Synthesis of 3-acyl-4-alkenylpyrrolidines by platinum-catalyzed hydrative cyclization of allenynes

Article abstract of DOI:10.1002/hlca.200690165

A series of nitrogen-tethered allenynes ('5-aza-1,2-dien-7-ynes') 1 were transformed to the corresponding 3-acyl-4-alkenylpyrrolidines 3 when treated with a catalytic amount of PtCl₂ in MeOH at 70°. Initial Pt-promoted cyclization forms a noncl

Full text of DOI:10.1002/hlca.200690165

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Helvetica Chimica Acta – Vol. 89 (2006)
Synthesis of 3-Acyl-4-alkenylpyrrolidines by Platinum-Catalyzed Hydrative
Cyclization of Allenynes
by Takanori Matsuda, Sho Kadowaki, and Masahiro Murakami*
Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura,
Kyoto 615-8510, Japan
(fax: +81-75-383-2748; e-mail: murakami@sbchem.kyoto-u.ac.jp)
Dedicated to Professor Giambattista Consiglio on the occasion of his 65th birthday
A series of nitrogen-tethered allenynes (‘5-aza-1,2-dien-7-ynes’) 1 were transformed to the corre-
sponding 3-acyl-4-alkenylpyrrolidines 3 when treated with a catalytic amount of PtCl2 in MeOH at
708. Initial Pt-promoted cyclization forms a nonclassical carbocationic intermediate. In contrast to the
cycloisomerization in toluene, which produced the bicyclic cyclobutenes 2, the intermediate is inter-
cepted by addition of an oxygen nucleophile to achieve the formal hydrative cyclization.
Introduction. – The cycloisomerization of enynes catalyzed by electrophilic transi-
tion-metal salts or complexes has received significant attention in recent years because
these reactions give rise to structurally highly diverse products, depending on the teth-
ers connecting the enynes, substituents, catalysts, and reaction conditions [1]. The
enyne cycloisomerization is generally thought to proceed through intermediates of car-
bocationic and/or cyclopropylcarbenoid characters. It would provide a useful method
to prepare more densely functionalized cyclic compounds if such an intermediate is
subsequently intercepted with an intramolecular unsaturated functionality [2] or by
another molecule [3].
We have been studying the cycloisomerization of allenynes (1,2-dien-7-ynes)
expecting reactivities different from those of enynes [4][5]1), and recently found that
heteroatom-tethered allenynes of type 1 undergo a Pt-catalyzed cycloisomerization
reaction in toluene at 808 to produce the bicyclic cyclobutenes 2 (Scheme 1) [6][7]2).
Herein, we report that a formal hydrative cyclization pathway becomes viable with
the same allenynes when the Pt-catalyzed reaction is carried out in MeOH.
Results and Discussion. – The tosylamine-tethered allenyne 1a was heated in
MeOH at 708 (bath temperature) in the presence of a catalytic amount of PtCl2 (10
mol-%) for 24 h (Scheme 2). After evaporation of the volatile materials, chromato-
graphic isolation on silica gel afforded ‘3-benzoyl-4-isobutenyl-1-tosylpyrrolidine’
1
)
For cycloisomerizations of allenynes involving b-hydride elimination, see [4], and for [2+2] cyclo-
additions of allenynes, see [5].
For the metathesis-type reaction, see [7].
2
)
© 2006 Verlag Helvetica Chimica Acta AG, Zürich

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Scheme 1. Pt-Catalyzed Cycloisomerization of Allenyne 1a to the Bicyclic Cyclobutene 2a
(3a)3) in 78% yield as a separable mixture of the corresponding cis- and trans-isomers in
a ratio of 52 :48. No cyclobutene derivative, which had been observed in the reaction
1
run in toluene, was detected by H-NMR in the crude mixture. When the alternative
product, cyclobutene 2a (Scheme 1), was heated in MeOH at 708 in the presence of
PtCl2, no 3a was formed. This suggests that 2a is not involved in the pathway leading
to 3a. The reaction with AuCl (10 mol-%) was sluggish and gave 3a only in 14%
yield. Other metal salts like InCl3 and YbCl3 failed to exhibit any catalytic activity.
