93 (m, 4H), 8.12 (d, J = 7.3 Hz, 2H). 13C NMR (100 MHz,
CDCl3): 70.7, 73.3, 77.0, 125.7, 127.10, 127.16, 127.19, 128.6, 128.7,
129.0, 129.3, 129.4, 130.6, 130.7, 131.1, 131.5, 133.9, 134.0, 137.3,
138.8, 166.4. IR (neat): 3059, 2853, 1717, 1601, 1508, 1452, 1361,
1314, 1266, 1175, 1106, 1069, 1025, 968, 858, 818, 749, 711 cm−1.
HRMS (EI): calcd for C28H24O3 [M+] 408.1725, found 408.1727.
(E)-6-(Benzyloxy)-2,2-dimethyl-4-hexen-3-yl Benzoate (1j).
Starting from 4.6 mmol of 4j, almost pure 5j (866 mg) was obtained.
Then 494 mg of the intermediary 5j was used to give 1j (328 mg, 37%
for 2 steps) as an oil. 1H NMR (400 MHz, CDCl3): 1.02 (s, 9H), 4.04
(d, J = 4.5 Hz, 2H), 4.50 (s, 2H), 5.28 (d, J = 6.0 Hz, 1H), 5.84 (dd, J
= 15.5, 6.0 Hz, 1H), 5.86 (dt, J = 15.5, 4.5 Hz, 1H), 7.26−7.38 (m,
5H), 7.45 (dd, J = 7.8, 7.7 Hz, 2H), 7.57 (t, J = 7.8 Hz, 1H), 8.07 (d, J
= 7.7 Hz, 2H). 13C NMR (100 MHz, CDCl3): 25.9, 34.7, 69.7, 71.9,
81.4, 127.5, 127.7, 127.9, 128.3, 129.5, 130.5, 130.7, 132.8, 138.0,
165.6. IR (neat): 3063, 3031, 2965, 2868, 1718, 1601, 1452, 1395,
1365, 1316, 1270, 1176, 1111, 1069, 1025, 970, 736, 711 cm−1. HRMS
(EI): calcd for C22H26O3 [M+] 338.1882, found 338.1878.
5.62 (dd, J = 11.0, 8.7 Hz, 1H), 5.95 (d, J = 8.7 Hz, 1H), 6.28 (t, J =
11.0 Hz, 1H), 6.63 (d, J = 15.6 Hz, 1H), 7.21 (dd, J = 15.6, 11.0 Hz,
1H), 7.24−7.59 (m, 9H). Selected data of (2E,4E)-isomer; 5.51 (d, J =
6.8 Hz, 1H), 5.81 (dd, J = 15.5, 6.4 Hz, 1H), 6.43 (dd, J = 15.5, 11.0
Hz, 1H), 6.58 (d, J = 16.0 Hz, 1H), 6.78 (dd, J = 16.0, 11.0 Hz, 1H).
13C NMR (100 MHz, CDCl3): 19.4, 67.4, 123.3, 125.3, 126.4, 126.6,
127.5, 128.0, 128.7, 130.4, 130.5, 132.3, 134.9, 135.1, 136.9, 141.2. IR
(neat): 3440, 3024, 1599, 1489, 1457, 1372, 1241, 1158, 1046, 989,
749, 699 cm−1. HRMS (EI): calcd for C18H18O [M+] 250.1358, found
250.1359.
(2Z,4E)-1-(3-Methylphenyl)-5-phenyl-2,4-pentadien-1-ol
(2c). Compound 2c (50 mg, 58% from 0.35 mmol 1c) was obtained as
an oil. 1H NMR (400 MHz, CDCl3): 1.97 (br, 1H), 2.40 (s, 3H), 5.68
(dd, J = 11.0, 9.1 Hz, 1H), 5.78 (d, J = 9.1 Hz, 1H), 6.29 (t, J = 11.0
Hz, 1H), 6.63 (d, J = 15.5 Hz, 1H), 7.08−7.12 (m, 1H), 7.23−7.44
(m, 9H). 13C NMR (100 MHz, CDCl3): 21.5, 70.1, 123.0, 123.4,
126.55, 126.61, 128.0, 128.4, 128.5, 128.7, 130.2, 133.1, 135.0, 137.0,
138.4, 143.1. IR (neat): 3331, 3025, 1605, 1489, 1448, 1306, 1152,
1029, 987, 946, 779, 754, 692 cm−1. HRMS (EI): calcd for C18H18O
[M+] 250.1358, found 250.1347.
