Synthesis, reactivity and demetallation of tungsten-azacyclic carbeniums via cycloalkenation of tungsten-alkynylamine compounds

Article abstract of DOI:10.1016/S0040-4020(00)00215-5

Treatment of tungsten-η¹-αδ-alkynylamine compounds with aldehyde and BF₃Et₂O led to cycloalkenation reaction, giving good yields of tungsten- η¹-pyrrolylidium salts. These azacyclic carbeniums provide a short sy

Full text of DOI:10.1016/S0040-4020(00)00215-5

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 5029±5035
Synthesis, Reactivity and Demetallation of Tungsten±Azacyclic
Carbeniums via Cycloalkenation of
Tungsten±Alkynylamine Compounds
*
Ming-Jung Chen, Shie-Tsung Chang and Rai-Shung Liu
Department of Chemistry, National Tsing Hua University, Hsinchu, 30043, Taiwan, ROC
Received 11 November 1999; accepted 30 December 1999
AbstractÐTreatment of tungsten±h1-a,d-alkynylamine compounds with aldehyde and BF3´Et2O led to cycloalkenation reaction, giving
good yields of tungsten±h1-pyrrolylidium salts. These azacyclic carbeniums provide a short synthesis of a-alkylidene-g-lactam via oxidation
with m-CPBA. In contrast with tungsten±h1-oxacyclic carbenium, this salt reacts with one molecule of organometallic reagents such as
NaBH3CN, CH3MgBr and Me2CuLi to give tungsten±h1-4,5-dihydropyrrole complexes. An alternative use of this cyclialkenation is to
provide a short synthesis of 3-vinyl-D2-pyrrolines. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
derivatives (Eqs. (3) and (4)). A noticeable example is the
reaction with di-Grignard reagent MgBr(CH2)4MgBr to give
spirofuran and -pyran compounds in 66±70% yields (Eq.
Alkynyl complexes of silanes, stannanes, boranes, zinc and
titanium1 are not as useful as their allyl, allenyl and pro-
pargyl complexes.2,3 As shown in Scheme 1, these alkynyl
organometallics react with carbon electrophiles at the
Ca-carbon to form unstable vinyl cation that is easily
destroyed by any basic species to afford functionalized
alkynyl compounds.1 Transition metal±alkynyl compounds
react with carbon electrophiles at the Cb-carbon to form
metal±allenylidenium cations which are fairly kinetically
stable.4 Nucleophilic attack at cations of these types
proceeds with regiochemistry at their Ca-carbons to effect
a 1,2-addition.
Scheme 1.
To highlight the synthetic utility of these allenylidenium
species, we recently reported that tungsten±h1-alkynol
compounds underwent Lewis acid-catalyzed cycloalkena-
tion reaction with aldehydes to form tungsten±oxacarbenium
salts.5 The reaction works well for both ®ve- and six-
membered ring systems. In contrast with conventional
transition-metal±carbeniums, these oxacyclic carbeniums
function as a dication equivalent upon treatment with
suitable nucleophiles.6 Scheme 2 shows the protocol to
utilize this unique reactivity for synthesis of various oxygen
heterocycles. Treatment of this carbenium salt with water
and air produced the a-alkylidene g- and e-lectones exclu-
sively (Eq (2)). NaBH3CN and RMgBr effected a,a-double
addition of the salt to afford b-alkylidene furan and pyran
Keywords: cycloalkenations; tungsten±azacyclic carbeniums; azacyclic
compounds.
* Corresponding author. Tel.: 1886-3-7521424; fax: 1886-3-5711082;
e-mail: rsliu@faculty.nthu.edu.tw
Scheme 2. (1) R0CHO/BF3´Et2O, (2) H2O/air, (3) NaBH3CN, (4) R00MgBr,
(5) MgBr(CH2)4MgBr, (6) R002CuLi, (7) NaBH(OMe)3/MeOH, (8) CH2N2,
H2O.
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00215-5

5030
M.-J. Chen et al. / Tetrahedron 56 (2000) 5029±5035
Scheme 3.
(5)). Organocuperate R2CuLi effected 1,3-addition reaction
of the salt in the cases that the sizes of R and R0 substituents
are large (Eq. (6)). If a MeOH solution of NaBH4 was used
in the reaction, ®ve- and six-membered lactols were formed
exclusively (Eq. (7)). Finally, treatment of this salt with
CH2N2 led to cyclopropanation reaction with excellent dia-
stereoselectivities, yielding a single diastereomeric product
(Eq. (8)).5
rated for various oxygen heterocycles, it is desired to extend
this cycloalkenation reaction to tungsten±h1-alkynyl
amines to afford tungsten±azacyclic carbeniums. In this
article, we report the preparation and the use of such salts
for the synthesis of nitrogen hetrocycles.
