Reactions of thioketones possessing a conjugated C=C bond with diazo compounds

Article abstract of DOI:10.1002/hlca.200690274

The reactions of several thioketones containing a conjugated C=C bond with diazo compounds were investigated. All of the selected compounds reacted via a 1,3-dipolar cycloaddition with the C=S group and subsequent N₂ elimination to yield thioca

Full text of DOI:10.1002/hlca.200690274

Helvetica Chimica Acta – Vol. 89 (2006)
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Reactions of Thioketones Possessing a Conjugated C=C Bond with Diazo
Compounds
by Daniel H. Egli1), Anthony Linden, and Heinz Heimgartner*
Organisch-chemisches Institut der Universität Zürich, Winterthurerstr. 190, CH-8057 Zürich
(phone: +41446354282; fax: +41446356812; e-mail: heimgart@oci.unizh.ch)
The reactions of several thioketones containing a conjugated C=Cbond with diazo compounds were
investigated. All of the selected compounds reacted via a 1,3-dipolar cycloaddition with the C=S group
and subsequent N2 elimination to yield thiocarbonyl ylides as intermediates, which underwent a 1,3-dipo-
lar electrocyclization to give the corresponding thiirane 25, or, by a subsequent desulfurization, to give
the olefins 33a and 33b. None of the intermediate thiocarbonyl ylides reacted via 1,5-dipolar electrocyc-
lization. If the a,b-unsaturated thiocarbonyl compound bears an amino group in the b-position, the reac-
tions with diazo compounds led to the 2,5-dihydrothiophenes 40a–40d. In these cases, the proposed
mechanism of the reactions led once more to the thiocarbonyl ylides 36 and thiiranes 38, respectively.
The thiiranes reacted via an SNi’-like mechanism to give the corresponding thiolate/ammonium zwitter-
ion 39, which underwent a ring closure to yield the 2,5-dihydrothiophenes 40. Also in these cases, no 1,5-
dipolar electrocyclization could be observed. The structures of several key products were established by
X-ray crystallography.
1. Introduction. – The reactions of thiocarbonyl compounds 1 with diazo com-
pounds 2 have been investigated extensively (e.g., [1–3]; for reviews, see [4][5]). The
reactions proceed via a 1,3-dipolar cycloaddition to give the five membered 2,5-dihy-
dro-1,3,4-thiadiazoles 3, which, in general, undergo at room temperature N2 elimina-
tion in a cycloreversion to give a thiocarbonyl ylide 4 (Scheme 1). In the absence of
Scheme 1
1
)
Part of the Ph.D. thesis of D. H. E., University of Zürich, 2006.
ꢀ 2006 Verlag Helvetica Chimica Acta AG, Zürich

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dipolarophiles, the thiocarbonyl ylides 4 react in a 1,3-dipolar electrocyclization to give
the thiiranes 5, which, either spontaneously or by treatment with Ph3P, undergo a desul-
furization to yield the olefins 6. In the presence of appropriate dipolarophiles, e.g., an
excess of the thiocarbonyl compound 1 [6][7], the thiocarbonyl ylides 4 can be inter-
cepted to give five-membered heterocycles of type 7 which are formed by a 1,3-dipolar
cycloaddition (Scheme 1).
In 1979, Bak and Praefcke have shown that the reaction of 1,2-diphenyl-2-thioxo
ethanone (8) with diazo(diphenyl)methane (2a) yields the corresponding 1,3-oxathiole
9a, which is formed by a 1,5-dipolar electrocyclization of the intermediate thiocarbonyl
ylide 4a under incorporation of the C=O bond [8] (Scheme 2). Analogous products
have been obtained from thioketones and a-diazo carbonyl compounds [9–11].
Scheme 2
Recently, we have investigated reactions of diazo compounds with thiocarbonyl
compounds containing a conjugated p-system, such as a-thioxoketones, a-thioxothio-
ACHTREUNGamides, etc. Since the reactions of 8, N,N-dimethyl-2-phenyl-2-thioxothioacetamide
(10), and N-[(dimethylamino)methylidene]thiobenzamide (11) with different diazo
compounds led to the five membered heterocycles 9, 12 and 13, respectively, usually
in good yields [12][13] (Scheme 3), we decided to investigate whether the analogous
reaction takes place with a,b-unsaturated thioketones, i.e., when the conjugated p-sys-
tem is a C=Cbond.
Scheme 3

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The synthesis of such a,b-conjugated thioketones proved to be a nontrivial task,
because these products tend to dimerize in a [2+4] cycloaddition. In a few cases, it
was possible to prepare the desired synthon and to react it with diazo(diphenyl)me-
thane (2a). To make the thioketone less amenable to dimerization and to be able to
carry out reactions with different diazo components, we extended the study to a,b-unsa-
turated thioketones with a b-amino substituent, i.e., to vinylogous thioamides.
2. Results and Discussion. – 2.1. Reaction with (3,4-Dihydro-2,4,6-triphenyl-2H-
thioACHTERpUNG yran-3-yl)(phenyl)methanethione (14). It was attempted first to synthesize the
ꢁD-dimerꢂ 15 of thiachalcone 16 by thionation of chalcone 17 [14]. The dimer would
then be subjected to a retro-Diels–Alder reaction in the presence of diazo(diphenyl)me-
thane (2a), which should lead to 2,3-dihydro-2,3,5,5-tetraphenylthiophene (18) via 1,5-
dipolar electrocyclization of the intermediate thiocarbonyl ylide with an extended p-
system. Unfortunately, as reported by Li et al. [15], we were unable to reproduce the
results of Saito et al. [14] and failed to isolate 15. The only product obtained after thio-
nation of 17 was the so-called ꢁT-Dimerꢂ 14 [15]. Although 14 is less suitable as a pre-
cursor of 16 than 15, we tried to carry out the reaction with 2a. A reaction temperature
of 508 to 608 and slow addition of the diazo compound to the solution of 14 in benzene
were chosen as the reaction conditions to make a retro-Diels–Alder reaction possible.
However, 14 reacted with 2a at the C=S group before the retro-Diels–Alder reaction
took place and gave thiirane 19 (Scheme 4). The structure of 19 was elucidated by an
X-ray crystal-structure determination (Fig. 1). The asymmetric unit contains one mol-
ecule of 19 plus one half of a H2O molecule disordered across two sites. The six-mem-
bered thiopyrane ring shows a distorted envelope conformation with C(3) as the enve-
lope flap, and the Ph substituents at C(4) and C(7) are almost coplanar. Surprisingly, 19
could not be desulfurized with Ph3P to yield the corresponding alkene, most likely
because the S-atom is too hindered for an attack of Ph3P. Fig. 1 shows that the S-
atom of the thiirane is indeed sheltered from a nucleophilic attack.
Scheme 4
2.2. Reactions with g-Oxo-a,b-unsaturated Thioketones. As a,b-unsaturated thioke-
tones are prone to dimerize via [2+4] cycloaddition, the preparation of these synthons

