Catalyst-controlled ring-opening cycloisomerization reactions of cyclopropenyl carboxylates for highly regioselective synthesis of different 2-alkoxyfurans

Article abstract of DOI:10.1002/asia.201000324

Differently substituted 2-alkoxyfurans (2,3,4- or 2,3,5-trisubstituted furans) were highly regioselectively synthesized by means of the ring-opening cycloisomerization of the same cyclopropenyl carboxylates with good yields in different solvents and excel

Full text of DOI:10.1002/asia.201000324

DOI: 10.1002/asia.201000324
Catalyst-Controlled Ring-Opening Cycloisomerization Reactions of
Cyclopropenyl Carboxylates for Highly Regioselective Synthesis of Different
2-Alkoxyfurans
Jie Chen[b] and Shengming Ma*[a, b]
Abstract: Differently substituted 2-alkoxyfurans (2,3,4- or 2,3,5-trisubstituted
furans) were highly regioselectively synthesized by means of the ring-opening cy-
cloisomerization of the same cyclopropenyl carboxylates with good yields in differ-
Keywords: copper · cyclopropene ·
furans · regioselectivity · ruthenium
ent solvents and excellent regioselectivity by using [Cu
ACHTUNGERTN(NUNG acac)2] (acac=acetylaceto-
nate) or [RuCl2A(PPh3)3] as the catalyst, respectively. The structures of these two
CHTUNGTRENNUNG
different types of furans were established by X-ray diffraction studies. A rationale
has been proposed.
Introduction
highly reactive C=C double bond or cyclopropane could un-
dergo a variety of addition and ring-opening reactions.[9,10]
There are several reports on metal-catalyzed rearrangement
reactions of cyclopropenes, thus leading to various dienes[11]
and carbo-[12] and heterocycles.[13] Padwaꢀs and our group re-
ported regioselective synthesis of furans from cyclopropenyl
ketones under different catalysts.[13a,b] However, regioselec-
tive isomerization of cyclopropenyl esters, which are very
readily available from the corresponding alkynes and the re-
lated diazo compounds,[14] has not been established on ac-
count of the much lower reactivity of the ester group to-
wards ring opening and the subsequent cyclization relative
to the ketone group. In addition, 2-alkoxy-substituted furans
that result from cycloisomerization of cyclopropenyl carbox-
ylates may undergo further alkylation at the 5-position to
afford butenolides,[15] an important structural unit in natural
products, pharmaceuticals, and intermediates for organic
synthesis.[16] Herein, we wish to report a catalyst-controlled,
highly selective synthesis of differently substituted 2-alkoxy-
furans by means of ring-opening cycloisomerization of the
same cyclopropenyl carboxylates in different solvents under
mild reaction conditions with good yields and excellent re-
gioselectivity.[17]
Furans are not only key structural units in many natural
products,[1] pharmaceuticals,[2] and molecular materials,[3] but
also useful intermediates in organic synthesis.[4] For this
reason, synthesis of furan derivatives has attracted tremen-
dous attention over the past century.[5] Polysubstituted
furans may be prepared by the functionalization of simple
furans; however, it should be noted that functionalization at
the 2- or 5-position to obtain substituted furans is relatively
easily compared with that at the 3- or 4-position.[6] In the
meantime, highly selective cyclization reactions of nonfuran
starting materials are also efficient for the synthesis of poly-
substituted furans.[7] On the other hand, cyclopropenes,
highly strained but readily accessible carbocyclic molecules,
have been shown to possess useful reactivity in organic syn-
thesis.[8] Over the past several years, more and more atten-
tion has been paid to the reactions of cyclopropenes: the
[a] Prof. Dr. S. Ma
Shanghai Key Laboratory of Green Chemistry and Chemical Process
Department of Chemistry, East China Normal University
3663 North Zhongshan Road, Shanghai 200062 (P.R. China)
Fax : (+86)21-62609305
E-mail: masm@mail.sioc.ac.cn
[b] J. Chen, Prof. Dr. S. Ma
Results and Discussion
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry
Chinese Academy of Sciences
Cycloisomerization of cyclopropenyl dicarboxylate 1a was
complicated when [PdCl2ACHTNUTRGNE(UNG CH3CN)2] was used as the catalyst
354 Fenglin Road, Shanghai 200032 (P.R. China)
(Table 1, entry 1) and 2a was formed in 34% NMR spectro-
scopic yield by using CuI as the catalyst (entry 7). Then we
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201000324.
Chem. Asian J. 2010, 5, 2415 – 2421
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2415

FULL PAPERS
Table 1. Cycloisomerization of cyclopropenyl carboxylates 1a under dif-
ferent reaction conditions.
AHCTUNGTERG(NNUN acac)2] in THF while heating to reflux with a 3a/2a selec-
tivity of 94:6 (entry 15). Finally it was observed that the re-
action in CH3CN is catalytic; it afforded 3a exclusively with
5.9 mol% of [Cu
ditions B).
ACHTUNGTERNN(UNG acac)2] at 1008C (entry 16, defined as con-
With the optimized cycloisomerization reaction condition-
s A and B in hand, the generality of the reaction was exam-
ined. Some of the typical results are summarized in Table 2.