Results and Discussion
The tungsten±h1-a,d-alkynylamine 1 was easily prepared
from CpW(CO)3Cl, Et2NH and CuI catalysts; the yield
was 64%.7 Treatment of compound 1 with MeCHO and
BF3´Et2O (1.0 equiv.) in cold diethyl ether deposited a
dark red precipitate, characterized as tungsten±h1-pyrrolyl-
idenium salt. In contrast with its h1-oxacyclic carbenium,
1H NMR spectra of this azacarbenium salt (2308C) showed
the presence of two conformational isomers 2-anti and
2-syn (2-anti/2-synˆ4:1) which are distinguishable by
different orientations of their lone pair electrons to the
phenyl group. Both species showed the diagnostic carbene
13C NMR resonances at 259.9 and 262.0 ppm, respectively,
in addition to NMR resonances assignable to ethylidene
group. The 1H NMR resonances of these two isomers
became broad as the temperatures were warmed to 408C.
Unfortunately, we could not measure the coalescing
temperatures to obtain the activation energy because the
sample decomposed abruptly above 408C. This structural
assignment is further supported by structural characteri-
zation of the tungsten±h1-2,3-dihydropyrrolyl complex
3-anti and 3-syn produced from LiAlH4-reduction of the
salt 2. Although tungsten±h1-oxacyclic carbenium under-
goes double addition reaction upon treatment with
NaBH3CN, RMgBr and R2CuLi, the azacarbenium salt 2a
and 2b only undergoes single addition with organometallic
reagents. NaBH3CN was ineffective for reduction of the salt
even if excess amount was used. The reaction of this salt
In a subsequent study, we employed this cycloalkenation in
intramolecular system for synthesis of various unsaturated
bicyclic lactones,6 and the reaction protocol is shown in
Scheme 3. The reaction not only works well for tungsten±
h1-alkynols tethered with dimethoxymethane, and also
ef®ciently for those bearing a tethered ketone and
trimethoxymethane group. With alternation of lengths of
the alcohol and electrophile chains, various sizes of bicyclic
lactones can be prepared in good yields including the
medium ring compounds [4.6.0] and [5.5.0]-bicyclic
lactones. Since the bicyclic tungsten±oxacyclic carbeniums
can be isolated, they are useful for synthesis of various
oxygen heterocycles via treatment with CH2N2, Et3SiH
and MeMgBr to effect cyclopropanation, reduction of
CvC bond and a,a-dialkylation reaction. A summary of
the products is given in Eq. (2), and the yields exceeded
62%. This synthetic method is also applicable to a short
synthesis of natural bicyclic lactones such as mitsugashiwa-
lactone and onikulactone. Addition of Me2CuLi to this
bicyclic oxacarbenium, followed by demetallation with
hydrolysis, affords mitsugashiwalactone and onikulactone
in 56 and 13% yields6, respectively, based on starting
tungsten±alkynol species.
Nitrogen heterocycles are equally important as oxygen
heterocycles in synthetic organic chemistry. The fact that
the preceding tungsten±oxacarbenium salts can be elabo-

M.-J. Chen et al. / Tetrahedron 56 (2000) 5029±5035
5031
Scheme 4.
with LiAlH4 gave two conformers 3-anti and 3-syn which
The synthetic utility of this cycloalkenation is best mani-
fested by a short and ef®cient synthesis of a-alkylidene-g-
lactam. The results are shown in Table 1; the yields exceed
54%. In a typical operation, tungsten±h1-a,g-alkynylamine
was treated with aldehyde and BF3´Et2O in cold diethyl
ether to deposit a red precipitate which was isolated by
®ltration for oxidative demetallation with m-chloroperben-
zoic acid or Me3NO in CH2Cl2. Unlike their oxacarbenium
salts, treatment of these pyrrolylidenium salts with water
and air did not effect oxidative demetallations. The synth-
esis of a-alkylidene-g-lactam works well for both aliphatic
and aromatic aldehydes. In addition to tosylamine, tethered
mesyl amine and aliphatic amide are also very ef®cient to
give good yields of g-lactams as shown in entries 3±5.
Attempts to prepare larger nitrogen heterocycles such as
a-alkylidene-d-lactams from tungsten±h1-alk-1-yn-1-yl-4-
tosylamines were unsuccessful and their reactions with
aldehydes and BF3´Et2O failed to give the desired azacyclic
carbenium salt in cold diethyl ether.
1
were indicated by low-temperature H and 13C NMR spec-
tra. The H NMR resonances of these two species became
1
broad and eventually coalesced as the temperatures were
raised; the energy barrier was calculated to be 13.6 kcal/
mol. The reaction of the salt 2 with excess MeMgBr and
Me2CuLi led to single addition to give a mixture of two
conformers 4-anti and 4-syn; the yields were 72 and 69%,
1
respectively (Scheme 4). H NMR signals of 3-anti and
3-syn also coalesced into one resonance as the temperatures
were raised. No cyclopropanation took place for the reaction
of these salts with CH2N2 over a prolonged reaction period.
Fig. 1 shows the ORTEP drawing of the molecular structure
of compound 3 in which the tosylate and the phenyl group
are trans to each other, i.e. the molecule adopts an anti-
conformation. Notably, this ®ve-membered pyrrolyl ring
is coplanar to the plane de®ned by C16±W1±C2 atoms,
similar to those of tungsten±oxacarbenium salts. This struc-
tural arrangement is very favorable for overlap of the C16-
p-orbital with tungsten-dxy-orbital (SHOMO).6 However,
this arrangement renders it very dif®cult for the pyrrolyl
nitrogen to undergo inversion of con®guration because it
will force a steric interaction between the tosylate and
cyclopentadienyl groups.