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Fig. 1. ORTEP Plot [16] of the molecular structure of 19 (50% probability ellipsoids, arbitrary num-
bering of the atoms, the H2O molecules have been omitted for clarity)
needs special reaction conditions. One possibility is to create the thiocarbonyl group in
the last step, e.g., by a base-catalyzed reaction at low temperature. The ethyl acetate 20
was synthesized according to a procedure described by Mc Murryet al. [17]. Silylation
of 20 was achieved at room temperature by using NaI as a catalyst in an equimolar ratio
to give the silyloxy compound 21, which was converted into 23 by using sulfenyl chlo-
ride 22 at À788 in CH2Cl2 (Scheme 5). The addition of 22 in the 2-position of com-
pounds of type 21 has never been observed in such reactions (see also the reaction
of 30a,b with 22, Scheme 7). Then, the thioxo ester 24 was generated in situ by 1,8-dia-
zabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed elimination at low temperature and used
immediately for the reaction with 2a. After chromatographic workup, thiirane 25 was
obtained in 30% yield as a brownish oil.
A mechanistic interpretation of the reaction is shown in Scheme 6. The reaction of
24 with 2a led to the intermediate thiocarbonyl ylide 26, which could react to give stable
products via three different pathways. Reactions a and b, i.e., 1,5-dipolar electrocycliza-
tions via the conjugated C=Cor C =O bond, respectively, could yield either thiophene
27 or 1,3-oxathiole 28. The third pathway c would lead to thiirane 25 by a 1,3-dipolar
electrocyclization. The spectroscopic data of the isolated product (IR: three intense
absorptions at 1741 (CO2Et), 1714 (CO), and 1642 cmÀ1 (C=C); 13C-NMR: 199.2
(CO), 167.3 (CO2Et), 158.7 (s), and a d between 132.1 and 127.7 ppm (C=CH)) show
clearly that it was neither the expected dihydrothiophene 27, nor the 1,3-oxathiole
28, but the thiirane 25.

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Scheme 5
Scheme 6
Two other a,b-unsaturated thioketones 29a and 29b have been prepared as depicted
in Scheme 7. In a Wittig-like reaction of cyclohex-2-enone (30) with PhCHO and pen-
tanal, respectively, using the method of Kozikowski and Jung [18], the silyl enolethers
31a and 31b were obtained. In the following steps, the protocol of Capozzi et al. was
applied [19]. Treatment of 31 with 22 in THF at À788 gave the isoindole-dione deriv-
atives 32 in ca. 70% yield with a significant amount of the corresponding ketones of
the hydrolyzed silyl enolethers 31. The crude products 32 in THF were treated with
DBU at À788 to give the cyclohexenones 29 by elimination of phthalimide. The
crude 29a and 29b, respectively, were reacted with 2a to give the alkenyl-cyclohexe-

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Helvetica Chimica Acta – Vol. 89 (2006)
Scheme 7
nones 33a and 33b (Scheme 7). None of the expected intermediate thiiranes could be
detected, but they spontaneously underwent desulfurization.
The structures of 33a and 33b have been established by X-ray crystallography (Fig.
2). Both structures are, with the exception of the substituent at C(7), quite similar. The
conjugated p-system comprising O(1), C(1), C(2), C(3), C(7), and C(8) in 33a or C(12)
in 33b is twisted about C(3)ÀC(7) (torsion angles C(2)ÀC(3)ÀC(7)ÀC(8) 131.5(3)8 and
C(2)ÀC(3)ÀC(7)ÀC(12) 124.5(2)8, resp.). All Ph substituents in compound 33a are,
because of steric reasons, twisted out of the plane formed by C(3), C(7), and C(8) (tor-
sion angles C(7)ÀC(8)ÀC(21)ÀC(22) 126.6(3)8, C(7)ÀC(8)ÀC(15)ÀC(16) À47.0(5)8,
and C(8)ÀC(7)ÀC(9)ÀC(10) 134.2(3)8). The situation in 33b is almost the same as in
33a, with the exception of the Bu substituent at C(7), which is in the expected staggered
arrangement.
The reactions of 2a with the a,b-unsaturated thioxo compounds 24, 29a, and 29b
show that these conjugated thiocarbonyl compounds, which do not possess a hetero-
ACHTREUNG
ACHTREUNG
conjugated C=O, C=S, or C=N groups, these intermediates do not undergo a 1,5-dipo-
lar electrocyclization. The products obtained, namely the alkenyl-cyclohexenones 33a
and 33b, and the thiirane 25 are the result of a 1,3-electrocyclization.
2.3. Reactions with (E)-1-Phenyl-3-(piperidin-1-yl)prop-2-ene-1-thione (34) [20].
The a,b-unsaturated thione 34 reacted with 2a much more slowly than with other thio-
ACHTREUNGketones [12][13] (Scheme 8). Normally, the reactions between thioketones and diazo
compounds are complete in a few min or h, while, in the case of 34, the reactions needed
several days at 40–808. Nevertheless, the results were satisfactory as all spectra (MS,
1H- and 13C-NMR, and IR) indicated the presence of dihydrothiophenes as the main
products. In the case of 2a, the reaction had to be catalyzed with Rh2(OAc)4. After
4 h at room temperature, a dihydro(triphenyl)(piperidino)thiophene was obtained in
50% yield. Analogous products were isolated in relatively good yields, when 34 was

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Fig. 2. ORTEP Plots [16] of the molecular structures of a) 33a and b) 33b (50% probability ellipsoids,
arbitrary numbering of the atoms)
treated with diazo compounds 2b,c, and diazocyclohexane (2d), respectively, under
thermal conditions. In two cases, i.e., with 2b and 2c, we were able to grow single crystals
of the resulting products and determine their crystal structures (Fig. 3). Surprisingly,
the products were not the expected 4,5-dihydrothiophenes 37, which should be formed
via 1,5-dipolar electrocyclization of the intermediate thiocarbonyl ylide 36, but 2,5-
dihydrothiophenes of type 40 (Scheme 8). Apparently, the S-atom is in a different posi-
tion in the ring. A likely mechanistic explanation is given in Scheme 8: instead of the
expected 1,5-dipolar electrocyclization of thiocarbonyl ylide 36 to give 37, 36 reacted
Scheme 8

