Efficient Synthesis of 4-(3′-Furanyl)butenolide Derivatives via PdII-Catalyzed Oxidative Heterodimeric Cyclization Reaction of 2,3-Allenoic Acids and 1,2-Allenyl Ketones

Article abstract of DOI:10.1002/chem.200305341

The oxidative cyclization/dimerization reaction between two classes of allenes with different functionalities was reported to provide an efficient route to polysubstituted 4-(3′-furanyl)-2(5H)-furanones, which are not readily available from the known methods. The highly optically active butenolides could be easily formed from the optically active 2,3-allenoic acids, which was obtained conveniently through chiral resolution with optically active amines, that is, cinchonidine or α-methyl benzylamine. A mechanistic study showed that the reaction proceeded via a matched double oxypalladation-reductive elimination process. The Pd^II species may be regenerated via the subsequent cyclometallation of two equivalents of 1,2-allenyl ketones with Pd⁰ and protonlysis of Pd enolates formed with the in situ generated HCl.

Full text of DOI:10.1002/chem.200305341

FULL PAPER
Efficient Synthesis of 4-(3’-Furanyl)butenolide Derivatives via PdII-Catalyzed
Oxidative Heterodimeric Cyclization Reaction of 2,3-Allenoic Acids and
1,2-Allenyl Ketones
Shengming Ma* and Zhanqian Yu[a]
Abstract: The oxidative cyclization/di-
merization reaction between two
classes of allenes with different func-
tionalities was reported to provide an
efficient route to polysubstituted 4-(3’-
furanyl)-2(5H)-furanones, which are
not readily available from the known
methods. The highly optically active
butenolides could be easily formed
from the optically active 2,3-allenoic
acids, which was obtained conveniently
through chiral resolution with optically
active amines, that is, cinchonidine or
a-methyl benzylamine. A mechanistic
study showed that the reaction pro-
ceeded via a matched double oxypalla-
dation reductive elimination process.
The PdII species may be regenerated
via the subsequent cyclometallation of
two equivalents of 1,2-allenyl ketones
with Pd0 and protonlysis of Pd enolates
formed with the in situ generated HCl.
Keywords: allenes
¥
chirality
¥
cyclization ¥ furans ¥ lactones
Introduction
we reported the oxidative self-dimeric cyclization reaction
of 2,3-allenoic acids,[18] producing bicyclic bibutenolides, in
which the catalyst was regenerated with alkyl iodide and
oxygen. The more attractive pattern is dimeric cyclization
reaction between two differently functionalized allenes to
give interesting compounds with two different cycles in a
single step. The formidable challenges are to match the reac-
tivities of two different allenes and regenerate the catalyst.
More significantly, optically active products may be formed
via the efficient transfer of chirality of allenes.
Allenes are a class of compounds with a 1,2-diene function-
ality possessing two perpendicular p-orbitals showing
unique reactivities due to the presence of the axial chirality
as well as the substituent-loading capability.[1] At present, a
series of preparative useful methodologies are available to
access substituted allenes,[2] which can serve as potential pre-
cursors for the synthesis of highly complex and strained
target molecules of biological and industrial importance.[3,4]
Three reaction patterns were established in the cyclization
reactions of functionalized allenes (Scheme 1). One is the
In
a
preliminary communication, we described
a
[Pd(CH3CN)2Cl2]-catalyzed one step methodology for the
efficient synthesis of b-(3’-furanyl)butenolides via oxidative
cyclization dimerization reaction of 2,3-allenoic acids and
1,2-allenyl ketones.[19] Here, we wish to present a detailed
study on this reaction: the scope of the reaction, mechanism,
and the highly efficient chirality transfer leading to optically
active butenolides.
6]
14]
uniallene reaction. We[5 and others[7
have established
the transition-metal-catalyzed or mediated cyclization reac-
tion of functionalized allenes for the formation of carbon
À
À
carbon bonds as well as carbon heteroatom bonds leading
to cyclic products. The second pattern is the self-dimeriza-
tion cyclization reactions of functionalized allenes. In this
area, three reaction pathways were observed. In the dimeric
reactions leading to monocyclic products,[15] the catalyst was
regenerated by b-heteroatom elimination for the reactions
with allenols, while the dimeric reactions of 1,2-allenyl ke-
tones regenerated the catalyst via protonation.[16,17] Recently,
Results and Discussion
Optimization of reaction conditions for oxidative dimeric
coupling reaction: We studied the PdII-catalyzed oxidative
dimerization cyclization reaction of 2,3-allenoic acid 1a and
1,2-allenyl ketone 2a under different reaction conditions.
The results are summarized in Table 1 showing that the oxi-
dative dimeric coupling reaction occurred smoothly. These
phenomena elucidate that the reactivities of 2,3-allenoic
acids and 1,2-allenyl ketones may be well matched. Under
the catalysis of 5 mol% [PdCl2(CH3CN)2], the cyclizative
[a] Prof. S. Ma, Dr. Z. Yu
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry
Chinese Academy of Sciences, 354 Fenglin Lu
Shanghai 200032 (PR China)
Fax : (+86)21-64166128
E-mail: masm@mail.sioc.ac.cn
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DOI: 10.1002/chem.200305341
Chem. Eur. J. 2004, 10, 2078 2087

2078 2087
(Table 1, entry 5). The best results were obtained in CH3CN
(Table 1, entry 6) with 5 equiv 2a. With less amount of 1,2-
propdienyl methyl ketone 2a, the reaction in CH3CN also
afforded 4a as the by-product (Table 1, entry 7).
Oxidative dimeric cyclization reaction of 2,3-allenoic acids
and 1,2-allenyl ketones: Using these standard conditions, the
oxidative dimerization cyclization reaction of various 2,3-al-
lenoic acids bearing different R1, R2 and R3 substituents
with different 1,2-allenyl ketones were studied. From the re-
sults summarized in Table 2, we observed that the reaction
can be furnished under mild conditions (RT, 4 h) and the
yields are from moderate to fairly good. It should be noted
that this is the first example of oxidative sequential cycliza-
tive cross coupling reaction of two differently functionalized
allenes to give interesting bicyclic compounds in a single
step. In this reaction, differently substituted 2,3-allenoic
acids could be used: monosubstituted 2,3-allenoic acids re-
acted with the 1,2-allenyl ketones smoothly to give the cor-
responding products (Table 2, entries 9, 16 and 22); disubsti-
tuted 2,3-allenoic acids are more popularly used in this reac-
tion. The substituents of 2,3-allenoic acids could be aryl,
alkyl, benzyl and allyl. As a result of the allyl group, further
elaboration of the C=C bond may provide an efficient
access to other butenolide derivatives (Table 2, entries 4, 13
and 19); with the fully substituted 2,3-allenoic acids, the re-
action also afforded the products in fairly good yields
(Table 2, entries 8, 15 and 21). Furthermore, the substituent
of 1,2-allenyl ketones could be an alkyl or benzyl group.
The polysubstituted 1,2-allenyl ketones, however, could not
be used to yield the corresponding products probably due to
the low reactivity towards oxypalladation [Eqs. (1) and (2)].
Scheme 1. Three reaction patterns for cyclization of functionalized al-
lenes.
Table 1. Cyclizative cross coupling reaction of 1a and 2a.[a]
Entry
Solvent
t [h]
Yield of 3a [%]
Yield of 4a [%]
1
2
THF
CH2Cl2
11
11
11
40
14
0
2314
0
3acetone
4
5
6
toluene
DMA
CH3CN
CH3CN
CH3CN
CH3CN
16.5
17.5
4
11.5
4
1318
76
90
57
90
0
0
12
0
7[b]
8[c]
9[d]
11
0
[a] The reaction was carried out in
a
solvent (3mL) using 1a
(0.25 mmol), 2a (1.25 mmol), and 5 mol% [PdCl2(CH3CN)2]. [b] 3equiv
2a were used. [c] The reaction was carried out in an atmosphere of
argon. [d] 1 equiv K2CO3 and 1 equiv Bu4NBr were used.
cross coupling reaction of 3-(n-propyl)-4-phenyl-2,3-butadie-
noic acid (1a) with five equivalents of 1,2-propdienyl methyl
ketone (2a) in THF afforded a 14% yield of 3-(n-propyl)-4-
Chirality transfer: After matching the reactivities of 2,3-alle-
noic acids with 1,2-allenyl ketones, we turned our attention
to the synthesis of the optically active b-(3’-furanyl)buteno-
lide. From our previous work, we could easily obtain the op-
tically active 2,3-allenoic acids via chiral resolution of 2,3-al-
lenoic acids with optically active amines.[1d] With the optical-
ly active (S)-(+)-2,3-allenoic acid (1j) (99% ee) in hand, we
examined the oxidative coupling cyclization reaction of 1,2-
pentadien-3-one 2a with 1j under the standard reaction con-
ditions [Eq. (3)].