An alternative use of tungsten±azacarbenium salt is to
provide a convenient synthesis of 3-vinyl D2-pyrrolines,
and synthesis of compounds of this class was reported to
involve a long sequence of procedures.8 As shown in
Figure 1. The molecular structure of compound 3-anti.

5032
M.-J. Chen et al. / Tetrahedron 56 (2000) 5029±5035
Table 1. Direct synthesis of a-alkylidene-g-lactam
Table 2. Cycloadditions of 3-vinyl-D2-prolline (14)
Scheme 5, treatment of these salts with Et3N led to depro-
tonation to yield tungsten±4,5-dihydropyrroles 11 and 12 in
91% and 89% respectively. Hydrodemetallation of
compounds 11 and 12 was achieved smoothly via treatment
with anhydrous Me3NO in CH3CN (238C, 12 h). Under this
circumstance, 3-vinyl D2-pyrrolines 13 and 14 were
obtained in 46% and 39% yields respectively in addition
to a-ethylidene-g-lactams 6 and 8 in 18 and 19% yields.
Solvents are very critical to obtain good yields of azacyclic
dienes. If CH2Cl2 was used as the solvent, pyrrolines 13 and
14 were obtained in 21 and 20% yields respectively whereas
a-ethylidene-g-lactams 6 and 8 were increased to 45 and
42% yields, respectively. We believe that CH3CN is a better
proton source than CH2Cl2 in the hydrodemetallation
reaction.
de®cient ole®ns. The cycloaddition proceeds very rapidly
for maleic anhydride and N-phenylmaleimide (entries 1 and
2) to afford only endo-addition products 15 and 16 in 93
and 91% yields, respectively. The stereochemistries of 15
and 16 were determined by proton NOE spectra. In this
manner, dienophiles preferably approach the diene from
endo face opposite the phenyl substituent. The reactions
with dimethyl maleate and dimethyl fumarate (entries 3
and 4) require higher temperatures and longer reaction
time for completion, giving only endo-addition products
17 and 18 in 80 and 78%, respectively. Determination of
the stereochemistries of 17 and 18 relied on 1H NMR NOE
effect. Azacyclic diene 14 also reacted well with 3-butyn-2-
one to affod the cycloadduct 19 in 50% yield in addition to
aromatic compound 20 (13%). Over a prolonged heating,
compound 20 will undergo substantial aromatization to
yield the amine 20 (70% yield) exclusively.
Cycloaddition reactions of simple dienamines has been
studied extensively over last two decades. Considerable
attentions have focused on the Diels±Alder reaction of
azacyclic dienes for the synthesis of pericyclic nitrogen
compounds.8±11 Boeckman and corworkers has studied the
cycloaddition of 3-vinyl-D2-pyrrolines as an approach to
Amaryllidaceae alkaloid lycorine.8 3-Vinyl-D2-pyrrolines
13 and 14 with an additional substituent seem to be more
challenging because the cycloaddition may form additional
diastereomeric products. Table 2 shows the results for
cycloadditions of 3-vinyl-D2-pyrroline 14 with electron-
Experimental
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
benzophenone and distilled before use. Dichloromethane
Scheme 5.

M.-J. Chen et al. / Tetrahedron 56 (2000) 5029±5035
5033
was dried over CaH2 and distilled before use. W(CO)6,
sodium, dicyclopentadiene, propargyl bromide, methane-
sulfonamide, p-toluenesulphonamide and benzaldehyde
were obtained commercially and used without puri®cation.
92.7, 64.5, 41.7, 27.5, 21.7, 11.6. syn-form, 218.9, 218.3,
151.8, 143.5, 142.2, 141.9, 128.1, 128.0, 127.5, 126.7 125.8,
116.1, 93.6, 64.5, 39.1, 22.2, 21.7, 12.2. MS (EI, m/z): 659.4
(M1) 631.4 (M12CO).
Tungsten±h1-4-phenyl-4-tosylamino-but-1-yn-1-yl (1).
To a diethylamine solution (25 mL) of CpW(CO)3Cl
(3.00 g, 8.15 mmol), CuI (0.16 g, 0.82 mmol) was added
4-phenyl-3-tosylamino-1-butyne (2.31 g, 7.74 mmol), and
the mixtures were stirred at 238C 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 1 as
a yellow solid (3.18 g, 5.03 mmol, 65%). IR (neat, cm21):
n(CO) 2027(vs), 1934(vs), n(SO2) 1349(s); 1H NMR
(300 MHz, CDCl3): d 7.10±7.56 (9H, m) 5.50 (5H, s)
5.31 (s, br s) 4.38 (1H, dd, Jˆ11.8, 4.9 Hz) 2.71 (2H, m,
Jˆ15 Hz), 2.34 (3H, s); 13C NMR (75 MHz, CDCl3): d
228.9, 212.2, 212.1, 142.9, 140.4, 137.5, 129.3, 127.9,
127.2, 127.0, 126.7, 122.5, 91.4, 63.9, 56.7, 31.3, 21.4.
MS (EI, m/z): 631 (M1), 603 (M12CO), 547 (M123CO).
Anal. Calcd for WC25H21SO5N: C, 47.54; H, 3.25; N, 2.23.