Scheme 2
The following mechanism is conceivable for the formation of 3a from the allenyne
1a in MeOH solution (Scheme 3). Initially, the alkyne moiety of 1a coordinates to PtCl2
to form the alkyneꢀPt complex A. The latter then undergoes an endo cyclization with
the proximal allenic C=C bond to form the seven-membered ring intermediate B (just
as is the case in toluene). The cationic intermediate B is viewed as a nonclassical cation,
to which the resonance form C also contributes. A nucleophile, either MeOH or H2O,
then adds to C to give intermediate D4). We assume that a small amount of H2O might
be formed by dehydration of MeOH, which possibly occurs in the presence of the Pt
catalyst [8]. Then, the four-membered ring of D is opened through b-carbon elimina-
tion [9] to afford the alkenylplatinum(II) species E4). Finally, reductive elimination
from E furnishes the enol derivative 4, which leads to the formal hydration product 3
in the presence of H2O. When the above reaction was carried out at 408 under otherwise
identical conditions, the methyl enol ether 4 (R=Me) was isolated in 25% yield, which
supports this species being a true intermediate5).
When the above reaction was performed in CD3OD, [D2]-3a was obtained, with one
G
D-atom each in a- and vinylic position (Scheme 4). The degree of deuterium incorpo-
3
)
)
)
For systematic names, see the Exper. Part.
Species D and E are formally depicted as hydride complexes.
Obtained as a mixture of stereoisomers (E/Z) 4:1).
4
5

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Helvetica Chimica Acta – Vol. 89 (2006)
Scheme 3. Proposed Catalytic Cycle for the Reaction of 1 in MeOH
ration was >96% for both positions. The high deuterium content in a-position to the
C=O group was rationalized by assuming that D2O was present in the reaction medium
to convert 4 to 3.6)
AHCTREUNG
Scheme 4
Next, we studied the effect of solvent on the reaction of 1a (Table 1). When reacted
in the presence of 10 equiv. of MeOH in toluene at 708, not 3a, but cyclobutene 2a was
obtained exclusively, suggesting that a large amount of MeOH is required for its forma-
tion (Table 1, Entry 1). The cyclization of 1a to 3a also occurred in protic solvents other
6
)
The intermediacy of the corresponding dimethyl acetal cannot be ruled out, although it has not been
isolated under any conditions in the reaction of 1a.

Helvetica Chimica Acta – Vol. 89 (2006)
1675
than MeOH, but with less efficiency. In EtOH, e.g., the yield was only 42% (Entry 3).
The effect of the amount of H2O on the reaction was also examined. Whereas MeOH/
H2O 100 :1 served as a medium of comparable efficiency (Entry 4), higher proportions
of H2O decreased the product yield (Entry 5)7).
Table 1. Solvent Effects in the PtCl2-Catalyzed Reaction of 1a
Entry
Solvent
Product
Yield [%]
cis/transa)
1
2
3
4
5
Tolueneb)
MeOH
EtOH
MeOH/H2O 100 :1
MeOH/H2O 10 :1
2a
3a
3a
3a
3a
70
78
42
71
36
–
42 :48
51:49
51:49
49 :51
a) Determined by 1H-NMR. b) Containing 10 equiv. of MeOH (rel. to 1a).
To obtain further information on the role of H2O, the reaction was carried out in the
presence of 3-Å molecular sieves, which should remove any trace of H2O from the reac-
tion medium. Under these conditions, neither 3a nor 2a were formed, and 1a was recov-
ered. At present, it remains unclear how a small amount of H2O mechanistically oper-
ates. Interestingly, the reaction carried out in THF/H2O 10 :1 furnished the open-chain
ketone 5 in 50% yield, arising from formal addition of H2O to the central allenic C-
atom (Scheme 5). We, thus, conclude that the activation mode of the allenyne 1a by
PtCl2 varies dramatically with the reaction medium.