For cyclopropenyl dicarboxylate substrates, with R1 being
alkyl (Table 2, entries 1, 2, and 5), benzyl (Bn; entry 6), aryl
(entries 7, 8, and 9), or the vinyl (entry 10) group, both
Entry Cat. (x [mol%])
Solvent T [8C] t [h] Yield [%][a]
(2a/3a)
AHCTUNGTRENNUNG
1
N
N
80 15
80 13
80 16
80 18
complicated[b]
complicated[b]
NR[c]
2
A
toluene
toluene
3
4
N
U
68 (82:18)[d]
trace (2a)[e]
NR[f]
5
G
U
80
80
9
9
6
G
U
toluene
7
8
CH3CN
80 20
34 (>99:1)[g]
NR[h]
Table 2. Regioselective cycloisomerization of cyclopropenyl carboxylates
CH3CN
THF
100 48
1.[a]
9
A
reflux 32.5 trace (3a)[i]
10
11
12
13
14
15
16
17
18
19
CuBr2 (104)
CuCl2 (48.8)
THF
THF
toluene
THF
THF
reflux 72
100 46
RT 15
RT 10
complicated[j]
30 (26:73)[k]
86 (>99:1)[l]
95 (>99:1)[l]
90 (>99:1)[l]
86 (6:94)[l]
A
G
E
G
ACHTUNGTRENNUNG
Entry
R1
R2
Conditions A
Conditions B
A
reflux
8
yield of 2 [%][b]
yield of 3 [%][b]
E
THF
100 46
100 48
80 48
50 48
RT 48
A
U
CH3CN
CH3CN
CH3CN
CH3CN
88 (<1:99)[l,m]
17 (<1:99)[m,n]
NR[m,o]
1
2
3
4
5
6
7
8
nC4H9
nC8H17
TBSOACHTGNUETRNNU(G CH2)3
HOCH2CH2
PhCH2CH2
Bn
Ph
p-MeC6H4
p-MeO2CC6H4
CH2=CH
nC4H9
Ph
H
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
SO2Ph
95 (2a)
87 (2b)
93 (2c)
78ACTHNGUTRENNU(G 2d)
96 (2e)
92 (2 f)
89 (2g)
86 (2h)
81 (2i)
88 (3a)
76 (3b)
74 (3c)
85 (3d)
87 (3e)
86 (3 f)
96 (3g)
[Cu
[Cu
[Cu
ACHTUNGTRENNUNG
[c]
ACHTUNGTRENNUNG
A
NR[m,p]
[a] Unless otherwise noted, the yield was determined by 1H NMR spec-
troscopic analysis with CH3NO2 as the internal standard, and the regiose-
lectivity was determined by 1H NMR spectroscopic analysis. [b] The con-
version is 100% and no desired product was detected. [c] Compound 1a
was recovered in 80% yield as determined by 1H NMR spectroscopic
analysis. [d] The conversion is 96%. [e] Compound 1a was recovered in
88% yield as determined 1H NMR spectroscopic analysis. [f] Compound
1a was recovered in 84% yield as determined by 1H NMR spectroscopic
analysis. [g] The conversion is 60%. [h] Compound 1a was recovered in
83% yield as determined by 1H NMR spectroscopic analysis. [i] Com-
pound 1a was recovered in 87% yield as determined by 1H NMR spec-
troscopic analysis. [j] The conversion is 86% and no desired product was
detected. [k] The conversion is 95%. [l] Yield of isolated product.
[m] The reaction was conducted in a Schlenk tube with a screw cap.
[n] Compound 1a was recovered in 68% yield as determined by
1H NMR spectroscopic analysis. [o] Compound 1a was recovered in 86%
88ACTHNGUTRENNU(G 3h)
78 (3i)
9
10
11
12
13
14
83 (2j)
58 (3j)
87 (3k)
67 (3l)
45 (2m)[f]
33 (2n)
76 (2k)[d]
78 (2l)[d]
68 (2m)[e]
63 (2n)[d]
SO2Ph
CO2Me
SO2Ph
H
[a] Conditions A: The reaction was conducted by using 1 (0.20 mmol)
and [RuCl2A(PPh3)3] (2.4–2.6 mol%) in THF (0.1m) at RT. Conditions B:
The reaction was conducted by using 1 (0.2 mmol) and [Cu(acac)2] (5.1–
5.9 mol%) in CH3CN (0.1m) at 1008C. [b] Yield of isolated product.
Unless otherwise noted, the regioselectivity is >99:1 (2/3 or 3/2) as deter-
mined by 1H NMR spectroscopic analysis. [c] TBS=t-butyldimethylsilyl.
[d] The reaction was conducted in toluene while heating at reflux. [e] The
reaction was carried out using 1m (0.30 mmol) in THF (3 mL) while
heating at reflux. [f] The reaction was carried out using 1m (0.30 mmol)
in CH3CN (3 mL) at 1008C.
CTHUNGTRENNUNG
AHCTUNGTRENNUNG
1
yield as determined by H NMR spectroscopic analysis. [p] Compound 1a
was recovered in 87% yield as determined by 1H NMR spectroscopic
analysis.
tested the cycloisomerization reaction of 1a in the presence
of a number of other transition-metal catalysts (Table 1).
2,3,5-trisubstituted furans and 2,3,4-trisubstituted furans
could be obtained in good to excellent yields with >99:1 se-
lectivity. Interestingly, these two catalytic systems can also
tolerate a free hydroxyl group to afford the corresponding
furans 2d and 3d in good yield without loss of the selectivity
(entry 4). In addition, the benzenesulfonyl group was well
tolerated; however, the reaction should be conducted in tol-
The reaction was also complicated when [Pd
ACHTUNGTRENNUNG
CuBr2 was used (entries 2 and 10). PdI2, [NiCl CTHUNGTRENNNUG
(dppe=1,2-bis(diphenylphosphino)ethane), and CuSO4
were also ineffective (entries 3, 6, and 8). However, we start-
ed to observe the formation of products 2a and 3a when
[Rh
2ACHTUNGTRENNUNG(OAc)4] or CuACHTUNGTRENNUNG
agent (entries 5 and 9). With [IrCl(CO)
N
uene heated at reflux and by using 2.6 mol% [RuCl2ACHTUNGTRENNUNG(PPh3)3]
mixture of 2a and 3a was formed (entries 4 and 11). After
numerous screenings, we were pleased to find that 2a was
obtained in 86% yield using 2.6 mol% [RuCl2ACTHNUTRGEN(NUG PPh3)3] in
toluene at room temperature (entry 12). The reaction in
THF is slightly better at room temperature (entry 13, de-
fined as conditions A). Furthermore, the regioisomeric prod-
uct 3a was obtained in 86% yield using 1.0 equiv [Cu-
(entries 11 and 12). In entries 13 and 14, in addition to the
expected products, more polar unidentified products were
formed. It should be pointed out that it is easy to conduct
the reaction on the gram scale as demonstrated in the Ex-
perimental Section. The structure of products 2h[18] and
3k[19] were established by X-ray diffraction studies (Fig-
ures 1 and 2).