Found: C, 47.54; H, 3.52; N, 2.29.
Reaction of 2 with MeMgBr. To a CH2Cl2 solution of
azacyclic carbenium salt 2 (0.30 g, 0.40 mmol) was added
MeMgBr (ca. 1.2 mmol) at 2788C, and the solution was
stirred for 2 h before treatment with a saturated NH4Cl
solution. The organic layer was extracted with diethyl
ether, and eluted through a silica column to afford
compound 4 as a yellow solid (0.16 g, 0.30 mmol, 76%).
IR (neat, cm21): n(CO) 2023(vs), 1921(s), n(SO2) 1333(s);
1H NMR (400 MHz, CDCl3, 2208C): anti-form d 7.14±
7.36 (9H, m) 5.63 (5H, s) 5.21(1H, d, Jˆ7.8 Hz), 3.24
(1H, m), 2.50 (1H, m) 2.26 (1H, m), syn-form d 7.14±
7.36 (9H, m), 5.86 (5H, s), 5.21 (1H, d, Jˆ7.5 Hz), 3.05
(1H, m), 2.50 (1H, m), 2.18 (1H, m); MS (EI, m/z): 549
(M1), 521 (M12CO). Anal Calcd for WC22H23SO5N: C,
48.15; H, 4.22; N, 2.55. Found: C, 48.99; H, 4.16; N, 2.32.
1-Tosyl-3-benzylidene-5-phenyl-g-lactam (5). To
a
diethyl ether solution of alkynyltungsten compound 1
(0.80 g, 1.27 mmol) at 2788C was added benzaldehyde
(1 mL) and BF3´Et2O (0.16 mL, 1.30 mmol) at 2788C,
and the solution was stirred and warmed to 238C over a
period of 6 h. The resulting red precipitate was collected
by ®ltration and washed with diethyl ether. The precipitate
was redissolved in CH2Cl2 (15 mL) and to this solution was
added m-chloroperbenzoic acid (1.31g, 50%, 7.62 mmol).
The mixtures were stirred for 6 h at 238C, concentrated and
eluted through a preparative silica TLC to afford g-lactam 5
as a colorless oil (0.35 g, 0.86 mmol, 67%). IR (neat, cm21):
Tungsten±h1-pyrrolylidenium salt (2). To a diethyl ether
solution of alkynyltungsten compound
1
(0.80 g,
1.27 mmol) at 2788C was added acetaldehyde (1.0 mL)
and BF3´Et2O (0.16 mL, 1.30 mmol), and the solution was
warmed to 238C over a period of 8 h. During this period, red
precipitate of tungsten±h1-azacyclic carbenium salt 2 was
slowly deposited, collected by ®ltration and washed with
diethyl ether. The yield was 91% (0.86 g, 1.15 mmol). IR
(neat, cm21): n(CO) 1991(vs), 1920(s); 1H NMR (400 MHz,
CDCl3, 2408C): d anti-form, 7.50±6.90 (10H, m), 6.01
(5H, s), 4.89 (1H, dd, Jˆ9.4, 4.9 Hz), 3.63 (1H, dd,
Jˆ15.9, 9.4 Hz), 2.74 (1H, dd, Jˆ15.9, 4.9 Hz), 2.65 (3H,
s), 2.10 (3H, d, Jˆ6.3 Hz), syn-form, d 7.50±6.90 (10H, m),
6.06 (5H, s), 5.39 (1H, dd, Jˆ9.4, 4.9 Hz), 3.48 (1H, dd,
Jˆ15.9, 9.4 Hz), 3.10 (1H, dd, Jˆ15.9, 4.9 Hz), 2.35 (3H,
s), 2.10 (3H, d, Jˆ6.3Hz); 13C NMR (100 MHz, CDCl3,
2308C): anti-form d 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, d 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.
1
n(CO) 1719(vs), n(CvC) 1648(m), n(SO2) 1354(s); H
NMR (300 MHz, CDCl3): d 7.53 (1H, s), 7.07±7.45 (9H,
m), 5.50 (1H, d, Jˆ9.2 Hz), 3.60 (1H, m, Jˆ17.4, 9.2 Hz)
3.04 (1H, d, Jˆ17.4 Hz) 2.34 (3H, s); 13C NMR (75 MHz,
CDCl3): d 167.2, 144.7, 140.9, 134.6, 130.1, 129.7, 129.1,
128.8, 128.5, 128.3, 127.6, 126.5, 135.9, 59.8, 35.1, 21.6.
HRMS (m/z): Calcd for C24H21O3SN: 403.1242; found
403.1243.
1-Tosyl-3-ethylidene-5-phenyl-g-lactam (6). This com-
pound was prepared according to the procedure for the
synthesis of 5; the yield was 57%. IR (neat, cm21): n(CO)
1719(vs), n(CvC) 1675(m), n(SO2) 1361(s); 1H NMR
(300 MHz, CDCl3): d 7.04±7.40 (9H, m, 2 Ph) 6.76 (1H,
m), 5.39 (1H, t, Jˆ9.5 Hz) 5.15 (1H, m, Jˆ15.9, 9.5 Hz),
2.62 (1H, m, Jˆ15.9 Hz, 6.2 Hz) 2.32 (3H, s), 1.82 (3H, d,
Jˆ6.9 Hz); 13C NMR (75 MHz, CDCl3): d 166.1, 144.5,
141.3, 135.5, 129.9, 128.8, 128.7, 128.3, 128.3, 127.8,
134.5, 59.7, 32.4, 21.5, 14.9. HRMS (m/z): Calcd for
C19H19O3NS, 341.1086; found 341.1085.