Scheme 5
We also tested other allenynes, and the results are summarized in Table 2. The 2-
naphthyl and 3-anisyl derivatives 1b and 1c similarly underwent the cyclization to
afford the corresponding products 3b and 3c, respectively, as 1:1 mixtures of stereo-
isomers (Entries 1 and 2 in Table 2). Whereas the carbon-tethered allenyne 1d also
gave the cyclopentane derivative 3d in 66% yield (Entry 3), the oxygen-tethered alle-
nyne 1e afforded an inseparable mixture of products, which contained ca. 10% of 3e
(Entry 4). The reaction of the allenyne 1f, with an unsymmetrically substituted allene
terminus, gave rise to all four possible isomers (cis/trans 51:49, (E/Z) 1.3 :1 for both
isomers; Entry 5). The allenyne 1g, having two bulky i-Pr groups, failed to undergo
the cyclization, probably due to steric reasons (Entry 6).
The reaction of 1h, carrying a terminal alkyne, gave a mixture of the open-chain
product 6 (38%) and the cyclization product 7 (36%), as shown in Scheme 6. The ter-
7
)
The use of toluene/H2O 1:1 or EtOH/H2O 10 :1 resulted in the formation of a complex mixture.

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Helvetica Chimica Acta – Vol. 89 (2006)
Table 2. Hydrative Cyclization of Allenynes 1b–g Catalyzed by PtCl2 in MeOH
Entry Series Starting material (1)
Product (3)
Isolated yield [%] cis/transa)
1
b
91
49 :51
2
c
72
49 :51
3
4
5
6
d
e
f
66
10b)
63
0
48 :52
–
51:49
g
–
a) Determined by 1H-NMR. b) Estimated by 1H-NMR.
minal alkyne moiety of 1h was reactive enough to undergo the Pt-catalyzed double
addition of MeOH, giving the former linear acetal 6. Such an anti-Markovnikov addi-
tion is rather unusual for PtII catalysts (vide infra). The cyclized product 7 had a trans-
oriented dimethylacetal and 2-mehylbut-2-enyl group. It can be argued whether 7 is
formed by a mechanism similar to that proposed for 3 (see Scheme 4). Another mech-
anistic possibility, however, would involve a sequential, stepwise process triggered by
addition of MeOH to the CꢁC bond.
A control experiment was carried out with the monoyne 8 (Scheme 7). The formal
hydration of the CꢁC bond occurred, and ketone 9, the Markovnikov adduct, was iso-

Helvetica Chimica Acta – Vol. 89 (2006)
1677
Scheme 6
lated in 58% yield [10]. An oxygen nucleophile, either MeOH or H2O, thus was added
regioselectively at the internal position of the propargyl moiety. The formation of the
ketone supports the presence of a small amount of H2O in the reaction medium. Note
the opposite regioselectivity in the addition of an oxygen nucleophile to the terminal
acetylenic groups of the allenyne 1h compared to the monoyne 8. These contrasting
results suggest that intramolecular coordination of the allene moiety of 1h directs the
addition site of MeOH to the terminal position of the CꢁC bond.
Scheme 7
Conclusions. – A Pt-catalyzed cyclization reaction of allenynes producing 3-acyl-4-
alkenylpyrrolidines has been developed. Changing the solvent from toluene to MeOH
directs the reaction pathway from cycloisomerization to formal hydrative cyclization.
We have shown that the reaction pattern of allenynes dramatically varies depending
on the reaction conditions, particularly on the solvent and its water content.
Experimental Part
General. All manipulations were carried out in a glove box under N2 atmosphere, or by standard
Schlenk techniques under Ar atmosphere. PtCl2 was purchased from Wako Pure Chemical Industries,
Ltd. All other commercially available chemicals were used without further purification. Column chroma-
tography (CC) was performed on silica gel 60 N (Kanto). Prep. thin-layer chromatography (TLC) was
performed on silica gel 60 PF254 (Merck). NMR Spectra were recorded on a Varian Gemini-2000 appa-
ratus at 300.77 (1H) or 75.46 MHz (13C); d in ppm rel. to residual solvent signals (d(CHCl3) 7.26 and
77.00, resp.). High-resolution mass spectra (HR-MS) were recorded on a JEOL JMS-SX102A apparatus;
in m/z.
