Facile synthesis of oxa- and azacyclic dienes via cycloalkenation of alkynyltungsten compounds. Stereoselective construction of tricyclic furan and pyran derivatives via intramolecular diels-alder reaction

Article abstract of DOI:10.1021/jo000044q

A convenient and short synthesis of functionalized oxacyclic and azacyclic dienes is developed on the basis of organotungsten chemistry. Alkynyltungsten compounds bearing a tethered alcohol and amine are treated with aldehydes and BF₃·Et₂O in cold diethyl ether to give tungsten-heterocyclic carbenium salts, further leading to tungsten-heterocyclic dienes via deprotonation with Et₃N. Hydrodemetalation of these tungsten-heterocyclic dienes is performed by the action of anhydrous Me₃NO in CH₃CN. This method is applicable to the synthesis of a number of oxa- and azacyclic dienes, including those tethered with an electron-deficient olefin. The oxacyclic 1,3,8-nonatrienes and 1,3,9-decatrienes undergo intramolecular Diels-Alder reactions upon heating in toluene, yielding tricyclic tetrahydropyran and -furan derivatives with excellent diastereoselectivities.

Full text of DOI:10.1021/jo000044q

J . Org. Chem. 2000, 65, 3761-3766
3761
F a cile Syn th esis of Oxa - a n d Aza cyclic Dien es via Cycloa lk en a tion
of Alk yn yltu n gsten Com p ou n d s. Ster eoselective Con str u ction of
Tr icyclic F u r a n a n d P yr a n Der iva tives via In tr a m olecu la r
Diels-Ald er Rea ction
Wen-Tai Li, Min-Hui Pan, Yi-Ru Wu, Sue-Lein Wang, Fen-Lin Liao, and Rai-Shung Liu*
Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan, R.O.C
Received J anuary 12, 2000
A convenient and short synthesis of functionalized oxacyclic and azacyclic dienes is developed on
the basis of organotungsten chemistry. Alkynyltungsten compounds bearing a tethered alcohol and
amine are treated with aldehydes and BF3‚Et2O in cold diethyl ether to give tungsten-heterocyclic
carbenium salts, further leading to tungsten-heterocyclic dienes via deprotonation with Et3N.
Hydrodemetalation of these tungsten-heterocyclic dienes is performed by the action of anhydrous
Me3NO in CH3CN. This method is applicable to the synthesis of a number of oxa- and azacyclic
dienes, including those tethered with an electron-deficient olefin. The oxacyclic 1,3,8-nonatrienes
and 1,3,9-decatrienes undergo intramolecular Diels-Alder reactions upon heating in toluene,
yielding tricyclic tetrahydropyran and -furan derivatives with excellent diastereoselectivities.
Sch em e 2
In tr od u ction s
Oxa- and azacyclic dienes 1-5 are useful building
blocks for complex oxa- and azacyclic compounds.1-4
Cycloadditions of these heterocyclic dienes with electron-
deficient olefins normally proceed with high diastereo-
selectivities.1,2 The resulting [4 + 2]-cycloadducts provide
a concise approach to naturally occurring compounds.
Boeckman and co-workers3 previously reported a highly
convergent synthesis of racemic lycorine through in-
tramolecular [4 + 2]-cycloaddition of 3-vinyl-4,5-dihy-
dropyrrole derivative 2. Recently, Overman et al.4 have
employed compound 5 as an intermediate for total
synthesis of (+)-aloperine. One major problem with the
use of these heterocyclic dienes is the diversity of
synthetic methods that often require long procedures.1,2
A general and short synthesis of these heterocyclic dienes
will be valuable in synthetic organic chemistry.
tatively as shown in Scheme 2.5,6 Further treatment of
these carbenium salts with Et3N led to deprotonation,
yielding tungsten-η1-oxacyclic dienes B in excellent yields.7
If organic nitrile was used as a solvent, the tungsten-η1-
3-vinyl-4,5-dihydrofur-2-yl species B underwent cyano-
[4 + 2]-cycloaddition, yielding furopyridines in the pres-
ence of excess Me3NO‚2H2O or upon photolysis.7 In this
paper, we describe a convenient synthesis of functional-
ized heterocyclic dienes through hydrodemetalations of
tungsten-η1-oxa- and -azacyclic dienes under appropriate
conditions. These heterocyclic dienes can undergo inter-
and intramolecular Diels-Alder reactions to give poly-
cyclic furan and pyran derivatives with high diastereo-
selectivities.
Sch em e 1
We recently reported that tungsten-alkynol compounds
underwent cycloalkenations with aldehydes and BF3‚
Et2O to give tungsten-η1-oxacarbenium salts A quanti-
Resu lts a n d Discu ssion
(1) (a) Boeckman, R. K. J r.; Breining, S. R.; Arvanitis, A. Tetrahe-
dron 1997, 53, 8941. (b) Aelterman, W.; De kimpe, N. Tetrahedron
1998, 54, 2563. (c) Bigogno, C.; Danieli, B.; Lesma, G.; Passarella, D.
Heterocycles 1995, 41, 973. (d)
(2) (a) Breitmaier, E.; Potthoff, B. Chem. Ber. 1986, 119, 3204. (b)
Breitmaier, E.; Ruffer, U. Synthesis 1986, 584. (c) Breitmaier, E.;
Ruffer, U. Synthesis 1989, 623. (d) Cornwall, P.; Dell, C. P.; Knight,
D. W. J . Chem. Soc., Perkin Trans. 1 1993, 2395.
Syn th esis of Heter ocyclic Dien es. The starting
compounds tungsten-η1-oxacyclic dienes B were easily
prepared from deprotonation of their corresponding oxa-
(5) Liang, K.-W.; Li, W.-T.; Lee, G.-H., Peng S.-M.; Liu, R.-S. J . Am.