(3’-(5’-methyl)furanyl)-5-phenyl-2(5H)-furanone
(3a)
(Table 1, entry 1). The structure of compound 3a was con-
firmed by the X-ray single crystal diffractional analysis
(Figure 1).[20]
The reaction can also be carried out in CH2Cl2, acetone,
toluene, DMA, and CH3CN. In CH2Cl2 or toluene, the
major by-product is the cycloisomerization product of 1a,
that is, furanone 4a (Table 1, entries 2 and 4). The reaction
in DMA afforded 3a in 76% yield highly selectively
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S. Ma and Z. Yu
FULL PAPER
dard reaction conditions. The
absolute configuration of the
product 3j was determined by
the X-ray single crystal diffrac-
tional analysis (Figure 2).[21]
From (S)-(+)-2,3-allenoic acids
1j, the product 3j was obtained
in S configuration, which indi-
cates that the reaction may pro-
ceed via the PdII-mediated oxy-
palladation rather than the p-
allyl Pd-formating carbopalla-
dation mechanism.[23]
Some other typical results
are listed in Table 3; the yields
ranged from moderate to excel-
lent. The chirality of 2,3-alleno-
ic acids was completely trans-
ferred into the products. The
absolute configurations of other
products were assigned based
on the absolute configuration of
2,3-allenoic acids according to
the oxypalladation result of (S)-
1j [Eq. (3)].
Figure 1. The X-ray structure of compound 3a.
Table 2. PdII-Catalyzed cyclizative cross coupling reaction of 2,3-allenoic acids and 1,2-allenyl ketones.[a]
Entry
1
2
3
Yield [%]
R1
R2
R3
R4
1
2
3Ph
4
5
6
7
8
9
10
11
12
13Ph
14
15
16
17
18
19
20
21
22
Ph
Ph
nC3H7
CH3
H (1a)
H (1b)
H (1c)
H (1d)
H (1e)
H (1 f)
H (1g)
Et (1h)
H (1i)
H (1j)
H (1a)
H (1b)
1d)
H (1e)
Et (1h)
H (1i)
H (1a)
H (1b)
H (1d)
H (1e)
Et (1h)
H (1i)
CH3 (2a)
CH3 (2a)
CH3 (2a)
CH3 (2a)
CH3 (2a)
CH3 (2a)
CH3 (2a)
CH3 (2a)
3a
3b
3c
3d
3e
3 f
3g
3h
3i
90
73
92
86
84
86
90
85
69
70
84
63
66
79
86
69
74
86
82
90
84
71
Mechanism of oxidative dimeric
cyclization reaction: Comparing
the products with starting mate-
rials, we observed that two hy-
drogen atoms were lost after
the reaction. Where had they
gone? Two control experiments
were conducted to answer this
question. In an atmosphere of
argon, the reaction occurred
smoothly to afford 3a in 90%
yield (Table 1, entry 8), indicat-
ing that oxygen does not partic-
ipate the catalytic cycle. Anoth-
er interesting point is that the
reaction did not yield 3a in the
presence of 1 equiv K2CO3
(Table 1, entry 9), indicating
that H+ may be formed from
the loss of two protons from
both starting materials and
plays an important role in this
reaction.
PhCH
2
Ph
allyl
CH3
nC3H7
a-naphthyl
a-naphthyl
CH3
PhCH2
CH3
H
nC3H7
nC3H7
CH3
H (
CH3
CH3
H
nC3H7
CH3
allyl
CH3
CH3
H
Ph
nC7H15
4-Br-Ph
Ph
CH3 (2a)
CH3 (2a)
3j
3k
3l
nC4H9 (2b)
nC4H9 (2b)
nC4H9 (2b)
nC4H9 (2b)
nC4H9 (2b)
nC4H9 (2b)
PhCH2 (2c)
PhCH2 (2c)
PhCH2 (2c)
PhCH2 (2c)
PhCH2 (2c)
PhCH2 (2c)
Ph
allyl
3m
3n
3o
3p
3q
3r
3s
3t
a-naphthyl
Ph
nC7H15
Ph
Ph
Ph
a-naphthyl
Ph
nC7H15
3u
3v
[a] The reaction was carried out in CH3CN (3mL) using
[PdCl2(CH3CN)2].
1 (0.25 mmol), 2 (1.25 mmol), and 5 mol%
Further study shows that the reaction also afforded the
homodimerization product of 2a, (i.e., furan 5a), 4,5-dime-
thyleneocta-2,7-dione (6a) and its C=C double bond isomers
7a, and 8a as the by-products (Scheme 2). The structures of
6a, 7a and 8a were established by the X-ray single crystal
diffractional analysis of 8a (Figure 3),[22] indicating that the
missing hydrogens were transferred from starting materials
into 2,4-dien-1,6-diketones 6a, 7a and 8a.
We found that the reaction occurred smoothly to give the
product 3j in a 76% yield and 99% ee. This result elucidat-
ed that chirality transfer is highly efficient under the stan-
Based on these facts, a plausible mechanism is proposed
for this reaction (Scheme 3). Firstly, the intermediate 9a is
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(Furanyl)butenolide Derivatives
2078 2087
Figure 2. The X-ray structure analysis shows that compound 3j is in S configuration.
Scheme 2. Oxidative cyclization-dimerization reaction of 2,3-allenoic acid
1a with 1,2-allenyl ketone 2a. [a] Yields are calculated based on penta-
3,4-dienone.
Scheme 3. Proposed catalytic cycle for the oxidative cyclization dimeriza-
tion reaction.
Conclusion
We have realized the first example of oxidative cyclization/
dimerization reaction between two kinds of allenes with dif-
ferent functionalities providing an efficient route to polysub-
stituted 4-(3’-furanyl)-2(5H)-furanone (3), which are not
readily available by known method. In this reaction, the
chirality transfer was highly efficient. The highly optical
active butenolides could be easily formed from the optically
active 2,3-allenoic acids, which can be prepared conveniently
through chiral resolution of racemic 2,3-allenoic acids with
optically active amines. The control experiment showed that
the product 3 along with the Pd0 species may be generated
from the reductive elimination of palladium intermediate
9a. Then the Pd0 species cyclometalated with 2 equiv alka-
1,2-dien-3-one followed by protonation with the in situ gen-
erated HCl to regenerate [LnPdCl2] to furnish the catalytic
Figure 3. ORTEP drawing of compound 8a.
formed from the 1,2-allenoic ketone and 2,3-allenoic acids
via double oxypalladation, which is further supported by the
highly efficient chirality transfer. In our previous work, we
observed that the chirality transfer is not efficient in a car-
bopalladation pathway but very efficient in an oxypallada-
tion pathway.[24] After the reductive elimination of 9a, the
product 3a is formed along with the Pd0 species. Then, the
Pd0 species cyclometalate with 2 equiv of penta-3,4-dien-2-
one to form the cyclic Pd intermediate 10a and/or 10a’,[25]
which may be protonated with the in situ generated HCl
(2 equiv) to form 6a, 7a and 8a and regenerate LnPdCl2 to
furnish the catalytic cycle.[26]
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S. Ma and Z. Yu
FULL PAPER
Table 3. PdII-Catalyzed cross coupling cyclizations of 1,2-allenyl ketones with optically active 2,3-allenoic acids.
Entry
1
1
2
3
Yield of 3
ee% of 3
2a
87
95
(S)-(+)-1a (98% ee)
2
3
2b
2c
75
86
>99
>99
(R)-(À)-1a (97% ee)
(R)-(À)-1a (97% ee)
4
5
6
7
2a
2b
2c
2a
76
97
99
96
(R)-(À)-1b (99% ee)
(R)-(À)-1b (99% ee)
81
(R)-(À)-1b (99% ee)
72
7397
(S)-(À)-1d (98% ee)
(S)-(À)-1d (98% ee)
8
9
2b
2c
2a
67
67
74
99
98
97
(S)-(À)-1d (98% ee)
10
(S)-(+)-1e (98% ee)
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(Furanyl)butenolide Derivatives
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Table 3. (Continued)
Entry
11
1
2
3
Yield of 3
ee% of 3
(S)-(+)-1e (98% ee)
2b
76
99
12
(S)-(+)-1e (98% ee)
2c
87
>99
2H), 3.97 (AB, A part of AB, J=15.4 Hz, Dn˜ =18 Hz, 1H), 3.91 (AB, B
part of AB, J=15.4 Hz, Dn˜ =18 Hz, 1H), 2.19 (s, 3H); 13C NMR (CDCl3,
75.4 MHz): d=13.16, 30.10, 83.10, 104.60, 117.77, 124.24, 126.52, 127.76,
127.96, 128.68, 128.96, 129.49, 135.51, 137.51, 141.80, 151.84, 153.81,
174.02; MS (70 eV): m/z (%): 331 (28.96) [M ++H], 330 (100) [M +]; IR
(neat): n˜ =1743, 1648, 1601, 1585, 1538 cmÀ1; elemental analysis calcd for
C22H18O3 (%): C 79.98, H 5.49; found C 80.27, H 5.57.
cycle. Synthetic application for target molecules with poten-
tial bioactivities is currently being carried out in our labora-
tory.