Typical Procedure for the Preparation of Allenynes 1 (outlined for 1a). To a soln. of (3-phenylprop-2-
ynyl)tosylamine (=4-methyl-N-(3-phenylprop-2-yn-1-yl)benzenesulfonamide) (810 mg, 2.84 mmol) [11]
in THF (19.0 ml) were added Ph3P (1.27 g, 4.84 mmol), 4-methylpenta-2,3-dien-1-ol (557 mg, 5.68 mmol)
G
[7], and diisopropyl azodicarboxylate (DIAD; 1.15 g, 5.69 mmol) successively at 08. The mixture was
allowed to warm to r.t. over 30 min, and was then stirred for another 30 min. The solvent was removed

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Helvetica Chimica Acta – Vol. 89 (2006)
under reduced pressure, and the residue was purified by CC (SiO2; hexane/AcOEt 14 :1) to afford 4-
methyl-N-(4-methylpenta-2,3-dien-1-yl)-N-(3-phenylprop-2-yn-1-yl)benzenesulfonamide (1a; 959 mg,
1
92%). H-NMR: 1.70 (d, J=2.7, 6 H); 2.36 (s, 3 H); 3.88 (d, J=6.9, 2 H); 4.41 (s, 2 H); 4.91–4.97 (m,
1 H); 7.04 (d, J=8.1, 2 H); 7.23–7.33 (m, 5 H); 7.71 (d, J=8.1, 2 H). 13C-NMR: 20.3; 21.4; 36.5; 46.8;
81.7; 83.7; 85.3; 97.0; 122.3; 127.7; 128.0; 128.2; 129.4; 131.4; 135.9; 143.3; 203.9. HR-EI-MS: 365.1457
(M+, C22
A
G
N
General Procedure for the Pt-Catalyzed Hydrative Cyclization of Allenynes 1 (outlined for 1a). To a
suspension of PtCl2 (7.6 mg, 0.029 mmol) in MeOH (8.6 ml) was added 1a (104.5 mg, 0.286 mmol). The
mixture was stirred under Ar atmosphere for 24 h at 708, the volatile material was removed under
reduced pressure, and the residue was purified by prep. TLC (SiO2; hexane/AcOEt 3 :1) to afford 3-ben-
zoyl-1-[(4-methylphenyl)sulfonyl]-4-(2-methylprop-1-enyl)pyrrolidine (3a) as a mixture of cis- (45.0 mg,
41%) and trans-isomers (40.7 mg, 37%).
Data of cis-3a. 1H-NMR: 1.12 (d, J=1.2, 3 H); 1.29 (d, J=0.9, 3 H); 2.45 (s, 3 H); 3.06 (dd, J=9.9, 4.8,
1 H); 3.32–3.45 (m, 1 H); 3.59–3.73 (m, 3 H); 4.07 (q, J=7.7, 1 H); 4.42 (dt, J=10.5, 1.4, 1 H); 7.32–7.55
(m, 5 H); 7.70–7.79 (m, 4 H). 13C-NMR: 17.5; 21.5; 25.4; 40.6; 48.3; 49.2; 54.0; 120.1; 127.7; 128.0; 128.5;
129.6; 133.0; 133.5; 135.2; 136.9; 143.5; 197.9. HR-FAB-MS: 384.1639 ([M+H]+, C22
A
G
N
384.1628).