(2Z,4E)-1-(4-Methylphenyl)-5-phenyl-2,4-pentadien-1-ol
(2d). Compound 2d (55 mg, 63% from 0.35 mmol 1d) was obtained
1
as an oil. H NMR (400 MHz, CDCl3): 1.95 (br, 1H), 2.34 (s, 3H),
5.69 (dd, J = 11.0, 9.1 Hz, 1H), 5.79 (d, J = 9.1 Hz, 1H), 6.28 (t, J =
11.0 Hz, 1H), 6.63 (d, J = 15.1 Hz, 1H), 7.16−7.44 (m, 10H). 13C
NMR (100 MHz, CDCl3): 21.1, 70.0, 123.4, 125.8, 126.6, 127.9,
128.7, 129.3, 130.1, 133.2, 134.9, 137.0, 137.4, 140.2. IR (neat): 3421,
3024, 2920, 1604, 1512, 1492, 1449, 1374, 1242, 1178, 1044, 986, 811,
749, 693 cm−1. HRMS (EI): calcd for C18H18O [M+]: 250.1358, found
250.1363.
(E)-6-(Benzyloxy)-2-methyl-4-hexen-3-yl Benzoate (1k).
Starting from 7.4 mmol of 4k, almost pure 5k (1.58 g) was obtained.
Then 547 mg of the intermediary 5k was used to give 1k (528 mg,
1
57% for 2 steps) as an oil. H NMR (400 MHz, CDCl3): 1.00 (d, J =
6.9 Hz, 3H), 1.01 (d, J = 6.4 Hz, 3H), 1.99−2.10 (m, 1H), 4.04 (d, J =
5.5 Hz, 2H), 4.50 (s, 2H), 5.35 (t, J = 6.4 Hz, 2H), 5.80 (dd, J = 16.5,
6.4 Hz, 1H), 5.87 (dt, J = 16.5, 5.5 Hz, 1H), 7.26−7.58 (m, 8H), 8.06
(d, J = 8.2 Hz, 2H). 13C NMR (100 MHz, CDCl3): 18.0, 18.2, 32.2,
69.8, 72.0, 78.9, 127.5, 127.7, 128.2, 128.3, 129.1, 129.5, 130.0, 132.8,
138.0, 165.7. IR (neat): 3063, 3031, 2965, 2873, 1717, 1601, 1584,
1494, 1452, 1387, 1368, 1270, 1176, 1111, 1069, 1025, 971, 738, 712
cm−1. HRMS (EI): calcd for C21H24O3 [M+] 324.1725, found
324.1721.
Representative Procedure for Sequential 1,4-Elimination
Reaction and [1,2]-Wittig Rearrangement of (E)-2-Butenyl
Benzoate 1a (Table 2, entry 1). To a mixture of powdered KOH
(21 mg, 1.05 mmol) and [Pd(dppe)2] (16 mg, 0.018 mmol) was
added compound 1a (125 mg, 0.35 mmol) in THF (12 mL) dropwise
at room temperature, and the reaction mixture was stirred for 18 h.
After MS4A was added and the resulting mixture was stirred for 30
min, the mixture was cooled to 0 °C, and n-BuLi (1.27 mL of 1.62 M
solution in hexane, 2.1 mmol) was added. After 5 min, the reaction
mixture was quenched with a satd aq solution of NH4Cl. The aqueous
layer was separated and extracted with Et2O. The combined organic
extracts were washed with H2O and brine and dried over Na2SO4. The
crude product was purified by silica gel column chromatography
(hexane/AcOEt = 10/1 with 1% Et3N) to give 2a (56 mg, 68%, Z/E =
>20/1) as an oil.
(2Z,4E)-1-(4-Methoxyphenyl)-5-phenyl-2,4-pentadien-1-ol
(2e). Compound 2e (66 mg, 71% from 0.35 mmol 1e) was obtained as
an oil. 1H NMR (400 MHz, CDCl3): 1.92 (br, 1H), 3.80 (s, 3H), 5.71
(dd, J = 11.0, 8.7 Hz, 1H), 5.77 (d, J = 8.7 Hz, 1H), 6.28 (t, J = 11.0
Hz, 1H), 6.63 (d, J = 15.5 Hz, 1H), 6.90 (d, J = 8.6 Hz, 2H), 7.18 (dd,
J = 15.5, 11.0 Hz, 1H), 7.26−7.44 (m, 7H). Selected data of (2E,4E)-
isomer; 5.29 (m, 1H), 5.99 (dd, J = 15.1, 6.4 Hz, 1H), 6.46 (dd, J =
15.1, 10.5 Hz, 1H), 6.57 (d, J = 15.5 Hz, 1H), 6.78 (dd, J = 15.5, 10.5
Hz, 1H). 13C NMR (100 MHz, CDCl3): 55.3, 69.7, 114.0, 123.4,
126.6, 127.2, 127.9, 128.6, 129.8, 133.2, 134.8, 135.3, 136.9, 159.1. IR
(neat): 3382, 3026, 2956, 2834, 1610, 1584, 1509, 1449, 1302, 1247,
1173, 1033, 986, 946, 862, 830, 741, 692 cm−1. HRMS (ESI-TOF):
calcd for C18H18O2Na [M + Na+] 289.1204, found 289.1198.
