Stereocontrolled synthesis of acyclic 1,3-diols via condensation of tungsten-syn-π-pentadienyl complexes with aldehydes. A new Prins reaction via s-trans-diene cationic intermediates

Article abstract of DOI:10.1021/jo001664u

In the presence of BF₃·Et₂O, condensation of CpW(CO)₂(syn-π-2-methoxycarbonylpentadienyl) with aldehydes generated tungsten-η⁴-trans-diene cation in cold toluene, and hydrolysis of this salt afforded tungsten-π-allyl-anti-1,3-diols in good yields. This new synthesis of anti-1,3-diols represents an atypical Prins reaction that is applicable to normal aldehydes. The anti/syn ratios of 1,3-diols increased with an increase in the size of the aldehydes. These anti-1,3-diols were transformed into various complex oxygen heterocycles based on two demetalations: (1) conversion to an allyl cation followed by nucleophilic attack and (2) condensation with aldehydes via its CpW-(NO)Cl derivative, to give functionalized α-methylene butyrolactones. A semi-emperical calculation was performed to deduce the transition-state structure to rationalize the anti-stereoselectivity.

Full text of DOI:10.1021/jo001664u

J . Org. Chem. 2001, 66, 1781-1786
1781
Ster eocon tr olled Syn th esis of Acyclic 1,3-Diols via Con d en sa tion
of Tu n gsten -syn -π-P en ta d ien yl Com p lexes w ith Ald eh yd es. A New
P r in s Rea ction via s-tr a n s-Dien e Ca tion ic In ter m ed ia tes
Yian-Lian Lin, Ming-Huei Cheng, Wei-Chen Chen, Shie-Ming Peng, Sue-Lein Wang,
Hongyun Kuo, and Rai-Shung Liu*
Department of Chemistry, National Tsing-Hua University, Hsinchu, 30043, Taiwan, ROC
rsliu@mx.nthu.edu.tw
Received November 27, 2000
In the presence of BF3‚Et2O, condensation of CpW(CO)2(syn-π-2-methoxycarbonylpentadienyl) with
aldehydes generated tungsten-η4-trans-diene cation in cold toluene, and hydrolysis of this salt
afforded tungsten-π-allyl-anti-1,3-diols in good yields. This new synthesis of anti-1,3-diols
represents an atypical Prins reaction that is applicable to normal aldehydes. The anti/syn ratios of
1,3-diols increased with an increase in the size of the aldehydes. These anti-1,3-diols were
transformed into various complex oxygen heterocycles based on two demetalations: (1) conversion
to an allyl cation followed by nucleophilic attack and (2) condensation with aldehydes via its CpW-
(NO)Cl derivative, to give functionalized R-methylene butyrolactones. A semi-emperical calculation
was performed to deduce the transition-state structure to rationalize the anti-stereoselectivity.
Sch em e 1
In tr od u ction
The condensation of olefins with formaldehyde in the
presence of acid is called the Prins reaction, which can
produce 1,3-diol derivatives efficiently via a carbocation
intermediate (Scheme 1, eq 1).1 Unfortunately, this
condensation is not applicable to common aliphatic and
aromatic aldehydes which in the presence of Lewis acid
give homoallylic alcohols following an “ene” reaction
pathway (Scheme 1, eq 2).2 In the presence of Lewis acid
catalysts, alkenyl complexes of boranes, silanes, and
stannanes have been proposed to form carbocationic
intermediates in condensation with aldehydes.3,4 How-
ever, the carbocation intermediates cannot be trapped by
water to yield the desired 1,3-diols (Scheme 1, eq 3) and
instead give homoallylic alcohols exclusively. A similar
phenomenon is observed for their allyl and propargyl
analogues.3,4 1,3-Diols are versatile building blocks for
complex natural molecules.5 The synthesis of 1,3-diols
from an olefin and common aldehydes is a challenging
issue in synthetic chemistry.
Sch em e 2
Recently, we reported that molybdenum- and tung-
sten-η4-cyclohexadienyl complexes form stable η4-cyclo-
* To whom correspondence should be addressed. Phone: (886)-3-
5721424. Fax: (886)-3-5711082.
(1) For a review of the Prins reaction, see: Adams, D. R.; Bhatnagar,
S. Synthesis 661, 1977.
(2) For the ene reaction, see selected review papers: (a) Mikami,
K.; Shimizu, M. Chem, Rev. 1992, 92, 1021. (b) Snider, B. B. In
Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.;
Pergamon: London, 1991; Vols. 2 and 5. (c) Hoffmann, R. W. Angew.
Chem. 1987, 26, 489.
(3) (a) Lozar, L. D.; Clark, R. D.; Heathcock, C. H. J . Org. Chem.
1977, 42, 1386. (b) J ohnson, W. S.; Yarnell, T. M.; Myers, R. F.; Morton,
D. R. Tetrahedron Lett. 1978, 26, 1201. (c) J ohnson, W. S. Yarnell, T.
M.; Myers, R. F.; Morton, D. R.; Boots, D. R. J . Org. Chem. 1980, 45,
1254.