Chem. Soc. 1997, 119, 4404.
(3) Boeckman, R. K. J r.; Goldstein, S. W.; Walters, M. A. J . Am.
Chem. Soc. 1988, 110, 8250
(4) Brosius, A. D.; Overman, L. E.; Schwink, L. J . Am. Chem. Soc.
1999, 121, 700.
(6) Liang, K.-W.; Chandrasekharam, M.; Li, C.-L.; Liu, R.-S. J . Org.
Chem. 1998, 63, 7289.
(7) Li, W,-T.; Lai, F.-C.; Lee, G.-H.; Peng, S.-M.; Liu, R. S. J . Am.
Chem. Soc. 1998, 120, 4520.
10.1021/jo000044q CCC: $19.00 © 2000 American Chemical Society
Published on Web 05/23/2000

3762 J . Org. Chem., Vol. 65, No. 12, 2000
Li et al.
Ta ble 1. Yield s for Dem eta la tion of η1-Heter ocyclic
cyclic carbenium salts A with Et3N; the yields normally
exceeded 90% (Scheme 2).7 The tungsten-azacyclic car-
benium salt, however, is not available at the present time
because cycloalkenation of tungsten-η1-R,δ-alkynylamines
is not known yet. Scheme 3 shows an instance for
cycloalkenation of tungsten-alkynylamine compound 6
with acetaldehyde and BF3‚Et2O to yield dark red
precipitates, characterized as tungsten-η1-azacarbenium
salt 7. Sequential treatment of this salt with Et3N
Dien es w ith An h yd r ou s Me3NOa
Sch em e 3
afforded tungsten-η1-3-vinyl-4.5-dihydropyrrolyl species
8 in 83% yield based on starting tungsten-η1-alkynyl-
amine species 6. The cycloalkenation is not applicable
to tungsten-η1-R,δ-alkynylamine that did not form the
corresponding tungsten-piperdinyl salt upon treatment
with MeCHO and BF3‚Et2O.
Hydrodemetalation of tungsten-heterocyclic dienes was
achieved via treatment with Me3NO, but the yields of the
desired heterocyclic dienes depended on the types of
tungsten-heterocyclic dienes, the solvents, and the con-
tents of water in Me3NO. Scheme 4 shows the yields of
a
W ) CpW(CO)3, Me3NO (5.0 equiv), CH3CN, 23 °C, 6 h.
demetalation was performed with anhydrous Me3NO in
CH2Cl2 (entry 4), the unsaturated γ-lactone 9b was
formed as the major product (56% yield). Demetalation
of tungsten-η1-oxacyclic diene 10 proceeded more smoothly
for the desired oxacyclic diene 10a (entries 5 and 6), no
cyano-[4 + 2]-cycloaddition adduct was formed even
though Me3NO‚2H2O was employed.
Sch em e 4
The results in Scheme 4 suggest that hydrodemetala-
tion of tungsten-η1-oxacyclic dienes 9 and 10 was best
performed with anhydrous Me3NO in CH3CN. The proton
(or hydrogen) sources for the resulting dienes 9a and 10a
were presumbly from either CH3CN or other reactants.8
Although the mechanism of hydrodemetalation is not
clear at the present stage, it is a reliable tool for the
synthesis of a variety of oxa- and azacyclic dienes 16-
21 as shown in Table 1. The hydrodemetalations of
tungsten-η1-heterocyclic dienes 11-15 and 8 were per-
formed exclusively with anhydrous Me3NO in CH3CN
according to the preceding procedures. The tungsten-η1-
oxacyclic dienes 11-15 were prepared from the corre-
sponding tungsten-η1-R,δ- or -R,ꢀ-alkynols and aldehydes
according to the synthetic protocol shown in Scheme 2;
the yields exceeded 85% in most cases. Entries 1 and 2
show two additional examples for syntheses of 4,5-
dihydrofuryl dienes 16 and 17, and the yields were 58%
and 55%, respectively. The Me3NO-promoted hydrode-
metalation is applicable for preparation of six-membered
oxacycles including the electron-rich dienes 19 and 20;
the yields were reasonable (47-53% yields). No signifi-
cant byproducts were found in entries 3-5. In contrast,
hydrodemetalation of tungsten-η1-azacyclic species 8
yielded 4,5-dihydropyrrole 21 (46% yield) in addition to
unsaturated γ-lactam 22 (37% yield).
products for demetalation of tungsten-η1-oxacyclic dienes
9-10 under various conditions. Treatment of 9 with
anhydrous excess Me3NO in CH3CN gave the hydrode-
metalation products 9a in 61% yields. With increasing
contents of water in Me3NO, the yields of unsatuated
γ-lactone 9b and furopyridine 9c increased steadily
together with loss of the yields of oxacyclic diene 9a .
Furopyridine 9c was formed preferably (58% yield) with
the use of excess Me3NO‚2H2O. Compound 9c were also
obtained in good yield upon irradiation with UV light in
CH3CN.7 The role of water for the formation of 9c seems
to enhance the coordination of CH3CN to tungsten center
after one of the CO group was removed by Me3NO. If the
(8) We have performed hydrodemetalation of tungsten-η1-oxacyclic
diene 9 with anhydrous Me3NO in CD3CN, and mass analysis of the
resulting oxacyclic diene 16 show the deuterium content ca. 25%,
indicating that CH3CN is not the only source for hydrogen (or proton).