(2Z,4E)-1-(4-Chlorophenyl)-5-phenyl-2,4-pentadien-1-ol (2f).
Compound 2f (59 mg, 63% from 0.35 mmol 1f) was obtained as an
oil. 1H NMR (400 MHz, CDCl3): 1.98 (br, 1H), 5.62 (dd, J = 10.5, 9.1
Hz, 1H), 5.80 (d, J = 9.1 Hz, 1H), 6.31 (t, J = 10.5 Hz, 1H), 6.68 (d, J
= 15.5 Hz, 1H), 7.20 (dd, J = 15.5, 10.5 Hz, 1H), 7.25−7.42 (m, 9H).
Selected data of (2E,4E)-isomer; 5.30 (d, J = 6.4 Hz, 1H), 5.94 (dd, J =
15.1, 6.4 Hz, 1H), 6.46 (dd, J = 15.1, 11.0 Hz, 1H), 6.59 (d, J = 16.0
Hz, 1H), 6.77 (dd, J = 16.0, 11.0 Hz, 1H). 13C NMR (100 MHz,
CDCl3): 69.3, 123.0, 126.6, 127.3, 128.1, 128.7, 130.6, 132.5, 133.3,
135.5, 136.8, 141.5. IR (neat): 3351, 3027, 1636, 1595, 1489, 1449,
1400, 1090, 1013, 986, 945, 861, 826, 744, 691 cm−1. HRMS (EI):
calcd for C17H15OCl [M+] 270.0811, found 270.0814.
In a similar manner, (2Z,4E)-2,4-pentadien-1-ols 2b−2k were
obtained from 1b−1k.
(2Z,4E)-1,5-Diphenyl-2,4-pentadien-1-ol (2a).24 1H NMR (400
MHz, CDCl3): δ 2.04 (br s, 1H), 5.69 (dd, J = 11.0, 8.7 Hz, 1H), 5.81
(d, J = 8.7 Hz, 1H), 6.30 (t, J = 11.0 Hz, 1H), 6.64 (d, J = 15.5 Hz,
1H), 7.21 (dd, J = 15.5, 11.0 Hz, 1H), 7.26−7.45 (m, 10H). 13C NMR
(100 MHz, CDCl3): δ 70.0, 123.6, 125.9, 126.6, 127.5, 127.9, 128.5,
128.6, 130.1, 133.1, 134.9, 136.9, 143.1. IR (neat): 3366, 3027, 1599,
1492, 1449, 1280, 1073, 1027, 986, 945, 859, 740, 697 cm−1. HRMS
(EI): calcd for C17H16O [M+] 236.1201, found 236.1207.
(2Z,4E)-1-(2-Naphthalenyl)-5-phenyl-2,4-pentadien-1-ol
(2g). Compound 2g (68 mg, 68% from 0.35 mmol 1g) was obtained
1
as an oil. H NMR (400 MHz, CDCl3): 2.09 (br, 1H), 5.76 (dd, J =
11.0, 8.7 Hz, 1H), 5.98 (d, J = 8.7 Hz, 1H), 6.35 (t, J = 11.0 Hz, 1H),
6.67 (d, J = 15.1 Hz, 1H), 7.26−7.55 (m, 9H), 7.81−7.91 (m, 4H).
13C NMR (100 MHz, CDCl3): 70.2, 123.3, 124.1, 124.3, 125.9, 126.2,
126.6, 127.6, 128.0, 128.4, 128.7, 130.4, 132.8, 132.9, 133.3, 135.2,
136.8, 140.4. IR (neat): 3447, 3024, 1599, 1507, 1492, 1449, 1371,
1242, 1158, 1123, 1046, 990, 896, 858, 818, 747, 693 cm−1. HRMS
(EI): calcd for C21H18O [M+] 286.1358, found 286.1353.
During the optimization of the reaction conditions, a mixture of
(2Z,4E)-2a and the (2E,4E)-isomer was obtained as shown in Table 1.