2416
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Chem. Asian J. 2010, 5, 2415 – 2421

Catalyst-Controlled Ring-Opening Cycloisomerization Reactions
new catalytic conditions: 2,3,5-trisubstituted furan 5 could
be obtained in 83% yield with >99:1 selectivity with
2.6 mol% [RuCl
tuted furan 6 was obtained in 71% yield with 98:2 selectivi-
ty with 5.9 mol% [Cu(acac)2] as the catalyst.
2ACHTUNGERTN(NUNG PPh3)3] as the catalyst, and 2,3,4-trisubsti-
AHCTUNGTRENNUNG
A rationale was proposed for these cycloisomerization re-
actions (Scheme 2). In cycle A, the chlorometalation oc-
curred when the chloride anion attacks the less-substituted
Figure 1. ORTEP representation of 2h.
Scheme 2. Plausible mechanism of cycloisomerization reactions.
sp2-carbon atom,[20] whereas in the [Cu
ACTHNUTRGNEUNG(acac)2]-catalyzed re-
action (cycle B), the cationic center was obviously stabilized
by the presence of the R1 group.[21] Then the intermediate I
or I’ would undergo a ring-opening isomerization to afford
metal carbene intermediate II or II’.[22] Subsequently, the
carbonyl oxygen atom attacks the metal carbene carbon
atom, thereby leading to a cyclic metal intermediate III or
III’, which immediately gives the corresponding products 2
or 3 and regenerates the catalyst.[23]
Figure 2. ORTEP representation of 3k.
It should be noted that the isomerization of 2a to 3a did
not occur with 5.9 mol% [CuACHTNUTRGNENG(U acac)2] as the catalyst in
CH3CN at 1008C for 48 h, and furan 2a was recovered in
92% yield as determined by H NMR spectroscopic analysis
Conclusion
1
[Eq. (1)]:
In conclusion, we have developed an excellent catalyst-con-
trolled, highly regioselective cycloisomerization reaction of
cyclopropenyl carboxylates in different solvents to afford
substituted furans: 2-alkoxy-3,5-trisubstituted furans were
obtained in THF with [RuCl
alkoxy-3,4-trisubstituted furans were obtained in CH3CN
with [Cu(acac)2] as catalyst. Further mechanistic investiga-
2ACHTUGNTRENN(GNU PPh3)3] as catalyst, and 2-
AHCTUNGTRENNUNG
tion, the factors controlling the selectivity, and synthetic ap-
plication are currently underway in our laboratory.
The cycloisomerization reaction of cyclopropenyl ketone
4[13a] was also examined under conditions A and
B
(Scheme 1). The reactions did occur smoothly under these
Experimental Section
Representative Procedure for the
Synthesis of 2a
A
E
(5 mg,
5.2ꢂ
10À3 mmol), cyclopropenyl dicarboxy-
late 1a (42 mg, 0.20 mmol), and THF
(2 mL) were added sequentially to a
Schlenk reaction tube that had been
Scheme 1. Cycloisomerization reaction of cyclopropenyl ketone 4.
Chem. Asian J. 2010, 5, 2415 – 2421
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
2417

S. Ma and J. Chen
FULL PAPERS
evacuated and backfilled with argon. The resulting mixture was stirred at
room temperature. After 11 h, the reaction was complete as monitored
by TLC. Evaporation and column chromatography on silica gel (eluent:
petroleum ether/ethyl acetate, 5:1) afforded the desired product 2a as an
oil (40 mg, 95% yield). 1H NMR (300 MHz, CDCl3): d=6.15 (s, 1H),
4.05 (s, 3H), 3.76 (s, 3H), 2.48 (t, J=7.4 Hz, 2H), 1.62–1.48 (m, 2H),
1.42–1.26 (m, 2H), 0.90 ppm (t, J=7.2 Hz, 3H); 13C NMR (75.4 MHz,
CDCl3): d=163.6, 160.9, 146.0, 105.8, 91.1, 57.9, 51.0, 29.5, 27.1, 22.0,
13.7 ppm; IR (neat): n˜ =2955, 2873, 1720, 1607, 1470, 1407, 1279, 1212,
1138, 1089 cmÀ1; MS (EI): m/z (%): 212 (20.53) [M+], 169 (100) [M+
Compound 3c
Oil; 1H NMR (300 MHz, CDCl3): d=6.65 (s, 1H), 4.05 (s, 3H), 3.77 (s,
3H), 3.64 (t, J=6.5 Hz, 2H), 2.60 (t, J=7.5 Hz, 2H), 1.81–1.68 (m, 2H),
0.89 (s, 9H), 0.04 ppm (s, 6H); 13C NMR (75.4 MHz, CDCl3): d=164.0,
163.0, 128.9, 126.7, 90.7, 62.6, 57.4, 50.9, 31.8, 25.9, 21.5, 18.3, À5.3 ppm;
IR (neat): n˜ =2952, 2857, 1713, 1607, 1583, 1473, 1412, 1361, 1299, 1255,
1209, 1097, 1006 cmÀ1; MS (ESI): m/z: 626 [2
ACHTUNGTRENNUNG
HRMS (EI): m/z: calcd for C16H28O5Si+ [M+]: 328.1706; found:
328.1711.