Facile Synthesis of Oxa- and Azacyclic Dienes
J . Org. Chem., Vol. 65, No. 12, 2000 3763
Ta ble 2. Cycloa d d ition s of Oxa cyclic Dien e 16
group with 27a assignable to the endo isomer and 27b
assignable to exo isomer. Diagnostic for the structures
are the proton coupling constants J 23 ) 4.5 Hz and J 23
)
10.5 Hz for 27a and 27b, respectively, indicative of axial-
equatorial and axial-axial proton couplings. The reaction
of oxacyclic diene 16 with less reactive olefins such as
methyl vinyl ketone and methyl acrylate proceeded very
sluggishly, and that four cycloadducts were formed in
equal proportions. No further efforts were made for
characterization of these cycloadducts.
In tr am olecu lar Diels-Alder Reaction s. The present
method is also applicable to the synthesis of oxacyclic
dienes bearing an electron-deficient olefin; these func-
tionalized dienes can provide an easy entry to tricyclic
oxacycles through intramolecular Diels-Alder reac-
tions.10 Synthesis of a representative compound 31 is
given in Scheme 6. Treatment of tungsten-η1-alkynol 28
Sch em e 6
In ter m olecu la r Diels-Ald er Rea ction of 4,5-Di-
h yd r ofu r yl Dien e. Diels-Alder reaction of heterocyclic
dienes 1-4 have been studied previously over the last
two decades for the synthesis of complex heterocyclic
compounds.1-4 The heterocyclic dienes in these studies1-4
have no substituents on the heterocyclic ring. Heterocy-
clic dienes 9a -10a and 16-22 seem to be more chal-
lenging because additional diastereomeric products will
form compared to previous studies. Table 2 shows [4 +
2]-cycloadditions for 4,5-dihydrofuryl diene 16 with a
number of electron-deficient olefins. The cycloadditions
of 16 with maleic anhydride and maleic imide (entries
1-3) proceeded with high diastereoselectivities, and only
endo diastereomers 23-25 were formed in excellent
yields. The stereochemistry of cycloadduct 23 was deter-
with aldehyde 29 with BF3‚Et2O in cold diethyl ether led
to formation of insoluble precipitate, presumbly oxacar-
benium salt that was collected by filtration. Deprotona-
tion of this salt with Et3N (3.0 equiv) in CH2Cl2 delivered
tungsten-η1-oxacyclic diene 30 in 92% yield. Further
hydrodemetalation of compound 30 with anhydrous Me3-
NO in CH3CN produced an organic diene 31 in 57% yield.
Shown in Table 3 (entries 2-4) are the four oxacyclic
dienes 32-35 bearing an unsaturated ester. Compounds
32-35 were obtained in 56-60% yields by Me3NO-
promoted hydrodemetalation of their corresponding tung-
sten-η1-oxacyclic dienes.11 A scheme showing this process
is provided in the Supporting Information. Intramolecu-
lar Diels-Alder cycloadditions of these functionalized
dienes 31-35 proceeded smoothly upon heating in tolu-
ene to give only one diastereomeric product 36-40 in
good yields as shown in Table 3. Determination of the
1
mined by an H NMR NOE effect and further confirmed
by X-ray diffraction study.9 The ORTEP drawing suggests
that maleic anhydride approaches the diene moiety in
the endo face and opposite the phenyl substituent. One
regioisomer is found for the cycloadduct 26 derived from
3-butyn-2-one. The reaction of 16 with dimethyl maleate
proceeded very slowly, yielding a mixture of two diaster-
eomers 27a and 27b in a 56/44 ratio, which were
unseparable by preparative silica plate. The structures
Sch em e 5
1
structures of these cycloadducts relied primarily from H
NMR NOE effect. The NOE-map of the representative
compounds 36 is shown in Scheme 7. The NOE maps of
the remaining compounds 37-4012 indicate that these
four tricyclic oxacycles (entries 2-5) have trans-fused
structures similar to that for compound 36.
1
of these two isomers are determined by an H NMR NOE
effect, which indicates that both isomers are produced
by approach of the diene moiety opposite the phenyl
(10) Review article of intramolecular Diels-Alder reaction, see:
Roush, W. R. In Comprehensive Organic Synthesis; Trost, B. M., Ed.;
Pergamon Press: Oxford, 1991; Vol. 5, p 513.
(9) Crystal data for 23: monoclinic, space group P21/n, a ) 9.1021-
(1) Å, b ) 9.2417(1) Å, c ) 17.6166(3) Å, â ) 102.092(20)°, V ) 1449.0-
(5) Å3, Z ) 4; final R ) 0.0431 and Rw ) 0.0466. The X-ray data of 23
is provided in the Supporting Information.
(11) Details in the syntheses of oxacyclic dienes 32-35 are provided
in the Supporting Information.
(12) The NOE maps of the compounds 37-40 are given in the
Experimental Section.

3764 J . Org. Chem., Vol. 65, No. 12, 2000
Li et al.