Selected NMR data for the (2E,4E)-isomer:25 δ 5.32 (d, J = 6.4 Hz,
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(2Z,4E)-5-(4-Methylphenyl)-1-phenyl-2,4-pentadien-1-ol
(2h). Compound 2h (63 mg, 72% from 0.35 mmol 1h) was obtained
as an oil. H NMR (400 MHz, CDCl3): 1.98 (br, 1H), 2.35 (s, 3H),
Notes
The authors declare no competing financial interest.
1
5.66 (dd, J = 11.0, 8.7 Hz, 1H), 5.82 (d, J = 8.7 Hz, 1H), 6.29 (t, J =
11.0 Hz, 1H), 6.61 (d, J = 15.6 Hz, 1H), 7.13−7.48 (m, 10H). 13C
NMR (100 MHz, CDCl3): 21.3, 70.0, 122.4, 125.9, 126.5, 127.6,
128.6, 129.4, 130.4, 132.4, 134.1, 135.0, 138.0, 143.1. IR (neat): 3293,
3023, 1630, 1603, 1509, 1490, 1453, 1343, 1287, 1191, 1017, 984, 954,
941, 908, 839, 806, 765, 735, 696 cm−1. HRMS (EI): calcd for
C18H18O [M+] 250.1358, found 250.1343.
(2Z,4E)-5-(2-Naphthalenyl)-1-phenyl-2,4-pentadien-1-ol (2i).
Compound 2i (67 mg, 67% from 0.35 mmol 1i) was obtained as an
oil. 1H NMR (400 MHz, CDCl3): 2.05 (br, 1H), 5.73 (dd, J = 11.0, 9.1
Hz, 1H), 5.89 (d, J = 9.1 Hz, 1H), 6.37 (t, J = 11.0 Hz, 1H), 6.81 (d, J
= 15.6 Hz, 1H), 7.32−7.48 (m, 8H), 7.66 (d, J = 7.8 Hz, 1H), 7.78−
7.81 (m, 4H). Selected data of (2E,4E)-isomer; 5.35 (d, J = 5.9 Hz,
1H), 6.05 (dd, J = 15.1, 5.9 Hz, 1H), 6.54 (dd, J = 15.1, 9.6 Hz, 1H),
6.74 (d, J = 16.4 Hz, 1H), 6.88 (dd, J = 16.4, 9.6 Hz, 1H). 13C NMR
(100 MHz, CDCl3): 70.1, 123.5, 123.6, 125.9, 126.1, 126.4, 126.9,
127.6, 127.7, 128.0, 128.3, 128.6, 130.3, 133.10, 133.15, 133.5, 134.4,
135.2, 143.0. IR (neat): 3397, 3030, 1626, 1600, 1506, 1491, 1454,
1268, 1115, 1008, 985, 953, 851, 822, 750, 700 cm−1. HRMS (EI):
calcd for C21H18O [M+] 286.1358, found 286.1363.
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1
pound 2j (44 mg, 53% from 0.35 mmol 1j) was obtained an oil. H
NMR (400 MHz, CDCl3): 1.06 (s, 9H), 1.90 (br, 1H), 5.51 (dd, J =
11.0, 8.7 Hz, 1H), 5.72 (d, J = 8.7 Hz, 1H), 5.83 (d, J = 15.1 Hz, 1H),
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698 cm−1. HRMS (EI): calcd for C15H20O [M+] 216.1514, found
216.1522.
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A mixture of 2k and 3 (40 mg, 59% from 0.35 mmol 1k) was
1
obtained as an oil. The yields of 2k and 3 were determined by H
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NMR spectrum of their mixture. After further separation of 2k and 3
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(2Z,4E)-6-Methyl-1-phenyl-2,4-heptadien-1-ol (2k). Com-
pound 2k (34% from 0.35 mmol 1k). 1H NMR (400 MHz,
CDCl3): 1.03 (d, J = 6.9 Hz, 3H), 1.04 (d, J = 6.9 Hz, 3H), 1.89
(br, 1H), 2.35−2.43 (m, 1H), 5.50 (dd, J = 11.0, 8.7 Hz, 1H), 5.70 (d,
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(E)-6-Methyl-1-phenyl-3,5-heptadien-1-ol (3). Compound 3
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(25% from 0.35 mmol 1k). H NMR (400 MHz, CDCl3): 1.75 (s,
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1H), 2.89 (dd, J = 13.2, 5.0 Hz, 1H), 4.40 (dd, J = 12.4, 5.0 Hz, 1H),
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ASSOCIATED CONTENT
■
S
* Supporting Information
1H NMR and 13C NMR spectra of compounds 1−4. This
material is available free of charge via the Internet at http://
pubs.acs.org.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: ukaji@staff.kanazawa-u.ac.jp.
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