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in a 1,3-dipolar electrocyclization to yield thiirane 38. The latter underwent a ring open-
ing in an SNi’-like reaction supported by the free electron pair of the N-atom to give the
zwitterion 39, which underwent a 5-exo-trig cyclization to give 40.
Whereas the reaction of 34 with 2c yielded 40c as the only product, the reaction with
2b resulted in two diastereoisomeric products (cis-40b and trans-40b), which could be
separated by MPLC. Recrystallization of the cis-isomer of 40b and of 40c gave crystals
suitable for X-ray crystallography (Fig. 3). The data of the second isomer are in accord-
ance with the estimated values for trans-40b.
Fig. 3. ORTEP Plots [16] of the molecular structures of a) cis-40b and b) 40c (50% probability ellip-
soids, arbitrary numbering of the atoms)
3. Conclusions. – The results in the present work show that it is possible to prepare
the a,b-unsaturated thioketones 24, 29a, and 29b in situ by a base-catalyzed reaction at
low temperature. The products of their reactions with diazo(diphenyl)methane (2a)
indicate that thiocarbonyl ylides (i.e., 26, Scheme 6) are formed as intermediates,
which react in a 1,3-dipolar electrocyclization to give the corresponding thiiranes
(i.e., 25), but they do not undergo the expected 1,5-dipolar electrocyclization.
In the case of 34 with an amino group in the b-position, diazo compounds 2a–2d
react also in a 1,3-dipolar cycloaddition onto the C=S group to give the 2,5-dihydro-
1,3,4-thiadiazoles 35 as intermediates, followed by a spontaneous cycloreversion,
which leads to the thiocarbonyl ylides 36. A subsequent 1,3-dipolar electrocyclization
yields the thiiranes 38, which further rearrange to give finally the 2,5-dihydrothio-
phenes 40a–40d. In all of the investigated reactions of a,b-unsaturated thioketones,
no 1,5-dipolar electrocyclization was observed.
We thank the analytical units of our institute for spectra and analyses, and the Swiss National Science
Foundation and F. Hoffmann-La Roche AG, Basel, for financial support.

Helvetica Chimica Acta – Vol. 89 (2006)
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Experimental Part
1. General. See [12][13].
2. Starting Materials. All thiocarbonyl derivatives and their precursors and all diazo compounds were
prepared according to known protocols: (3,4-Dihydro-2,4,6-triphenyl-2H-thiopyran-3-yl)(phenyl)metha-
nethione (14) [14], diazo(diphenyl)methane (2a) [8], diazo(phenyl)methane (2b) [21], diazomethane (2c)
[22], diazocyclohexane (2d) [23], ethyl 2-(3-oxocyclohex-1-en-1-yl)acetate (20) [17], 1,3-dihydro-1,3-
dioxo-2H-isoindole-2-sulfenyl chloride (22) [24], (E)-1-phenyl-3-(piperidin-1-yl)prop-2-ene-1-thione
(34) [20]. All other reagents are commercially available.
3. General Procedure A (GP A). A stirred soln. of the precursor of the thiocarbonyl compound (2–6
mmol) in THF (50–100 ml) was cooled to À788, and DBU was added dropwise by means of a syringe.
The color of the soln. changed rapidly. After a few min, a purple soln. of 2a in benzene (10–25 ml, 3–7
mmol) was added slowly, and N2 evolved. The color of the soln. changed again, and the mixture was
allowed to warm to r.t. The solvent was removed, and the crude product was purified by chromatography.
4. General Procedure B (GP B). To a soln. of the thiocarbonyl compound (1–7 mmol) in CH2Cl2
(30–100 ml), the diazo compound (2–8 mmol) in toluene, Et2O, THF, or benzene (30–130 ml) was
added by means of a dropping funnel, or, in the case of 2c, by means of a Pasteur pipette. After total con-
version of the thiocarbonyl compound, monitored either by TLC(treated for 20 s with a soln. of 1% Et 3N
2
in Et2O), color change or evolution of N2 ), the solvent was evaporated, and the mixture was purified by
chromatography using silica gel, which had been treated with 3% Et3N. Furthermore, the solvent was
doped with 1% of Et3N.
5. Reaction of (3,4-Dihydro-2,4,6-triphenyl-2H-thiopyran-3-yl)(phenyl)methanethione (14) with 2a. A
soln. of 14 (2 mmol) in benzene (20 ml) was heated to 508 and 2a (ca. 5 mmol) in benzene (10 ml) was
added slowly. After total conversion of the starting material (TLC, changing of the color of the soln.
from blue to yellow-brown), the solvent was evaporated, the crude product was purified by CC (hex-
ane/AcOEt 10 :1), and recrystallized from CH2Cl2/hexane: 313 mg (51%) of 3,4-dihydro-2,4,6-tri-
phenyl-3-(2,3,3-triphenylthiiran-2-yl)-2H-thiopyrane (19). Yellowish crystals. M.p. 137–1418. IR:
3054m, 3024m, 2932w, 1598m, 1491vs, 1444s, 1267w, 1235w, 1180w, 1156w, 1077w, 1031m, 1001w, 778m,
751vs, 696vs. 1H-NMR: 7.75 (d, J=6.9, 2 arom. H); 7.61 (d, J=6.9, 2 arom. H); 7.56–6.45 (m, 26
arom. H); 6.12 (d, J=4.0, =CH); 4.32 (d-like, CH(2)); 3.71 (t-like, CH(4)); 3.55 (br. s, CH(3)). 13C-
NMR: 142.0, 139.9, 139.8, 137.2 134.3, 133.4 (6s, 6 arom. C); 132.0, 130.3, 128.5, 128.4, 128.1, 128.0,
127.8, 127.0, 126.7, 126.5, 126.1, 126.0, 125.9, 125.4 (14d, 30 arom. CH); 120.3 (d, =CH); 65.3, 64.7 (2s,
2
C (’)2, C(3’)); 52.3 (d, C(2)); 47.9 (d, C(4)); 39.4 (d, C(3)). CI-MS (isobutane): 391 (42,
[M+1ÀC15H12S)]+), 358 (100, [MÀC15H12S2]+), 225 (100, [C15H12S]+). Anal. calc. for C43H34S2·0.5 H2O
(623.88): C82.79, H 5.66, S 10.28; found: C83.44, H 5.65, S 9.96.
Crystals suitable for an X-ray crystal-structure determination were grown from CH2Cl2 by slow evap-
oration of the solvent.
6. Reaction of Ethyl 2-(3-Oxocyclohexen-1-yl)-2-thioxoacetate (24) with 2a. 6.1. Ethyl (E/Z)-2-{3-
[(Trimethylsilyl)oxy]cyclohex-2-en-1-yliden}acetate (21). To a soln. of 20 (2 g, 10.98 mmol) and Me3SiCl
(1.63 g, 15 mmol) in DMF (15 ml), Et3N (1.52 g, 15 mmol) was added slowly (10 min), whereby a white
precipitate was formed. After a few min, NaI (1.8 g, 12 mmol) was added in one portion, and the mixture
was stirred for 3 d at r.t. Pentane (30 ml) was added, and the resulting suspension was stirred for 1 h to
give a more easily treatable precipitate. The soln. was filtered, and the solvent was removed in vacuo. The
residue was once more suspended in pentane (20 ml) and filtered to give 21 as a mixture of the (E/Z)-
1
isomers: 2.54 g (96%). Pale yellowish oil. H-NMR (major product)3): 6.95 (s, CH(2)); 5.22 (s,
CH(2’)); 4.11–4.04 (m, C HO); 2.26–2.21 (m, C H(6’)); 2.18–2.13 (m, C H(4’)); 1.75–1.70 (m,
2
2
2
CH2(5’)); 1.22–1.17 (m, MeCH2); 0.24 (s, Me3Si); (minor product): 5.38 (s, CH(2)); 5.34 (s, CH(2’));
0.18 (s, Me3Si)4). 13C-NMR (major product)3): 166.9 (s, C O); 163.4 (s, C (1’)); 154.7 (s, C (3’)); 109.6,
2
2
)
)
The evolution of N2 was determined volumetrically with a gas burette attached to the reaction vessel.
It was not possible to assign the spectra to (E)-21 and (Z)-21 on the basis of the available informa-
tion. Due to thermodynamic stability, we expect that the minor product is the (Z)-isomer.
Other signals overlap with the corresponding signals of the major product.
3
4
)