Experimental Section
3-Allyl-4-(3’-(5’-methylfuranyl))-5-phenyl-2(5H)-furanone (3d):
A mix-
ture of 1d (50 mg, 0.25 mmol), 2a (108 mg, 1.32 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 6 h. Flash chromatography on silica gel (petroleum
ether/ethyl acetate 5:1) afforded 3d as an oil (60 mg, 86%). 1H NMR
(CDCl3, 300 MHz): d=7.40 7.25 (m, 5H), 7.22 (s, 1H), 6.03 5.90 (m,
3H), 5.22 5.14 (m, 2H), 3.36 3.30 (m, 2H), 2.23 (s, 3H); 13C NMR
(CDCl3, 75.4 MHz): d=13.20, 28.33, 83.00, 104.68, 116.47, 117.69, 123.06,
127.74, 128.93, 129.49, 132.74, 135.43, 141.70, 151.73, 153.73, 173.76; MS
(70 eV): m/z (%): 281 (11.13) [M ++H], 280 (79.49) [M +], 146 (100); IR
(neat): n˜ =1751, 1655, 1605, 1540, 1455 cmÀ1; HRMS: m/z: calcd for
C18H16O3: 280.10995; found: 280.10757.
Synthesis of starting materials: Allenoic acids (1a j) were prepared ac-
cording to the known method by treatment of the acid chlorides with
ethyl 2-(triphenylphoranylidene) propionate and subsequent hydrolysis
of 2,3-allenoic esters with 1.5 equiv NaOH.[27] The optically active 2,3-al-
lenoic acids was prepared via chiral resolution with optically active
amine.[1c]
General procedure for the synthesis of compound 3: [PdCl2(CH3CN)2]
(5 mol%) was added to a mixture of 2,3-allenoic acids 1 (0.25 mmol),
1,2-allenyl ketones 2 (1.25 mmol) in CH3CN (3mL). Then the mixture
was stirred at room temperature for 4 h. After evaporation, the residue
was purified on a silica gel column to give pure compound 3.
3-Methyl-4-(3’-(5’-methylfuranyl))-5-(1’-naphthyl)-2(5H)-furanone (3e):
A mixture of 1e (56 mg, 0.25 mmol), 2a (103mg, 1.256 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/ethyl acetate 4:1, then CH2Cl2) afforded 3e as a white solid (64 mg,
84%). M.p. 151 1528C (ethyl acetate/petroleum ether); 1H NMR
(CDCl3, 300 MHz): d=8.17 (d, J=8.40 Hz, 1H), 7.81 (t, J=9.30 Hz,
2H), 7.58 7.42 (m, 2H), 7.30 (t, J=7.50 Hz, 1H), 7.19 7.10 (m, 2H), 6.66
(s, 1H), 5.93 (s, 1H), 2.16 (s, 3H), 2.11 (s, 3H); 13C NMR (CDCl3,
75.4 MHz): d=10.51, 13.18, 78.86, 104.64, 118.72, 122.32, 122.66, 125.15,
126.06, 126.37, 127.03, 128.89, 130.15, 131.21, 131.92, 133.77, 141.61,
150.20, 153.70, 174.27; MS (70 eV): m/z (%): 304 (100) [M +]; IR (neat):
n˜ =1736, 1653, 1607, 1600 cmÀ1; elemental analysis calcd for C20H16O3
(%): C 78.93, H 5.30; found C 78.89, H 5.27.
4-(3’-(5’-Methylfuranyl))-5-phenyl-3-propyl-2(5H)-furanone (3a): A mix-
ture of 1a (50 mg, 0.248 mmol), 2a (103mg, 1.26 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/Et2O 3:1) afforded 3a as a white solid (63mg, 90%). M.p. 84 85 8C
(ethyl acetate/petroleum ether); 1H NMR (CDCl3, 300 MHz): d=7.41
7.21 (m, 5H), 7.18 (s, 1H), 6.04 (s, 1H), 5.89 (s, 1H), 2.55 (t, J=8.26 Hz,
2H), 2.24 (s, 3H), 1.78 1.63 (m, 2H), 1.06 (t, J=7.33 Hz, 3H); 13C NMR
(CDCl3, 75.4 MHz): d=13.30, 14.14, 21.39, 26.51, 82.99, 104.77, 118.09,
126.24, 127.86, 129.04, 129.55, 135.85, 141.42, 150.37, 153.82, 174.30; MS
(70 eV): m/z (%): 283(28.39) [
M
++H], 282 (100) [M +]; IR (neat): n˜ =
2960, 2920, 1732, 1654, 1603 cmÀ1; elemental analysis calcd for C18H18O3
(%): C 76.57, H 6.43; found C 76.46, H 6.45.
3-Methyl-4-(3’-(5’-methylfuranyl))-5-phenyl-2(5H)-furanone (3b): A mix-
ture of 1b (44 mg, 0.253mmol), 2a (108 mg, 1.317 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (CH2Cl2,
then ethyl acetate/petroleum ether 1:2) afforded 3b as a white solid
4-(3’-(5’-Methylfuranyl))-5-(1’-naphthyl)-3-propyl-2(5H)-furanone (3 f): A
mixture of 1 f (126 mg, 0.5 mmol), 2a (205 mg, 2.5 mmol) and
[PdCl2(CH3CN)2] (6 mg, 0.023mmol) in acetonitrile (5 mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/Et2O 5:1) afforded 3 f as an oil (143mg, 86%). 1H NMR (CDCl3,
300 MHz): d=8.25 (d, J=8.56 Hz, 1H), 7.89 (t, J=9.17 Hz, 2H), 7.64
7.50 (m, 2H), 7.38 (t, J=7.95 Hz, 1H), 7.22 (d, J=7.33 Hz, 1H), 7.17 (s,
1H), 6.74 (s, 1H), 6.03(s, 1H), 2.68 2.58 (m, 2H), 2.20 (s, 3H), 1.81 1.67
(m, 2H), 1.10 (t, J=7.33 Hz, 3H); 13C NMR (CDCl3, 75.4 MHz): d=
13.22, 14.15, 21.23, 26.68, 78.76, 104.60, 118.33, 122.63, 125.17, 126.05,
126.26, 126.98, 127.01, 128.88, 130.09, 131.37, 131.89, 133.74, 141.50,
149.98, 153.76, 174.06; MS (70 eV): m/z (%): 333 (15.13) [M ++H], 332
1
(47 mg, 73%). M.p. 112 113 8C (ethyl acetate/petroleum ether); H NMR
(CDCl3, 300 MHz): d=7.40 7.35 (m, 3H), 7.30 7.23 (m, 2H), 7.22 (s,
1H), 6.03(s, 1H), 5.89 (s, 1H), 2.23(s, 3H), 2.15 (s, 3H);
13C NMR
(CDCl3, 75.4 MHz): d=10.23, 13.25, 82.99, 104.61, 118.32, 121.50, 127.86,
128.96, 129.54, 135.54, 141.44, 150.37, 153.67, 174.48; MS (70 eV): m/z
(%): 254 (100) [M +]; IR (neat): n˜ =1735, 1658, 1550, 1498 cmÀ1; elemen-
tal analysis calcd for C16H14O3 (%): C 75.57, H 5.55; found C 75.29, H
5.44.
(62.66) [M +], 84 (100); IR (neat): n˜ =2960, 1747, 1651, 1538, 1511 cmÀ1
HRMS: m/z: calcd for C22H20O3: 332.14125; found 332.14557.
;
3-Benzyl-4-(3’-(5’-methylfuranyl))-5-phenyl-2(5H)-furanone (3c): A mix-
ture of 1c (125 mg, 0.5 mmol), 2a (205 mg, 2.5 mmol) and
[PdCl2(CH3CN)2] (6 mg, 0.023mmol) in acetonitrile (5 mL) was stirred at
room temperature for 3.5 h. Flash chromatography on silica gel (CH2Cl2,
then petroleum ether/ethyl acetate 15:1) afforded 3c as a white solid
(151 mg, 92%). M.p. 122 1238C (petroleum ether/ethyl acetate);
1H NMR (CDCl3, 300 MHz): d=7.41 7.20 (m, 10H), 7.17 (s, 1H), 5.99 (s,
3-Benzyl-5-methyl-4-(3’-(5’-methylfuranyl))-2(5H)-furanone (3g): A mix-
ture of 1g (94 mg, 0.5 mmol), 2a (207 mg, 2.5 mmol) and
[PdCl2(CH3CN)2] (6 mg, 0.023mmol) in acetonitrile (5 mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/ethyl acetate 10:1, then CH2Cl2) afforded 3g as an oil (120 mg,
2083
Chem. Eur. J. 2004, 10, 2078 2087
www.chemeurj.org
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

S. Ma and Z. Yu
FULL PAPER
90%). 1H NMR (CDCl3, 300 MHz): d=7.46 (s, 1H), 7.35 7.16 (m, 5H),
6.13(s, 1H), 5.22 (q, J=6.42 Hz, 1H), 3.90 (d, J=15.27 Hz, 1H), 3.71 (d,
J=15.28 Hz, 1H), 2.30 (s, 3H), 1.52 (d, J=6.42 Hz, 3H); 13C NMR
(CDCl3, 75.4 MHz): d=13.63, 20.68, 30.19, 77.96, 104.93, 117.95, 123.35,
126.80, 128.22, 128.98, 137.84, 141.58, 154.69, 155.19, 174.48; MS (70 eV):
m/z (%): 269 (2.49) [M ++H], 268 (12.51) [M +], 43(100); IR (neat): n˜ =
2986, 2934, 1754, 1653, 1603 cmÀ1; HRMS: m/z: calcd for C17H16O3:
268.10995; found 268.11098.