Data of trans-3a. 1H-NMR: 1.42 (d, J=0.9, 3 H); 1.55 (d, J=0.9, 3 H); 2.46 (s, 3 H); 3.07 (dd, J=9.6,
7.8, 1 H); 3.18–3.32 (m, 1 H); 3.36–3.44 (m, 1 H); 3.46 (dd, J=9.5, 7.7, 1 H); 3.62–3.76 (m, 2 H); 4.93 (d,
J=9.3, 1 H); 7.35 (d, J=8.1, 2 H); 7.40–7.47 (m, 2 H); 7.53–7.60 (m, 1 H); 7.73 (d, J=8.1, 2 H); 7.82 (d,
J=7.5, 2 H). 13C-NMR: 18.1; 21.6; 25.6; 41.3; 50.7; 51.3; 53.2; 122.9; 127.6; 128.4; 128.6; 129.7; 133.4;
133.5; 135.8; 136.2; 143.6; 198.1. HR-FAB-MS: 384.1636 ([M+H]+, C22
C
G
N
1
(cis-[D2]-3a). H-NMR: 1.12 (s, 3 H); 1.29 (s, 3 H); 2.45 (s, 3 H); 3.06 (dd, J=10.1, 5.0, 1 H); 3.37 (t,
J=5.4, 1 H); 3.60–3.71 (m, 3 H); 7.33–7.44 (m, 4 H); 7.48–7.55 (m, 1 H); 7.72–7.79 (m, 4 H). 13C-
NMR8): 17.5; 21.5; 25.3; 40.5; 48.3; 53.9; 127.7; 128.0; 128.5; 129.6; 133.1; 133.5; 135.1; 136.9; 143.5;
198.0. HR-FAB-MS: 386.1758 ([M+H]+, C22
A
D2
G
N
Data of trans-[D2]-3a. 1H-NMR: 1.41 (s, 3 H); 1.55 (s, 3 H); 2.46 (s, 3 H); 3.07 (dd, J=9.6, 7.8, 1 H);
3.24 (t, J=7.7, 1 H); 3.40 (d, J=9.6, 1 H); 3.46 (dd, J=9.6, 7.5, 1 H); 3.71 (d, J=9.9, 1 H); 7.35 (d, J=8.1,
2 H); 7.40–7.47 (m, 2 H); 7.53–7.60 (m, 1 H); 7.72 (d, J=8.1, 2 H); 7.79–7.85 (m, 2 H). 13C-NMR8): 18.0;
21.6; 25.5; 41.2; 50.6; 53.2; 127.6; 128.4; 128.6; 129.7; 133.4; 133.5; 135.7; 136.2; 143.6; 198.1. HR-FAB-
MS: 386.1754 ([M+H]+, C22
A
D2
G
N
Data of cis-1-[(4-Methylphenyl)sulfonyl]-3-(2-methylprop-1-enyl)-4-[(naphthalen-2-yl)carbonyl]pyr-
rolidine (cis-3b). 1H-NMR: 1.10 (d, J=1.2, 3 H); 1.26 (d, J=1.2, 3 H); 2.47 (s, 3 H); 3.11 (dd, J=9.8, 5.3, 1
H); 3.42–3.53 (m, 1 H); 3.65–3.80 (m, 3 H); 4.25 (q, J=7.6, 1 H); 4.49 (dt, J=10.5, 1.2, 1 H); 7.37 (d,
J=7.8, 2 H); 7.51–7.63 (m, 2 H); 7.77–7.94 (m, 6 H); 8.28 (s, 1 H). 13C-NMR: 17.6; 21.6; 25.4; 40.8;
48.5; 49.2; 54.0; 120.2; 123.7; 126.9; 127.7; 128.4; 128.6; 129.4; 129.6; 129.8; 132.3; 133.5; 134.2; 135.3;
135.4; 143.5; 197.9; one arom. signal missing due to overlapping. HR-FAB-MS: 434.1784 ([M+H]+, C26-
A
G
A
H); 3.75–3.90 (m, 2 H); 5.02 (dt, J=9.6, 1.4, 1 H); 7.36 (d, J=8.1, 2 H); 7.50–7.65 (m, 2 H); 7.75 (d,
J=8.4; 2 H); 7.84–7.95 (m, 4 H); 8.32 (s, 1 H). 13C-NMR: 18.1; 21.6; 25.6; 41.5; 50.8; 51.4; 53.3; 123.1;
123.9; 126.9; 127.1; 127.66; 127.72; 128.5; 128.8; 129.5; 129.7; 130.5; 133.4; 133.6; 135.6; 135.8; 143.6;
197.9. HR-FAB-MS: 434.1791 ([M+H]+, C26
A
G
N
Data of cis-3-[(3-Methoxyphenyl)carbonyl]-1-[(4-methylphenyl)sulfonyl]-4-(2-methylprop-1-enyl)-
pyrrolidine (cis-3c). 1H-NMR: 1.15 (d, J=1.2, 3 H); 1.32 (d, J=0.9, 3 H); 2.45 (s, 3 H); 3.07 (dd,
J=10.1, 4.7, 1 H); 3.32–3.43 (m, 1 H); 3.58–3.73 (m, 3 H); 3.81 (s, 3 H); 4.04 (q, J=7.8, 1 H); 4.43 (dt,
J=10.5, 1.3, 1 H); 7.04–7.09 (m, 1 H); 7.25–7.29 (m, 1 H); 7.30–7.38 (m, 4 H); 7.77 (d, J=8.4, 2 H).