LiAlH4-reduction of the salt 2. To a CH2Cl2 solution
(10 mL) of azacyclic carbenium salt 2 (0.30 g, 0.40 mmol)
was added a THF solution of LiAlH4 (51 mg, 1.20 mmol)
and the solution was stirred for 0.5 h. Monitoring of the
solution by silica-TLC showed the presence of a yellow
band. The solution was ®ltered through a thin silica bed to
yield a yellow solid of tungsten±h1-4,5-dihydropyrrolyl
complex 3 (0.14 g, 0.21 mmol, 53%). IR (neat, cm21):
n(CO) 2023(vs), 1926(s); 1H NMR (400 MHz, CDCl3,
2208C): anti-form d 7.04±7.85 (9H, m), 5.66 (5H, s) 4.93
(1H, dd, Jˆ9.4, 4.9 Hz), 2.41 (3H, s), 1.74±2.05 (4H, m),
0.70 (3H, t, Jˆ5.5 Hz), syn-form, d 7.04±7.85 (9H, m), 5.70
(5H, s), 4.93 (1H, dd, Jˆ9.4, 4.9 Hz), 2.38 (3H, s), 1.74±
2.05 (4H, m), 0.85 (3H, t, Jˆ5.5 Hz); 13C NMR (100 MHz,
CDCl3): anti-form d 229.5, 215.9, 214.7, 155.7, 143.6,
141.9, 135.8, 134.2, 129.3, 128.1, 127.5, 126.9, 118.1,
1-Mesyl-3-benzylidene-5-phenyl-g-lactam (7). This com-
pound was prepared according to the procedure for the
synthesis of 5; the yield was 62%. IR (neat, cm21) n(CO)
1719(vs), n(CvC) 1648(m), n(SO2) 1354(s); 1H NMR
(300 MHz, CDCl3): d 7.67 (1H, m) 7.27±7.51 (10H, m),
5.30 (1H, dd, Jˆ9.4, 1.8 Hz), 3.67 (1H, dd, Jˆ15.5,
9.4 Hz), 3.12 (1H, dd, Jˆ15.5, 1.8 Hz), 3.01 (3H, s); 13C
NMR (75 MHz, CDCl3): d 168.2, 140.9, 136.2, 134.4,
130.3, 129.2, 129.1, 128.9, 128.6, 127.2, 126.1, 59.4, 41.5,

5034
M.-J. Chen et al. / Tetrahedron 56 (2000) 5029±5035
34.9; HRMS: Calcd for C18H17SO3N: 327.0929; found:
327.0929.
1H NMR(400 MHz, CDCl3, 2408C): anti-form d 7.12±7.37
(5H, m), 6.64 (1H,dd, Jˆ17.1, 10.8 Hz), 5.60 (5H, s), 5.32
(1H, dd, Jˆ8.3, 7.5 Hz), 5.10 (1H, d, Jˆ10.8 Hz), 5.01(1H,
d, Jˆ17.1 Hz), 3.39 (1H, m, Jˆ8.3 Hz), 2.88 (3H, s), 2.44
(1H, d, Jˆ7.5 Hz), syn-form 7.12±7.37 (5H, m), 6.40 (1H,
dd, Jˆ17.4, 10.7 Hz), 5.68 (5H, s), 5.32 (1H, overlapped
with that of anti isomer), 5.07 (2H, m), 3.18 (1H, m), 2.80
(3H, s), 2.63 (1H, m); 13C NMR (100 MHz, CDCl3, 2208C):
d 228.3, 215.6, 149.1, 142.8, 128.3, 126.9, 125.4, 135.6,
128.4, 114.7, 92.8, 64.5, 39.8, 25.7; MS (EI, m/e): 581
(M1). Anal Calcd for WC21H19SO5N: C, 43.39; H, 3.29;
N, 2.41; found C: 43.23; H, 3.55; N, 2.20.
1-Mesyl-3-ethylidene-5-phenyl-g-lactam (8). This com-
pound was prepared according to the procedure for the
synthesis of 5; the yield was 59%. IR (neat, cm21): n(CO)
1719(vs), n(CvC) 1655(m), n(SO2) 1354(s); 1H NMR
(300 MHz, CDCl3): d 7.22±7.37 (5H, m, Ph), 6.89 (1H,
m), 5.28 (1H, dd, Jˆ9.2, 1.8 Hz), 3.20 (1H, m, Jˆ16.0,
9.2 Hz), 2.91 (3H, s), 2.71 (1H, dd, Jˆ16.0, 1.8 Hz), 1.81
(3H, d, Jˆ2.6 Hz); 13C NMR (75 MHz, CDCl3): d 166.9,
141.2, 135.5, 129.6, 125.9, 129.1, 128.4, 59.2, 41.4, 32.3,
15.1. HRMS: Calcd for C13H15SO3N, 265.0784; found
265.0772.