(4) (a) Yamamoto, Y.; Asao, N. Chem. Rev. 1993, 93, 2207. (b) Masse,
C.; Panek, J . S. Chem. Rev. 1995, 95, 1293. (c) Langkopf E.; Schinzer,
D. Chem. Rev. 1995, 95, 1375. (d) Weinreb, S. M. J . Heterocycl. Chem.
1996, 33, 1429. (e) Marshall, J . A. Chem. Rev. 1996, 96, 31.
(5) (a) Yue, S.; Duncan, J . S.; Yamamoto, Y.; Hutchinson, C. R. J .
Am. Chem. Soc. 1987, 109, 1253 (b) Floyd, D. M.; Fritz, A. W.
Tetrahedron Lett. 1981, 22, 2847.
hexadiene cations upon condensation with BF3/RCHO
(Scheme 2, eq 1).6,7 However, the cation is too stable to
react with water over a prolonged period. 1,3-Diols may
be obtained if the intermediate involves reactive metal-
η4-trans-diene species. Along these lines, we report here
a detailed stereocontrolled synthesis of 1,3-diols via acid-
promoted condensation of metal-π-pentadienyl com-
plexes with aldehydes; this process involves a η4-trans-
diene cationic intermediate (Scheme 2, eq 2).
(6) Wang, S.-H.; Cheng Y.-C.; Lee, G.-H.; Peng, S.-M.; Liu, R.-S.
Organometallics 1993, 12, 3282.
(7) Cheng, M.-F.; Ho, Y.-H.; Lee G.-H.; Peng, S.-M.; Liu R.-S. J .
Chem. Soc., Chem. Commun. 1991, 697.
10.1021/jo001664u CCC: $20.00 © 2001 American Chemical Society
Published on Web 02/15/2001

1782 J . Org. Chem., Vol. 66, No. 5, 2001
Lin et al.
Sch em e 3
Sch em e 4
functionalized alcohols were unsuccessful via the addition
of NH3(aq), NaSH(aq), and NaI(aq) to the trans-diene
cation A generated from 2 and benzaldehyde. Compound
2 was recovered exclusively, indicating that these nu-
Resu lts
Our synthetic protocol requires the synthesis of metal-
syn-π-pentadienyl complexes to realize the Prins reaction.
Scheme 3 shows the synthesis of tungsten-syn-2-meth-
oxycarbonylpentadienyl complex 2 via alkoxycarbonyla-
tion of tungsten-η1-vinylpropargyl complex 1.8 Com-
pound 2 is speculated to lead to complex oxygen
heterocycles if it can effect the Prins reaction. Condensa-
tion of compound 2 with aldehydes was performed in cold
toluene (-40 °C), and yellow precipitates slowly deposited
when 1 equiv of Lewis acid was added to the solution.
Treatment of this yellow slurry with a mixture of
NaHCO3(aq)/CH3CN at -40 °C afforded tungsten-syn-
π-allylic diols 3-6 as a mixture of anti- and syn-diols.
These two diastereomers were separable on a silica
column, and the isolated yields are shown in eq 2
(Scheme 3). The major anti-diols 3(anti)-6(anti) were
formed preferably (yields >55%) if BF3‚Et2O was used
(entries 1-4). The anti/syn ratios increased with an
increase in the size of the aldehydes. The stereochemistry
of the major diastereomers was determined by X-ray
diffraction studies of the lactonyl derivatives of compound
5-anti (vide infra). Compounds 3-6 have a syn-π-allyl
configuration; i.e., the diol fragment lies on the same side
as the methoxycarbonyl group. This implies that η4-trans-
diene cation is the observed precipitate that yields diols
upon hydrolysis. The water attacks regioselectively at the
diene Cδ carbon opposite the tungsten fragment. BF3‚
Et2O is superior to other Lewis acids including TiCl4,
SnCl4, and AlCl3; these acids gave compound 6-anti in
lower yields (entries 5-7).
-
cleophiles attack at the OBF3 end of species A to give
the reverse reaction. Reduction of the cation A by NaBH3-
CN and NaBD3CN proceeded smoothly to yield the allyl
alcohol 7 and 7D in 82% yield. Although this Prins-type
condensation does not work for ketones, imines, and
epoxides, it is applicable to trimethoxymethane.10 1,3-
Difunctionalized compound 8 was obtained from tri-
methoxymethane in 75% yield following the same reac-
tion sequence. Scheme 4 (eq 3) shows a remarkable
diastereoselectivity in the condensation of 2 with 2-phe-
nylpropionaldehyde (2.0 equiv) with BF3‚Et2O (1.0 equiv),
and hydrolysis of the resulting η4-trans-diene cation gave
only a single diastereomer 9 in 83% isolated yield.
Compound 9 is assigned an erythro-configuration by
comparison of its proton NMR spectral data and proton
NOE effect to those of related homoallylic alcohol ana-
logues.11 This configuration is consistent with the Fel-
kin-Ahn model.