+
ÀC3H7]; HRMS (EI): m/z: calcd for C11H16O4 [M+]: 212.1049; found:
Compound 2d
212.1052. The reaction on the gram scale: the reaction of [RuCl2ACTHNUTRGEN(UNG PPh3)3]
Oil; 1H NMR (300 MHz, CDCl3): d=6.29 (s, 1H), 4.05 (s, 3H), 3.81 (t,
J=6.5 Hz, 2H), 3.75 (s, 3H), 2.76 (t, J=6.3 Hz, 2H), 2.08 ppm (brs, 1H);
13C NMR (75.4 MHz, CDCl3): d=163.5, 161.3, 142.4, 107.9, 91.3, 60.3,
58.0, 51.2, 31.1 ppm; IR (neat): n˜ =3437, 2953, 2885, 1705, 1606, 1476,
1438, 1409, 1282, 1209, 1137, 1089, 1053 cmÀ1; MS (EI): m/z (%): 200
(18.99) [M+], 169 (100) [M+ÀOCH3]; HRMS (EI): m/z: calcd for
(120 mg, 0.13 mmol) and cyclopropenyl dicarboxylate 1a (1.060 g,
5.0 mmol) in THF (50 mL) for 10 h afforded 2a (1.033 g, 97%). Com-
pounds 2 and 5 were prepared according to this procedure.
Representative Procedure for the Synthesis of 3a
+
C9H12O5 [M+]: 200.0685; found: 200.0688.
[CuACHTUNGTRENNUNG(acac)2] (3 mg, 0.011 mmol), cyclopropenyl dicarboxylate 1a (41 mg,
0.19 mmol), and CH3CN (2 mL) were added sequentially to a Schlenk re-
action tube with a screw cap that had been evacuated and backfilled with
argon. The resulting mixture was heated at reflux at 1008C. After 48 h
the reaction was complete as monitored by TLC. Evaporation and
column chromatography on silica gel (eluent: petroleum ether/ethyl ace-
tate, 10:1) afforded the desired product 3a as an oil (36 mg, 88% yield).
1H NMR (300 MHz, CDCl3): d=6.63 (t, J=1.2 Hz, 1H), 4.05 (s, 3H),
3.78 (s, 3H), 2.54 (td, J=7.6, 0.8 Hz, 2H), 1.58–1.44 (m, 2H), 1.43–1.28
(m, 2H), 0.91 ppm (t, J=7.4 Hz, 3H); 13C NMR (75.4 MHz, CDCl3): d=
164.1, 162.9, 128.8, 127.3, 90.6, 57.4, 50.9, 31.0, 24.8, 22.4, 13.9 ppm; IR
(neat): n˜ =2954, 1712, 1606, 1583, 1473, 1436, 1412, 1319, 1299, 1214,
1094 cmÀ1; MS (EI): m/z (%): 212 (14.03) [M+], 170 (100) [M+H+
Compound 3d
Oil; 1H NMR (400 MHz, CDCl3): d=6.75 (s, 1H), 4.04 (s, 3H), 3.77 (s,
3H), 3.77 (t, J=6.2 Hz, 2H), 2.81 (t, J=6.2 Hz, 2H), 2.35 ppm (brs, 1H);
13C NMR (100 MHz, CDCl3): d=164.4, 163.0, 130.0, 123.5, 90.5, 62.2,
57.5, 51.1, 28.1 ppm; IR (neat): n˜ =3428, 2953, 2883, 1704, 1606, 1585,
1477, 1437, 1413, 1313, 1214, 1098, 1050, 1020 cmÀ1; MS (EI): m/z (%):
200 (36.21) [M+], 182 (28.14) [M+ÀH2O], 170 (72.55) [M+À2CH3], 123
(100) [M+ÀCO2MeÀH2O]; HRMS (EI): m/z: calcd for C9H12O5 [M+]:
+
200.0685; found: 200.0683.
+
ÀC3H7]; HRMS (EI): m/z: calcd for C11H16O4 [M+]: 212.1049; found:
Compound 2e
212.1051. The reaction on the gram scale: the reaction of [CuACTHNUTRGNEUNG(acac)2]
Oil; 1H NMR (300 MHz, CDCl3): d=7.33–7.25 (m, 2H), 7.24–7.13 (m,
3H), 6.19 (s, 1H), 4.04 (s, 3H), 3.77 (s, 3H), 2.95–2.87 (m, 2H), 2.86–
2.78 ppm (m, 2H); 13C NMR (100 MHz, CDCl3): d=163.5, 161.0, 144.9,
140.6, 128.4, 128.2, 126.1, 106.5, 91.3, 57.9, 51.0, 33.9, 29.4 ppm; IR (neat):
n˜ =3027, 2950, 1713, 1606, 1497, 1473, 1454, 1437, 1407, 1279, 1204, 1146,
1129, 1086 cmÀ1; MS (EI): m/z (%): 260 (9.71) [M+], 169 (100) [M+
(66 mg, 0.25 mmol) and cyclopropenyl dicarboxylate 1a (1.060 g,
5.0 mmol) in CH3CN (50 mL) for 10 h afforded 3a (0.795 g, 75%). Com-
pounds 3 and 6 were prepared according to this procedure.
Compound 2b
ÀPhCH2]; HRMS (EI): m/z: calcd for C15H16O4 [M+]: 260.1049; found:
+
Oil; 1H NMR (300 MHz, CDCl3): d=6.15 (s, 1H), 4.05 (s, 3H), 3.76 (s,
3H), 2.47 (t, J=7.4 Hz, 2H), 1.62–1.48 (m, 2H), 1.40–1.18 (m, 10H),
0.86 ppm (t, J=6.5 Hz, 3H); 13C NMR (100 MHz, CDCl3): d=163.6,
161.0, 146.1, 105.8, 91.2, 57.9, 51.0, 31.8, 29.2, 29.1, 28.9, 27.5, 27.4, 22.6,
14.0 ppm; IR (neat): n˜ =2928, 2856, 1720, 1607, 1468, 1407, 1278, 1260,
1201, 1138, 1084 cmÀ1; MS (EI): m/z (%): 268 (15.53) [M+], 169 (100)
260.1047.