174.51; MS (70 eV): m/z (%): 296 (100) [M +]; IR (neat): n˜ =1757, 1656,
1601 cmÀ1; HRMS: m/z: calcd for C19H20O3: 296.14125; found 296.14227.
3-Allyl-4-(3’-(5’-butylfuranyl))-5-phenyl-2(5H)-furanone (3m): A mixture
of 1d (50 mg, 0.25 mmol), 2b (157 mg, 1.266 mmol) and [PdCl2(CH3CN)2]
(3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at room tempera-
ture for 4 h. Flash chromatography on silica gel (petroleum ether/ethyl
acetate 6:1) afforded 3m as an oil (53mg, 66%). 1H NMR (CDCl3,
300 MHz): d=7.35 7.19 (m, 5H), 7.16 (s, 1H), 5.99 5.83 (m, 3H), 5.16
5.04 (m, 2H), 3.36 3.18 (m, 2H), 2.47 (t, J=7.50 Hz, 2H), 1.53 1.41 (m,
2H), 1.30 1.16 (m, 2H), 0.82 (t, J=7.20 Hz, 3H); 13C NMR (CDCl3,
75.4 MHz): d=13.65, 22.03, 27.31, 28.42, 29.65, 83.15, 103.92, 116.57,
117.56, 123.10, 127.83, 129.00, 129.58, 132.84, 135.46, 141.71, 151.93,
158.17, 173.94; MS (70 eV): m/z (%): 322 (9.87) [M +], 84 (100); IR
5-Ethyl-3-methyl-4-(3’-(5’-methylfuranyl))-5-phenyl-2(5H)-furanone (3h):
A
mixture of 1h (101 mg, 0.5 mmol), 2a (205 mg, 2.5 mmol) and
[PdCl2(CH3CN)2] (6 mg, 0.023mmol) in acetonitrile (5 mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/Et2O 10:1) afforded 3h as an oil (120 mg, 85%). 1H NMR (CDCl3,
(neat): n˜ =1755, 1655, 1600 cmÀ1
; HRMS: m/z: calcd for C21H22O3:
300 MHz): d=7.33(s, 5H), 7.13(s, 1H), 5.94 (d,
J=1.22 Hz, 1H), 2.61
322.15689; found 322.15984.
2.49 (m, 1H), 2.33 2.19 (m, 4H), 2.11 (s, 3H), 0.81 (t, J=7.33 Hz, 3H);
13C NMR (CDCl3, 75.4 MHz): d=7.47, 10.46, 13.53, 28.34, 89.83, 105.34,
118.12, 122.80, 126.53, 128.92, 129.00, 138.74, 141.56, 153.77, 154.53,
174.71; MS (70 eV): m/z (%): 283(1.68) [ M ++H], 282 (11.89) [M +], 253
(100); IR (neat): n˜ =2977, 2938, 2879, 1759 cmÀ1; HRMS: m/z: calcd for
C18H18O3: 282.12559; found 282.12471.
3-Methyl-4-(3’-(5’-butylfuranyl))-5-(1’-naphthyl)-2(5H)-furanone (3n): A
mixture of 1e (58 mg, 0.259 mmol), 2b (162 mg, 1.306 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/ethyl acetate 5:1) afforded 3n as an oil (71 mg, 79%). 1H NMR
(CDCl3, 300 MHz): d=8.25 (d, J=7.80 Hz, 1H), 7.90 (t, J=9.30 Hz,
2H), 7.66 7.51 (m, 2H), 7.38 (t, J=7.65 Hz, 1H), 7.27 7.20 (m, 2H), 6.75
(s, 1H), 6.02 (s, 1H), 2.51 (t, J=7.50 Hz, 2H), 2.24 (s, 3H), 1.57 1.45 (m,
2H), 1.34 1.20 (m, 2H), 0.86 (t, J=7.20 Hz, 3H); 13C NMR (CDCl3,
75.4 MHz): d=10.53, 13.62, 22.00, 27.27, 29.63, 78.90, 103.83, 118.53,
122.27, 122.71, 125.15, 126.07, 126.39, 127.02, 128.90, 130.15, 131.26,
131.94, 133.79, 141.58, 150.31, 158.09, 174.33; MS (70 eV): m/z (%): 346
(100) [M +]; IR (neat): n˜ =1751, 1656, 1598 cmÀ1; HRMS: m/z: calcd for
C23H22O3: 346.15689; found 346.15762.
5-Heptyl-4-(3’-(5’-methylfuranyl))-2(5H)-furanone (3i): A mixture of 1i
(91 mg, 0.5 mmol), 2a (208 mg, 2.5 mmol) and [PdCl2(CH3CN)2] (6 mg,
0.023mmol) in acetonitrile (5 mL) was stirred at room temperature for
4 h. Flash chromatography on silica gel (petroleum ether/Et2O 2.5:1) af-
forded 3i as an oil (91 mg, 69%). 1H NMR (CDCl3, 300 MHz): d=7.52
(s, 1H), 6.15 (d, J=2.0 Hz, 1H), 5.96 (d, J=1.0 Hz, 1H), 5.18 (dt, J=7.5
and 2.2 Hz, 1H), 2.29 (d, J=1.0 Hz, 3H), 2.06 1.92 (m, 1H), 1.64 1.51
(m, 1H), 1.42 1.13(m, 10H), 0.81 (t, J=7.0 Hz, 3H); 13C NMR (CDCl3,
75.4 MHz): d=13.57, 14.27, 22.79, 24.32, 29.25, 29.42, 31.88, 34.50, 82.32,
104.79, 112.68, 118.38, 140.96, 154.90, 160.37, 173.47; MS (70 eV): m/z
(%): 233 (9.00) [M +ÀC2H5], 107 (100); IR (neat): n˜ =2954, 2927, 2856,
1751, 1635, 1606 cmÀ1; elemental analysis calcd for C16H22O3 (%): C
73.25, H 8.45; found C 73.16, H 8.49.
4-(3’-(5’-Butylfuranyl))-5-ethyl-3-methyl-5-phenyl-2(5H)-furanone (3o):
A mixture of 1h (50 mg, 0.248 mmol), 2b (153mg, 1.23mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/Et2O 3:1, then CH2Cl2) afforded 3o (69 mg, 86%) as an oil.
1H NMR (CDCl3, 300 MHz): d=7.38 7.29 (m, 5H), 7.13 (s, 1H), 5.96 (s,
1H), 2.60 2.47 (m, 3H), 2.31 2.19 (m, 1H), 2.11 (s, 3H), 1.61 1.50 (m,
2H), 1.38 1.24 (m, 2H), 0.89 (t, J=7.2 Hz, 3H), 0.81 (t, J=7.5 Hz, 3H);
13C NMR (CDCl3, 75.4 MHz): d=7.53, 10.52, 13.99, 22.42, 27.68, 28.43,
30.00, 89.75, 104.49, 117.91, 122.80, 126.56, 128.88, 128.96, 138.83, 141.41,
154.51, 158.11, 174.65; MS (70 eV): m/z (%): 325 (6.02) [M ++H], 324
4-(3’-(5’-Methylfuranyl))-5-(4’-bromo-phenyl)-3-propyl-2(5H)-furanone
(3j): A mixture of 1j (70 mg, 0.249 mmol), 2a (103mg, 1.26 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4.5 h. Flash chromatography on silica gel (petrole-
um ether/Et2O 3:1) afforded 3j as an white solid (63mg, 70%). M.p.