We also prepared tungsten-π-pentadienyl complex 10
in three steps from 2 following a convenient operation
(Scheme 5). Compound 10 shows a preference for anti-
diols in analogous reactions; the isolated yields are given
in eq 1 (Scheme 5). The condensation proceeded with less
efficiency compared to compound 2. Structural charac-
terization of the anti-diols relies on the X-ray character-
ization12 of compound 14 obtained from the addition of
Ph2CuLi to the η4-trans-diene cationic intermediate (eq
2). Notably, tungsten-π-2-vinylallyl compound 11 can
potentially undergo BF3-promoted addition with alde-
According to our previous study8 on CpW(CO)2(η4-
trans-2-methoxycarbonylpentadiene) cation, the Cδ-
carbon of η4-trans-diene cation A (Scheme 4) can be
attacked selectively by amines, alcohols, thiols, and
hydride. RMgBr and R2CuLi can attack at the CR-carbon.
Attempts to obtain 1,3-amino alcohols and related 1,3-
(9) The crystal data for 15b: monoclinic, C2/c, a ) 23.876 (7) Å, b
) 13.635(3) Å, c ) 11.617(3) Å, â ) 97.43 (2)°, Z ) 8, V ) 3750.0(15)
Å3, R ) 0.0278, and Rw ) 0.0245 for 3326 independent reflections with
2123 > 3σ(I).
(10) Li, Y.-L.; Liu, R.-S. Unpublished results.
(11) Heathcock, C. H.; Kiyooka, S. K.; Blumenkopf, T. A. J . Org.
Chem. 1984, 49, 4214.
(12) Crystal data for compound 14: triclinic, space group P-1, a )
10.6375(19) Å, b ) 15.574(4) Å, c ) 17.542(3) Å, R ) 110.266(18)°, â )
102.446(15)°, γ ) 98.656(19)°, z ) 2580.5(9) A3.
(8) Cheng, M.-H.; Ho, Y.-H.; Lee, G.-H.; Peng, S.-M.; Chu, S.-Y.; Liu,
R.-S. Organometallics 1994, 13, 4082.

Synthesis of Acyclic 1,3-Diols
Sch em e 5
J . Org. Chem., Vol. 66, No. 5, 2001 1783
Sch em e 7
Sch em e 6
show two instances for the synthesis of furanones 17-
18 via the addition of PhSNa to allyl cations derived from
16b,c. Reduction of the same cations with NaBH4 (entries
3-4) gave R-methylene butyrolactones 19B and 20B
exclusively, and the regiochemistry is distinct from those
in entries 1-2. Only a small amount of γ-lactone 20A
was found for 16C (entry 4). Isomerization probably
occurred when tungsten-olefin species were formed.16
Equation 3 shows an intramolecular cyclization for the
allyl cation generated from 16b,c. The bicyclic lactones
21 and 22 were obtained in 65-74% yield. The stereo-
chemistries of 21 and 22 were determined by proton
NOE-difference spectra. These two lactones were pro-
duced from attack of the hydroxy group of the cations at
their allyl Cγ-carbons opposite the tungsten fragment.
Scheme 8 shows an alternative demetalation of tung-
sten-π-allyl complex; this involves condensation of their
CpW(NO)Cl derivatives with aldehydes to yield homoal-
lylic alcohols.17 A chairlike transition state is proposed
hydes at its 2-vinyl group, and η4-trimethylenemethane
cation is the intermediate that can be trapped by nu-
cleophiles.13 However, no such products were found for
compound 10 in which the 3-vinyl group is more reactive
and forms the trans-η4_diene cationic intermediate.
Highly functionalized tungsten-π-allylic diols are use-
ful intermediates for the synthesis of complex butyrolac-
tones. As shown in Scheme 6, treatment of the diols
4(anti)-6(anti) and 9 with NaH afforded the π-lactonyl
complexes 15a -d in good yields (>82%). Compounds
15a -d were protected with an acetyl group to yield
16a -d with yields exceeding 80%. The molecular struc-
ture of 15b was determined by an X-ray diffraction study9
to clarify its stereochemistry.
Two efficient methods have been developed for de-
metalation of molybdenum and tungsten-π-allyl com-
plexes (Scheme 7), and both can be performed in a one-
pot operation. The carbonyl group of CpM(CO)2(π-allyl)
(M ) Mo, W) is easily replaced by NOBF4 to yield an allyl
cation that reacts with nucleophiles to give functionalized
olefins after oxidation.14,15 Entries 1 and 2 (Scheme 7)
(16) In eq 2 (Scheme 7), formation mechanism of R-methylene
butyrolactones 19 and 20 is proposed in the following mechanism. In
this isomerization, the tungsten-olefin species (I) are the kinetically
favorably products that undergo isomerization to the more stable
species (II) via a tungsten-allyl hydride species.
(13) Yang, G.-M.; Yang, G.-M.; Liu, R.-S. Organometallics 1992, 11,
3444.