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105.3 (2d, C(2), C(2’)); 58.9 (t, C HO); 31.7 (t, C (6’)); 30.8 (t, C (4’)); 22.2 (t, C (5’)); 14.3 (q, MeCH2); 0.0
2
(q, (Me3Si); (minor product): 167.2 (s, C O); 162.5 (s, C (1’)); 156.4 (s, C (3’)); 107.5 (d, C(2) or C(2’)); 58.9
2
(t, C HO); 30.5 (t, C (6’)); 25.4 (t, C (4’)); 22.0 (t, C (5’)); 14.3 (q, MeCH2); 0.1 (q, (Me3Si).
2
6.2. Ethyl 2-[(1,3-Dihydro-1,3-dioxo-2H-isoindol-2-yl)sulfanyl]-2-(3-oxocyclohex-1-en-1-yl)acetate
(23). A soln. of 21 (0.50 g, 2.1 mmol) in dry CH2Cl2 (40 ml) was cooled to À788, and a soln. of 22
(0.47g, 2.2 mmol) in dry CH2Cl2 (ca. 20 ml) was added within 10 min by means of a syringe. The soln.
was allowed to warm to r.t., the solvent was removed, and the crude product was dried (h.v.) and analyzed
without further purification: 0.69 g (100%) 23 (containing small amounts of 20). 1H-NMR: 7.91–7.84 (m,
2 arom. H); 7.81–7.29 (m, 2 arom. H); 5.71 (s, CH(2’)); 4.67 (s, CH(2)); 4.27 (2q, J=7.1, CH2O);
2.42–2.32 (m, C H(4’), CH2(6’)); 2.11–2.05 (m, C H(5’)); 1.31 (t, J=7.1, Me). 13C-NMR: 198.6 (s,
2
2
C=O); 167.5 (s, N(CO)2); 166.3 (s, =C(1’)); 155.3 (s, CO2Et); 134.9, 124.0 (2d, 4 arom. CH); 131.5 (s,
2 arom. C); 130.0 (d, C (2’)); 62.7 (t, C HO); 59.5 (d, C(2)); 37.1 (t, C H(4’)); 25.4 (t, C H(6’)); 22.2 (t,
2
2
2
CH2(5’)); 13.9 (q, Me).
6.3. Ethyl 2-(3-Oxocyclohex-1-en-1-yl)-3,3-diphenylthiirane-2-carboxylate (25). According to GP A,
a soln. of 23 (3.1 mmol) in CH2Cl2 (30 ml) was treated with a cat. amount of DBU. After 30 min, an excess
of 2a (ca. 5 mmol) dissolved in benzene (20 ml) was added dropwise. The mixture was diluted with 40 ml
of CH2Cl2 and extracted with cold, sat. aq. NH4Cl. The org. layer was dried (Na2SO4), and the solvent was
removed. CC (CH2Cl2/Et2O 200 :1): 344 mg (30%) of 25. Brownish oil. IR: 3058w, 3027w, 2942m, 1741vs,
1714vs, 1642vs, 1623m, 1491m, 1445s, 1341m, 1324m, 1298m, 1241vs, 1187s, 1135m, 1094m, 1018m, 974w,
1
754m, 703vs. H-NMR: 7.50–7.18 (m, 10 arom. H); 6.30 (s, =CH); 3.95–3.83 (m, C HO); 2.58 (ddd,
2
J=17.8, 2.7, 1.7, 1 H of CH2(6’)); 2.30–2.10 (m, C H(4’)); 1.97 (ddd, J=17.8, 4.3, 0.9, 1 H of CH2(6’));
2
1.76–1.65, 1.31–1.19 (2m, C H(5’)); 0.91 (t, J=7.1, Me). 13C-NMR: 199.2 (s, CO); 167.3 (s, CO2Et);
2
158.7 (s, C (1’)); 139.5, 137.4 (2s, 2 arom. C); 132.1, 129.8, 129.6, 127.9, 127.8, 127.8, 127.7 (7d, 10 arom.
C, =CH); 77.3 (s, C(3)); 62.7 (s, C(2)); 62.3 (t, C HO); 37.3 (t, C (4’)); 30.7 (t, C (6’)); 22.7 (t, C (5’));
2
13.5 (q, Me). CI-MS: 396 (5, [M+NH4]+), 379 (54, [M+1]+), 364 (5), 347 (100, [M+1ÀS]+).
7. Reactions of (3-Oxocyclohex-1-en-1-yl)(phenyl)methanethione (29a) and 1-(3-Oxocyclohex-1-en-
1-yl)pentane-1-thione (29b) with 2a. 7.1. (E/Z)-3-{3-[(Trimethylsilyl)oxy]cyclohex-2-en-1-ylidene}me-
thyl)benzene (31a). To a cold (08) soln. of cyclohex-2-enone (30) (2.06 g, 21.44 mmol) and Ph3P ACHTREU(NG 5.62 g,
21.44 mmol) in dry THF (50 ml), TMSOTf (4.15 ml, 21.44 mmol) was added slowly. The mixture was
cooled to À788, and a soln. of BuLi (2.5M in hexane; 8.4 ml, 21.44 mmol) was added slowly, whereby
the soln. changed to a dark brown suspension. Then, PhCHO (2.17 ml, 21.44 mmol) was added where-
upon the color turned to pale-orange. The solvent was removed, and the residue was purified by bulb-
1
to-bulb distillation (1158/5 mbar): 3.53 g (64%) of almost pure 31a. Colorless oil. H-NMR: 7.12–7.02,
6.97–6.93 (2m, 5 arom. H); 5.88, 5.82, 5.81, 5.37 (4s, CH(2), PhCH)5); 2.38–2.33, 2.17–2.12 (2m,
CH2(4)); 2.04–1.97 (m, C H(6)); 1.66–1.61, 1.57–1.52 (2m, C H(5)); 0.01 (s, Me3Si). GC/MS (EI): 258
2
2
(100, M+C).
7.2. (E/Z)-3-Pentylidene-1-[(trimethylsilyl)oxy]cyclohex-1-ene (31b). To a cold (08) soln. of (30) (1.92
g, 20 mmol) and Ph3P (5.25 g, 20 mmol) in dry THF (60 ml), TMSOTf (4.76 g, 20 mmol) was added
slowly. The soln. was cooled to À788, and a soln. of BuLi (1.6M in hexane; 13 ml, 20 mmol) was added
slowly, whereby the soln. changed to a dark brown suspension. Then, pentanal (1.72 ml, 20 mmol) was
added by means of a syringe, and the color turned to orange. A part of the solvent was removed, and
the suspension was filtered. Then, the solvent was removed completely, and the residue was purified
by bulb-to-bulb distillation (80–1208/0.2 mbar): 1.53 g (32%) of almost pure 31b. Colorless oil. 1H-
NMR: 5.32 (s, CH(2)); 4.95 (t-like, CH(1’)); 2.17–2.13 (m, C H(6)); 2.12–2.10 (m, C H(4)); 2.05–1.97
2
2
(m, C H(2’)); 1.70–1.63 (m, C H(5)); 1.29–1.24 (m, C H(3’), CH2(4’)); 0.85–0.80 (m, Me); 0.14 (s,
2
2
2
Me3Si). 13C-NMR: 153.9 (s, C(1)); 134.2 (s, C(3)); 122.2 (d, C(2)); 110.4 (d, C (1’)); 31.8 (t, C(6)); 30.2
(t, C(4)); 27.0 (t, C (2’)); 24.1 (t, C(5)); 22.3 (t, C (3’)); 22.0 (t, C (4’)); 13.6 (q, C (5’)); 0.0 (q, Me3Si).
7.3.
1,3-Dihydro-2-{[(3-oxocyclohex-1-en-1-yl)(phenyl)methyl]sulfanyl}-2H-isoindole-1,3-dione
(32a). A soln. of 31a (1.01 g, 3.90 mmol) in dry THF (40 ml) was cooled to À788, and a soln. of 22
5
)
The product is a mixture of two stereoisomers (E/Z); therefore, four signals for the two olefinic H-
atoms are to be expected. The assignment of the signals to CH(2) and PhCH is not clear.