Ta ble 3. Syn th esis of Tr icyclic Oxa cycles via
state. A generally accepted interpretation is that a
terminally activating group CO2Me on decatriene prefers
trans-fused stereoselection because of the polarization
effect of the double bond, which enhances the interaction
of the C(2)- and C(7)-carbons.14-16 This model accounts
well for the observed trans-stereoselection for intramo-
lecular cycloaddition of the nona- and decatrienes 31-
33. On the other hand, an internal activating group
CO2Me on decatriene-like state D generally prefers cis-
fused products because it increases the C(1) coefficient
of the LUMO orbital to enhance its C(1)-C(10) interac-
tion;14-16 this speculation contradicts with our observa-
tions (entries 4 and 5, Table 3). We envision that the
trans selectivities of cycloadducts 39 and 40 may have
two reasons according to related studies in the litera-
tures.15,16 First, two substituents (RdCO2Me) at the C(5)-
carbon destabilizes the structure of state E through
increasing steric interaction with the axial C(7)dC(8)
bond.17 Furthermore, the C(10)-oxygen atom is expect to
decrease the C(10) coefficient of the diene HOMO orbital
to make the C(1)-C(10) interaction less pronounced,18
diminishing the preference for cis-stereoselection.
In tr a m olecu la r Diels-Ald er Rea ction
Con clu sion . In this study, we have successfully
developed a short and convenient synthesis of function-
alized oxa- and azacyclic dienes based on cycloalkenations
of alkynyltungsten compounds. The key step in the
syntheses is the dehydrodemetalation of tungsten-
heterocyclic dienes via treatment with anhydrous Me3-
NO in CH3CN. This method is applicable to the syntheses
of oxacyclic dienes including those tethered with an
electron-deficient olefin. Intramolecular Diels-Alder re-
actions of these oxacyclic trienes afforded tricyclic furan
and pyran derivatives with high diastereoselectivities.
Sch em e 7
Exp er im en ta l Section
Unless otherwise noted, all reactions were carried out under
nitrogen atmosphere in oven-dried glassware using standard
syringe, cannula, and septa apparatus. Benzene, diethyl ether,
tetrahydrofuran, and hexane were dried with sodium ben-
zophenone and distilled before use. Dichloromethane was dried
over CaH2 and distilled before use. W(CO)6, sodium, dicyclo-
pentadiene, propargyl bromide, methanesulfonamide, p-tolu-
enesulfoamide, and benzaldehyde were obtained commercially
and used without purification. Spectral data of compounds 9,
9b, 9c, 10, 11, and 28 were published previously.5,7 Spectral
data of compounds 10, 10a , 13-22, 24-27, and 32-35 in
repetitive experiments are provided in the Supporting Infor-
mation.
Intramolecular Diels-Alder cycloadditions have been
studied extensively,12-16 and stereoselection of cis- or
trans-fused products depends on both electronic and
steric effects. Scheme 8 shows the two transition states
Sch em e 8
Tu n gsten -η1-4-p h en yl-4-tosyla m in obu t-1-yn e (6). To a
diethylamine solution (25 mL) of CpW(CO)3Cl (3.00 g, 8.15
mmol) and CuI (0.16 g, 0.82 mmol) was added 4-phenyl-3-
tosylamino-1-butyne (2.31 g, 7.74 mmol), and the mixture was
stirred at 23 °C for 6 h. The solution was concentrated to ca.
3.0 mL and eluted through a silica column to yield a yellow
band that afforded compound 6 as a yellow solid (3.18 g, 5.03
mmol, 65%): IR (neat, cm-1) υ(CO) 2027(vs), 1934(vs), υ(SO2)
1349(s); 1H NMR (300 MHz, CDCl3) δ 7.10-7.56 (9H, m), 5.50
(5H, s), 5.31 (s, br s), 4.38 (1H, dd, J ) 11.8, 4.9 Hz), 2.71 (2H,
m, J ) 15 Hz), 2.34 (3H, s); 13C NMR (75 MHz, CDCl3) δ 228.9,
212.2, 212.1, 142.9, 140.4, 137.5, 129.3, 127.9, 127.2, 127.0,
C and D for cis- and trans-fused stereoselections for
decatriene according to the Houk’s concept of “twist
asynchronicity”.13 In this concept, stereoselection is con-
trolled by the timing of bond formation in the transition
(16) (a) Marshall, J . A.; Audia, J . E.; Crote, J . J . Org. Chem. 1984,
49, 5277. (b) Marshall, J . A.; Audia, J . E.; Crote, J . J . Am. Chem. Soc.
1988, 110, 1290.
(17) Trost, B. M.; Lautens, M.; Hung, M.-H.; Carmichael, C. S. J .
Am. Chem. Soc. 1984, 106, 7641.
(13) (a) Brown, F. K.; Houk, K. N. Tetrahedron Lett. 1985, 26, 2297.
(b) Wu, T.-C.; Houk, K. N. Tetrahedron Lett. 1985, 26, 2293.
(14) Roush, W. R.; Essenfeld, A. P.; Warmus, J . S. Tetrahedron Lett.
1987, 28, 2447.
(15) (a) Ichihara, A.; Miki, M.; Tazaki, H.; Sakamura, S. Tetrahedron
Lett. 1987, 28, 1175. (b) Burke, S. D.; Piscopio, A. D.; Buchana, J . L.
Tetrahedron Lett. 1988, 29, 2757. (c) Matikainen, J . K. T.; Kaltia, S.
A. A.; Hase, T. A. Tetrahedron Lett. 1988, 29, 2685.
(18) (a) Burke, S. D.; Magnin, D. R.; Oplinger, J . A.; Baker, J . P.;
Abdelmagid, A. Tetrahedron Lett. 1984, 25, 19. (b) Hashimoto, S.;
Sakata, S.; Sonegawa, M.; Ikegami, S. J . Am. Chem. Soc. 1988, 110,
3760.