(14) (a) Faller, J . W.; Rosan, A. M., J . Am. Chem. Soc. 1976, 98,
3388. (b) Faller, J . W.; Rosan, A. M. J . Am. Chem. Soc. 1977, 99, 4858.
(15) Adams, R. D.; Chodosh, D. F. Faller, J . W.; Rosan, A. M. J . Am
Chem. Soc. 1979, 101, 2570.

1784 J . Org. Chem., Vol. 66, No. 5, 2001
Lin et al.
Sch em e 8
F igu r e 1. Two most likely structures of transition states in
the condensation of compound 2 with RCHO..BF3‚Et2O. Part
of the methoxycarbonyl group of 2-iPr(C) was omitted for
clarity.
Ta ble 1. Rela tive En er gies of Tr a n sition Sta tes for
Con d en sa tion of Com p ou n d 2 w ith Ald eh yd es
entry
reactants
T.S. (kcal/mol)
selectivities
anti/syn
70/10
1
PhCHO+
BF3‚Et2O
EtCHO+
BF3‚Et2O
MeCHO+
BF3‚Et2O
iPrCHO+
BF3‚Et2O
2-P h (A), -3.86
2-P h (B), 0.00
2-Et(A), -2.58
2-Et(B), 0.00
2-Me(A), -0.89
2-Me(B), 0.00
2-iP r (A), -5.37
2-iP r (B), 0.00
anti-diol
syn-diol
anti-diol
syn-diol
anti-diol
syn-diol
anti-diol
syn-diol
to control the product stereochemistry. We previously
reported18 that the syn- and anti-isomers of tungsten-
π-lactonyl complexes gave the same trans-R-methylene
lactones bearing an anti-homoallylic alcohol (Scheme 8,
eq 1). We used such functionalized lactones for the
synthesis of natural lactones such as (+)-dihydroca-
nadensolide,19 racemic avenociolide,20 and (+)-methyl-
enelactocin.21 Equation 2 (Scheme 8) shows applications
of tungsten-π-allyl complexes 16a -d to the synthesis
of highly functionalized trans-R-methylene lactones fol-
lowing this approach. The whole reaction was carried out
in a one-pot operation. The π-allyl complexes 16a -d were
sequentially treated with NOBF4, NaI in CH3CN, and
finally aldehydes, and the resulting R-methylene buty-
rolactones 23a -e were obtained in respective yields of
51-65%. The 1H NMR spectral data of 23a -e match
those of isostructural trans-R-methylene butyrolactones,18
as represented by eq 1 (Scheme 8).
2
3
4
65/14
58/24
79/8
using the program suit SPARTAN 5.0.23 Table 1 shows
the relative energies of the two most likely transition
states in condensation of compound 2 with various
aldehydes. The structures of representative transition
states are shown in Figure 1. In the case of benzaldehyde,
the two structures 2-P h (A) and 2-P h (B) adopt synclinal
conformation with OBF4- fragment approaching tungsten
fragment to maximize electrostatic attraction. The tung-
sten fragment becomes a cationic center as η4-trans-diene
cation is forming as a reaction intermediate. This orien-
tation stabilizes these two states to control reaction
stereoselectivities. State 2-P h (A) is lower in energy than
2-P h (B) by -3.86 cal/mol because the latter adopts an
unfavorable s-cis-conformation for the BF3-PhCHO com-
plex. The corresponding s-trans-conformation is desta-
Discu ssion s
Condensations of tungsten-π-pentadienyl complexes
with aldehydes proceeds in open transition states.22 We
have performed semi-emperical calculation with the pm3
-
bilized by stereic hindrance between OBF4 and allyl
fragment. This model accounts for the observed anti-
stereoselection. A similar pattern is found for the reaction
of compound 2 with RCHO‚BF3 (R ) Et, Me) as shown
in entries 2 and 3. The energy differences between these
two states become smaller for less bulky aldehydes (R )
Et, ∆E ) 2.58 kcal/mol; R ) Me, ∆E ) 0.89 kcal/mol),
consistent with the observed anti/syn ratios. For isobu-
tyraldehyde, a different structure 2-iP r (C) is found to
be the second favorable state that has ca. 5.37 kcal/mol
(17) (a) Faller, J . W.; Linebarrier, D. L. J . Am. Chem. Soc. 1989,
111, 1937 (b) Faller, J . W.; Diverdi, M. J .; J ohn, J . A. Tetrahedron
Lett. 1991, 32, 1271. (c) Faller, J . W.; Nguyen, J . T.; Ellis, W.; Mazzieri,
M. R. Organometallics 1993, 12, 1434.
(18) Chen C.-C.; Fan J .-S.; Shieh, S.-J .; Lee G.-H.; Peng S.-M.; Wang
S.-L.; Liu, R.-S. J . Am. Chem. Soc. 1996, 118, 9279.
(19) .Chen M.-J .; Narkulan, K.; Liu, R.-S. J . Org. Chem. 1999, 64.
8311.