Helvetica Chimica Acta – Vol. 89 (2006)
3051
(0.71g, 3.90 mmol) in dry THF (ca. 25 ml) was added by means of a dropping funnel (30 min). The soln.
was allowed to warm to r.t., the solvent was removed, and the crude product was dried (h.v.) and analyzed
without further purification: 1.27 g (89%) of 32a6). Yellowish plates. IR: 2954s, 2871m, 1784s, 1738vs,
1704vs, 1666vs, 1495m, 1454m, 1340m, 1279vs, 1037vs, 968m, 866s, 763m, 710vs. 1H-NMR: 7.87–7.76
(AA’BB’, 2 arom. H); 7.74–7.66 (AA’BB’, 2 arom. H); 7.38–7.14 (m, 4 arom. H); 7.10–7.07 (m, 1
arom. H); 5.80 (t, J=1.37), PhCH); 5.18 (s, CH(2’)); 2.31–2.06 (m, C H(4’), CH2(6’)); 1.92–1.75 (m,
2
CH2(5’)). 13C-NMR: 199.1 (s, CO); 167.6 (s, N(CO)2); 160.6 (s, =C); 136.9 (d, 1 arom. C); 134.7, 123.8
(2d, 4 arom. CH); 131.5 (s, 2 arom. C); 129.0, 128.9, 128.7, 128.3 (4d, 5 arom. CH, C(2’)); 60.7 (d,
PhCH); 37.2 (t, C (4’)); 29.1 (t, C (6’)); 25.8 (t, C (5’)). GC/MS (EI): 220 (30), 205 (100), 177 (30), 133 (15).
7.4. 2-{[(Butyl)(1-oxocyclohex-1-en-1-yl)methyl]sulfanyl}-1,3-dihydro-2H-isoindole-1,3-dione (32b).
A soln. of 31b (1.44 g, 6 mmol) in dry THF (100 ml) was cooled to À788, and a soln. of 22 (1.28 g, 6
mmol) in dry THF (ca. 40 ml) was added by means of a dropping funnel (30 min). The soln. was allowed
to warm to r.t., the solvent was then removed, and the crude product was dried (h.v.) and analyzed with-
out further purification: 1.97 g (92%) of 32b. Yellowish oil. 1H-NMR: 7.90–7.83, 7.79–7.71 (2m, 4 arom.
H); 5.54 (s, CH(2’)); 3.84–3.72 (dd, J=6.4, 6.2, CH(1’’)); 2.40–2.29 (m, C H(4’)); 2.09–1.98 (m, C H(6’));
2
2
1.76–1.60 (m, C H(5’)); 1.50–1.29 (m, C H(2’’), CH2(3’’), CH2(4’’)); 0.94–0.90 (m, Me). 13C-NMR: 199.2
2
2
(s, CO); 167.9 (s, N(CO)2); 161.7 (s, =C); 134.7, 123.8 (d, 4 arom. CH); 131.5 (s, 2 arom. C); 128.1 (d,
C(2’)); 57.6 (d, C (1’’)); 37.4 (t, C (4’)); 29.4 (t, C (6’)); 27.9 (t, C (5’)); 24.4 (t, C (2’’)); 22.2 (t, C (3’’),
C(4’’)); 13.7 (q, Me).
7.5. 3-(1,2,2-Triphenylethenyl)cyclohex-2-en-1-one (33a). According to GP A, a soln. of 32a (1.35
mmol) in THF (60 ml) was treated with a cat. amount of DBU. Then, an excess of 2a dissolved in benzene
was added dropwise. CC (hexane/AcOEt 10 :1 to 1:1) yielded 200 mg (42%) of 33a. Colorless crystals.
M.p. 179–1818. IR: 3077m, 3053m, 3026m, 2947m, 2920m, 2878m, 2864m, 1651vs, 1597s, 1490s, 1454m,
1443s, 1410m, 1360m, 1344s, 1323m, 1306m, 1296m, 1253m, 1240s, 1193m, 1183m, 1154m, 1132m,
1075m, 884m, 773s, 762m, 751m, 726m, 699vs. 1H-NMR: 7.22–6.85 (m, 15 arom. H); 5.76 (t, J=1.4,
CH); 2.24–2.14 (m, C H(6), CH2(4)); 1.81–1.73 (m, C H(5)). 13C-NMR: 199.4 (s, CO); 165.4 (s, C(3));
2
2
142.9, 142.5, 142.0, 140.6 (4s, 3 arom. C, 2 =C)8); 131.2, 131.1, 130.3, 129.8, 128.1, 127.7, 127.6, 127.0,
126.9 (9d, 15 arom. CH, =CH); 37.3 (t, C(6)); 30.5 (t, C(4)); 23.1 (t, C(5)). ESI-MS: 350 (100, M+),
273 (58, [MÀPh]+), 215 (18), 165 (17).
Crystals suitable for an X-ray crystal-structure determination were grown from CH2Cl2/hexane by
slow evaporation of the solvent.
7.6. 3-(1-Butyl-2,2-diphenylethenyl)cyclohex-2-en-1-one (33b). According to GP A, a soln. of 32b (6
mmol) in THF (60 ml) was treated with DBU (6 mmol). Then, an excess of 2a dissolved in benzene was
added dropwise. CC (hexane/Et2O 2 :1 to 1:3) gave 480 mg (25%) of 33b. Colorless crystals. M.p.
115–1168. IR: 2949s, 2923m, 2891m, 2865m, 2858m, 2844m, 1671vs, 1606s, 1582m, 1492m, 1446m,
1413w, 1375w, 1343m, 1322m, 1293m, 1254s, 1235m, 1186m, 1163w, 1127m, 1101m, 1077m, 1029m,
1
884m, 774m, 768s. H-NMR: 7.37–7.07 (m, 10 arom. H); 6.00 (s, =CH); 2.31–2.25 (m, C H(6), CH2 of
2
Bu)); 2.17–2.13 (m, C H(4)); 1.82–1.74 (m, C H(5)); 1.46–1.36, 1.32–1.20 (2m, 2 C H of Bu); 0.84 (t,
2
2
2
J=7.3, Me). 13C-NMR: 199.4 (s, CO); 166.0 (s, C(3)); 142.4, 142.0, 140.4, 140.1 (4s, 2 arom. C, 2 =C);
129.4, 129.2, 129.1, 128.0, 127.8, 127.1, 127.0 (7d, 10 arom. CH, =CH); 37.3 (t, C(6)); 34.4 (t, C(4));
30.9, 30.7 (2t, C(5), CH2 of Bu)); 23.0, 22.7 (2t, 2 C H of Bu); 13.7 (q, Me). CI-MS: 331 (100,
2
[M+1]+). Anal. calc. for C24H26O (330.470): C87.23, H 7.93; found: C87.05, H 7.97.
Crystals suitable for an X-ray crystal-structure determination were grown from CH2Cl2/hexane by
slow evaporation of the solvent.
8. Reaction of (E)-1-Phenyl-3-(piperidin-1-yl)prop-2-ene-1-thione (34). 8.1. 1-(2,5-Dihydro-4,5,5-tri-
phenylthiophen-2-yl)piperidine (40a). According to GP B, 34 (1.86 mmol) in CH2Cl2 (40 ml) and 2a (ca.
2.5 mmol) in benzene (ca. 40 ml) were used. To the soln., a cat. amount (10 mg) of Rh2(OAc)4 was added,
6
)
The NMR and mass spectra indicated a large amount of a side product, which was formed by hydrol-
ysis of 31a.
The coupling constant of 1.3 Hz is also observed in one pair of signals in the m of CH2(6’).
The signals of two of the three arom. C-atoms overlap.
7
8
)
)