102 1038C (ethyl acetate/petroleum ether); 1H NMR (CDCl3, 300 MHz):
d=7.48 (d, J=7.35 Hz, 2H), 7.20 (s, 1H), 7.12 (d, J=7.35 Hz, 2H), 6.01
(s, 1H), 5.85 (s, 1H), 2.58 2.47 (m, 2H), 2.23(s, 3H), 1.72 1.58 (m, 2H),
1.03(t, J=7.20 Hz, 3H); 13C NMR (CDCl3, 75.4 MHz): d=13.30, 14.10,
21.28, 26.45, 81.98, 104.56, 117.78, 123.60, 126.44, 129.41, 132.18, 134.82,
141.21, 149.80, 153.96, 173.91; MS (70 eV): m/z (%): 362 (99.04) [M +
(81Br)], 360 (100) [M +(79Br)]; IR (neat): n˜ =1748, 1735, 1653 cmÀ1; ele-
mental analysis calcd for C18H17BrO3 (%): C 59.85, H 4.74; found C
59.73, H 4.82.
(22.46) [M +], 295 (100); IR (neat): n˜ =2895, 2932, 2872, 1751, 1650 cmÀ1
HRMS: m/z: calcd for C21H24O3: 324.17255; found 324.17509.
;
4-(3’-(5’-Butylfuranyl))-5-heptyl-2(5H)-furanone (3p): A mixture of 1i
(45 mg, 0.247 mmol), 2b (154 mg, 1.24 mmol) and [PdCl2(CH3CN)2]
(3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at room tempera-
ture for 4 h. Flash chromatography on silica gel (petroleum ether/Et2O
3:1) afforded 3p as an oil (52 mg, 69%). 1H NMR (CDCl3, 300 MHz):
d=7.53(s, 1H), 6.14 (d, J=0.7 Hz, 1H), 5.97 (d, J=1.4 Hz, 1H), 5.21
5.15 (m, 1H), 2.60 (t, J=7.5 Hz, 2H), 2.07 1.90 (m, 1H), 1.67 1.53(m,
3H), 1.45 1.14 (m, 12H), 0.9 (t, J=7.3Hz, 3H), 0.82 (t, J=6.6 Hz, 3H);
13C NMR (CDCL3, 75.4 MHz): d=13.65, 13.95, 22.06, 22.48, 24.04, 27.34,
28.92, 29.10, 29.62, 31.57, 34.23, 82.01, 103.59, 112.28, 117.84, 140.54,
158.95, 160.11, 173.16; MS (70 eV): m/z (%): 304 (61.56) [M +], 206
(100); IR (neat): n˜ =2956, 2928, 2858, 1751, 1635, 1600 cmÀ1; HRMS:
m/z: calcd for C19H28O3: 304.20385; found 304.20228.
4-(3’-(5’-Butylfuranyl))-5-phenyl-3-propyl-2(5H)-furanone (3k):
A mix-
ture of 1a (50 mg, 0.248 mmol), 2b (157 mg, 1.27 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/Et2O 3:1, then CH2Cl2) afforded 3k as an oil (67 mg, 84%).
1H NMR (CDCl3, 300 MHz): d=7.38 7.14 (m, 5H), 7.16 (d, J=1.0 Hz,
1H), 6.03(s, 1H), 5.89 (s, 1H), 2.59 2.50 (m, 4H), 1.74 1.63(m, 2H),
1.58 1.48 (m, 2H), 1.37 1.22 (m, 2H), 1.04 (t, J=7.4 Hz, 3H), 0.88 (t,
J=7.3Hz, 3H); 13C NMR (CDCl3, 75.4 MHz): d=13.65, 14.08, 21.32,
22.04, 26.43, 27.31, 29.66, 82.93, 103.78, 117.75, 126.10, 127.79, 128.94,
129.46, 135.68, 141.24, 150.30, 158.05, 174.27; MS (70 eV): m/z (%): 324
(4.43) [M +], 197 (100); IR (neat): n˜ =2959, 2931, 2872, 1754, 1653,
1600 cmÀ1; HRMS: m/z: calcd for C21H24O3: 324.17255; found 324.17118.
4-(3’-(5’-Benzylfuranyl))-5-phenyl-3-propyl-2(5H)-furanone (3q): A mix-
ture of 1a (50 mg, 0.248 mmol), 2c (197 mg, 1.25 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/Et2O 3:1) afforded 3q as an oil (66 mg, 74%). 1H NMR (CDCl3,
300 MHz): d=7.40 7.15 (m, 11H), 6.08 (d, J=0.9 Hz, 1H), 5.88 (s, 1H),
3.90 (s, 2H), 2.53 (t, J=8.4 Hz, 2H), 1.73 1.61 (m, 2H), 1.03 (t, J=
7.5 Hz, 3H); 13C NMR (CDCl3, 75.4 MHz): d=14.36, 21.61, 26.76, 34.48,
83.26, 105.68, 118.26, 126.79, 127.08, 128.11, 128.86, 129.31, 129.84, 135.92,
137.22, 142.24, 150.41, 156.47, 174.49; MS (70 eV): m/z (%): 358 (5.85)
[M +], 91 (100); IR (neat): n˜ =2961, 1750, 1653, 1495, 1455 cmÀ1; HRMS:
m/z: calcd for C24H22O3: 358.15689; found 358.15212.
4-(3’-(5’-Butylfuranyl))-3-methyl-5-phenyl-2(5H)-furanone (3l):
A mix-
ture of 1b (44 mg, 0.253mmol), 2b (156 mg, 1.258 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (ethyl ace-
tate/petroleum ether 1:5) afforded 3l as an oil (47 mg, 63%). 1H NMR
(CDCl3, 300 MHz): d=7.42 7.34 (m, 3H), 7.32 7.22 (m, 2H), 7.20 (s,
1H), 6.04 (s, 1H), 5.90 (s, 1H), 2.53(t, J=7.65 Hz, 2H), 2.15 (s, 3H),
1.60 1.48 (m, 2H), 1.37 1.22 (m, 2H), 0.88 (t, J=7.20 Hz, 3H); 13C NMR
(CDCl3, 75.4 MHz): d=10.25, 13.65, 22.04, 27.32, 29.67, 83.02, 103.78,
118.11, 121.44, 127.88, 128.95, 129.52, 135.57, 141.38, 150.47, 158.04,
4-(3’-(5’-Benzylfuranyl))-3-methyl-5-phenyl-2(5H)-furanone (3r): A mix-
ture of 1b (44 mg, 0.253mmol), 2c (198 mg, 1.253mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
2084
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 2078 2087

(Furanyl)butenolide Derivatives
2078 2087
room temperature for 4 h. Flash chromatography on silica gel (ethyl ace-
tate/petroleum ether 1:5) afforded 3r (72 mg, 86%) as an oil. 1H NMR
(CDCl3, 300 MHz): d=7.42 7.14 (m, 11H), 6.10 (s, 1H), 5.89 (s, 1H),
3.90 (s, 2H), 2.14 (s, 3H); 13C NMR (CDCl3, 75.4 MHz): d=10.27, 34.12,
82.99, 105.24, 118.23, 121.72, 126.76, 127.86, 128.53, 128.55, 128.97, 129.58,
135.41, 136.88, 142.06, 150.19, 156.06, 174.43; MS (70 eV): m/z (%): 330
(100) [M +]; IR (neat): n˜ =1752, 1657, 1601 cmÀ1; HRMS: m/z: calcd for
C22H18O3: 330.12559; found 330.12942.
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (ethyl acetate/petroleum ether 1:2, then CH2Cl2) afforded
(R)-(À)-3b (49 mg, 76%, 97% ee). (HPLC condition: AD column; rate:
0.7 mLminÀ1; hexane/iPrOH 85:15); [a]2D0 =À1358 (c=1.145, EtOH, T=
208C).
(S)-(+)-3-Allyl-4-(3’-(5’-methylfuranyl))-5-phenyl-2(5H)-furanone (3d):
A
mixture of (S)-(À)-1d (50 mg, 0.25 mmol, 98% ee), 2a (104 mg,
1.27 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 6 h. Flash chromatography
on silica gel (petroleum ether/ethyl acetate 5:1) afforded (S)-(+)-3d
(51 mg, 73%, 97% ee). (HPLC condition: OD column; rate:
0.7 mLminÀ1; hexane/iPrOH 80:20); [a]D20 =+708 (c=1.045, CHCl3, T=
208C).
3-Allyl-4-(3’-(5’-benzylfuranyl))-5-phenyl-2(5H)-furanone (3s): A mixture
of 1d (31 mg, 0.155 mmol), 2c (125 mg, 0.791 mmol) and
[PdCl2(CH3CN)2] (2 mg, 0.0077 mmol) in acetonitrile (2 mL) was stirred
at room temperature for 4 h. Flash chromatography on silica gel (petrole-
1
um ether/ethyl acetate 5:1) afforded 3s as an oil (45 mg, 82%). H NMR
(CDCl3, 300 MHz): d=7.42 7.11 (m, 11H), 6.05 (s, 1H), 6.01 5.86 (m,
2H), 5.18 5.08 (m, 2H), 3.88 (s, 2H), 3.38 3.21 (m, 2H); 13C NMR
(CDCl3, 75.4 MHz): d=28.47, 34.15, 83.10, 105.50, 116.63, 117.74, 123.49,
126.79, 127.83, 128.56, 129.03, 129.61, 132.80, 135.37, 136.87, 142.37,
151.58, 156.20, 173.75; MS (70 eV): m/z (%): 356 (83.18) [M +], 91 (100);
IR (neat): n˜ =1752, 1655, 1601 cmÀ1; HRMS: m/z: calcd for C24H20O3:
356.14125; found 356.14052.