Compound 3e
Oil; 1H NMR (300 MHz, CDCl3): d=7.32–7.24 (m, 2H), 7.24–7.14 (m,
3H), 6.60 (s, 1H), 4.06 (s, 3H), 3.82 (s, 3H), 2.86 ppm (s, 4H); 13C NMR
(75.4 MHz, CDCl3): d=163.9, 163.0, 141.8, 129.1, 128.4, 128.2, 126.3,
125.8, 90.5, 57.4, 50.9, 35.5, 27.1 ppm; IR (neat): n˜ =3026, 2950, 1708,
1606, 1584, 1496, 1474, 1454, 1435, 1411, 1351, 1302, 1210, 1097 cmÀ1; MS
(ESI): m/z: 283 [M+Na+], 261 [M+H+]; HRMS (EI): m/z: calcd for
+
[M+ÀC7H15]; HRMS (EI): m/z: calcd for C15H24O4 [M+]: 268.1675;
found: 268.1676.
Compound 3b
+
C15H16O4 [M+]: 260.1049; found: 260.1048.
Oil; 1H NMR (300 MHz, CDCl3): d=6.63 (t, J=1.1 Hz, 1H), 4.05 (s,
3H), 3.78 (s, 3H), 2.53 (td, J=7.7, 1.1 Hz, 2H), 1.58–1.44 (m, 2H), 1.43–
1.18 (m, 10H), 0.86 ppm (t, J=6.8 Hz, 3H); 13C NMR (75.4 MHz,
CDCl3): d=164.1, 162.9, 128.8, 127.4, 90.6, 57.4, 50.8, 31.8, 29.43, 29.38,
29.3, 28.8, 25.1, 22.6, 14.1 ppm; IR (neat): n˜ =2927, 2855, 1712, 1607,
1583, 1472, 1411, 1300, 1210, 1096 cmÀ1; MS (EI): m/z (%): 268 (15.53)
[M+], 183 (33.11) [M+ÀC6H13], 170 (100) [M+H+ÀC7H15]; HRMS (EI):
Compound 2 f
Oil; 1H NMR (300 MHz, CDCl3): d=7.35–7.28 (m, 2H), 7.28–7.18 (m,
3H), 6.20 (s, 1H), 4.05 (s, 3H), 3.85 (s, 2H), 3.76 ppm (s, 3H); 13C NMR
(75.4 MHz, CDCl3): d=163.5, 161.4, 144.0, 137.0, 128.6, 128.5, 126.7,
107.7, 91.4, 58.0, 51.1, 34.0 ppm; IR (neat): n˜ =2951, 1713, 1606, 1499,
1473, 1455, 1437, 1407, 1279, 1212, 1132, 1085 cmÀ1; MS (ESI): m/z: 269
+
m/z: calcd for C15H24O4 [M+]: 268.1675; found: 268.1676.
[M+Na+]; HRMS (EI): m/z: calcd for C14H14O4 [M+]: 246.0892; found:
+
246.0894.
Compound 2c
Compound 3 f
Oil; 1H NMR (300 MHz, CDCl3): d=6.16 (s, 1H), 4.05 (s, 3H), 3.76 (s,
3H), 3.63 (t, J=6.0 Hz, 2H), 2.56 (t, J=7.5 Hz, 2H), 1.84–1.71 (m, 2H),
0.88 (s, 9H), 0.03 ppm (s, 6H); 13C NMR (100 MHz, CDCl3): d=163.6,
161.0, 145.5, 106.1, 91.2, 61.8, 57.9, 51.0, 30.5, 25.8, 23.9, 18.2, À5.4 ppm;
IR (neat): n˜ =2953, 2930, 2857, 1720, 1608, 1472, 1437, 1407, 1257, 1207,
1135, 1089 cmÀ1; MS (EI): m/z (%): 328 (10.28) [M+], 271 (100) [M+
ÀtC4H9]; HRMS (EI): m/z: calcd for C16H28O5Si+ [M+]: 328.1706; found:
328.1707.
Oil; 1H NMR (300 MHz, CDCl3): d=7.33–7.15 (m, 5H), 6.42 (s, 1H),
4.05 (s, 3H), 3.92 (s, 2H), 3.75 ppm (s, 3H); 13C NMR (75.4 MHz,
CDCl3): d=163.9, 163.0, 139.3, 130.1, 128.8, 128.2, 126.7, 126.1, 90.7, 57.5,
50.8, 31.5 ppm; IR (neat): n˜ =3027, 2950, 1710, 1607, 1583, 1495, 1475,
1435, 1411, 1342, 1300, 1258, 1213, 1096 cmÀ1; MS (ESI): m/z: 269
[M+Na+]; HRMS (EI): m/z: calcd for C14H14O4 [M+]: 246.0892; found:
246.0894.
+
2418
www.chemasianj.org
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2010, 5, 2415 – 2421

Catalyst-Controlled Ring-Opening Cycloisomerization Reactions
Compound 2g
1641, 1605, 1558, 1475, 1435, 1415, 1395, 1281, 1221, 1135, 1086 cmÀ1; MS
+
(EI): m/z (%): 182 (100) [M+]; HRMS (EI): m/z: calcd for C9H10O4
Solid; m.p.: 80–828C (petroleum ether/ethyl acetate); 1H NMR
(300 MHz, CDCl3): d=7.54 (d, J=7.8 Hz, 2H), 7.37 (t, J=7.8 Hz, 2H),
7.24 (t, J=7.4 Hz, 1H), 6.86 (s, 1H), 4.21 (s, 3H), 3.83 ppm (s, 3H);
13C NMR (75.4 MHz, CDCl3): d=163.3, 161.5, 143.4, 129.6, 128.7, 127.1,
122.7, 106.2, 93.0, 58.0, 51.3 ppm; IR (KBr): n˜ =3108, 2951, 1692, 1615,
1598, 1570, 1497, 1480, 1435, 1409, 1291, 1268, 1247, 1190, 1162, 1108,
1073, 1039, 1019 cmÀ1; MS (EI): m/z (%): 232 (87.21) [M+], 217 (100)
[M+ÀCH3]; elemental analysis calcd (%) for C13H12O4: C 67.23, H 5.21;
found: C 67.30, H 5.05.
[M+]: 182.0579; found: 182.0578.
Compound 3j
Oil; 1H NMR (300 MHz, CDCl3): d=7.00 (s, 1H), 6.85 (dd, J=17.9,
11.3 Hz, 1H), 5.50 (d, J=17.7 Hz, 1H), 5.19 (d, J=11.1 Hz, 1H), 4.08 (s,
3H), 3.80 ppm (s, 3H); 13C NMR (75.4 MHz, CDCl3): d=163.8, 162.9,
128.5, 127.2, 125.8, 115.5, 90.1, 57.7, 51.1 ppm; IR (neat): n˜ =2952, 1712,
1603, 1570, 1473, 1436, 1399, 1298, 1271, 1216, 1190, 1110, 1089, 1068,
1036 cmÀ1; MS (EI): m/z (%): 182 (100) [M+]; HRMS (EI): m/z: calcd
+
for C9H10O4 [M+]: 182.0579; found: 182.0580.
Compound 3g
Oil; 1H NMR (300 MHz, CDCl3): d=7.42–7.26 (m, 5H), 6.89 (s, 1H),
4.12 (s, 3H), 3.70 ppm (s, 3H); 13C NMR (75.4 MHz, CDCl3): d=163.5,
163.1, 131.6, 129.5, 128.9, 128.1, 127.8, 127.5, 90.5, 57.7, 50.9 ppm; IR
(neat): n˜ =3031, 2997, 2951, 1713, 1599, 1579, 1491, 1469, 1406, 1324,
1296, 1275, 1231, 1190, 1131, 1084, 1004 cmÀ1; MS (EI): m/z (%): 232
Compound 2k
Oil; 1H NMR (300 MHz, CDCl3): d=7.98–7.88 (m, 2H), 7.58–7.42 (m,
3H), 6.14 (t, J=0.9 Hz, 1H), 4.02 (s, 3H), 2.45 (td, J=7.5, 0.9 Hz, 2H),
1.58–1.44 (m, 2H), 1.40–1.25 (m, 2H), 0.89 ppm (t, J=7.2 Hz, 3H);
13C NMR (75.4 MHz, CDCl3): d=157.7, 146.7, 143.0, 132.6, 128.9, 126.6,
104.9, 99.8, 58.4, 29.3, 27.1, 22.0, 13.6 ppm; IR (neat): n˜ =2956, 2872,
1603, 1446, 1371, 1320, 1290, 1268, 1154, 1134, 1071 cmÀ1; MS (EI): m/z
(%): 294 (29.49) [M+], 251 (100) [M+ÀC3H7]; HRMS (EI): m/z: calcd
for C15H18O4S+ [M+]: 294.0926; found: 294.0923.
+
(76.32) [M+], 129 (100); HRMS (EI): m/z: calcd for C13H12O4 [M+]:
232.0736; found: 232.0738.
Compound 2h
Solid; m.p.: 108–1098C (petroleum ether/ethyl acetate); 1H NMR
(300 MHz, CDCl3): d=7.42 (d, J=8.1 Hz, 2H), 7.17 (d, J=8.1 Hz, 2H),
6.78 (s, 1H), 4.19 (s, 3H), 3.82 (s, 3H), 2.35 ppm (s, 3H); 13C NMR
(75.4 MHz, CDCl3): d=163.4, 161.3, 143.7, 137.0, 129.3, 126.9, 122.7,
105.3, 92.9, 58.0, 51.2, 21.2 ppm; IR (KBr): n˜ =3109, 3025, 2952, 1695,
1596, 1567, 1509, 1481, 1438, 1417, 1400, 1291, 1269, 1249, 1192, 1163,
1105, 1030, 1015 cmÀ1; MS (EI): m/z (%): 246 (75.90) [M+], 231 (100)
[M+ÀCH3]; elemental analysis calcd (%) for C14H14O4: C 68.28, H 5.73;
found: C 68.31, H 5.62.
Compound 3k
Solid; m.p.: 119–1218C (petroleum ether/ethyl acetate); 1H NMR
(300 MHz, CDCl3): d=7.96–7.90 (m, 2H), 7.58–7.43 (m, 3H), 6.63 (t, J=
1.2 Hz, 1H), 4.04 (s, 3H), 2.51 (td, J=7.7, 0.9 Hz, 2H), 1.53–1.40 (m,
2H), 1.40–1.26 (m, 2H), 0.88 ppm (t, J=7.2 Hz, 3H); 13C NMR
(75.4 MHz, CDCl3): d=160.2, 143.5, 132.6, 129.0, 128.8, 126.5, 125.8, 99.1,
58.0, 30.5, 23.8, 22.3, 13.8 ppm; IR (KBr): n˜ =2948, 2868, 1596, 1582,
1449, 1392, 1366, 1336, 1317, 1305, 1289, 1243, 1233, 1178, 1154, 1121,
1107, 1075, 1044, 1022, 1004 cmÀ1; MS (EI): m/z (%): 294 (11.29) [M+],
252 (100) [M+H+ÀC3H7]; elemental analysis calcd (%) for C15H18O4S:
C 61.20, H 6.16; found: C 60.87, H 6.04.
Compound 3h
Solid; m.p.: 81–838C (petroleum ether/ethyl acetate); 1H NMR
(300 MHz, CDCl3): d=7.28 (d, J=8.1 Hz, 2H), 7.17 (d, J=7.8 Hz, 2H),
6.87 (s, 1H), 4.12 (s, 3H), 3.71 (s, 3H), 2.37 ppm (s, 3H); 13C NMR
(75.4 MHz, CDCl3): d=163.5, 163.0, 137.2, 129.4, 128.8, 128.6, 128.5,
128.1, 90.6, 57.7, 50.9, 21.2 ppm; IR (KBr): n˜ =2950, 2871, 1713, 1600,
1580, 1509, 1469, 1435, 1398, 1323, 1294, 1271, 1231, 1212, 1189, 1130,
1084 cmÀ1; MS (EI): m/z (%): 246 (100) [M+]; elemental analysis calcd
(%) for C14H14O4: C 68.28, H 5.73; found: C 68.38, H 5.87.
Compound 2l
Solid; m.p.: 146–1478C (ethyl acetate/ether); 1H NMR (300 MHz,
CDCl3): d=8.03–7.96 (m, 2H), 7.62–7.45 (m, 5H), 7.36 (t, J=7.5 Hz,
2H), 7.26 (t, J=7.4 Hz, 1H), 6.82 (s, 1H), 4.18 ppm (s, 3H); 13C NMR
(100 MHz, CDCl3): d=158.2, 144.0, 142.7, 132.8, 129.0, 128.9, 128.7,
127.7, 126.7, 122.9, 105.0, 102.2, 58.6 ppm; IR (KBr): n˜ =3120, 2947, 1594,
1570, 1491, 1459, 1447, 1374, 1318, 1291, 1260, 1166, 1125, 1080 cmÀ1; MS
(EI): m/z (%): 314 (37.99) [M+], 77 (100); elemental analysis calcd (%)
for C17H14O4S: C 64.95, H 4.49; found: C 65.24, H 4.60.
Compound 2i
Solid; m.p.: 150–1518C (petroleum ether/ethyl acetate); 1H NMR
(300 MHz, CDCl3): d=8.01 (d, J=8.1 Hz, 2H), 7.55 (d, J=8.1 Hz, 2H),
6.99 (s, 1H), 4.22 (s, 3H), 3.90 (s, 3H), 3.82 ppm (s, 3H); 13C NMR
(100 MHz, CDCl3): d=166.6, 163.0, 162.0, 142.4, 133.6, 130.1, 128.3,
122.2, 109.0, 93.6, 58.2, 52.1, 51.4 ppm; IR (KBr): n˜ =3124, 3007, 2957,
1712, 1618, 1604, 1587, 1507, 1477, 1433, 1407, 1318, 1293, 1279, 1249,
1185, 1097, 1026, 1011 cmÀ1; MS (ESI): m/z: 384 [M+Na++K++MeOH],
329 [M+K+], 291 [M+H+]; elemental analysis calcd (%) for C15H14O6:
C 62.07, H 4.86; found: C 62.10, H 4.59.
Compound 3l
Solid; m.p.: 139–1418C (petroleum ether/ethyl acetate); 1H NMR
(300 MHz, CDCl3): d=7.64 (d, J=7.8 Hz, 2H), 7.47 (t, J=7.4 Hz, 1H),
7.40–7.24 (m, 7H), 6.84 (s, 1H), 4.14 ppm (s, 3H); 13C NMR (75.4 MHz,
CDCl3): d=160.2, 142.8, 132.6, 129.8, 129.7, 129.6, 128.5, 128.1, 127.8,
126.8, 126.7, 99.8, 58.4 ppm; IR (KBr): n˜ =3145, 1597, 1578, 1489, 1445,
1370, 1318, 1304, 1289, 1183, 1168, 1142, 1101, 1086, 1071, 978 cmÀ1; MS
(EI): m/z (%): 314 (100) [M+]; elemental analysis calcd (%) for
C17H14O4S: C 64.95, H 4.49; found: C 64.59, H 4.48.
Compound 3i
Solid; m.p.: 124–1268C (petroleum ether/ethyl acetate); 1H NMR
(300 MHz, CDCl3): d=8.01 (d, J=8.1 Hz, 2H), 7.44 (d, J=8.1 Hz, 2H),
6.93 (s, 1H), 4.12 (s, 3H), 3.90 (s, 3H), 3.69 ppm (s, 3H); 13C NMR
(75.4 MHz, CDCl3): d=166.9, 163.3, 163.2, 136.4, 130.0, 129.0, 128.9,
127.4, 90.4, 57.8, 52.0, 51.0 ppm; IR (KBr): n˜ =2952, 1720, 1598, 1582,
1459, 1436, 1303, 1277, 1236, 1076 cmÀ1; MS (EI): m/z (%): 290 [M+]
(100); elemental analysis calcd (%) for C15H14O6: C 62.07, H 4.86; found:
C 62.07, H 4.80.
Compound 2m
1
Oil; H NMR (300 MHz, CDCl3): d=6.82 (d, J=2.4 Hz, 1H), 6.59 (d, J=
2.4 Hz, 1H), 4.08 (s, 3H), 3.77 ppm (s, 3H); 13C NMR (75.4 MHz,
CDCl3): d=163.3, 162.0, 132.0, 111.6, 90.8, 57.8, 51.0 ppm; IR (neat): n˜ =
2953, 1720, 1612, 1543, 1477, 1437, 1413, 1310, 1276, 1197, 1133, 1082,
1021 cmÀ1; MS (EI): m/z (%): 156 (61.73) [M+], 141 (30.31) [M+ÀCH3],
125 (100) [M+ÀOCH3]; HRMS (EI): m/z: calcd for C7H8O4 [M+]:
+
156.0423; found: 156.0422.