3052
Helvetica Chimica Acta – Vol. 89 (2006)
and the mixture was stirred for 4 h. The crude product was purified by CC (CH2Cl2/Et2O 400 :1): 365 mg
(ca. 50%) of 40a. Yellowish crystals. M.p. 130–1338. IR: 3055m, 3029m, 2931vs, 2852s, 2804m, 1633w,
1597m, 1575m, 1493s, 1465m, 1442s, 1385w, 1365m, 1335s, 1323m, 1308m, 1266w, 1237m, 1221m,
1
1182w, 1155m, 1115s, 1098vs, 1034m, 981s, 895m, 861m, 774s, 763vs, 736vs, 697vs. H-NMR9): 7.75–6.97
(m, 15 arom. H); 6.19 (d, J=2.9, CH(3’)); 4.65 (d, J=2.9, CH(2’)); 2.43 (br. s, 2 C HN); 1.12 (br. s, 2
2
CH2); 0.97 (br. s, C H). 13C-NMR ((D6)DMSO): 149.2, 144.5, 141.5, 139.8 (4s, 3 arom. C, C(4’)); 133.1,
2
132.6, 129.5, 129.4, 128.6, 128.5, 128.3, 128.0, 127.8, 127.5, 127.1, 127.0, 126.8, 126.3, 126.1 (15d, 15
arom. CH); 117.0 (d, C (3’)); 78.8 (d, C (2’)); 71.4 (s, C (5’)); 50.2 (t, 2 C HN); 25.9 (t, 2 C H); 23.8 (t,
2
CH2). CI-MS (NH3): 398 (10, [M+1]+), 361 (10), 348 (30), 313 (100, [M+1À2piperidine]+), 299 (6), 86 (9).
8.2. cis- and trans-1-(2,5-Dihydro-4,5-diphenylthiophen-2-yl)piperidine (cis-40b and trans-40b, resp.).
According to GP B, 34 (1.2 mmol) in toluene (10 ml) and 2b (ca. 4 mmol) in toluene (ca. 50 ml) were
used. The soln. was stirred at 808 for 4 d. After total conversion of the starting material (TLC), the
soln. was cooled to r.t., the solvent was removed in vacuo, and the crude product was purified by CC (hex-
ane/AcOEt 10 :1+3% Et3N): 181 mg (49%) of a mixture of cis-40b and trans-40b, which was separated
by MPLC(hexane/AcOEt 20 :1 +2% Et3N) to give 60 mg (16%) of cis-40b and 50 mg (14%) of trans-
40b.
Data of cis-40b. Oily, yellowish crystals. M.p. 106–1238. IR (Golden Gate ATR): 2934w, 2849w,
2810w, 1644w, 1601w, 1574w, 1495w, 1454w, 1439w, 1392w, 1368w, 1338w, 1309w, 1245w, 1222w, 1149w,
1
1100m, 1076w, 1036w, 977w, 911w, 860w, 846w, 773w, 759m, 724m, 698s, 688m. H-NMR: 7.38–7.09 (m,
10 arom. H); 6.37 (dd, J=2.4, 2.0, CH(3’)); 5.92 (dd, J=2.4, 2.0, CH(5’)); 5.73 (t-like, J=2.0, CH(2’));
2.56 (t-like, 2 CH2N); 1.71–1.51 (m, 2 C H); 1.50–1.38 (m, C H). 13C-NMR: 144.6, 143.0, 134.9 (3s,
2
2
C(4’), 2 arom. C); 129.6, 128.7, 128.5, 128.3, 127.7, 127.0, 126.7 (7d, 10 arom. CH, C(3’)); 83.3 (d,
C(2’)); 55.7 (d, C (5’)); 50.2 (t, 2 C HN); 26.2 (t, 2 C H); 23.9 (t, C H). CI-MS (NH3): 291 (24), 290
2
2
2
(100, [M+1ÀS]+). Anal. calc. for C21H25NS (321.16): C78.46, H 7.21, N 4.36, S 9.97; found: C78.13,
H 6.82, N 4.29, S 9.54.
Crystals suitable for an X-ray crystal-structure determination were grown from Et2O/hexane by slow
evaporation of the solvent.
Data of trans-40b. Pale yellowish oily crystals. M.p. 110–1388. IR (Golden Gate ATR): 2933w, 2877w,
2851w, 2798w, 1575w, 1496w, 1446m, 1363w, 1331w, 1208w, 1149w, 1092m, 1034w, 977m, 850w, 820w, 768m,
754m, 726m, 714m, 693m. 1H-NMR: 7.33–7.07 (m, 10 arom. H); 6.31 (dd, Jꢀ2.5, 1.9, CH(3’)); 5.99 (dd,
J=5.1, 2.5, CH(5’)); 5.68 (dd, J=5.1, 1.9, CH(2’)); 2.63–2.47 (m, 2 C HN); 1.71–1.52 (m, C H);
2
2
1.49–1.42 (m, C H)). 13C-NMR: 145.9 (s, C (4’)); 142.6, 134.7 (2s, 2 arom. C); 129.5, 128.5, 128.2, 127.7,
2
127.6, 126.9 (6d, 10 arom. CH, C(3)); 83.3 (d, C (2’)); 57.3 (d, C (5’)); 49.7 (t, 2 C HN); 25.6 (t, 2 C H);
2
2
24.2 (t, C H). CI-MS (NH3): 291 (24), 290 (100, [M+1ÀS]+).
2
8.3. 1-(2,5-Dihydro-4-phenylthiophen-2-yl)piperidine (40c). According to GP B, 34 (1.3 mmol) in
CH2Cl2 (20 ml) and 2c (ca. 6 mmol) in THF (30 ml) were used. The crude product was purified by CC
(hexane/AcOEt 2 :1): 174 mg (55%) of 40c. Yellowish oily crystals. M.p. not measurable. IR: 2932vs,
2852s, 2816s, 2788s, 2748m, 1639w, 1598w, 1575w, 1496s, 1468m, 1450s, 1441s, 1429m, 1384m, 1365s,
1335s, 1321s, 1304s, 1282w, 1263w, 1247m, 1232s, 1213s, 1152s, 1128m, 1116s, 1099vs, 1075m, 1036m,
1
994s, 975s, 964m, 921m, 863s, 847s, 776s, 758vs, 748vs, 713vs, 687vs, 636m. H-NMR (CDCl3): 7.39–7.18
(m, 5 arom. H); 6.14 (q-like, =CH); 5.72 (q-like, CH(2’)); 3.93 (q-like, CH2(5’)); 2.50–2.36 (m, 2
CH2N); 1.57–1.36 (m, 3 C H). 13C-NMR: 142.2 (s, C (4’)); 134.3 (s, 1 arom. C); 127.6, 127.2, 125.1 (3d,
2
5 arom. CH); 125.0 (d, C (3’)); 83.4 (d, C (2’)); 48.6 (t, C (5’)); 36.8 (t, 2 C HN); 24.7, 23.3 (2t, 3 C H).
2
2
CI-MS (NH3): 246 (100, [M+1]+), 214 (86, [M+1ÀS]+), 86 (27, [piperidine+1]+).
Crystals suitable for an X-ray crystal-structure determination were grown from Et2O/hexane by slow
evaporation of the solvent.
8.4. 1-(4-Phenyl-1-thiaspiro[4.5]dec-3-en-2-yl)piperidine (40d). According to GP B, 34 (1.3 mmol) in
CH2Cl2 (10 ml) and 2d (ca. 4 mmol) in CH2Cl2 (ca. 50 ml) were used. To the soln. a cat. amount (5 mg) of
Rh2(OAc)4 was added, and the mixture was stirred at r.t. for 7 h. Then, the solvent was removed i.v., and
9
)
The spectra are not ꢁcleanꢂ because of fast decomposition of the substance.