1-Tosyl-3-vinyl-5-phenyl-4,5-dihydropyrrole (13). To a
CH3CN solution of compound 11 (0.33 g, 0.50 mmol) was
added Me3NO (75 mg, 1.00 mmol), and the mixtures were
stirred for 6 h. The solution was concentrated and eluted
through a preparative silica plate to afford compound 13
as a colorless oil (74 mg, 0.23 mmol, 46%). IR(neat,
cm21): n(CvC) 1638(m), n(SO2) 1341(s); 1H NMR
(300 MHz, CDCl3): d 7.18±7.58 (9H, m, 2 Ph), 6.58 (1H,
s), 6.46 (1H, dd, Jˆ17.3, 10.6 Hz), 4.97 (1H, d, Jˆ10.7 Hz),
4.80±4.84 (2H, m), 3.04 (1H, m, Jˆ15.9, 9.2 Hz), 2.54
(1H, dd, Jˆ15.9, 6.4 Hz), 2.39 (3H, s); 13C NMR
(75 MHz, CDCl3): d 143.8, 142.3, 129.7, 129.4, 128.9,
128.6, 128.4, 127.6, 126.4, 126.4, 113.4, 63.6, 39.5,
21.6; HRMS: Calcd for C19H19SO2N, 325.1136; found
325.1142.
1-(But-3-enoyl)-3-(phenylethenyl)-g-lactam (9). This
compound was prepared according to the procedure for
the synthesis of 5; the yield was 72%. IR (neat, cm21):
1
1750(s), 1711(s), 1647(m); H NMR (CDCl3, 400 MHz):
d 7.31 (5H, m), 6.53 (1H, dd, Jˆ16.0, 1.6 Hz), 6.25 (1H,
dd, Jˆ16.0, 6.4 Hz), 5.85 (1H, m), 5.06 (1H, dd, Jˆ10.4,
3.6 Hz), 4.99 (1H, dd, Jˆ10.4, 2.8 Hz), 3.95 (1H, m), 3.65
(1H, m), 3.47 (1H, m), 3.03 (2H, t, Jˆ7.2 Hz), 2.37 (3H, m),
2.02 (1H, m); 13C NMR (100 MHz, CDCl3): 175.1, 173.7,
137.0, 136.4, 133.2, 128.6, 127.8, 126.4, 124.8, 115.4, 47.7,
43.4, 36.2, 28.1, 24.4. HRMS Calcd for C17H18NO2:
269.1416, found: 269.1418.
1-(But-3-enoyl)-3-(ethylidene)-g-lactam (10). This com-
pound was prepared according to the procedure for the
synthesis of 5; the yield was 71%. IR (neat, cm21):
1-Mesyl-3-vinyl-5-phenyl-4,5-dihydropyrrole (14). This
compound was prepared according to the procedure for
synthesis of compound 13. IR (neat, cm21): n(CvC)
1638(m), n(SO2) 1341(s); 1H NMR (400 MHz, CDCl3,
2408C): anti-form, d 7.12±7.37 (5H, m) 6.64 (1H, dd,
Jˆ17.1 Hz, 10.8 Hz), 5.60 (5H, s), 5.32 (1H, dd, Jˆ8.3,
7.5 Hz), 5.10 (1H, d, Jˆ10.8 Hz), 5.01 (1H, d, Jˆ
17.1 Hz), 3.39 (1H, m, Jˆ8.3 Hz), 2.88 (3H, s) 2.44 (1H,
m, Jˆ7.5 Hz), syn-form, 7.12±7.37 (5H, m), 6.40 (1H, dd,
Jˆ17.4, 10.7 Hz), 5.68 (5H, s), 5.32 (1H, dd, Jˆ8.3,
7.5 Hz), 5.07 (2H, m), 3.18 (1H, m), 2.80 (3H, s), 2.63
(1H, m); 13C NMR (100 MHz, CDCl3, 2208C): d 228.3,
215.6, 149.1, 142.8, 128.3, 126.9, 125.4, 135.6, 128.4,
114.7, 92.8, 64.5, 39.8, 25.7; MS (EI, m/z): 581 (M1).
Anal. Calcd for WC21H19SO5N: C, 43.39; H, 3.29; N,
2.41; found C, 43.23; H, 3.55; N, 2.24.
1
1750(s), 1711(s), 1647(m); H NMR (CDCl3, 400 MHz):
d 6.76 (dq, Jˆ7.6, 2.4 Hz), 5.86 (1H, m), 5.06 (1H, ddd,
Jˆ9.6, 2.4, 1.6 Hz), 4.97 (1H, dd, Jˆ9.6, 2.4 Hz), 3.78 (1H,
t, Jˆ7.6 Hz), 3.07 (2H, t, Jˆ7.6 Hz), 2.65 (2H, m), 2.40
(2H, m), 1.82 (3H, dt, Jˆ7.6, 2.4 Hz); 13C NMR
(100 MHz, CDCl3): 174.3, 167.7, 137.2, 134.1, 132.6,
115.3, 42.0, 36.2, 28.2, 20.3, 15.0. HRMS: Calcd for
C11H15NO2: 193.1103; found: 193.1095.
CpW(CO)3(h1-1-tosyl-3-vinyl-5-phenyl-4,5-dihydropyrrol-
2-yl) (11). To a CH2Cl2 solution of azacyclic carbenium salt
2
(0.30 g, 0.40 mmol) was added Et3N (0.081 mL,
0.80 mmol) at 08C, and the mixtures were stirred for 1 h.
The residues were chromatographed through a short
alumina column to give a yellow band to afford 11 as a
yellow solid (0.23 g, 0.36 mmol, 89%). IR (neat, cm21):
n(CO) 2025(vs) 1922(s), n(SO2) 1332(s); 1H NMR
(400 MHz, CDCl3, 2408C): anti-form d 7.04±7.40 (9H,
m, 2 Ph), 6.50 (1H, dd, Jˆ17.0, 10.8 Hz), 5.58 (5H, s),
5.30 (1H, dd, Jˆ8.3, 7.5 Hz), 5.14 (1H, d, Jˆ10.8 Hz),
5.01 (1H, d, Jˆ17.1 Hz), 3.30 (1H, m, Jˆ8.3 Hz), 2.87
(3H, s), 2.51 (1H, d, Jˆ7.5 Hz), syn-form 7.12±7.47 (5H,
m), 6.43 (1H, dd, Jˆ17.4, 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, s), 2.69 (1H, m); MS (EI, m/e): 657. Anal.
Calcd for C27H23WNSO5: C, 49.31; H, 3.53; Found: C,
49.04; H, 3.66.
1-(Methylsulfonyl)-2-phenyl-2,3,5,5a,6,8,8a,8b-octahydro-
1H-furo[3,4-g]indole-6,8-dione (15). To a d8-toluene
solution (1.0 mL) of diene 14 (30 mg, 0.12 mmol) was
added maleic anhydride (13 mg, 0.132 mmol) in a sealed
NMR tube, and the NMR sample was heated at 608C for
2 h. NMR spectra of this solution showed the completion of
reaction. The solution was concentrated and eluted through
a preparative silica TLC-plate to afford compound 14 as a
colorless solid (38 mg, 0.11 mmol, 92%). IR (neat, cm21):
1
n(CvO) 1767(vs); H NMR (400 MHz, CDCl3): d 7.30
(5H, m), 5.84 (1H, m), 5.04 (1H, dd, Jˆ8.0, 3.6 Hz), 4.31
(2H, t, Jˆ6.4 Hz), 3.37 (1H, m), 3.06 (1H, dd, Jˆ17.2,
8.0 Hz), 2.78 (2H, m), 2.38 (3H, s), 2.34 (1H, m); 13C
NMR (100 MHz, CDCl3): d 173.8, 170.0, 143.2, 140.6,
128.9, 128.7, 127.7, 118.3, 64.9, 59.3, 45.1, 40.8, 39.9,
38.2, 25.9. HRMS: Calcd for C17H17NO5S, 347.0827;
found 347.0831.
CpW(CO)3(h1-1-mesyl-3-vinyl-5-phenyl-4,5-dihydropyrrol-
2-yl) (12). This compound was prepared according to the
procedure for synthesis of compound 11; the yield was 91%.
IR (neat, cm21): n(CO) 2025(vs), 1922(s); n(SO2) 1332(s);

M.-J. Chen et al. / Tetrahedron 56 (2000) 5029±5035
5035
1-(Methylsulfonyl)-2,7-diphenyl-1,2,3,5,5a,6,7,8,8a,8b-
deca-hydropyrrolo[3,4-g]indole-6,8-dione (16). This
compound was prepared similarly from compound 14 and
N-phenylmaleimide; the yield was 91%. IR (neat, cm21):
[2-(3-Acetylphenyl)-1-phenylethyl]methanesulfonamide
(20). This compound was prepared by heating a toluene
solution of compound 14 with dimethyl furmate (1008C,
1
6 h); the yield was 70%. H NMR (300 MHz, CDCl3): d
1
n(CvO) 1767(s); H NMR (300 MHz, CDCl3): d 7.38
7.79 (1H, d, Jˆ7.4 Hz), 7.60 (1H, s), 7.32 (7H, m, Ph),
4.90 (1H, d, Jˆ7.2 Hz), 4.73 (1H, dd, Jˆ14.5, 7.3 Hz),
3.14 (2H, d, Jˆ7.2 Hz), 2.51 (3H, s), 2.45 (3H, s); 13C
NMR (75 MHz, CDCl3): d 197.9, 140.3, 137.3, 137.1,
134.1, 129.4, 128.9, 128.8, 128.3, 127.1, 126.8, 59.2, 43.8,
41.8, 26.6. HRMS: Calcd for C17H19NO3S, 317.1086; found
317.1099.
(10 H, m), 5.81 (1H, m), 4.89 (1H, dd, Jˆ9.9, 8.0 Hz),
4.66 (1H, d, Jˆ8.2 Hz), 4.04 (1H, t, Jˆ8.2, 7.4 Hz), 3.32
(1H, t, Jˆ7.4 Hz), 3.14 (1H, dd, Jˆ17.2, 8.0 Hz), 2.93 (1H,
dd, Jˆ14.6, 7.4 Hz), 2.67 (1H, dd, Jˆ17.2, 9.9 Hz), 2.60
(3H, s), 2.27 (1H, m); 13C NMR (75 MHz, CDCl3): d
178.3, 175.1, 139.5, 139.0, 132.0, 129.3, 128.9, 128.8,
128.5, 128.4, 126.6, 118.1, 65.1, 60.2, 43.1, 42.8, 40.7,
39.7, 25.2. HRMS: Calcd for C23H22N2O4S, 422.1300;
found 422.1298.