(20) Narkunan, K.; Liu, R.-S. J . Chem. Soc., Chem. Commun. 1998,
1521.
(21) Chandrasekharam, M.; Liu, R.-S. J . Org. Chem. 1998, 63, 9122..
(22) (a) Yamamoto, Y.; Asao, N. Chem. Rev. 1993, 93, 2207. (b)
Roush W. R. In Comprehensive Organic Chemistry: Addition to C-X
π-bond. Part II; Trost, B. M., Fleming, I., Eds.; Pergamon Press:
Oxford, 1991; Chapter 1.1, p 1.
(23) (a) Stewart, J . J . P. J . Comput. Chem. 1989, 10, 209. (b)
Stewart, J . J . P. J . Comput. Chem. 1991, 12, 320. (c) SPARTAN 5.1.1,
Wavefunction Inc., Irvine, CA.

Synthesis of Acyclic 1,3-Diols
J . Org. Chem., Vol. 66, No. 5, 2001 1785
EI) 538 (M+). Anal. Calcd for C21H22WO5: C, 46.86; H, 4.12.
Found: C, 46.71; H, 4.33.
higher in energy than state 2-iP r (A), in favor of anti-
stereoselection
Syn t h esis of Tu n gst en -syn -π-Allylic Alcoh ol 8. To a
cold toluene (-40 °C) solution (25.0 mL) of compound 2 (1.00
g, 2.33 mmol) were added BF3‚Et2O (0.35 mL, 2.79 mL) and
trimethoxymethane (0.51 mL, 4.65 mmol), the mixtures were
stirred for 2 h before addition of water, and the solution was
warmed to 23 °C. The organic layer was separated, concen-
trated, and eluted through a silica column (diethyl ether/
hexane ) 2/1) to give compound 8 as a yellow solid (0.94 g,
1.75 mmol, 75%): IR (Nujol) υ(CO) 1960 (vs), 1891 (vs), 1691
cm-1; 1H NMR (300 MHz, CDCl3) δ 1.11 (1H. s), 2.06 (1H, m),
2.50 (1H, m), 3.36 (1H, s), 3.51 (3H, s), 3.62 (3H, s), 3.73 (3H,
s), 3.88 (3H, s), 4.68 (5H, s), 5.22 (1H, dd, J ) 8.0, 3.2 Hz),
5.32 (1H, dt, J ) 9.8, 3.0 Hz); 13C NMR (100 MHz, CDCl3) δ
221.9, 221.8, 170.8, 102.7, 88.6, 77.7, 77.2, 56.2, 54.4, 52.2, 51.5,
51.1, 41.5, 24.4; MS (12v eV, EI) 536 (M+). Anal. Calcd for
In summary, we have reported a new tungsten-medi-
ated Prins reaction via condensation of tungsten-syn-
π-pentadienyl complexes with aldehydes/BF3‚Et2O in cold
toluene. This reaction generates tungsten-η4-trans-diene
cationic intermediates that react with water to yield
tungsten-π-allyl-anti-1,3-diols. These anti-1,3-diols were
transformed into various complex oxygen heterocycles
based on two demetalations yielding functionalized
R-methylene butyrolactones: (1) conversion to an allyl
cation followed by nucleophilic attack and (2) condensa-
tion with aldehydes via its CpW(NO)Cl derivative.
Exp er im en ta l Section
C
18H24WO7: C, 40.29; H, 4.51. Found: C, 40.00; H, 4.33.
Unless otherwise noted, all reactions were carried out under
a 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, BF3‚Et2O, dicy-
clopentadiene, propargyl alcohol, and sodium were obtained
commercially and used without purification. Mass data of
tungsten compounds were reported according to 184W. Allyl-
tungsten compounds 2 were prepared according to procedures
described in the literature. Spectral data of compounds 4-6,
9-13, 18, 15b,c, 16b-d , 18, 20, 22, and 23b-e in repetitive
experiments are provided in the Supporting Information.
Syn th esis of Tu n gsten -syn -π-Allyl-1,3-d iol 3. To a
toluene solution (10 mL) of compound 2 (200 mg, 0.46 mmol)
were added acetaldehyde (0.04 mL, 0.71 mmol) and BF3‚Et2O
(0.07 mL, 0.56 mmol) at -40 °C, and the mixtures were stirred
for 2 h to complete the generation of orange precipitates. To
this suspension was added a CH3CN/H2O mixture at -40 °C
to yield a clear yellow solution. The organic layer was
separated, dried in vacuo, and chromatographed through a
silica column (diethyl ether/hexane ) 2/1) to yield the anti-
diol (0.13 g, 0.27 mmol, 58%, Rf ) 0.18) and syn-diol (50 mg,
0.11 mmol, 24%).