Helvetica Chimica Acta – Vol. 89 (2006)
3053
Table. Crystallographic Data of Compounds 19, 33a, 33b, cis-40b, and 40c
19
33a
33b
cis-40b
40c
Crystallized from
Empirical formula
CH2Cl2
C43H34S2 ·0.5
H2O
CH2Cl2/hexane CH2Cl2/hexane Et2O/hexane
Et2O/hexane
C15H19NS
C26H22O
350.46
C24H26O
330.47
C21H23NS
321.48
Formula weight [g molÀ1] 623.87
245.38
Crystal color, habit
colorless, prism yellow, prism
colorless, prism yellow, prism
red, plate
Crystal dimensions [mm] 0.12”0.22”0.30 0.17”0.22”0.27 0.25”0.30”0.30 0.10”0.15”0.17 0.03”0.13”0.13
Temp. [K]
Crystal system
Space group
Z
160(1)
160(1)
monoclinic
P21
160(1)
orthorhombic
Pca21
4
160(1)
monoclinic
P21/c
160(1)
monoclinic
C2/c
triclinic
ꢀ
P1
2
2
4
8
Reflections for cell
determination
2q Range for cell
determination [8]
Unit cell
32416
1806
2521
73098
18871
4–60
4–50
4–55
4–60
4–50
parameters: a [Š]
b [Š]
9.7018(2)
13.0899(3)
13.9694(2)
85.716(1)
83.236(1)
75.462(1)
1703.41(6)
1.216
9.9821(5)
9.4828(4)
10.7165(5)
90
107.853(2)
90
965.56(8)
1.205
0.0714
w
22.0889(5)
9.7500(2)
8.8389(2)
90
90
90
1903.61(7)
1.153
0.0682
f and w
55
12.3385(2)
5.9839(1)
23.8454(5)
90
91.564(1)
90
1759.91(6)
1.213
0.183
24.832(1)
5.1847(2)
21.2611(9)
90
109.014(3)
90
2587.9(2)
1.259
0.227
c [Š]
a [8]
b [8]
g [8]
V [Š3]
Dx [g cmÀ3
]
m(MoKa) [mmÀ1
Scan type
]
0.187
f and w
60
f and w
60
f and w
50
2q(max) [8]
50
Transmission factors
(min; max)
0.867; 0.982
–
–
0.884; 0.985
0.891; 0.996
Total reflections
measured
Symmetry independent 9964
reflections
46930
12782
1803
26913
2328
49425
5157
19009
2279
Reflections with I>2s(I) 7526
1634
1802
1915
2325
3741
5156
1623
2278
Reflections used in
refinement
9959
Parameters refined
Final R(F) [I>2s(I)
reflections]
424
0.0465
245
0.0448
228
0.0424
209
0.0496
155
0.0561
wR(F2) (all data)
Weighting parameters
(a; b)a):
0.1271
0.1178
0.1063
0.1261
0.1418
0.0582; 0.6749 0.0639; 0.2654 0.0552; 0.1724 0.0555; 0.6236 0.0577; 4.4843
Secondary extinction
coeff.
–
0.05(1)
0.026(4)
0.041(3)
0.013(1)
Goodness-of-fit
1.018
1.054
1.057
1.046
1.097
Final Dmax/s
D1 (max; min) [e Š
0.001
0.53; À0.32
0.001
0.28; À0.18
0.001
0.19; À0.15
0.001
0.31; À0.25
0.001
0.31; À0.25
À3
]
a) wÀ1 =s2(F 2o)+(aP)2 +bP where P=(F o2 +2F 2c )/3.