8
)
Two signals are missing due to the magnetic relaxation of C–D.

Helvetica Chimica Acta – Vol. 89 (2006)
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13C-NMR: 17.6; 21.6; 25.5; 40.7; 48.4; 49.4; 54.0; 55.5; 112.5; 119.4; 120.1; 120.6; 127.2; 127.7; 129.5; 129.6;
133.5; 135.3; 138.3; 143.5; 159.8; 197.7. HR-FAB-MS: 414.1745 ([M+H]+, C23
A
G
N
Data of trans-3c. 1H-NMR: 1.44 (d, J=1.2, 3 H); 1.57 (d, J=0.9, 3 H); 2.46 (s, 3 H); 3.05 (dd, J=9.9,
7.5, 1 H); 3.19–3.32 (m, 1 H); 3.40 (dd, J=9.0, 7.5, 1 H); 3.47 (dd, J=9.8, 7.7, 1 H); 3.58–3.74 (m, 2 H);
3.83 (s, 3 H); 4.92 (dt, J=9.6, 1.5, 1 H); 7.08–7.13 (m, 2 H); 7.32–7.38 (m, 5 H); 7.73 (d, J=8.1, 2 H). 13C-
NMR: 18.1; 21.6; 25.6; 41.3; 50.7; 51.5; 53.2; 55.4; 112.7; 119.9; 121.0; 122.9; 127.6; 129.5; 129.7; 133.4;
135.8; 137.6; 143.6; 159.8; 197.9. HR-FAB-MS: 414.1737 ([M+H]+, C23
A
G
N
Data of Dimethyl cis-3-Benzoyl-4-(2-methylprop-1-enyl)cyclopentane-1,1-dicarboxylate (cis-3d). 1H-
NMR: 1.25 (d, J=1.2, 3 H); 1.37 (d, J=1.2, 3 H); 2.21 (dd, J=13.8, 8.4, 1H); 2.48 (ddd, J=7.3, 4.1, 1.2, 1
H); 2.52 (ddd, J=7.3, 3.9, 1.2, 1 H); 2.82 (dd, J=14.1, 8.7, 1 H); 3.31–3.44 (m, 1 H); 3.78 (s, 2×3 H);
4.01–4.11 (m, 1 H); 4.79 (dt, J=10.5, 1.4, 1 H); 7.38–7.44 (m, 2 H); 7.47–7.54 (m, 1 H); 7.80–7.85 (m,
2 H). 13C-NMR: 17.7; 25.4; 35.5; 40.6; 40.8; 49.4; 52.8; 52.9; 59.4; 123.8; 128.2; 128.3; 132.6; 133.4;
137.7; 172.0; 173.2; 200.6. HR-EI-MS: 344.1621 (M+, C20
N
N
Data of trans-3d. 1H-NMR: 1.46 (d, J=0.9, 3 H); 1.54 (d, J=0.9, 3 H); 1.90 (dd, J=13.7, 10.4, 1 H);
2.44 (dd, J=13.8, 9.9, 1 H); 2.72 (dd, J=8.1, 4.5, 1 H); 2.76 (dd, J=8.1, 4.5, 1 H); 3.21–3.35 (m, 1 H);
3.60–3.72 (m, 1 H); 3.75 (s, 3 H); 3.76 (s, 3 H); 4.97 (d, J=9.6, 1 H); 7.40–7.47 (m, 2 H); 7.51–7.58
(m, 1 H); 7.89–7.94 (m, 2 H). 13C-NMR: 18.1; 25.6; 38.3; 41.1; 42.6; 52.4; 52.8; 52.9; 59.2; 125.7; 128.3;
128.5; 133.0; 134.2; 137.0; 172.0; 172.8; 200.7. HR-EI-MS: 344.1621 (M+, C20
N
N