(S)-(À)-3-Methyl-4-(3’-(5’-methylfuranyl))-5-(1’-naphthyl)-2(5H)-fura-
none (3e): A mixture of (S)-(+)-1e (56 mg, 0.25 mmol, 98% ee), 2a
(104 mg, 1.27 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in aceto-
nitrile (3mL) was stirred at room temperature for 4 h. Flash chromatog-
raphy on silica gel (petroleum ether/ethyl acetate 3:1) afforded (S)-(À)-
3e (56 mg, 74%, 97% ee). (HPLC condition: OD column; rate:
0.7 mLminÀ1; hexane/iPrOH 60:40); [a]D20 =À348 (c=1.635, CHCl3, T=
208C).
4-(3’-(5’-Benzylfuranyl))-3-methyl-5-(1’-naphthyl)-2(5H)-furanone (3t): A
mixture of 1e (55 mg, 0.246 mmol), 2c (199 mg, 1.259 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/ethyl acetate 5:1) afforded 3t as an oil (84 mg, 90%). 1H NMR
(CDCl3, 300 MHz): d=8.23(d, J=8.40 Hz, 1H), 7.90 (t, J=9.30 Hz,
2H), 7.66 7.51 (m, 2H), 7.39 (t, J=7.50 Hz, 1H), 7.34 7.12 (m, 7H), 6.74
(s, 1H), 6.10 (s, 1H), 3.86 (s, 2H), 2.23 (s, 3H); 13C NMR (CDCl3,
75.4 MHz): d=10.48, 34.03, 78.87, 105.24, 118.63, 122.52, 122.62, 125.14,
126.07, 126.35, 126.68, 127.04, 128.46, 128.49, 128.91, 130.16, 131.14,
131.87, 133.79, 136.84, 142.22, 150.08, 156.09, 174.21; MS (70 eV): m/z
(%): 380 (100) [M +]; IR (neat): n˜ =1749, 1657, 1598 cmÀ1; HRMS: m/z:
calcd for C26H20O3: 380.14125; found 380.13813.
(S)-(+)-4-(3’-(5’-Methylfuranyl))-5-(4’-bromo-phenyl)-3-propyl-2(5H)-fur-
anone (3j): A mixture of (S)-(+)-1j (43mg, 0.153mmol, 99% ee), 2a
(67 mg, 0.817 mmol) and [PdCl2(CH3CN)2] (2 mg, 0.0077 mmol) in aceto-
nitrile (3mL) was stirred at room temperature for 4 h. Flash chromatog-
raphy on silica gel (petroleum ether/Et2O 3:1) afforded (S)-(+)-3j
(42 mg, 76%, 99% ee). (HPLC condition: AD column; rate:
0.7 mLminÀ1; hexane/iPrOH 95:5); [a]2D0 =+1228 (c=0.505, EtOH, T=
208C).
(R)-(À)-4-(3’-(5’-Butylfuranyl))-5-phenyl-3-propyl-2(5H)-furanone (3k):
A mixture of (R)-(À)-1a (50 mg, 0.248 mmol, 97% ee), 2b (154 mg,
1.24 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (petroleum ether/ethyl acetate 3:1) afforded (R)-(À)-3k
(60 mg, 75%, >99% ee). (HPLC condition: OD column; rate:
0.7 mLminÀ1; hexane/iPrOH=70/30),[a]D20 =À568 (c=1.190, CHCl3, T=
208C).
4-(3’-(5’-Benzylfuranyl))-5-ethyl-3-methyl-5-phenyl-2(5H)-furanone (3u):
A mixture of 1h (50 mg, 0.248 mmol), 2c (195 mg, 1.24 mmol) and
[PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at
room temperature for 4 h. Flash chromatography on silica gel (petroleum
ether/Et2O 2.5:1) afforded 3u as an oil (74 mg, 84%). 1H NMR (CDCl3,
300 MHz): d=7.39 7.13 (m, 11H), 6.03 (d, J=0.9 Hz, 1H), 3.91 (s, 2H),
2.61 2.49 (m, 1H), 2.31 2.19 (m, 1H), 2.10 (s, 3H), 0.83 (t, J=7.2 Hz,
3H); 13C NMR (CDCl3, 75.4 MHz): d=7.58, 10.53, 28.42, 34.50, 89.72,
105.98, 118.07, 123.09, 126.56, 127.10, 128.89, 128.91, 128.94, 129.02,
137.27, 138.73, 142.13, 154.27, 156.14, 174.57; MS (70 eV): m/z (%): 359
(13.54) [M ++H], 358 (15.81) [M +], 91 (100); IR (neat): n˜ =2975, 2937,
1748, 1650, 1599 cmÀ1; HRMS: m/z: calcd for C24H22O3: 358.15689; found
358.15234.
(R)-(À)-4-(3’-(5’-Butylfuranyl))-3-methyl-5-phenyl-2(5H)-furanone (3l):
A mixture of (R)-(À)-1b (44 mg, 0.253mmol, 99% ee), 2b (157 mg,
1.27 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (ethyl acetate/petroleum ether 1:5) afforded (R)-(À)-3l
(61 mg, 81%, 99% ee). (HPLC condition: OD column; rate:
0.7 mLminÀ1; hexane/iPrOH 90:10); [a]D20 =À428 (c=2.540, CHCl3, T=
208C).
(S)-(+)-3-Allyl-4-(3’-(5’-butylfuranyl))-5-phenyl-2(5H)-furanone (3m): A
mixture of (S)-(À)-1d (50 mg, 0.25 mmol, 98% ee), 2b (157 mg,
1.27 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (petroleum ether/ethyl acetate 6:1) afforded (S)-(+)-3m
(54 mg, 67%, 99% ee). (HPLC condition: OD column; rate:
0.7 mLminÀ1; hexane/iPrOH 90:10); [a]D20 =+498 (c=1.400, CHCl3, T=
208C).
4-(3’-(5’-Benzylfuranyl))-5-heptyl-2(5H)-furanone (3v): A mixture of 1i
(45 mg, 0.247 mmol), 2c (197 mg, 1.25 mmol) and [PdCl2(CH3CN)2]
(3mg, 0.012 mmol) in acetonitrile (3mL) was stirred at room tempera-
ture for 4 h. Flash chromatography on silica gel (petroleum ether/Et2O
2.6:1, then CH2Cl2) afforded 3v as an oil (59 mg, 71%). 1H NMR
(CDCl3, 300 MHz): d=7.57 (s, 1H), 7.38 7.22 (m, 5H), 6.18 (s, 1H), 5.98
(d, J=1.4 Hz, 1H), 5.23 5.16 (m, 1H), 3.98 (s, 2H), 2.04 1.93 (m, 1H),
1.68 1.53(m, 1H), 1.49 1.13(m, 10H), 0.86 (t, J=7.1 Hz, 3H); 13C NMR
(CDCl3, 75.4 MHz): d=14.29, 22.82, 24.41, 29.25, 29.43, 31.91, 34.56,
82.31, 105.42, 113.05, 118.41, 127.20, 128.96, 137.01, 141.45, 157.51, 160.13,
173.34; MS (70 eV): m/z (%): 339 (5.52) [M ++H], 338 (23.68) [M +], 91
(100); IR (neat): n˜ =2953, 2926, 2856, 1750, 1636, 1597 cmÀ1; HRMS: m/
z: calcd for C22H26O3: 338.18819; found 338.18783.
(S)-(À)-3-Methyl-4-(3’-(5’-butylfuranyl))-5-(1’-naphthyl)-2(5H)-furanone
(3n): A mixture of (S)-(+)-1e (56 mg, 0.25 mmol, 98% ee), 2b (160 mg,
1.29 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (petroleum ether/ethyl acetate 4:1) afforded (S)-(À)-3n
(66 mg, 76%, 99% ee). (HPLC condition: AS column; rate:
0.7 mLminÀ1; hexane/iPrOH 80:20); [a]D20 =À398 (c=3.125, CHCl3, T=
208C).
Preparation of optically active 4-(3’-furanyl)-2(5H)-furanone 3
(S)-(+)-4-(3’-(5’-Methylfuranyl))-5-phenyl-3-propyl-2(5H)-furanone (3a):
A mixture of (S)-(+)-1a (50 mg, 0.248 mmol, 98% ee), 2a (103mg,
1.26 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (petroleum ether/Et2O 5:1) afforded (S)-(+)-3a (61 mg,
(R)-(À)-4-(3’-(5’-Benzylfuranyl))-5-phenyl-3-propyl-2(5H)-furanone (3q):
A mixture of (R)-(À)-1a (50 mg, 0.248 mmol, 97% ee), 2c (198 mg,
1.25 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (petroleum ether/ethyl acetate 8:1) afforded (R)-(À)-3q
(76 mg, 86%, >99% ee). (HPLC condition: OD column; rate:
0.7 mLminÀ1; hexane/iPrOH 60:40); [a]D20 =À448 (c=1.785, CHCl3, T=
208C).