Syn th esis of Tu n gsten -π-Allyl Com p lex 14. To a cold
toluene (-40 °C) solution (5.0 mL) of compound 10 (0.20 g,
0.49 mmol) were added BF3‚Et2O (0.12 mL 0.49 mmol) and
benzaldehyde (0.060 mL, 0.60 mmol), and the mixtures were
stirred for 2 h before addition of a THF solution of Ph2CuLi
(0.62 mmol). The solution was stirred for 2 h before it was
brought to 23 °C, and to this mixture was added a saturated
NH4Cl solution. The organic layer was separated and chro-
matographed through a silica column to give compound 14
(diethyl ether/hexane )1/1) as a yellow solid (0.24 g, 0.37
mmol, 82%): IR (Nujol) υ(CO) 1921 (vs), 1839 (vs), υ(OH) 3350
1
cm-1; H NMR (400 MHz, CDCl3) δ 1.28 (s, 3H), 1.85 (1H, m,
J ) 11.2 Hz), 2.58 (1H, m), 2.60 (1H, d, J ) 16.0 Hz), 2.80
(1H, m), 2.84 (1H, d, J ) 16.0 Hz), 3.53 (1H, d, J ) 10.0 Hz),
4.41 (1H, s), 4.43 (1H, s), 4.86 (1H, dd, J ) 6.6, 5.1 Hz), 5.38
(5H, s); 13C NMR (100 MHz, CDCl3) δ 22.0, 47.2, 48.7, 49.3,
70.0, 73.3, 77.2, 91.8, 113.3, 125.7, 126.4, 127.4, 127.8, 127.9,
128.7, 140.5, 143.4, 145.9, 226.8, 226.9; MS (12 eV, EI) 596
(M+). Anal. Calcd for C28H28WO3: C, 56.39; H, 4.73. Found:
C, 56.64; H, 4.85.
Syn th esis of Tu n gsten -π-La cton yl Com p lex 15a . To a
THF solution (15 mL) of compound 4-a n ti (260 mg, 0.55 mmol)
was added NaH (22 mg, 0.55 mmol) at 0 °C, and the mixtures
were stirred for 2 h. To this mixture was added a saturated
NH4Cl solution, and the organic layer was extracted with
diethyl ether, concentrated, and eluted through a silica column
(diethyl ether/hexane ) 1/1) to give complex 15a (232 mg, 0.49
mmol, 89%): IR (Nujol) υ(CO) 1933 (vs), 1876 (vs), 1758 (s),
Spectral data for compound 3-a n ti: IR (Nujol) υ(CO) 1966
1
(vs), 1895 (vs), 1690 cm-1; H NMR (300 MHz, CDCl3) δ 1.18
(3H, d, J ) 7.0 Hz), 1.32 (1H, s), 1.66 (1H, m), 2.10 (1H, d, J
) 9.5 Hz), 2.90 (1H, s), 3.71 (3H, s), 4.09 (1H, m), 5.27 (5H, s);
13C NMR (75 MHz, CDCl3) δ 23.0, 24.5, 43.7, 51.8, 52.6, 65.5,
71.7, 77.5, 88.4, 173.4, 221.0, 222.4; MS (12 eV, EI) 492 (M+).
Anal. Calcd for C16H20WO6: C, 39.05; H, 4.10. Found: C 39.24;
H, 4.22.
1
υ(OH) 3350 cm-1; H NMR (400 MHz, CDCl3) δ 5.34 (5H, s),
4.87 (1H, dd. J ) 9.6, 3.8 Hz), 3.83-3.92 (1H, m), 3.47 (1H, s),
3.11 (1H, d, J ) 3.6 Hz), 1.77-1.99 (2H, m), 1.46-1.56 (2H,
m), 1.40 (1H, d, J ) 3.6 Hz); 13C NMR (100 MHz, CDCl3) δ
225.3, 219.4, 176.1, 93.9, 81.3, 77.2, 69.9, 67.1, 45.8, 31.0, 21.4;
MS (75 eV, m/e) 446 (M - CO). Anal. Calcd for C16H18WO5:
C, 40.50; H, 3.83. Found: C, 40.44; H, 3.69.
Spectral data for compound 3-syn : IR (Nujol) υ(CO) 1966
1
(vs), 1895 (vs), 1690 cm-1; H NMR (300 MHz, CDCl3) δ 1.18
(3H, d, J ) 6.1 Hz), 1.33 (1H, s), 1.55 (1H, m), 2.03 (1H, d, J
) 9.3 Hz), 2.90 (1H, s), 3.72 (3H, s), 4.08 (1H, m), 5.28 (5H, s);
13C NMR (75 MHz, CDCl3) δ 23.1, 24.5, 43.6, 51.9, 52.5, 65.6,
71.8, 77.6, 88.5, 173.5, 221.0, 222.4; MS (12 eV, EI) 492 (M+).
Anal. Calcd for C16H20WO6: C, 39.05; H, 4.10. Found: C, 38.78;
H, 4.30.