Data of (E/Z)-cis-3-Benzoyl-4-(2-methylbut-1-enyl)-1-[(4-methylphenyl)sulfonyl]pyrrolidine (cis-
1
3f). H-NMR: 0.57 (one isomer, t, J=7.4, 3 H); 0.59 (another isomer, t, J=7.5, 3 H); 1.12 (one isomer,
d, J=1.2, 3 H); 1.30 (another isomer, d, J=1.5, 3 H); 1.47–1.75 ((E)- and (Z)-isomers, m, 2× 2 H);
2.45 ((E)- and (Z)-isomers, s, 2×3 H); 3.00–3.10 ((E)- and (Z)-isomers, m, 2×1 H); 3.34–3.47 ((E)-
and (Z)-isomers, m, 2×1 H); 3.60–3.74 ((E)- and (Z)-isomers, m, 2×2 H); 4.02–4.15 ((E)- and (Z)-iso-
mers, m, 2×1 H); 4.41 ((E)- and (Z)-isomers, d, J=9.9, 2×1 H); 7.32–7.43 ((E)- and (Z)-isomers, m, 2×4
H); 7.48–7.55 ((E)- and (Z)-isomers, m, 2×1 H); 7.73–7.80 ((E)- and (Z)-isomers, m, 2×4 H). 13C-NMR:
12.1; 12.4; 15.7; 21.6; 22.5; 24.5; 32.1; 40.2; 40.4; 48.3; 48.4; 49.09; 49.15; 53.9; 54.3; 118.6; 119.5; 127.7;
128.0; 128.1; 128.46; 128.49; 129.6; 133.1; 133.5; 136.7; 136.9; 140.6; 140.7; 143.5; 197.9; some signals
were overlapped. HR-FAB-MS (mixture): 398.1791 ([M+H]+, C23
A
G
G
1
Data of trans-3f. H-NMR: 0.77 (one isomer, t, J=7.4, 3 H); 0.82 (another isomer, t, J=7.2, 3 H);
1.40 (one isomer, s, 3 H); 1.55 (another isomer, d, J=1.2, 3 H); 1.67–1.97 ((E)- and (Z)-isomers, m,
2×2 H); 2.46 ((E)- and (Z)-isomers, s, 2×3 H); 3.03–3.16 ((E)- and (Z)-isomers, m, 2×1 H);
3.18–3.32 ((E)- and (Z)-isomers, m, 2×1 H); 3.37–3.51 ((E)- and (Z)-isomers, m, 2×2 H); 3.62–3.76
((E)- and (Z)-isomers, m, 2×1 H); 4.86–4.96 ((E)- and (Z)-isomers, m, 2×1 H); 7.35 ((E)- and (Z)-iso-
mers, d, J=8.1, 2×2 H); 7.40–7.48 ((E)- and (Z)-isomers, m, 2×2 H); 7.53–7.60 ((E)- and (Z)-isomers,
m, 2×1 H); 7.71–7.76 ((E)- and (Z)-isomers, m, 2×2 H); 7.80–7.85 ((E)- and (Z)-isomers, m, 2×2 H).
13C-NMR: 12.4; 12.9; 16.3; 21.6; 22.7; 25.0; 29.7; 32.1; 41.0; 41.4; 50.7; 50.8; 51.38; 51.42; 53.4; 53.5;
121.3; 122.4; 127.7; 128.5; 128.57; 128.60; 129.7; 133.4; 133.50; 133.55; 136.27; 136.35; 141.3; 141.4;
143.6; 198.0; 198.3; some signals were overlapped. HR-FAB-MS (mixture): 398.1789 ([M+H]+, C23
NO
3S+; calc. 398.1784).