87%, 95% ee). (HPLC condition: AD column; rate: 0.7 mLminÀ1
hexane/iPrOH 80:20); [a]D20 =+1328 (c=1.07, EtOH, T=208C).
;
(R)-(À)-3-Methyl-4-(3’-(5’-methylfuranyl))-5-phenyl-2(5H)-furanone
(3b): A mixture of (R)-(À)-1b (44 mg, 0.253mmol, 99% ee), 2a (105 mg,
1.28 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
2085
Chem. Eur. J. 2004, 10, 2078 2087
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¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

S. Ma and Z. Yu
FULL PAPER
(R)-(À)-4-(3’-(5’-Benzylfuranyl))-3-methyl-5-phenyl-2(5H)-furanone (3r):
A mixture of (R)-(À)-1b (44 mg, 0.253mmol, 99% ee), 2c (198 mg,
1.253mmol) and [PdCl 2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (ethyl acetate/petroleum ether 1:3, then CH2Cl2) afforded
(R)-(À)-3r (60 mg, 72%, 96% ee). (HPLC condition: AS column; rate:
0.7 mLminÀ1; hexane/iPrOH 60:40); [a]D20 =À358 (c=2.570, CHCl3, T=
208C).
[5] For the recent synthesis of butenolides from 2,3-allenoic acids, see:
a) S. Ma, Z. Yu, Angew. Chem. 2003, 115, 1999; Angew. Chem. Int.
Ed. 2003, 42, 1955; b) S. Ma, Z. Shi, S. Wu, Tetrahedron: Asymmetry
2001, 12, 193; c) S. Ma, Z. Yu, S. Wu, Tetrahedron 2001, 57, 1585;
for the synthesis of 4-halopyrrol-2(5H)-ones, see: d) S. Ma, H. Xie,
Org. Lett. 2000, 2, 3801.
[6] For the cyclization coupling reaction of 2,3-allenols with halides,
see: a) S. Ma, S. Zhao, J. Am. Chem. Soc. 1999, 121, 7943; S. Ma, W.
Gao, Tetrahedron Lett. 2000, 41, 8933; b) for the synthesis of carbo-
cycles, see: S. Ma, S. Zhao, Org. Lett. 2000, 2, 2495; for the synthesis
of polysubstituted furans from 1,2-allenyl ketones, see: c) S. Ma, J.
Zhang, Chem. Commun. 2000, 117; S. Ma, L. Li, Org. Lett. 2000, 2,
941; S. Ma, J. Zhang, L. Lu, Chem. Eur. J. 2003, 9, 2447.
[7] For catalytic cycloisomerization of allenols, see: a) J. A. Marshall, X.
Wang, J. Org. Chem. 1990, 55, 2995; b) J. A. Marshall, X. Wang, J.
Org. Chem. 1991, 56, 960; c) L. I. Olsson, A. Claesson, Synthesis
1979, 743; d) S. S. Nikam, K. H. Chu, K. K. Wang, J. Org. Chem.
1986, 51, 745; e) R. Gelin, S. Gelin, M. Albrand, Bull. Soc. Chim. Fr.
1972, 1946; f) J. A. Marshall, C. A. Sehon, J. Org. Chem. 1995, 60,
5966; g) A. Hoffmann-Roder, N. Krause, Org. Lett. 2001, 3, 2537.
[8] For catalytic cycloisomerization of 2,3-allenoic acids, see: J. A. Mar-
shall, M. A. Wolf, E. M. Wallace, J. Org. Chem. 1997, 62, 367.
[9] For the Pd0-catalyzed coupling-cyclization reaction of allenols with
aryl or vinyl halides, see: a) K. Uemura, D. Shiraishi, M. Noziri, Y.
Inoue, Bull. Chem. Soc. Jpn. 1999, 1063; b) S.-K. Kang, T.-G. Baik,
A. N. Kulak, Synlett 1999, 324; c) S.-K. Kang, T. Yamaguchi, S.-J.
Pyun, Y.-T. Lee, T.-G. Baik, Tetrahedron Lett. 1998, 39, 2127.
[10] For the Ru-catalyzed cyclization reaction of allenols, see: a) E.
Yoneda, T. Kaneko, S.-W. Zhang, K. Onitsuka, S. Takahashi, Org.
Lett. 2000, 2, 441; b) B. M. Trost, A. B. Pinkerton, J. Am. Chem. Soc.
1999, 121, 10842.
(S)-(+)-3-Allyl-4-(3’-(5’-benzylfuranyl))-5-phenyl-2(5H)-furanone (3s): A
mixture of (S)-(À)-1d (31 mg, 0.155 mmol, 98% ee), 2c (124 mg,
0.785 mmol) and [PdCl2(CH3CN)2] (2 mg, 0.0077 mmol) in acetonitrile
(2 mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (petroleum ether/ethyl acetate 5:1) afforded (S)-(+)-3s
(37 mg, 67%, 99% ee). (HPLC condition: AS column; rate:
0.7 mLminÀ1;hexane/iPrOH 60:40); [a]D20 =+458 (c=1.315, CHCl3, T=
208C).
(S)-(À)-3-Methyl-4-(3’-(5’-benzylfuranyl))-5-(1’-naphthyl)-2(5H)-furanone
(3t): A mixture of (S)-(+)-1e (56 mg, 0.25 mmol, 98% ee), 2c (200 mg,
1.266 mmol) and [PdCl2(CH3CN)2] (3mg, 0.012 mmol) in acetonitrile
(3mL) was stirred at room temperature for 4 h. Flash chromatography
on silica gel (petroleum ether/ethyl acetate 5:1) afforded (S)-(À)-3t
(83mg, 87%, >99% ee). (HPLC condition: AS column; rate:
0.7 mLminÀ1
CHCl3, T=208C).
;
eluent: hexane/iPrOH 60:40); [a]2D0 =À9.78 (c=2.675,
4,5-Dimethylene-2,7-octanedione (6a):[28] 1H NMR (CDCl3, 300 MHz):
d=5.23(s, 2H), 5.15 (s, 2H), 3.40 (s, 4H), 2.16 (s, 6H).
4-Methyl-5-methylene-3-octene-2,7-dione
(7a):
1H NMR
(CDCl3,
300 MHz): d=6.13 (s, 1H), 5.69 (s, 1H), 5.38 (s, 1H), 3.37 (s, 2H), 2.25
(s, 3H), 2.20 (s, 3H), 2.13 (s, 3H); 13C NMR (CDCl3, 75.4 MHz): d=
15.59, 28.68, 32.31, 49.96, 122.44, 124.13, 142.69, 150.17, 199.40, 206.38;
IR (neat): n˜ =1716, 1683, 1589 cmÀ1; MS (70 eV): m/z (%): 166 (0.61)
[M +], 43(100); elemental analysis calcd (%) for C10H14O2: 166.09938;
found 166.09793.
[11] For the Pd0-catalyzed coupling-cyclization reaction of allenic amides
with aryl or vinyl halides, see: a) H. Ohno, M. Anzai, A. Toda, S.
Ohishi, N. Fujii, T. Tanaka, Y. Takemoto, T. Ibuka, J. Org. Chem.
2001, 66, 4904; b) S.-K. Kang, K.-J. Kim, Org. Lett. 2001, 3, 511;
c) M. Anzai, A. Toda, H. Ohno, Y. Takemoto, N. Fujii, T. Ibuka, Tet-
rahedron Lett. 1999, 40, 7393; d) F. P. J. T. Rutjes, K. C. M. F. Tjen,
L. B. Wolf, W. F. J. Karstens, H. E. Schoemaker, H. Hiemstra, Org.
Lett. 1999, 1, 717; e) H. Ohno, A. Toda, Y. Miwa, T. Taga, E. Osawa,
Y. Yamaoka, N. Fujii, T. Ibuka, J. Org. Chem. 1999, 64, 2992.
[12] For the Pd-catalyzed coupling-cyclization reaction of allenic amides
with allylic halides, see: a) W. F. J. Karstens, D. Klomp, F. P. J. T.
Rutjes, H. Hiemstra, Tetrahedron 2001, 57, 5123; b) M. Kimura, K.
Fugami, S. Tanaka, Y. Tamaru, J. Org. Chem. 1992, 57, 6377.
[13] For Ag+-catalyzed cycloisomerization of aminoallenes, see: a) M. O.
Amombo, A. Hausherr, H.-U. Reissig, Synlett 1999, 1871; b) I. W.
Davies, T. Gallagher, R. B. Lamont, D. I. C. Scopes, J. Chem. Soc.