Syn th esis of Tu n gsten -π-La cton yl Com p lex 16a . To a
Et3N (10 mL) solution of 15a (260 mg, 0.55 mmol) was added
acetic anhydride (1.0 mL) and CH2Cl2 (5.0 mL), and the
mixture was refluxed for 3 h. To this mixture was added H2O
(10 mL), and the organic layer was extracted with diethyl
ether. The extract was concentrated and eluted through a silica
column (diethyl ether/hexane ) 1/1) to yield compound 16a
as a yellow solid (223 mg, 0.43 mmol, 80%): IR (Nujol) υ(CO)
1950 (vs), 1870 (vs), 1725 (s) cm-1; 1H NMR (300 MHz, CDCl3)
δ 0.89 (3H, t, J ) 7.4 Hz), 1.48 (1H, d, J ) 3.8 Hz), 1.64 (2H,
m), 1.92-2.01 (1H, m), 2.07-2.17 (1H, m), 2.06 (3H, s), 3.10
(1H, d, J ) 3.8 Hz), 3.40 (1H, s), 4.61 (1H, dd, J ) 8.1, 4.7
Hz), 5.02-5.10 (1H, m), 5.32 (5H, s); 13C NMR (75 MHz, CDCl3)
δ 225.4, 219.1, 176.1, 170.7, 93.9, 81.1, 77.2, 72.4, 66.2, 42.5,
27.5, 21.5, 21.2, 9.2; MS (75 eV, m/e) 516 (M+). Anal. Calcd for
18H20WO6: C, 41.85; H, 3.91. Found: C, 41.77; H, 3.77.
Syn th esis of F u r a n on e 17. To a CH3CN solution (5.0 mL)
of compound 16b (0.18 g, 0.32 mmol) was added NOBF4 (0.040
g, 0.34 mmol), and the mixture was stirred for 20 min before
addition of NaSPh (0.40 mmol). The resulting red suspension
was stirred for 3 h, (NH4)2Ce(NO3)6 (0.35 g, 0.64 mmol) was
added, and the solution was evaporated to dryness. The
Syn t h esis of Tu n gst en -syn -π-Allylic Alcoh ol 7. To a
cold toluene (-40 °C) solution (5.0 mL) of compound 2 (0.20 g,
0.46 mmol) were added BF3‚Et2O (0.070 mL, 0.56 mL) and
benzaldehyde (0.070 mL, 0.69 mmol), and the mixtures were
stirred for 2 h for complete generation of s-trans-diene
precipitates. To this suspension was added a CH3CN solution
(2.0 mL) of NaBH3CN (150 mg, 2.39 mmol), and the solution
was warmed to 23 °C before addition of a saturated NH4Cl
solution. The organic layer was separated, concentrated, and
eluted through a silica column (diethyl ether/hexane ) 2/1) to
give compound 7 as a yellow solid (0.20 g, 0.38 mmol, 82%):
IR (Nujol) υ(CO) 1960 (vs), 1889 (vs), 1694 cm-1; 1H NMR (300
MHz, CDCl3) δ 1.05 (1H, s), 1.84 (2 H, m), 2.07 (1H, br t, J )
6.63 Hz), 2.34 (1H, m), 2.83 (1H, m), 2.91 (1H, s), 3.65 (1H, s),
4.77 (1H, t, J ) 7.5 Hz), 5.27 (5H, s), 7.30 (5H, m); 13C NMR
(75 MHz, CDCl3) δ 22.8, 29.0, 42.8, 50.6, 51.0, 73.1, 77.9, 88.3,
126.0, 127.4, 128.5, 145.1, 172.2, 223.3, 224.1; MS (12v eV,
C

1786 J . Org. Chem., Vol. 66, No. 5, 2001
Lin et al.
residue was extracted with diethyl ether and eluted through
a preparative TLC plate (diethyl ether/hexane ) 1/1) to yield
furanone 17 (90 mg, 0.24 mmol, 77%) as a colorless oil: IR
(neat) υ(CO) 1763 cm-1
;
1H NMR (400 MHz, CDCl3) δ 2.18
(1H, m), 2.74 (1H, m), 4.92 (1H, d, J ) 5.3 Hz), 4.96 (1H, m),
5.04 (1H, m), 6.01 (1H, s), 6.39 (1H, s), 7.30 (5H, m); 13C NMR
(100 MHz, CDCl3) δ 40.9, 78.5, 81.9, 126.1, 128.3, 128.4, 129.7,
135.7, 139.9, 169.2; HRMS calcd for C13H12O3 216.0785, found
216.0766.
1
(neat) υ(CO) 1760 (vs), 1732 (vs); H NMR (400 MHz, CDCl3)
δ 1.78 (1H, m), 2.00 (3H, s), 2.14 (1H, m), 3.64 (s, 2H), 4.90
(1H, dt, J ) 6.3, 2.3 Hz), 5.82 (1H, J ) 9.7, 3.5 Hz), 6.67 (1H,
d, J ) 2.3 Hz), 7.17-7.27 (m, 10H, Ph); 13C NMR (100 MHz,
CDCl3) 20.9, 28.1, 40.1, 72.4, 78.0, 126.3, 126.7, 127.2, 128.9,
129.3, 130.5, 131.1, 139.8, 150.0, 168.1, 170.1; MS (12 eV, m/e)
368 (M+); HRMS calcd for C21H20SO4 368.1083, found 368.1092.