Facile Synthesis of Oxa- and Azacyclic Dienes
J . Org. Chem., Vol. 65, No. 12, 2000 3765
126.7, 122.5, 91.4, 63.9, 56.7, 31.3, 21.4; MS (EI, m/z) 631 (M+),
(711 mg, 1.49 mmol) were added aldehyde 29 (512 mg, 1.79
mmol) and BF3‚Et2O (1.22 mL, 1.79 mmol) at -60 °C, and the
mixture was stirred for 8 h. The solution was warmed to 23
°C, and the resulting orange precipitates (937 mg, 96%) were
collected by filtration. The solids were redissolved in CH2Cl2
(10 mL) and treated with Et3N (1.03 mL, 7.45 mmol). The
solution was evaporated to dryness and eluted through a basic
Al2O3 column to yield tungsten-η1-4,5-dihydrofuryltriene 30
(899 mg, 1.21 mmol, 92%): IR (neat, cm-1) 2025 (s), 1927 (s),
1726 (s), 1601 (m), 1498 (m); 1H NMR (400 MHz, CDCl3) δ
7.30-7.18 (5H, m), 6.77 (1H, dt, J ) 15.0, 7.6 Hz), 6.07 (1H,
d, J ) 15.0 Hz), 5.82 (1H, d, J ) 15.8 Hz), 5.55 (5H, s), 5.39
(1H, dd, J ) 10.4, 7.4 Hz), 4.79 (1H, dt, J ) 15.8, 7.5 Hz), 3.65
(9H, s), 3.00 (1H, dd, J ) 14.2, 10.4 Hz), 2.73-2.67 (4H, m),
2.46 (1H, dd, J ) 14.2, 7.4 Hz); 13C NMR (100 MHz, CDCl3) δ
227.2, 215.8, 170.7, 166.1, 150.5, 144.3, 143.0, 132.7, 128.2,
127.8, 127.0, 125.2, 124.3, 115.3, 91.7, 83.7, 57.8, 52.3, 51.2,
603 (M+ - CO), 547 (M+ - 3CO). Anal. Calcd for WC25H21
-
SNO5: C, 47.54; H, 3.25; N, 2.23. Found: C, 47.54; H, 3.52;
N, 2.29.
Tu n gsten -η1-p yr r olylid en iu m Sa lt (7). To a diethyl ether
solution of alkynyltungsten compound 6 (0.80 g, 1.27 mmol)
at -78 °C were added acetaldehyde (1.0 mL) and BF3‚Et2O
(0.16 mL, 1.30 mmol), and the solution was warmed to 23 °C
over a period of 8 h. During this period, a red precipitate of
tungsten-η1-azacyclic carbenium salt 7 was slowly deposited,
collected by filtration, and washed with diethyl ether. The yield
was 91% (0.86 g, 1.15 mmol): IR (neat, cm-1) υ(CO) 1991(vs),
1920(s); 1H NMR (400 MHz, CDCl3, -40 °C) δ anti-form, 7.50-
6.90 (10H, m), 6.01 (5H, s), 4.89 (1H, dd, J ) 9.4, 4.9 Hz), 3.63
(1H, dd, J ) 15.9, 9.4 Hz), 2.74 (1H, dd, J ) 15.9, 4.9 Hz),
2.65 (3H, s), 2.10 (3H, d, J ) 6.3 Hz), syn-form, δ 7.50-6.90
(10H, m), 6.06 (5H, s), 5.39 (1H, dd, J ) 9.4, 4.9 Hz), 3.48 (1H,
dd, J ) 15.9, 9.4 Hz), 3.10 (1H, dd, J ) 15.9, 4.9 Hz), 2.35
(3H, s), 2.10 (3H, d, J ) 6.3 Hz); 13C NMR (100 MHz, CDCl3,
-30 °C) anti-form δ 259.9, 235.5, 230.2, 228.5, 152.6, 150.1,
148.4, 147.3, 136.9, 131.2, 129.4, 127.9, 127.2, 126.8, 94.8, 69.6,
38.2, 22.3, 18.4, syn-form δ 262.0, 235.5, 234.6, 231.5, 152.7,
146.3, 146.1, 130.1, 128.9, 128.4, 127.6, 127.0, 124.2, 94.4, 69.2,
37.4, 21.9, 18.7. Anal. Calcd for C27H24WSNO6BF3: C, 43.66;
H, 3.26; N, 1.89. Found: C, 43.61; H, 3.25; N, 1.86.
39.9, 37.0, 35.0. MS (EI, m/e) 746 (M+). Anal. Calcd for C31H30
-
WO10: C, 49.88; H, 4.05. Found: C, 49.89; H, 4.03.
Tr im eth yl(1E,6E)-7-(5-p h en yl-4,5-d ih yd r ofu r a n -3-yl)-
h ep ta -1,6-d ien e-1,4,4-tr ica r boxyla te] (31). To a CH3CN (10
mL) solution of compound 30 (113 mg, 0.15 mmol) was added
Me3NO (45.6 mg, 0.61 mmol), and the mixture was stirred for
3 h before a saturated NH4Cl solution was added. The organic
layer was extracted with diethyl ether and eluted through a
preparative silica gel column to yield compound 31 as a
colorless oil (35 mg, 0.090 mmol, 57%): IR (neat, cm-1) 2954
(w), 1731 (s), 1436 (m), 1267 (m); 1H NMR (400 MHz, CDCl3):
δ 7.32-7.19 (5H, m), 6.74 (1H, dt, J ) 16.1, 7.6 Hz), 6.47 (1H,
s), 6.18 (1H, d, J ) 15.3 Hz), 5.80 (1H, d, J ) 16.1 Hz), 5.51
(1H, t, J ) 9.4 Hz), 4.96 (1H, dt, J ) 15.3, 7.6 Hz), 3.63 (3H,
s), 3.04 (1H, t, J ) 9.4 Hz), 2.69 (1H, d, J ) 7.6 Hz), 2.62 (1H,
d, J ) 7.6 Hz), 2.57-2.55 (1H, m); 13C NMR (100 MHz, CDCl3)
δ 170.3, 165.9, 144.1, 142.7, 142.2, 128.5, 128.3, 127.5, 126.5,
124.4, 118.7, 114.8, 83.3, 57.5, 52.1, 51.3, 37.4, 36.4, 35.2; MS
(EI, m/e) 414 (M+); HRMS(EI) calcd for C23H26O7 414.1679,
found 414.1676.
Cp W(CO)3(η1-1-tosyl-3-vin yl-5-p h en yl-4,5-d ih yd r op yr -
r ol-2-yl) (8). To a CH2Cl2 solution of azacyclic carbenium salt
7 (0.30 g, 0.40 mmol) was added Et3N (0.081 mL, 0.80 mmol)
at 0 °C, and the mixture was stirred for 1 h. The residues were
chromatographed through a short alumina column to give a
yelow band to afford 8 as a yellow solid (0.23 g, 0.36 mmol,
89%): IR (neat, cm-1): υ(CO) 2025(vs) 1922(s), υ(SO2) 1332-
(s); 1H NMR (400 MHz, CDCl3, -40 °C) anti-form δ 7.04-7.40
(9H, m, 2 Ph), 6.50 (1H, dd, J ) 17.0, 10.8 Hz), 5.58 (5H, s),
5.30 (1H, dd, J ) 8.3, 7.5 Hz), 5.14 (1H, d, J ) 10.8 Hz), 5.01
(1H, d, J ) 17.1 Hz), 3.30 (1H, m, J ) 8.3 Hz), 2.87 (3H, s),
2.51 (1H, d, J ) 7.5 Hz), syn-form 7.12-7.47 (5H, m), 6.43
(1H, dd, J ) 17.4, 10.7 Hz), 5.69 (5H, s), 5.30 (1H, overlapped
with that of anti isomer), 5.08 (2H, m), 3.16 (1H, m), 2.82 (3H,
Tr im eth yl (1E,6E)-7-(5-P h en yl-4,5-d ih yd r ofu r a n -3-yl)-
h ep ta -1,6-d ien e-1,3,3-tr ica r boxyla te (32). This compound
was prepared according to a procedure similar to that for 31;
the yield was 57%: IR (neat, cm-1) 2953 (w), 2917 (w), 1731
s), 2.69 (1H, m); MS (EI, m/e) 657. Anal. Calcd for C27H23
-
WNSO5: C, 49.31; H, 3.53. Found: C, 49.04; H, 3.66.
1
3-Vin yl-5-n a p h th yl-4,5-d ih yd r ofu r a n (9a ). To a CH3CN
solution (5.0 mL) of tungsten-4,5-dihydrofuryl 9 (400 mg, 0.72
mmol) was added anhydrous Me3NO (229 mg, 3.60 mmol), and
the mixture was stirred for 2 h. To this solution was added
saturated NH4Cl (3.0 mL), and the organic layer was extracted
with diethyl ether, eluted through a preparative silica plate
to give compound 10a as a colorless oil (95.5 mg, 0.43 mmol,
61%): IR (neat,cm-1) υ(CdC) 1651 (w); 1H NMR (300 MHz,
CDCl3) δ 7.83-7.48 (7H, m), 6.65 (1H, s), 6.55 (1H, dd, J )
17.3, 10.5 Hz), 5.78 (1H, dd, J ) 10.5, 8.4 Hz), 4.91 (1H, d, J
) 10.5 Hz), 4.83 (1H, d, J ) 17.3 Hz), 3.24 (1H, dd, J ) 14.2,
10.5 Hz), 2.80 (1H, dd, J ) 14.2, 8.4 Hz); 13C NMR (75 MHz,
CDCl3) δ 144.9, 139.7, 133.2, 133.1, 128.7, 128.6, 128.0, 127.7,
126.2, 126.0, 124.5, 123.6, 116.4, 110.2, 83.9, 37.2; Mass (EI,
m/e) 222 (M+); HRMS calcd for C16H14O 222.1045, found
222.1041.
(s), 1435 (w), 1266 (w), 1171 (w); H NMR (300 MHz, CDCl3)
δ 7.29-7.20 (5H, m), 6.73 (1H, dt, J ) 15.5, 7.8 Hz), 6.45 (1H,
s), 6.14 (1H, d, J ) 15.5 Hz), 5.83 (1H, d, J ) 15.5 Hz), 5.51
(1H, dd, J ) 10.7, 8.1 Hz), 5.16-5.12 (1H, m), 3.65 (3H, s),
3.64 (6H, s), 3.07 (1H, dd, J ) 13.3, 10.7 Hz), 2.75 (1H, d, J )
8.2 Hz), 2.60 (1H, dd, J ) 13.3, 8.1 Hz), 1.96-1.89 (4H, m);
13C NMR (75 MHz, CDCl3) δ 170.7, 165.9, 143.1, 142.5, 142.4,
128.3, 127.5, 125.3, 124.9, 124.4, 122.7, 114.8, 83.0, 56.8, 52.3,
51.3, 37.5, 35.3, 32.5, 27.2; MS (EI, 75 m/e) 428 (M+); HRMS
(EI) calcd for C24H28O7 428.1835, found 428.1837.
Tr im eth yl (2R*,4aS*,7aR*,8S*,8aS*)-2-P h en yl-3,4a,5,6,7,-
7a ,8,8a -octa h yd r o-2H-in d en o[5,6-b]fu r a n -6,6,8-tr ica r box-
yla te (36). A toluene solution of compound 31 (35 mg, 0.090
mmol) was heated for 60 °C for 3 h. The solution was dried in
vacuo and eluted through a preparative silica plate to yield
36 as a colorless solid (32 mg, 0.082 mmol, 92%): IR (neat,
cm-1) 2953 (w), 2926 (w), 2854 (w), 1732 (s), 1436 (m), 1266
(m); 1H NMR (400 MHz, CDCl3) δ 7.32-7.25 (5H, m), 5.85 (1H,
d, J ) 2.1 Hz), 4.93 (1H, dd, J ) 9.6, 6.0 Hz), 4.74 (1H, d, J )
8.8 Hz), 3.72 (3H, s), 3.71 (3H, s), 3.70 (3H, s), 2.89 (1H, dd, J
) 10.8, 8.8 Hz), 2.87 (1H, dd, J ) 14.0, 6.0 Hz), 2.72-2.64
(2H, m), 2.57 (1H, dd, J ) 14.0, 9.6 Hz) 2.15-2.04 (1H, m),
1.97 (1H, t, J ) 12.8 Hz), 1.96-1.89 (1H, m), 1.84 (1H, t, J )
12.4 Hz); 13C NMR (100 MHz, CDCl3) δ 172.9, 172.5, 172.3,
142.8,140.3, 128.3, 127.2, 125.3, 122.6, 80.0, 74.2, 59.4, 52.7,
51.6, 49.1, 44.0, 42.0, 38.8, 37.9, 37.8; MS (EI, 75 eV, m/e) 414
(M+); HRMS (EI) calcd for C23H26O7 414.1679, found 414.1677.
Tr im eth yl (2R*,4a S*,8a R*,9S*,9a S*)-2-P h en yl-2,3,4a ,-
5,6,7,8,8a ,9,9a -d eca h yd r on a p h t h o[2,3-b]fu r a n -7,7,9-t r i-
ca r boxyla te (37). This compound was prepared similarly by
heating 32 in toluene; the yield was 90%: IR (neat, cm-1) 2953
(w), 1732 (s), 1450 (m), 1435 (m), 1253 (m); 1H NMR (400 MHz,
CDCl3) δ 7.28-7.20 (5H, m), 5.47 (1H, d, J ) 1.7 Hz), 4.90
(1H, dd, J ) 9.2, 6.0 Hz), 4.54 (1H, d, J ) 9.0 Hz), 3.74 (3H,
Cycloa d d it ion of Oxa cyclic Dien e 16 w it h Ma leic
An h yd r id e. To a toluene solution of compound 16 (46 mg,
0.25 mmol) was added maleic anhydride (26 mg, 0.27 mmol),
and the solution was heated for 60 °C for 3 h. The solution
was dried in vacuo and eluted through a preparative silica
plate to yield 23 as a colorless solid (66 mg, 0.23 mmol, 95%):
IR (neat, cm-1) υ(C0) 1753 (w), υ(CdC) 1673 (w); 1H NMR (300
MHz,CDCl3) δ 7.34 (5H, m), 5.61 (1H, s), 5.13 (1H, dd, J )
9.1, 6.4 Hz), 4.67 (1H, d, J ) 8.8 Hz), 3.74 (1H, t, J ) 8.8 Hz),
3.20 (1H, d, J ) 8.8, 6.2 Hz), 2.90 (1H, dd, J ) 14.4, 6.4 Hz),
2.63 (1H, dd, J ) 14.4, 9.1 Hz), 2.44 (1H, m),1.45 (3H, d, J )
7.3 Hz); 13C NMR (75 MHz, CDCl3): δ 171.0, 169.4, 142.5,
141.0, 128.4, 127.9, 126.0, 123.5, 82.0, 74.8, 45.2, 45.0, 37.9,
30.6,16.8; HRMS (m/z) calcd for C17H16O4 284.1049, found
284.1047.
Cp W(CO)3[η1-t r im et h yl(1E,6E)-7-(5-p h en yl-4,5-d ih y-
d r ofu r a n -3-yl)h ep ta -1,6-d ien e-1,4,4-tr ica r boxyla te] (30).
To a diethyl ether solution (20 mL) of tungsten-η1-alkynol 28

3766 J . Org. Chem., Vol. 65, No. 12, 2000
Li et al.
s), 3.65 (3H, s), 3.64 (3H, s), 2.84-2.76 (2H, m), 2.58-2.45 (3H,
m), 2.31-2.21 (1H, m), 1.95 (1H, dd, J ) 12.3, 8.5 Hz), 1.72-
1.34 (4H, m); 13C NMR (100 MHz, CDCl3) δ 172.7, 172.4, 171.0,
142.9, 139.4, 128.3, 127.3, 125.7, 124.5, 80.1, 73.3, 55.3, 52.,
52.6, 51.6, 51.3, 39.3, 37.5, 37.5, 36.5, 30.9, 29.1; MS (EI, 75
eV, m/e) 428 (M+); HRMS (EI) calcd for C24H28O7 428.1835,
found 428.1833.