Compound 2j
Compound 2n
Oil; 1H NMR (300 MHz, CDCl3): d=6.43 (s, 1H), 6.31 (dd, J=17.4,
11.4 Hz, 1H), 5.46 (d, J=17.4 Hz, 1H), 5.08 (d, J=11.7 Hz, 1H), 4.14 (s,
3H), 3.77 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=163.3, 161.6,
143.0, 123.9, 110.9, 109.6, 92.5, 57.9, 51.2 ppm; IR (neat): n˜ =2953, 1713,
Oil; 1H NMR (400 MHz, CDCl3): d=7.97–7.93 (m, 2H), 7.59–7.53 (m,
1H), 7.52–7.46 (m, 2H), 6.85 (d, J=2.4 Hz, 1H), 6.59 (d, J=2.4 Hz, 1H),
4.06 ppm (s, 3H); 13C NMR (75.4 MHz, CDCl3): d=158.9, 142.8, 132.8,
Chem. Asian J. 2010, 5, 2415 – 2421
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
2419

S. Ma and J. Chen
FULL PAPERS
132.5, 128.9, 126.6, 110.9, 100.0, 58.4 ppm; IR (neat): n˜ =3153, 3119, 1609,
1582, 1445, 1393, 1319, 1303, 1288, 1225, 1180, 1156, 1138, 1097,
1072 cmÀ1; MS (EI): m/z (%): 239 (13.96) [M+H+], 238 (100) [M+];
HRMS (EI): m/z: calcd for C11H10O4S+ [M+]: 238.0300; found: 238.0301.
Rubina, V. Gevorgyan, J. Am. Chem. Soc. 2005, 127, 10500; f) J.
Zhang, L. Lu, Chem. Eur. J. 2003, 9, 2447; g) S. Ma, Z. Yu, Angew.
Chem. 2002, 114, 1853; Angew. Chem. Int. Ed. 2002, 41, 1775;
h) A. S. K. Hashmi, L. Shwarz, J. H. Choi, T. M. Trost, Angew.
Chem. 2000, 112, 2382; Angew. Chem. Int. Ed. 2000, 39, 2285;
i) A. S. K. Hashmi, Angew. Chem. 1995, 107, 1749; Angew. Chem.
Int. Ed. Engl. 1995, 34, 1581. For selected examples of cycloisomeri-
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Xiao, J. Zhang, Angew. Chem. 2008, 120, 1929; Angew. Chem. Int.
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For selected examples of cycloisomerization approaches to substitut-
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p) S. Ma, L. Lu, J. Zhang, J. Am. Chem. Soc. 2004, 126, 9645; q) S.
Ma, J. Zhang, Angew. Chem. 2003, 115, 193; Angew. Chem. Int. Ed.
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by means of olefin cross-metathesis, see: T. J. Donohoe, J. F. Bower,
Proc. Natl. Acad. Sci. USA 2010, 107, 3373.
Compound 5[13a]
Oil; 1H NMR (300 MHz, CDCl3): d=6.21 (s, 1H), 4.25 (q, J=7.1 Hz,
2H), 2.57–2.50 (m, 5H), 1.69–1.52 (m, 2H), 1.42–1.29 (m, 5H), 0.91 ppm
(t, J=7.2 Hz, 3H); 13C NMR (75.4 MHz, CDCl3): d=164.4, 157.4, 154.3,
113.7, 105.3, 59.9, 29.8, 27.3, 22.1, 14.3, 13.75, 13.68 ppm; IR (neat): n˜ =
2958, 2933, 2873, 1714, 1619, 1585, 1276, 1230, 1214, 777 cmÀ1; MS (EI):
m/z (%): 210 (43.90) [M+], 167 (100) [M+ÀC3H7].
Compound 6[13a]
Oil; 1H NMR (300 MHz, CDCl3): d=7.01 (s, 1H), 4.28 (q, J=7.1 Hz,
2H), 2.60–2.51 (m, 5H), 1.58–1.45 (m, 2H), 1.43–1.29 (m, 5H), 0.91 ppm
(t, J=7.4 Hz, 3H); 13C NMR (75.4 MHz, CDCl3): d=164.7, 160.1, 137.2,
126.2, 112.9, 59.7, 31.7, 24.4, 22.5, 14.4, 14.3, 13.9 ppm; IR (neat): n˜ =
2958, 2931, 2861, 1712, 1606, 1560, 1445, 1300, 1268, 1093, 940, 788,
746 cmÀ1; MS (EI): m/z (%): 210 (16.35) [M+], 57 (100) [C4H9].
Crystallographic Data
CCDC 743564 (2h) and 743565 (3k) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre at www.ccdc.cam.
ac.uk/data_request/cif.
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Acknowledgements
Financial support from the Major State Basic Research Development
Program (2009CB825300) is greatly appreciated.
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space group P21/n; MoKa; a=8.1048(4) ꢆ, b=11.3026(5) ꢆ, c=
16.2124(7) ꢆ; a=908, b=99.5530(10)8, g=908; V=1464.55(12) ꢆ3;
T=173(2) K; Z=4; final R indices (I>2s(I)), R1=0.0291, wR2=
0.0741; R indices (all data): R1=0.0329, wR2=0.0785, reflections
collected/unique: 16598/2590 (Rint =0.0192); number of observations
(I>2s(I)) 2350, parameters 181.
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[18] X-ray data for compound 2h: C28H28O8, Mr =492.50; monoclinic;
space group P21/c; MoKa; a=15.1345 (2) ꢆ, b=13.4489 (2) ꢆ, c=
13.2905 (2) ꢆ; a=908, b=111.2860(10)8, g=908; V=2520.63(6) ꢆ3;
T=173(2) K; Z=4; final R indices (I>2s(I)); R1=0.0437; wR2=
0.1290; R indices (all data): R1=0.0525; wR2=0.1389; reflections
Received: May 4, 2010
Revised: June 7, 2010
Published online: August 30, 2010
Chem. Asian J. 2010, 5, 2415 – 2421
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
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