Acknowledgements
Dimethyl 1-(methylsulfonyl)-2-phenyl-2,3,5,6,7,7a-hexa-
hydro-1H-6,7-indole-dicarboxylate (17). This compound
was prepared similarly from compound 14 and dimethyl
maleate; the yield was 80%. IR (neat, cm21): n(CvO)
The authors wish to thank National Science Council,
Taiwan for ®nancial support of this work.
1
1735(s); H NMR (400 MHz,CDCl3): d 7.32 (5H, m, Ph),
References
5.60 (1H, s), 4.90 (1H, t, Jˆ7.2 Hz), 4.41 (1H, d, Jˆ4.0 Hz),
4.10 (1H, t, Jˆ4.0 Hz), 3.68 (3H, s), 3.58 (3H, s), 2.34,3.00
(5H, m), 2.21 (3H, s); 13C NMR (100 MHz, CDCl3): d
172.7, 169.8, 139.6, 134.6, 128.7, 128.6, 128.5, 119.1,
80.8, 64.,1 52.2, 51.7, 45.0, 41.0, 40.2, 39.3, 24.9. HRMS:
Calcd for C19H23NO6S: 393.1246; found 393.1242.
1. (a) Lozar, L. D.; Clark, R. D.; Heathcock, C. H. J. Org. Chem.
1977, 42, 1386. (b) Johnson, W. S.; Yarnell, T. M.; Myers, R. F.;
Morton, D. R. Tetrahedron Lett. 1978, 26, 1201. (c) Johnson, W. S.;
Yarnell, T. M.; Myers, R. F.; Morton, D. R.; Boots, D. R. J. Org.
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Dimethyl 1-(methylsulfonyl)-2-phenyl-2,3,5,6,7,7a-hexa-
hydro-1H-6,7-indoledicarboxylate (18). This compound
was prepared similarly from compound 14 and dimethyl
furmate; the yield was 78%. IR (neat, cm21): n(CvO)
1
1733(vs); H NMR (400 MHz, CDCl3): d 7.22 (5H, m,
3. (a) Herndon, J. W.; Wu, C. Synlett 1990, 1, 411. (b) Danheiser,
R. L.; Takahashi, T.; Bertok, R.; Dixon, B. R. Tetrahedron Lett.
1993, 34, 3845. (c) Danheiser, R. L.; Ksasigroch, C. A.; Tsai, Y. M.
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Ph), 5.47 (1H, t, Jˆ3.5 Hz), 5.16 (1H, d, Jˆ8.9 Hz), 4.54
(1H, d, Jˆ8.8 Hz), 3.71 (3H, s), 3.63 (3H, s), 3.05 (1H, dd,
Jˆ9.8, 8.8 Hz), 2.98 (1H, m,), 2.81 (3H, s), 2.21 (1H, dd,
Jˆ11.6, 9.8 Hz), 2.48 (2H, m), 2.08 (1H, ddd, Jˆ18.2, 11.6,
3.5 Hz); 13C NMR (100 MHz, CDCl3): d 174.0, 173.3,
141.6, 135.7, 128.7, 127.4, 125.9, 121.1, 62.3, 60.4, 52.3,
52.2, 48.9, 41.5, 40.3, 40.2, 28.4. HRMS: Calcd for
C19H23NO6S, 393.1246; found 393.1243.
4. (a) Bruce, M. I. Chem. Rev. 1991, 91, 257. (b) Davidson, A.;
Solar, J. P. J. Organomet. Chem. 1979, 166, c13.
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J. Org. Chem. 1998, 63, 7289.
1-[1-(Methylsulfonyl)-2-phenyl-2,3,5,7a-tetrahydro-1H-
7-indolyl]-1-ethanone (19). This compound was prepared
by heating a toluene solution of compound 14 with dimethyl
furmate (1008C, 4 h); the yield was 50%. IR (neat, cm21):
7. Bruce, M. L.; Humphrey, M. G.; Mattisons, J. G.; Roy, S.;
Swincer, A. G. Aust. J. Chem. 1984, 1041.
8. Boeckman Jr., R. K.; Breining, S. R.; Arvanitis, A. Tetrahedron
1997, 53, 8941.
1
n(CvO) 1715(s), n(CvC) 1635(w); H NMR (300 MHz,
CDCl3): d 7.22 (5H, m), 6.66 (1H, m), 5.60 (1H, m), 5.12
(2H, m), 3.06 (3H, s), 2.46,2.92 (4H, m), 2.40 (3 H, s); 13C
NMR (75 MHz, CDCl3): d 200.8, 142.8, 139.6, 137.0,
134.1, 128.3, 127.1, 125.8, 118.7, 62.0, 54.3, 40.3, 38.9,
28.1, 27.9. HRMS: Calcd for C17H19NO3S: 317.1086;
found 317.1084.
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1999, 121, 700.
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