Hz), 2.83 (1H, dd, J ) 14.5, 6.2 Hz), 2.67-2.54 (2H, m), 2.53
(1H, dd, J ) 14.5, 9.4 Hz), 2.65 (1H, d, J ) 14.6 Hz), 2.00 (1H,
t, J ) 13.0 Hz), 1.46 (1H, t, J ) 11.5 Hz); 13C NMR (100 MHz,
CDCl3) δ 176.2, 171.8, 171.5, 142.7, 140.4, 128.4, 127.5, 125.8,
119.0, 79.9, 74.5, 60.1, 52.9, 52.8, 52.4, 50.3, 45.0, 41.2, 40.2,
40.1, 37.2; MS (EI, m/e) 414 (M+); HRMS (EI) calcd for
C23H26O7 414.1679, found 414.1675.
Tr im eth yl (2R*,4aS*,8aR*,9aS*)-2-ph en yl-2,3,4a,5,6,7,8,-
8a ,9,9a -d eca h yd r on a p h th o[2,3-b]fu r a n -7,7,8a -tr ica r box-
yla te (40): IR (neat, cm-1) 2950 (w), 1731 (s), 1450 (m), 1434
Tr im eth yl 3-P h en yl-3,4,5a ,6,8,8a ,9,9a -octa h yd r ocyclo-
pen ta[g]ch r om en e-7,7,9(2H)-tr icar boxylate (38). This com-
pound was prepared similarly by heating 33 in toluene; the
yield was 91%: IR (neat, cm-1) 2916 (w), 2848 (w), 1734 (s),
1
(m), 1245 (m); H NMR (600 MHz, CDCl3) δ 7.26-7.17 (5H,
m), 5.44 (1H, d, J ) 1.7 Hz), 4.84 (1H, dd, J ) 9.3, 6.3 Hz),
4.28-4.26 (1H, m), 3.73 (3H, s), 3.63 (3H, s), 3.63 (3H, s), 2.71
(1H, dd, J ) 14.1, 6.3 Hz), 2.62-2.57 (1H, m), 2.53 (1H, dd, J
) 14.4, 2.1 Hz), 2.49-2.47 (1H, m), 2.35 (1H, ddd, J ) 14.1,
5.5, 2.5 Hz), 2.27 (1H, dd, J ) 11.9, 5.8 Hz), 2.12 (1H, d, J )
14.4 Hz), 1.75 (1H, ddd, J ) 14.1, 8.2, 3.9 Hz), 1.56-1.44 (2H,
m), 1.35 (1H, dd, J ) 11.9, 10.1 Hz); 13C NMR (75 MHz, CDCl3)
δ 176.2, 172.1, 171.4, 143.1, 137.2, 128.4, 127.4, 125.7, 122.9,
79.9, 74.9, 52.9, 52.6, 52.3, 45.4, 40.1, 38.8, 36.4, 31.8, 30.4,
26.8; MS (EI, 75 eV, m/e) 428 (M+); HRMS (EI) calcd for
1
1464 (w), 1257 (w); H NMR (600 MHz, CDCl3) δ 7.31-7.11
(5H, m), 5.29 (1H, s), 4.13 (2H, m), 3.98 (1H, dd, J ) 12.0, 2.4
Hz), 3.66 (3H, s), 3.66 (3H, s), 3.65 (3H, s), 2.94 (1H, br), 2.88
(1H, dd, J ) 12.4, 6.0 Hz), 2.81 (1H, m), 2.73 (1H, dd, J )
12.0, 6.0 Hz), 2.41 (1H, dd, J ) 12.4, 6.0 Hz), 2.28 (1H, d, J )
10.8 Hz), 2.07-1.93 (2H, m), 1.85 (1H, t, J ) 12.4 Hz), 1.71
(1H, t, J ) 10.8 Hz); 13C NMR (75 MHz, CDCl3) δ 173.3, 172.7,
171.8, 144.3, 133.6, 128.2, 127.3, 126.1, 125.0, 75.9, 71.9, 58.8,
52.5, 51.4, 50.9, 43.6, 42.5, 40.3, 39.8, 38.3, 37.8; MS (EI, 75
eV, m/e) 428 (M+); HRMS (EI) calcd for C24H28O7 428.1835,
found 428.1837.
C
24H28O7 428.1835, found 428.1834.
Ack n ow led gm en t. We gratefully acknowledge fi-
nancial support of this work from the National Science
Council, Republic of China.
Tr im et h yl (2R*,4a S*,7a R*,8a S*)-2-P h en yl-3,4a ,5,6,7,-
7a ,8,8a -oct a h yd r o-2H -in d en o[5,6-b]fu r a n -6,6,7a -t r ica r -
boxyla te (39). This compound was prepared similarly by
heating 34 in toluene; the yield was 82%: IR (neat, cm-1) 2958
(w), 1647 (w), 1600 (m), 1440 (w), 1233 (w); 1H NMR (600 MHz,
CDCl3) δ 7.30-7.15 (5H, m), 5.48 (1H, d, J ) 2.5 Hz), 4.91
(1H, dd, J ) 9.4, 6.2 Hz), 4.27-4.25 (1H, m), 3.66 (3H, s), 3.66
(3H, s), 3.65 (3H, s), 3.18-3.13 (1H, br), 2.90 (1H, d, J ) 14.6
Su p p or tin g In for m a tion Ava ila ble: Syntheses and spec-
tral data of compounds 10, 10a , 13-22, 24-27, and 32-35 in
repetitive experiments; tables of crystal data, atomic coordi-
nates, bond distances and angles of compound 23. This
material is available free of charge via the Internet at
http://pubs.acs.org.
J O000044Q