3054
Helvetica Chimica Acta – Vol. 89 (2006)
the crude product was purified by CC (hexane/AcOEt 2 :1): 364 mg (92%) of 40d. Yellowish crystals.
M.p. 130–1338. IR: 2933vs, 2853vs, 2752w, 1662w, 1574w, 1494m, 1441vs, 1363m, 1333s, 1322m, 1302m,
1262m, 1249m, 1222m, 1205m, 1157m, 1116s, 1097vs, 1072m, 1033m, 984vs, 967w, 904m, 867m, 766vs,
1
719m, 698vs. H-NMR: 7.33–7.22 (m, 3 arom. H); 7.13–7.07 (m, 2 arom. H); 5.56 (d, J=2.4, =CH);
5.45 (d, J=2.4, CH(3’)); 2.52–2.39 (m, 2 C HN); 1.79–1.38 (m, 8 C H). 13C-NMR: 153.0 (s, 1 arom.
2
2
C); 137.0 (s, C (4’)); 129.1, 128.0, 127.6, 127.2 (4d, 5 arom. CH, C(3’)); 79.9 (d, C (2’)); 66.4 (s, C (5’));
49.9 (br. t, 2 C HN); 39.3, 37.6 (2t, 2 C H); 25.7, 25.0, 24.8, 24.2, 23.9 (5t, 6 C H). EI-MS: 313 (35,
2
2
2
M+C), 280 (10, [MÀSÀ1]+), 229 (95, [MÀC5H10N]+), 199 (40), 99 (100), 98 (91), 81 (54), 69 (24), 55
(46), 43 (66).
9. X-RayCrystal-Structure Determination of 19, 33a, 33b, cis-40b, and 40c (Table and Figs. 1–3)10).
All measurements were performed on a Nonius KappaCCD diffractometer [25] using graphite-mono-
chromated MoKa radiation (l 0.71073 Š) and an Oxford Cryosystems Cryostream 700 cooler. The
data collection and refinement parameters are given in the Table, and views of the molecules are
shown in Figs. 1–3. Data reduction was performed with HKL Denzo and Scalepack [26]. The intensities
were corrected for Lorentz and polarization effects, and with the exceptions of 33a and 33b, absorption
corrections based on the multi-scan method [27] were applied. Equivalent reflections were merged. The
structures were solved by direct methods using SIR92 [28], which revealed the positions of all non-H-
atoms. In the case of 19, the asymmetric unit contains one molecule of the heterocyclic compound
plus two disordered sites for a H2O molecule, each of which is one quarter occupied, thus giving one
half of a H2O molecule in the asymmetric unit. For all structures, the non-H-atoms were refined aniso-
tropically. All of the H-atoms were placed in geometrically calculated positions and refined using a riding
model where each H-atom was assigned a fixed isotropic displacement parameter with a value equal to
1.2 Ueq of its parent C-atom (1.5 Ueq for the Me group in 33b). The refinement of each structure was car-
ried out on F2 using full-matrix least-squares procedures, which minimized the function Sw(Fo2 ÀF2c )2.
Corrections for secondary extinction were applied, except in the case of 19. For 19, 33a, 33b, cis-40b,
and 40c, 5, 1, 3, 1 and 1 reflections, resp., whose intensities were considered as extreme outliers, were
omitted from the final refinement. Compounds 33a and 33b crystallize in non-centrosymmetric space
groups. In each case, the absolute direction of the polar axis was chosen arbitrarily. Neutral-atom-scatter-
ing factors for non-H-atoms were taken from [29a], and the scattering factors for H-atoms were taken
from [30]. Anomalous dispersion effects were included in Fc [31]; the values for f ’ and f ’’ were those
of [29b]. The values of the mass attenuation coefficients are those of [29c]. All calculations were per-
formed using the SHELXL97 [32] program.
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CCDC-616929-616933 contain the supplementary crystallographic data for this publication. These
data can be obtained free of charge from the Cambridge Crystallographic Data Center via http://
www.ccdc.cam.ac.uk/data_request/cif.

Helvetica Chimica Acta – Vol. 89 (2006)
3055
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Received August 2, 2006