Data of (3E)-3-[(Methoxy)(phenyl)methylidene)-1-[(4-methylphenyl)sulfonyl]-4-(2-methylprop-1-
A
A
ACHTREUNG
1
enyl)pyrrolidine (4, R=Me). H-NMR: 1.27 (d, J=1.2, 3 H); 1.38 (d, J=1.2, 3 H); 2.43 (s, 3 H); 2.87
(dd, J=9.2, 5.0, 1 H); 3.31 (s, 3 H); 3.34 (dd, J=9.2, 7.1, 1 H); 3.44–3.53 (m, 1 H); 3.94 (dd, J=14.6,
1.7, 1 H); 4.13 (d, J=14.7, 1 H); 4.69 (dt, J=9.9, 1.4, 1 H); 7.13–7.18 (m, 2 H); 7.23–7.29 (m, 3 H);
7.33 (d, J=8.1, 2 H); 7.73 (d, J=8.4, 2 H). 13C-NMR: 17.5; 21.5; 25.3; 39.2; 49.9; 55.0; 57.0; 121.3;
124.3; 127.8; 128.0; 128.1; 128.8; 129.5; 132.0; 132.3; 133.4; 143.4; 148.7. HR-EI-MS: 397.1706 (M+,
C23
A
G
N
1.09 (d, J=6.9, 6 H); 2.32 (s, 3 H); 2.60 (sept., J=6.9, 1 H); 2.90 (t, J=6.6, 2 H); 3.47 (t, J=6.9, 2 H);
4.34 (s, 2 H); 7.06 (dd, J=7.8, 1.5, 2 H); 7.18–7.27 (m, 5 H); 7.76 (d, J=8.1, 2 H). 13C-NMR: 18.1;
21.4; 38.9; 40.0; 41.1; 42.4; 82.1; 85.4; 122.1; 127.8; 128.1; 128.4; 129.5; 131.4; 135.4; 143.6; 212.7. HR-
FAB-MS: 384.1634 ([M+H]+, C22
A
G
N
N-(3,3-Dimethoxypropyl)-4-methyl-N-(4-methylpenta-2,3-dien-1-yl)benzenesulfonamide (6). 1H-
NMR: 1.63 (d, J=3.0, 6 H); 1.87 (q, J=6.8, 2 H); 2.41 (s, 3 H); 3.22 (t, J=7.5, 2 H); 3.31 (s, 6 H); 3.76

1680
Helvetica Chimica Acta – Vol. 89 (2006)
(d, J=6.9, 2 H); 4.40 (t, J=5.4, 1 H); 4.64–4.74 (m, 1 H); 7.28 (d, J=8.1, 2 H); 7.69 (d, J=8.1, 2 H). 13C-
NMR: 20.2; 21.5; 31.6; 42.7; 48.1; 53.2; 84.3; 96.8; 102.5; 127.1; 129.6; 137.0; 143.1; 203.3. HR-FAB-MS:
353.1661 (M+, C18
A
G
N
trans-3-(Dimethoxymethyl)-1-[(4-methylphenyl)sulfonyl]-4-(2-methylprop-1-en-1-yl)pyrrolidine (7).
1H-NMR: 1.57 (d, J=1.2, 3 H); 1.63 (d, J=1.5, 3 H); 2.06 (quint., J=7.3, 1 H); 2.43 (s, 3 H); 2.72 (dd,
J=9.4, 8.3, 1 H); 2.78 (quint., J=8.1, 1 H); 3.20 (s, 3 H); 3.22 (dd, J=10.3, 7.1, 1 H); 3.26 (s, 3 H); 3.27
(dd, J=10.4, 8.2, 1 H); 3.43 (dd, J=8.7, 6.6, 1 H); 4.06 (d, J=6.0, 1 H); 4.78 (dd, J=9.2, 1.4, 1 H); 7.32
(d, J=7.8, 2 H); 7.70 (d, J=8.4, 2 H). 13C-NMR: 18.0; 21.5; 25.7; 39.3; 47.5; 48.5; 53.3; 53.4; 54.9;
105.1; 123.8; 127.7; 129.5, 133.3; 134.3; 143.3. HR-FAB-MS: 354.1739 ([M+H]+, C18
A
G
N
354.1734).
N,4-Dimethyl-N-(2-oxopropyl)benzenesulfonamide (9). 1H-NMR: 2.21 (s, 3 H); 2.43 (s, 3 H); 2.78 (s,
3 H); 3.83 (s, 2 H); 7.32 (d, J=8.1, 2 H); 7.67 (d, J=8.1, 2 H). 13C-NMR: 21.6; 27.0; 36.1; 59.4; 127.4;
129.7; 134.4; 143.7; 203.6. HR-FAB-MS: 242.0851 (C
A
G
N
We thank H. Fujita for assistance in the NMR structure determination and H. Ushitora for recording
the HR-MS data. This work was supported by a Grant-in-Aid for Young Scientists (B) (No. 17750087)
from the Ministry of Education, Culture, Sports, Science and Technology, Japan. S. K. thanks the Japan
Society for the Promotion of Science for a fellowship support.
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Received February 23, 2006