Syn th esis of r-Meth ylen e Bu tyr ola cton e 19A,B. To a
CH3CN solution of compound 16b (0.18 g, 0.32 mmol) was
added NOBF4 (50 mg, 0.40 mmol) at 0 °C, and the mixture
was stirred for 1.0 h before addition of solid NaBH3CN (0.10
g, 1.56 mmol). The mixtures were stirred for 1 h before addition
of (NH4)2Ce(NO3)6 (0.35 g, 0.64 mmol). The solution was
concentrated and eluted through a preparative TLC plate
(diethyl ether/hexane ) 1/1) to give compound 19A,B as a
colorless oil (19B/19A ) 4.2, 62 mg, 0.24 mmol, 75%): IR (neat)
Syn th esis of F u n ction a lized r-Meth ylen e Bu tyr ola c-
ton e 23a . To a CH3CN solution (5.0 mL) of compound 17a
(200 mg, 0.40 mmol) was added NOBF4 (52 mg, 0.44 mmol) at
0 °C, and the mixtures were stirred for 20 min before addition
of NaI (124 mg, 0.84 mmol). The resulting red solution was
stirred for an additional 20 min before benzaldehyde (220 mg,
2.04 mmol) was added. The mixtures were stirred for 8 h,
concentrated, and eluted through a preparative silica TLC
plate (diethyl ether/hexane ) 1/1) to give the lactone 23a (72
mg, 0.24 mmol, 57%) as a colorless oil: IR (neat) υ(CO) 1748
(vs), υ(OH) 3458 (vs) cm-1; 1H NMR (400 MHz, CDCl3) δ 0.89
(3H, t, J ) 7.6 Hz), 1.25-1.44 (2H, m), 1.59-1.66 (2H, m),
2.11 (3H, s), 3.03 (1H, m), 4.26 (1H, m), 4.67 (1H, dd, J ) 7.7,
3.4 Hz), 4.99-5.02 (1H, m), 5.80 (1H, d, J ) 2.3 Hz), 6.37 (1H,
d, J ) 2.3 Hz), 7.26-7.40 (5H, m); 13C NMR (75 MHz, CDCl3)
δ 9.2, 21.1, 27.5, 37.4, 52.7, 72.1, 76.3, 79.4, 126.1, 126.6, 128.1,
128.6, 135.1, 140.5, 169.6, 169.8; MS (75 eV, m/e) 318 (M+);
HRMS calcd for C18H22O5 318.1467, found 318.1467.
1
υ(CO) 1761 (vs), 1731 (vs), υ(CdC) 1655 cm-1; H NMR (400
MHz, CDCl3) 19B δ 2.00 (3 H, s), 2.05 (1H, m), 2.17 (1H, m),
2.55 (1H, m), 3.02 (1H, m), 4.55 (1H, m), 5.57 (1H, d. J ) 2.3
Hz), 5.85 (1H, dd, J ) 9.4, 4.0 Hz), 6.16 (1H, t, J ) 2,8 Hz),
7.20-7.30 (m, 5H), 19A selected peaks 6.91 (1H, s), 5.88 (1H,
dd, J ) 9.0, 4.2 Hz), 4.96 (1H, m), 2.32 (1H, m), 1.89 (1H, m);
13C NMR (100 MHz, CDCl3) δ 21.0, 33.4, 43.0, 72.3, 73.8, 122.5,
126.1, 128.2, 128.7, 134.0, 140.0, 170.0, 170.4; 13C NMR (100
MHz, CDCl3): δ 21.0, 33.4, 43.0, 72.3, 73.8, 122.5, 126.1, 128.2,
128.7, 134.0, 140.0. 170.0, 170.4; MS (12 eV, m/e) 260 (M+);
HRMS calcd for C15H16O4 260.1049, found 260.1055.
Ack n ow led gm en t. We thank the National Science
Council, Republic of China, for financial support of this
work.
Syn th esis of r-Meth ylen e Bu tyr ola cton e 21. To a CH3-
CN solution (7.0 mL) of compound 15b (0.20 g, 0.38 mmol)
was added NOBF4 (50 mg, 0.43 mmol) at 0 °C, and the mixture
was stirred for 0.50 h before addition of a saturated Na2CO3
(500 mg) solution. The mixture was stirred for 12 h in air at
23 °, and concentrated in vacuo. Elution of this residue on a
preparative TLC plate (diethyl ether/hexane ) 1/1) gave
compound 21 as a colorless oil (60 mg, 0.28 mmol, 74%): IR
Su p p or tin g In for m a tion Ava ila ble: Syntheses and spec-
tral data of compounds 4-6, 9-13, 18, 15b,c, 16b-d , 18, 20,
22, and 23b-e in repetitive synthesis; crystal data, ORTEP
drawing, atomic coordinates, thermal parameters, full bond
lengths and angles of compound 15b. This material is available
free of charge via the Internet at http://pubs.acs.org.
J O001664U