Chem. Commun. 1992, 335; c) D. N. A. Fox, D. Lathbury, M. F.
Mahon, K. C. Molloy, T. Gallagher, J. Chem. Soc. Chem. Commun.
1989, 1073; d) J. S. Prasad, L. S. Liebeskind, Tetrahedron Lett. 1988,
29, 4253; e) R. Kinsman, D. Lathbury, P. Vernon, T. Gallagher, J.
Chem. Soc. Chem. Commun. 1987, 243.
4,5-Dimethyl-octa-3,5-diene-2,7-dione
(8a):[29]
1H NMR
(CDCl3,
300 MHz): d=6.35 (br, 2H), 2.24 (d, J=1.2 Hz, 6H), 2.22 (s, 6H);
13C NMR (CDCl3, 75.4 MHz): d=199.21, 153.85, 125.59, 32.18, 16.20; MS
(70 eV): m/z (%): 166 (1.89) [M +], 123(100); IR (KBr): n˜ =1678, 1582,
1418 cmÀ1
.
Acknowledgment
Financial support from the National Natural Science Foundation of
China, the Major State Basic Research Development Program (Grant
No. G2000077500), and Shanghai Municipal Committee of Science and
Technology are greatly appreciated. S.M. is the recipient of 1999 Qiu Shi
Award for Young Scientific Workers issued by Hong Kong Qiu Shi Foun-
dation of Science and Technology (1999 2003).
[14] For Pd-catalyzed cycloisomerization of 2-(allenyl)malonates, see:
a) S. Kamijo, Y. Yamamoto, Tetrahedron Lett. 1999, 40, 1747; M.
Meguro, Y. Yamamoto, J. Org. Chem. 1999, 64, 694; M. Meguro, S.
Kamijo, Y. Yamamoto, Tetrahedron Lett. 1996, 37, 7453; for Pd-cata-
lyzed coupling cyclization of 2-(allenyl)malonates with organic hal-
ides, see: b) L. Besson, J. Bazin, J. Gore, B. Cazes, Tetrahedron Lett.
1994, 35, 2881; M. Ahmar, B. Cazes, J. Gore, Tetrahedron Lett. 1985,
26, 3795.
[1] For some typical examples of axial chirality transfer, see: a) G.
Kresze, L. Kloimstein, W. Runge, Justus Liebigs Ann. Chem. 1976,
64, 979; b) S. Musierowicz, A. E. Wroblewski, Tetrahedron 1978, 34,
461; c) S. Ma, S. Wu, Chem. Commun. 2001, 441.
[2] a) B. M. Trost, A. B. Pinkerton, M. Seidel, J. Am. Chem. Soc. 2001,
123, 12466; b) H. Ohno, K. Miyamura, T. Tanaka, S. Oishi, A. Toda,
Y. Takemoto, N. Fujii, T. Ibuka, J. Org. Chem. 2002, 67, 1359; c) The
Chemistry of the Allenes, Vol. 1 (Ed.: S. R. Landor), Academic,
London, 1982; d) Allenes in Organic Synthesis (Eds.: H. F. Schuter,
G. M. Coppola), Wiley, New York, 1984.
[15] a) M. Kimura, S. Tanaka, Y. Tamaru, J. Org. Chem. 1995, 60, 3764;
b) S. Ma, W. Gao, J. Org. Chem. 2002, 67, 6104.
[16] For dimerization of 1,2-allenyl ketones, see: a) A. S. K. Hashmi, J.-
H. Choi, J. W. Bats, J. Prakt. Chem. 1999, 341, 342; b) A. S. K.
Hashmi, T. L. Ruppert, T. Knˆfel, J. W. Bats, J. Org. Chem. 1997, 62,
7295; c) A. S. K. Hashmi, Angew. Chem. 1995, 107, 1749; Angew.
Chem. Int. Ed. Engl. 1995, 34, 1581; d) A. S. K. Hashmi, L. Schwarz,
J.-H. Choi, T. M. Frost, Angew. Chem. 2000, 112, 2382; Angew.
Chem. Int. Ed. 2000, 39, 2285.
[3] a) R. W. Bates, V. Satcharoen, Chem. Soc. Rev. 2002, 31, 12; b) R.
Zimmer, C. U. Dinesh, E. Nandanan, F. A. Khan, Chem. Rev. 2000,
100, 3067; c) Y. Yamamoto, U. Radhakrishnan, Chem. Soc. Rev.
1999, 28, 199.
[4] a) The Chemistry of Ketenes, Allenes and Related Compounds (Ed.:
S. Patai), Wiley, Chichester, 1980; b) The Chemistry of the Allenes,
Vol. 2 (Ed.: S. R. Landor), Academic, London, 1982.
[17] For a recent highlight, see: A. S. K. Hashmi, Angew. Chem. 2000,
112, 3 73 7A; ngew. Chem. Int. Ed. 2000, 39, 3590.
[18] S. Ma, Z. Yu, Org. Lett. 2003, 5, 1507.
2086
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Chem. Eur. J. 2004, 10, 2078 2087

(Furanyl)butenolide Derivatives
2078 2087
[19] S. Ma, Z. Yu, Angew. Chem. 2002, 114, 1853; Angew. Chem. Int. Ed.
2002, 41, 1775.
reflections collected/unique: 5830/2222 (Rint =0.1917), no observa-
tion [I > 2s(I)] 567, parameters 133.
[20] X-ray crystal data for compound 3a: C18H18O3, MW =282.32, Mono-
clinic, space group P2(1)/c, MoKa, final R indices [I >2s(I)], R1=
0.0433, wR2=0.1145, a=8.0816(6), b=11.2728(8), c=17.3410
(12) ä, a=90, b=103.1590 (10), g=908, V=1538.32(19) ä3, T=
CCDC-210550 contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge
CB21EZ, UK; fax: (+44)1223-336-033; or deposit@ccdc.cam.ac.uk).
[23] S. Ma, W. Gao, Synlett 2002, 65.
293(2) K, Z=4, reflections collected/unique: 9159/3553 (Rint
0.0324), no observation [I>2s(I)] 2456, parameters 262.
=
CCDC-210552 contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge
CB21EZ, UK; fax: (+44)1223-336-033; or deposit@ccdc.cam.ac.uk).
[24] S. Ma, Z. Shi, Chem. Commun. 2002, 540.
[25] For the Pd0 species cyclometallate with two allenes to form the
cyclic Pd intermediate, see: a) C. H. Oh, H. S. Yoo, S. H. Jung,
Chem. Lett. 2001, 1288; b) M. Arisawa, T. Sugihara, M. Yamaguchi,
Chem. Commun. 1998, 2615; c) R. Grigg, N. Kongkathip, B. Kong-
kathip, S. Luangkamin, H. A. Dondas, Tetrahedron 2001, 57, 7965.
[26] For protonolysis of Pd enolate to regenerate divalent palladium,
see: a) Z. Wang, X. Lu, J. Org. Chem. 1996, 61, 2254; b) G. Liu, X.
Lu, Org. Lett. 2001, 3, 3879; c) A. Lei, X. Lu, Org. Lett. 2000, 2,
2699; d) X. Xie, X. Lu, Synlett 2000, 707; e) H. Qian, R. A. Widen-
hoefer, J. Am. Chem. Soc. 2003, 125, 2056.
[21] X-ray crystal data for compound (S)-(+)-3j: C18H17BrO3, MW
=
361.23, monoclinic, space group P2(1), MoKa, final R indices [I>
2s(I)], R1=0.0593, wR2=0.1449, a=5.0626(9), b=13.984(3), c=
11.860(2) ä, a=90, b=92.835(4), g=908, V=838.6(3) ä3, T=
293(2) K, Z=2, reflections collected/unique: 5033/3558 (Rint
0.1186), no observation [I>2s(I)] 1617, parameters 205.
=
CCDC-210551 contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge
CB21EZ, UK; fax: (+44)1223-336-033; or deposit@ccdc.cam.ac.uk).
[22] X-ray crystal data for compound 8a: C10H14O2, MW =166.21, mono-
clinic, space group C2/c, MoKa, final R indices [I>2s(I)], R1=
0.0697, wR2=0.1869, a=14.336(4), b=12.844(4), c=10.683(3) ä,
a=90, b=90.999(7), g=908, V=1966.8(9) ä3, T=293(2) K, Z=8,
[27] For the synthesis of allenoic acids, see: H. J. Bestmann, H. Hartung,
Chem. Ber. 1966, 99, 1198.
[28] L. S. Hegedus, R. J. Perry, J. Org. Chem. 1985, 50, 4955.
[29] M. Franck-Neumann, M. Sedrati, M. Mokhi, Angew. Chem. 1986,
98, 1138; Angew. Chem. Int. Ed. Engl. 1986, 25, 1131.
Received: July 16, 2003
Revised: October 13, 2003 [F5341]
2087
Chem. Eur. J. 2004, 10, 2078 2087
www.chemeurj.org
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim