Intramolecular nonbonding interactions between selenium and sulfur - Spectroscopic evidence and importance in asymmetric synthesis

Article abstract of DOI:10.1002/ejoc.200600517

Chiral sulfur-containing electrophilic selenium reagents can be employed to effect efficient asymmetric syntheses. Spectroscopic and chemical evidence demonstrate that the observed high selectivity of the asymmetric reactions is associated with a nonbondi

Full text of DOI:10.1002/ejoc.200600517

FULL PAPER
DOI: 10.1002/ejoc.200600517
Intramolecular Nonbonding Interactions between Selenium and Sulfur –
Spectroscopic Evidence and Importance in Asymmetric Synthesis
Marcello Tiecco,*[a] Lorenzo Testaferri,[a] Claudio Santi,[a] Cristina Tomassini,[a]
Stefano Santoro,[a] Francesca Marini,[a] Luana Bagnoli,[a] Andrea Temperini,[a] and
Ferdinando Costantino[b]
Keywords: Asymmetric electrophilic additions / Chiral selenenylating reagents / Noncovalent interactions / Selenium /
Sulfur
Chiral sulfur-containing electrophilic selenium reagents can
ated with a nonbonding selenium–sulfur interaction that is
be employed to effect efficient asymmetric syntheses. Spec- present in both the crystalline form and in solution.
troscopic and chemical evidence demonstrate that the ob-
served high selectivity of the asymmetric reactions is associ-
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
formed by Tomoda and coworkers.[11] It was suggested by
them that these interactions will force the chiral center to
move closer to the reaction center, and that this will pro-
duce a better transfer of the chiral information during the
selenenylation reaction.
Recently, we have reported the synthesis of a new class
of enantiopure sulfur-containing diselenides and their use
as precursors to electrophilic reagents that are able to asym-
metrically add to olefins.[12] All of the reactions investigated
showed a very high facial selectivity that was higher than
those obtained with the corresponding nitrogen- or oxygen-
containing selenenylating reagents. It was suggested that
these excellent results were due to the fact that the sele-
nium–sulfur interaction is more efficient than the interac-
tions between selenium–oxygen or –nitrogen.
Introduction
Weak interactions play a crucial role in chemistry and
biochemistry and are often responsible for several impor-
tant properties of organic molecules.[1–3] Special attention
has been recently devoted to the intramolecular and inter-
molecular attractive interactions that exist between di- and
tetracoordinate sulfur, selenium, and tellurium atoms from
one side, and oxygen and nitrogen atoms from the other
side.[4–6] It has been observed that divalent selenium can
interact with a nearby heteroatom (O, N, etc.) to form a
pseudo high-valent selenium species.[4,7] Recent studies on
intramolecular stabilized organoselenium compounds
showed that Se–N and Se–O interactions play an important
role not only in the catalytic antioxidant activity of these
compounds but also in their use as reagents in synthetic
organic chemistry.[8]
In recent years, chiral nonracemic electrophilic selenenyl-
ating reagents have been extensively employed by us as well
as by other research groups for their efficiency in the pro-
motion of asymmetric additions to alkenes and also for
their use in cyclofunctionalization reactions.[9] A common
characteristic of all these reagents is the close proximity of
the selenium atom to an oxygen or nitrogen heteroatom that
is linked to a chiral carbon atom. From the results of exper-
imental and theoretical investigations, Wirth and coworkers
demonstrated that in these cases a nonbonding interaction
between the selenium and the heteroatom takes place.[10]
Detailed investigations on the nonbonding interactions of
divalent organic selenium with heteroatoms were also per-
In order to have unambiguous experimental evidence for
the existence of this Se–S interaction, we have now carried
out X-ray analysis of selenenylating reagents 2 and 3, which
are shown in Scheme 1. The NMR properties of reagents
2–4 and their efficiency in promoting asymmetric syntheses
have also been investigated (Scheme 1).
[a] Dipartimento di Chimica e Tecnologia del Farmaco, Sezione di
Chimica Organica, Università di Perugia,
06123 Perugia, Italy
[b] Dipartimento di Chimica, Università di Perugia,
06123 Perugia, Italy
Scheme 1. Synthesis of arylselenenyl halides.
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 4867
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M. Tiecco et al.
FULL PAPER
Results and Discussion
Selenenyl derivatives 2–4 were obtained from the reaction
of diselenide 1[13] with the reagents indicated in Scheme 1
in diethyl ether. All compounds were obtained in almost
quantitative yields, and derivatives 2 and 3 were crystallized
from diethyl ether as red and yellow solids, respectively.
They are stable at room temperature for several days, and
compound 3 can even be purified by chromatography on a
silica gel column with dichloromethane as the eluent. Io-
dide 4 was obtained as an oil. With respect to other se-
lenenyl iodides, most of which are rapidly oxidized to the
corresponding diselenides, compound 4 can be safely stored
in the refrigerator for several days. It can be suggested that
this stability is due to the formation of a five-membered
chelate which arises from the Se–S interaction.
Figure 2. ORTEP drawing and labeling scheme for 3. Se–S interac-
tion is shown as a dashed line. Ellipsoids are set at 50% probability.
Table 1. Selected bond lengths and angles for compound 2.
From compounds 2 and 3 crystals suitable for X-ray
analysis were obtained. The ORTEP views of compounds 2
and 3 are shown in Figures 1[14] and 2,[15] respectively. Se-
lected bond lengths and bond angles are listed in Tables 1
and 2. Compounds 2 and 3 are isostructural; the coordina-
tion geometry around the selenium atom is T-shaped with
a bond angle of 178.86(5)° for 2 and 177.74(4)° for 3. The
distance between Se1 and S1 [2.497(7) Å for 2 and
2.344(2) Å for 3] is significantly shorter than the sum of the
van der Waals radii (3.7 Å),[16] and this demonstrates that
an intramolecular interaction between selenium and sulfur
exists. The shorter distance observed in compound 3 com-
pared with that of compound 2 seems to indicate a stronger
interaction when the counterion is chlorine, and this obser-
vation is consistent with the calculated covalency factor χ
for bromide (0.826) and chloride (0.902) derivatives.[17]
Bond
Distance [Å]
Angle
Amplitude [°]
Se1–S1
Se1–Br1
Se1–C1
2.497(7)
2.587(2)
1.880(5)
C1–Se1–Br1
C1–Se1–S1
S1–Se1–Br1
98.0(2)
81.6(2)
178.8(6)
Table 2. Selected bond lengths and angles for compound 3.
Bond
Distance [Å]
Angle
Amplitude [°]
Se1–S1
Se1–Cl2
Se1–C8
2.344(2)
2.312(1)
1.929(3)
C8–Se1–Cl2
C8–Se1–S1
Cl2–Se1–S1
92.62(9)
85.32(9)
177.74(4)
This is very likely due to the interaction between the sele-
nium and sulfur atoms, which is not only present in the
crystal form, but also present in CDCl3 solutions as well.
Scheme 2. Main Overhauser correlations for compounds 3 and 5.
The presence of intramolecular interactions in these
compounds can also be deduced from other NMR spectro-
Figure 1. ORTEP drawing and labeling scheme for 2. Se–S interac-
tion is shown as a dashed line. Ellipsoids are set at 50% probability.
1
scopic data.[3,8b,c] Some selected H- and 13C NMR chemi-
cal shift values (δH, δC) that were measured for compounds
These selenenylating agents were then analyzed in solu- 2, 3, and 4 are listed in Table 3. It can be seen that the
tion by the acquisition of their proton, carbon and selenium chemical shifts for the methyl and the methine protons and
NMR spectra in CDCl3. In a first experiment, the Over- carbons depend on the electronegativity of the halogen at-
hauser dipolar correlations for arylselenenyl chloride 3 were tached to the selenium atom. In agreement with previous
measured and compared with those obtained for corre- observations in other arylselenenyl halides,[3,8b,c] the trend
sponding arylmethyl selenide 5. From the results indicated in the chemical shift values is RSeCl Ͼ RSeBr Ͼ RSeI, and
in Scheme 2, it can be deduced that compound 3 presents this suggests that the strongest Se–S interaction occurs in
a greater conformational rigidity than that observed in 5. the case of chloride 3.
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Intramolecular Nonbonding Interactions between Selenium and Sulfur
FULL PAPER
1
Table 3. Selected H-, 13C- and 77Se NMR δ values for 2, 3, and 4 and 797 ppm for compound 3). This observation is in agree-
in CDCl3.
ment with the trend observed by Tomoda in the case of Se–
O interaction.[3]
Compound δH SCH3 δC SCH3 δH CHS δC CHS
δSe
Finally, the efficiency of arylselenenyl halides 2, 3, and 4
in the promotion of the asymmetric inter- and intramolecu-
lar addition to alkenes was explored. For this purpose, some
selected hydroxy-, methoxy- and azidoselenenylation reac-
tions, as well as selenoetherification and selenolactonization
reactions were effected from alkenes 10a–e. The stereoselec-
tivity of the reactions of 8 and 9 was also examined. The
results of these experiments are collected in Table 4. All of
the reactions were carried out with a stoichiometric amount
of the selenenylating agent at the temperature indicated in
Table 4. Complete regioselectivity was observed in every
case and only two diastereomers, each of which is consti-
tuted by a single enantiomer, were obtained. Excellent levels
of diastereoselectivities were obtained in every case. These
diastereoselectivities were very similar to those obtained
from the same reactions carried out with the selenenyl trifl-
ate that is produced in situ from diselenide 1.[13,12a] In the
methoxyselenenylation of styrene carried out with reagents
8 and 9 (Entry b), no diastereoselectivity was observed; the
two racemic diastereomers were obtained in equal amounts.
This result confirms the importance of the presence of the
sulfur heteroatom in the chiral moiety and of its interaction
with the electrophilic selenium atom in directing selective
attack at the double bond.
Bromide 2
Chloride 3
Iodide 4
2.06
2.27
1.90
18.2
18.5
16.3
4.27
4.33
4.16
53.4
54.1
50.8
750.6
797.3
557
Further evidence came from the analysis of the 77Se
NMR spectra. In order to evaluate the influence of the Se–
S interaction on the 77Se NMR chemical shift values, ortho
alkyl-substituted diselenide
7 and the corresponding
halogenated derivatives 8 and 9, in which the sulfur was
replaced by a carbon atom, were prepared from bromide
6[18] according to the synthetic sequence indicated in
Scheme 3.
Scheme 3. Synthesis of diselenide 7 and halo derivatives 8 and 9.
Steric hindrance results in an upfield shift of the 77Se
NMR signals of bromide 8 (δ =832 ppm) and chloride 9
The diastereomeric ratios were determined from the
1
(1004 ppm) with respect to unsubstituted PhSeBr (δ analysis of the H NMR spectra of the crude reaction mix-
=867 ppm) and PhSeCl (1044 ppm). This upfield shift is a tures and were then confirmed after the product was puri-
result of the Se–S interaction (δ =750 ppm for compound 2 fied by column chromatography. The absolute configura-
Table 4. Asymmetric addition reactions promoted by the electrophilic reagents 2, 3, 4, 8, and 9.
Eur. J. Org. Chem. 2006, 4867–4873
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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4869

M. Tiecco et al.
FULL PAPER
(20 mL), a stoichiometric amount of I2 (0.1  solution in CCl4) was
added at 0 °C. The reaction mixture was stirred for 30 min. The
resulting solution was evaporated to afford 4 as a red oil. Yield
tions reported in Table 4 refer to the major diastereomer
and were assigned on the basis of a comparison with the
data reported in the literature.[19]
In conclusion, we have reported convincing experimental
evidence for the presence of an intramolecular selenium–
sulfur interaction in arylselenenyl halides, and we have
demonstrated the crucial role of this interaction in the at-
tainment of excellent levels of facial selectivity in several
selenium addition reactions.
1
571 mg, 80%. H NMR (400 MHz, CDCl3/TMS, 25 °C): δ = 8.15
3
(d, JH,H = 7.6 Hz, 1 H, CHAr), 7.30–7.20 (m, 2 H, 2CHAr), 7.07
3
3
(d, JH,H = 6.5 Hz, 1 H, CHAr), 4.16 (q, JH,H = 7.0 Hz, 1 H,
3
CHS), 2.06 (s, 3 H, SCH3), 1.75 (d, JH,H = 7.0 Hz, 3 H, CH3)
ppm. 13C NMR (100.62 MHz, CDCl3/TMS, 25 °C): δ = 143.0
(Cipso), 139.3 (CHAr), 130.4 (Cipso), 129.4 (CHAr), 127.9 (CHAr),
127.6 (CHAr), 50.8 (CHS), 18.7 (CH3), 16.3 (SCH3) ppm. 77Se
NMR (76.27 MHz, CDCl3/TMS, 25 °C): δ = 557 ppm.
Synthesis of 2-{[(1S)-1-Methylthio]-ethyl}phenylmethyl Selenide (5):
To a solution of diselenide 1 (0.460 g, 1 mmol) in diethyl ether
(25 mL), LiAlH4 (1  solution in hexane, 0.5 mL, 0.5 mmol) was
added at 0 °C. After 15 min, methyl iodide (0.9 mL, 1.5 mmol) was
added, and the mixture was stirred for 2 h at room temperature.
After the usual workup, the organic layers were dried (Na2SO4)
and the solvents evaporated under vacuum. The crude product was
purified by column chromatography on silica gel with a mixture of
diethyl ether and light petroleum ether (50:50) as the eluent to af-
ford 5 as an oil. Yield 392 mg, 80%. [α]3D0.0 = –1.20 (C = 0.725,
CHCl3). 1H NMR (400 MHz, CDCl3/TMS, 25 °C): δ = 7.55 (dd,
Experimental Section
General: All new compounds were fully characterized by H-, 13C-,
1
and 77Se NMR, mass spectra and elemental analyses. 1H-, 13C-,
and 77Se NMR spectra were recorded with a Bruker Avance-DRX
400 instrument. GC–MS analyses were carried out with an HP-
6890 gas chromatograph (dimethyl silicone column, 12.5 m)
equipped with an HP-5973 mass-selective detector. Optical rota-
tions were measured with a JASCO DIP-1000 digital polarimeter.
Elemental analyses were carried out with a Carlo Erba 1106 ele-
mental analyzer. Melting points were determined with a capillary
melting point apparatus and are uncorrected. Unless otherwise
indicated, all the starting materials are commercially available.
Physical and spectroscopic data for all of the new compounds are
reported below.
3
4
4JH,H = 1.7 Hz, JH,H = 7.5 Hz, 1 H, CHAr), 7.48 (dd, JH,H
=
3
4
1.6 Hz, JH,H = 7.4 Hz, 1 H, CHAr), 7.31 (ddd, JH,H = 1.6 Hz,
3JH,H = 7.3 Hz, JH,H = 7.5 Hz, 1 H, CHAr), 7.23 (ddd, JH,H
=
3
4
1.7 Hz, 3JH,H = 7.3 Hz, 3JH,H = 7.4 Hz, 1 H, CHAr), 4.50 (q, 3JH,H
= 7.0 Hz, 1 H, CHS), 2.39 (s, 3 H, SeCH3), 2.03 (s, 3 H, SCH3),
Synthesis of 2-{[(1S)-1-Methylthio]-ethyl}phenylselenenyl Bromide
(2): To a solution of diselenide 1 (0.460 g, 1 mmol) in diethyl ether
(20 mL), a stoichiometric amount of a Br2 (1  solution in CCl4)
was added at 0 °C. The reaction mixture was stirred for 30 min and
then evaporated under vacuum to afford a deep red solid. Com-
pound 2 was purified by crystallization from diethyl ether. Yield
3
1.65 (d, JH,H = 7.0, 3 H, CH3) ppm. 13C NMR (100.62 MHz,
CDCl3/TMS, 25 °C): δ = 144.1 (Cipso), 133.0 (Cipso), 130.9 (CHAr),
128.1 (CHAr), 127.3 (CHAr), 127.1 (CHAr), 44.1 (CHS), 22.0
(CH3), 14.6 (SCH3), 8.3 (SeCH3) ppm. 77Se NMR (76.27 MHz,
CDCl3/TMS, 25 °C): δ = 156.7 ppm. MS (70 eV, EI): m/z (%) =
246 (49) [M]+, 244 (25), 231 (88) [M – CH3]+, 216 (5), 199 (42)
[M – CH3]+, 183 (100) [C8H7Se]+, 104 (72), 91 (19), 77 (22), 51 (7).
558 mg, 90%. M.p. 114–116 °C. [α]1D3.7 = +237.0 (C = 0.1, CHCl3).
1H NMR (400 MHz, CDCl3/TMS, 25 °C): δ = 8.31 (d, JH,H
=
=
3
3
Synthesis of 2-(2-sec-Butyl)phenyl Diselenide (7): To a solution of 6
(1 mmol) in freshly distilled THF, tBuLi (1.7  solution in pentane,
1.5 mmol) was added at –78 °C. After 3 h, the temperature was
raised to 0 °C, and the mixture was stirred for an additional 30 min.
Elemental selenium was added (1.5 mmol), and the reaction mix-
ture was stirred for 3 h at room temperature. The resulting solution
was poured into HCl (7%) and was stirred overnight at room tem-
perature. After filtration, the aqueous layer was extracted twice
with ether, and the combined organic layers were dried with
Na2SO4 and the solvents evaporated under vacuum to afford a
crude product which was purified by flash chromatography on a
silica gel column with light petroleum ether as the eluent. Diselen-
ide 7 was obtained as an oil and as an equimolecular mixture of
syn and anti diastereomers which could not be separated. Yield
170 mg, 80%. MS (70 eV, EI): m/z (%) = 426 (100) [M]+, 424 (92),
345 (6), 212 (57), 197 (36), 183 (46), 157 (25), 155 (12), 132 (18),
117 (31), 91 (47), 77 (14), 55 (15).
7.3 Hz, 1 H, CHAr), 7.30–7.20 (m, 2 H, 2CHAr), 7.12 (d, JH,H
3
7.0 Hz, 1 H, CHAr), 4.27 (q, JH,H = 7.1 Hz, 1 H, CHS), 2.27 (s,
3
3 H, SCH3), 1.75 (d, JH,H = 7.1 Hz, 3 H, CH3) ppm. 13C NMR
(100.62 MHz, CDCl3/TMS, 25 °C): δ = 141.2 (Cipso), 134.8 (CHAr),
133.6 (Cipso), 129.6 (CHAr), 127.6 (CHAr), 127.3 (CHAr), 53.8
(CHS), 18.9 (CH3), 18.4 (SCH3) ppm. 77Se NMR (76.27 MHz,
CDCl3/TMS, 25 °C): δ = 750.6 ppm. C9H11SeBr (310.11): calcd. C
34.87, H 3.58; found C 34.33, H 3.22.
Synthesis of 2-{[(1S)-1-Methylthio]-ethyl}phenylselenenyl Chloride
(3): To a solution of diselenide 1 (0.460 g, 1 mmol) in diethyl ether
(20 mL), a stoichiometric amount of SO2Cl2 (0.135 g, 1 mmol) was
added at 0 °C. The reaction mixture was stirred for 30 min and then
evaporated under vacuum to afford an orange solid from which
compound 3 was obtained after crystallization from diethyl ether.
Yield 478 mg, 90%. M.p. 140–143 °C. [α]2D2.1 = +250.0 (C = 0.2,
CHCl3). 1H NMR (400 MHz, CDCl3/TMS, 25 °C): δ = 8.32 (dd,
3
4
4JH,H = 1.1 Hz, JH,H = 8.1 Hz, 1 H, CHAr), 7.33 (ddd, JH,H
=
1.4 Hz, 3JH,H = 7.5 Hz, 3JH,H = 8.1 Hz, 1 H, CHAr), 7.24 (dt, 4JH,H
Synthesis of 2-(2-sec-Butyl)phenylselenenyl Bromide (8) and 2-(2-
sec-Butyl)phenylselenenyl Chloride (9): Compounds 8 and 9 were
synthesized from 7 with the same procedure employed for 2 and 3.
3
4
= 1.1 Hz, JH,H = 7.5 Hz, 1 H, CHAr), 7.16 (dd, JH,H = 1.4 Hz,
3JH,H = 7.5 Hz, 1 H, CHAr), 4.33 (q, JH,H = 7.1 Hz, 1 H, CHS),
3
2.35 (s, 3 H, SCH3), 1.75 (d, JH,H = 7.1 Hz, 3 H, CH3) ppm. 13C
3
1
8: Oil. Yield 80%. H NMR (400 MHz, CDCl3/TMS, 25 °C): δ =
NMR (100.62 MHz, CDCl3/TMS, 25 °C): δ = 140.6 (Cipso), 135.6
(Cipso), 132.5 (CHAr), 129.4 (CHAr), 127.4 (CHAr), 127.2 (CHAr),
54.1 (CHS), 19.0 (CH3), 18.5 (SCH3) ppm. 77Se NMR (76.27 MHz,
CDCl3/TMS, 25 °C): δ = 797.3 ppm. C9H11SeCl (265.66): calcd. C
40.70, H 4.17; found C 41.15, H 4.29.
4
3
7.92 (dd, JH,H = 1.5 Hz, JH,H = 7.8 Hz, 1 H, CHAr), 7.43 (dt,
4JH,H = 1.5 Hz, JH,H = 7.3 Hz, 1 H, CHAr), 7.20 (ddd, JH,H
=
3
4
3
3
1.5 Hz, JH,H = 7.3 Hz, JH,H = 7.8 Hz, 1 H, CHAr), 3.39 (sext,
3JH,H = 7.0 Hz, 1 H, CH), 1.67 (dq, 3JH,H = 7.0 Hz, 3JH,H = 7.5 Hz,
3
3
2 H, CH2), 1.29 (d, JH,H = 7.0 Hz, 3 H, CH3), 0.88 (t, JH,H
=
Synthesis of 2-{[(1S)-1-Methylthio]-ethyl}phenylselenenyl Iodide (4):
To a solution of diselenide 1 (0.460 g, 1 mmol) in diethyl ether
7.5 Hz, 3 H, CH3) ppm. 13C NMR (100.62 MHz, CDCl3/TMS,
25 °C): δ = 151.0 (Cipso), 137.1 (CHAr), 131.5 (CHAr), 130.3 (Cipso),
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Intramolecular Nonbonding Interactions between Selenium and Sulfur
FULL PAPER
126.9 (CHAr), 126.5 (CHAr), 40.8 (CH), 31.1 (CH2), 22.0 (CH3), CHHSe), 3.10 (dd, 3JH,H = 4.9 Hz, 2JH,H = 12.1 Hz, 1 H, CHHSe),
3
12.2 (CH3) ppm. 77Se NMR (76.27 MHz, CDCl3/TMS, 25 °C): δ =
832.5 ppm.
3.26 (s, 3 H, OCH3), 1.95 (s, 3 H, SCH3), 1.57 (d, JH,H = 7.0 Hz,
3 H, CH3) ppm. 13C NMR (100.62 MHz, CDCl3/TMS, 25 °C): δ
= 144.9 (Cipso), 140.8 (Cipso), 133.3 (CHAr), 131.5 (Cipso), 128.5
(2CHAr), 128.0 (CHAr), 127.4 (CHAr), 127.3 (CHAr), 126.8
(CHAr), 126.5 (2CHAr), 82.9 (CHOCH3), 56.9 (OCH3), 43.8
(CHS), 35.8 (CH2Se), 21.4 (CH3), 14.0 (SCH3) ppm. MS (70 eV,
EI): m/z (%) = 366 (23) [M]+, 364 (12), 231 (79), 183 (100)
[ArSe]+, 135 (28), 121 (67), 103 (27), 91 (31), 77 (22), 61 (6), 51 (4).
1
9: Oil. Yield 80%. H NMR (400 MHz, CDCl3/TMS, 25 °C): δ =
3
3
8.23 (d, JH,H = 7.8 Hz, 1 H, CHAr), 7.61 (t, JH,H = 7.6 Hz, 1 H,
CHAr), 7.53 (ddd, 4JH,H = 1.2 Hz, 3JH,H = 7.6 Hz, JH,H = 7.8 Hz,
3
1 H, CHAr), 7.42 (dd, 4JH,H = 1.2 Hz, 3JH,H = 7.6 Hz, 1 H, CHAr),
3
2.94 (sext, JH,H = 6.7 Hz, 1 H, CH), 1.80–1.70 (m, 2 H), 1.36 (d,
3JH,H = 6.7 Hz, 3 H, CH3), 0.89 (t, 3JH,H = 7.4 Hz, 3 H, CH3) ppm.
13C NMR (100.62 MHz, CDCl3/TMS, 25 °C): δ = 147.7 (Cipso),
146.5 (Cipso), 134.2 (CHAr), 128.4 (CHAr), 127.5 (CHAr), 124.5
(CHAr), 39.7 (CH), 31.4 (CH2), 22.3 (CH3), 12.7 (CH3) ppm. 77Se
NMR (76.27 MHz, CDCl3/TMS, 25 °C): δ = 1004.1 ppm.
Azidoselenenylation of Styrene: To a solution of reagent 2 (1 mmol)
in CH3CN·NaN3 (1 mmol) was added at –30 °C. The reaction mix-
ture was stirred for 30 min, and styrene (1.0 mmol) was then added.
The reaction was warmed to room temperature, and the reaction
was then stirred for 3 d. The progress of the reaction was monitored
by 1H NMR and TLC. After the usual workup, the mixture was
filtered through anhydrous K2CO3, and the solvents were evapo-
rated under vacuum. The products were separated by flash
chromatography on a silica gel column with a mixture of diethyl
ether and light petroleum ether (1:9) as the eluent. The yield and
the diastereomeric ratio are reported in Table 4.
Hydroxyselenenylation of Styrene: To a solution of chiral electro-
philic selenenylating reagents 2, 3, or 4 (1 mmol) in CH3CN, sty-
rene (1 mmol) dissolved in a mixture of CH3CN/H2O (2:1) was
added at –30 °C. The resulting solution was stirred for 3 d. The
progress of the reaction was monitored by GC–MS and TLC. The
reaction mixture was then poured into a solution of NaHCO3
(10%) and extracted with CH2Cl2. The combined organic layers
were washed with brine, dried with Na2SO4, filtered, and the sol-
vents evaporated under vacuum. The products were purified by
flash chromatography on a silica gel column with a mixture of di-
ethyl ether and light petroleum ether (1:9) as the eluent. The reac-
tion yields and the diastereomeric ratios (dr) are reported in
Table 4.
1-{[(2R)-2-Azido-2-phenylethyl}selenenyl]-2-[(1S)-1-(methylthio)-
ethyl]benzene (11c): Oil. 1H NMR (400 MHz, CDCl3/TMS, 25 °C):
δ = 7.51 (dd, JH,H = 1.4 Hz, JH,H = 7.6 Hz, 1 H, CHAr), 7.52
4
3
4
3
4
(dd, JH,H = 1.2 Hz, JH,H = 7.7 Hz, 1 H, CHAr), 7.38 (dt, JH,H
3
4
= 1.2 Hz, JH,H = 7.6 Hz, 1 H, CHAr), 7.19 (dt, JH,H = 1.4 Hz,
3JH,H = 7.7 Hz, 1 H, CHAr), 4.57 (q, JH,H = 7.0 Hz, 1 H, CHS),
3
3
3
3
4.38 (ddd, JH,H = 4.4 Hz, JH,H = 6.5 Hz, JH,H = 7.8 Hz, 1 H,
(1R)-2-{2-[(1S)-1-(Methylthio)ethyl]phenylseleneny}-1-phenylethanol
(11a): Major isomer: Oil. 1H NMR (400 MHz, CDCl3/TMS,
3
3
3
CHO), 3.60 (ddd, JH,H = 6.5 Hz, JH,H = 8.0 Hz, JH,H = 8.4 Hz,
3
2
4
3
1 H, CHSe), 3.30 (dd, JH,H = 8.4 Hz, JH,H = 16.1 Hz, 1 H,
25 °C): δ = 7.61 (dd, JH,H = 1.5 Hz, JH,H = 7.5 Hz, 1 H, CHAr),
3
3
4
3
CHHCO), 2.62 (dd, JH,H = 8.0 Hz, JH,H = 16.1 Hz, 1 H,
CHHCO), 1.99 (s, 3 H, SCH3), 1.60 (d, 3JH,H = 7.0 Hz, 3 H, CH3),
1.80–1.70 (m, 1 H, CHHCH3), 1.65–1.60 (m, 1 H, CHHCH3), 0,96
7.50 (dd, JH,H = 1.7 Hz, JH,H = 7.8 Hz, 1 H, CHAr), 7.38 (m, 6
4
3
H, 6CHAr), 7.21 (dt, JH,H = 1.7 Hz, JH,H = 7.8 Hz, 1 H, CHAr),
3
3
4.76 (dd, JH,H = 3.5 Hz, JH,H = 9.6 Hz, 1 H, CHOH), 4.55 (q,
(t, JH,H = 7.4 Hz, 3 H, CH3) ppm. 13C NMR (100.62 MHz,
3
3JH,H = 7.0 Hz, 1 H, CHS), 3.38 (dd, JH,H = 3.5 Hz, JH,H
=
3
2
3
2
CDCl3/TMS, 25 °C): δ = 148.5 (Cipso), 142.1, 133.8, 131.2, 129.9,
12.6 Hz, 1 H, CHHSe), 3.10 (dd, JH,H = 9.6 Hz, JH,H = 12.6 Hz,
1 H, CHHSe), 3.00 (s, 1 H, OH), 2.02 (s, 3 H, SCH3), 1.65 (d,
3JH,H = 7.0 Hz, 3 H, CH3) ppm. 13C NMR (100.62 MHz, CDCl3/
TMS, 25 °C): δ = 150.9 (Cipso), 145.1 (Cipso), 134.0 (CHAr), 130.2
(Cipso), 128.5 (2CHAr), 127.9 (CHAr), 127.8 (CHAr), 127.6
(CHAr), 127.1 (CHAr), 125.7 (2CHAr), 72.5 (CHOH), 44.1 (CHS),
38.9 (CH2Se), 21.3 (CH3), 14.0 (SCH3) ppm. MS (70 eV, EI): m/z
(%) = 352 (10) [M]+, 231 (59), 229 (30), 185 (21), 183 (100), 181
127.9, 127.7, 127.6, 127.3, 124.6, 69.9 (CHN3), 47.7 (CHS), 31.2
(CH Se), 22.4 (CH ), 14.5 (SCH ) ppm. IR (neat): ν = 2090 cm–1
˜
2
3
3
(N3).
General Procedure for the Cyclofunctionalization Reactions: To a
solution of chiral electrophilic selenenylating reagent 2, 3, or 4
(1 mmol) in CH2Cl2, alkene 10d or 10e (1 mmol) dissolved in
CH2Cl2 and NaHCO3 (2 mmol) were added at room temperature.
The reaction mixture was stirred for 3 d. The progress of the reac-
tion was monitored by GC–MS and TLC. The reaction mixture
was then poured into a solution of NaHCO3 (10%) and extracted
with CH2Cl2. The combined organic layers were washed with brine,
dried with Na2SO4, filtered, and the solvents evaporated. The prod-
ucts were purified by flash chromatography on a silica gel column
with a mixture of diethyl ether and light petroleum ether (7:93) as
the eluent. The yields and the diastereomeric ratios are reported in
Table 4.
(52), 103 (20), 91 (25), 77 (24). IR (neat): ν = 3200 (OH) cm–1.
˜
Methoxyselenenylation of Styrene: To a solution of chiral electro-
philic selenenylating reagents 2, 3, 4, 8, or 9 (1 mmol) in CH2Cl2,
styrene (1 mmol) dissolved in MeOH was added at –30 °C. The
resulting solution was stirred for 3 d. The progress of the reaction
was monitored by GC–MS and TLC. The reaction mixture was
then poured into a solution of NaHCO3 (10%) and extracted with
CH2Cl2. The combined organic layers were washed with brine,
dried with Na2SO4, filtered, and evaporated in vacuo. The products
were separated by flash chromatography on a silica gel column with
a mixture of diethyl ether and light petroleum ether (7:93) as the
eluent. The reaction yields and the diastereomeric ratios are re-
ported in Table 4.
(4R,5S)-5-Ethyl-4-{2-[(1S)-1-(methylthio)ethyl]phenylselenenyl}-
dihydrofuran-2(3H)-one (11d): Oil. H NMR (400 MHz, CDCl3/
1
4
3
TMS, 25 °C): δ = 7.57 (dd, JH,H = 1.4 Hz, JH,H = 7.6 Hz, 1 H,
CHAr), 7.52 (dd, 4JH,H = 1.2 Hz, 3JH,H = 7.7 Hz, 1 H, CHAr), 7.38
3
4
1-{[(2R)-2-Methoxy-2-phenylethyl]selenenyl}-2-[(1S)-1-(methylthio)-
ethyl]benzene (11b): Oil. 1H NMR (400 MHz, CDCl3/TMS, 25 °C):
(dt, 4JH,H = 1.2 Hz, JH,H = 7.6 Hz, 1 H, CHAr), 7.19 (dt, JH,H
=
3
3
1.4 Hz, JH,H = 7.7 Hz, 1 H, CHAr), 4.57 (q, JH,H = 7.0 Hz, 1 H,
4
3
3
3
3
δ = 7.51 (dd, JH,H = 1.3 Hz, JH,H = 7.6 Hz, 1 H, CHAr), 7.48 CHS), 4.38 (ddd, JH,H = 4.4 Hz, JH,H = 6.5 Hz, JH,H = 7.8 Hz,
4
3
3
3
3
(dd, JH,H = 1.5 Hz, JH,H = 7.8 Hz, 1 H, CHAr), 7.40–7.30 (m, 5
1 H, CHO), 3.60 (ddd, JH,H = 6.5 Hz, JH,H = 8.0 Hz, JH,H =
H, 5CHAr), 7.26 (dt, JH,H = 1.3 Hz, JH,H = 7.8 Hz, 1 H, CHAr), 8.4 Hz, 1 H, CHSe), 3.30 (dd, JH,H = 8.4 Hz, JH,H = 16.1 Hz, 1
4
3
3
2
7.12 (dt, 4JH,H = 1.5 Hz, 3JH,H = 7.6 Hz, 1 H, CHAr), 4.58 (q, 3JH,H
H, CHHCO), 2.62 (dd, JH,H = 8.0 Hz, JH,H = 16.1 Hz, 1 H,
CHHCO), 1.99 (s, 3 H, SCH3), 1.60 (d, 3JH,H = 7.0 Hz, 3 H, CH3),
1.80-1.70 (m, 1 H, CHHCH3), 1.65–1.60 (m, 1 H, CHHCH3), 0.96
3
3
3
3
= 7.0 Hz, 1 H, CHS), 4.35 (dd, JH,H = 4.9 Hz, JH,H = 8.7 Hz, 1
3
2
H, CHOCH3), 3.30 (dd, JH,H = 8.7 Hz, JH,H = 12.1 Hz, 1 H,
Eur. J. Org. Chem. 2006, 4867–4873
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4871

M. Tiecco et al.
FULL PAPER
(t, JH,H = 7.4 Hz, 3 H, CH3) ppm. 13C NMR (100.62 MHz,
CDCl3/TMS, 25 °C): δ = 174.6 (CO), 146.5 (Cipso), 136.3 (Cipso),
130.3 (CHAr), 129.3 (CHAr), 127.7 (CHAr), 127.4 (CHAr), 87.3
(CHO), 44.0 (CHS), 39.1 (CHSe), 36.3 (CH2), 27.0 (CH2), 21.2
(CH3), 13.9 (SCH3), 9.6 (CH3) ppm. MS (70 eV, EI): m/z (%) = 344
(1) [M]+, 232 (13), 230 (58), 229 (25), 185 (20), 183 (100) [ArSe]+,
180 (22), 104 (12), 91 (10).
3
du Mont, S. Pohl, W. Saak, Angew. Chem. Int. Ed. 1988, 27,
431; f) W.-W. du Mont, A. Martens, S. Pohl, W. Saak, Inorg.
Chem. 1990, 29, 4847.
a) F. T. Burling, B. M. Goldstein, J. Am. Chem. Soc. 1992, 114,
2313; b) M. Iwaoka, S. Tomoda, Phosphorus Sulfur Silicon Re-
lat. Elem. 1992, 67, 125; c) M. Iwaoka, S. Tomoda, J. Org.
Chem. 1995, 60, 5299.
a) M. Iwaoka, H. Komatsu, T. Katsuda, S. Tomoda, J. Am.
Chem. Soc. 2004, 126, 5309; b) G. Mugesh, A. Panda, H. B.
Singh, R. J. Butcher, Chem. Eur. J. 1999, 5, 1411; c) M. Iwaoka,
S. Tomoda, J. Am. Chem. Soc. 1996, 118, 8077.
a) M. Tiecco, “Electrophilic Selenium, Selenocyclizations” in
Topics in Current Chemistry: Organoselenium Chemistry – Mod-
ern Developments in Organic Synthesis (Eds.: T. Wirth),
Springer-Verlag, Heidelberg, 2000, pp. 7–54; b) T. G. Back
(Ed.), Organoselenium Chemistry – A Practical Approach, Ox-
ford, New York, 2000; c) T. Wirth, Angew. Chem. Int. Ed. 2000,
39, 3742; d) M. Tiecco, L. Testaferri, C. Santi, C. Tomassini,
F. Marini, L. Bagnoli, A. Temperini, Tetrahedron: Asymmetry
2000, 11, 4645; e) M. Tiecco, L. Testaferri, F. Marini, S. Ster-
nativo, A. Temperini, L. Bagnoli, C. Santi, Tetrahedron: Asym-
metry 2001, 12, 1493; f) M. Tiecco, L. Testaferri, C. Santi, C.
Tomassini, F. Marini, L. Bagnoli, A. Temperini, Eur. J. Org.
Chem. 2000, 3451.
a) T. Wirth, G. Fragale, M. Spichty, J. Am. Chem. Soc. 1998,
120, 3376; b) X. Wang, K. N. Houk, M. Spichty, T. Wirth, J.
Am. Chem. Soc. 1999, 121, 8567; c) M. Spichty, G. Fragale, T.
Wirth, J. Am. Chem. Soc. 2000, 122, 10914.
a) M. Iwaoka, H. Komatsu, T. Kotsuda, S. Tomoda, J. Am.
Chem. Soc. 2002, 124, 1902; b) M. Iwaoka, T. Kotsuda, H.
Komatsu, S. Tomoda, J. Org. Chem. 2005, 70, 321; c) M.
Iwaoka, S. Tomoda, Phosphorous, Sulfur Silicon Relat. Elem.
2005, 180, 755.
[7]
[8]
[9]
(2S,3R)-3-{2-[(1S)-1-(Methylthio)ethyl]phenylselenenyl}-2-phenyl-
tetrahydrofuran (11e): Oil. 1H NMR (400 MHz, CDCl3/TMS,
4
3
25 °C): δ = 7.49 (dd, JH,H = 1.3 Hz, JH,H = 7.8 Hz, 1 H, CHAr),
3
3
7.48 (dd, JH,H = 1.3 Hz, JH,H = 7.7 Hz, 1 H, CHAr), 7.33-7.25
4
3
(m, 6 H, 6CHAr), 7.08 (dt, JH,H = 1.5 Hz, JH,H = 7.7 Hz, 1 H,
3
3
CHAr), 4.87 (d, JH,H = 6.0 Hz, 1 H, PhCHO), 4.58 (q, JH,H
=
=
=
3
2
7.0 Hz, 1 H, CHS), 4.20 (dt, JH,H = 4.9 Hz, JH,H
8.2 Hz, 1 H, CHHO), 4.15 (dt, JH,H = 7.4 Hz, JH,H
=
=
3JH,H
3JH,H
3
2
3
3
8.2 Hz, 1 H, CHHO), 3.60 (dt, JH,H = 6.0 Hz, JH,H = 7.7 Hz, 1
H, CHSe), 2.50–2.40 (m, 1 H, CHH), 2.20–2.10 (m, 1 H, CHH),
2.0 (s, 3 H, SCH3), 1.50 (d, JH,H = 7.0 Hz, 3 H, CH3) ppm. 13C
3
NMR (100.62 MHz, CDCl3/TMS, 25 °C): δ = 145.3 (Cipso), 140.8
(Cipso), 134.8 (CHAr), 129.9 (Cipso), 127.9 (CHAr), 127.8 (2CHAr),
125.3 (CHAr), 126.9 (CHAr), 126.6 (CHAr), 125.4 (2CHAr), 85.8
(OCHPh), 67.6 (OCH2), 47.9 (CHSe), 43.5 (CHS), 33.6 (CH2), 21.0
(CH3), 13.6 (SCH3) ppm. MS (70 eV, EI): m/z (%) = 378 (1) [M]+,
231 (49), 229 (27), 183 (93), 147 (100), 105 (37), 91 (31), 77 (19).
[10]
[11]
Acknowledgments
Financial support from MIUR, National Projects COFIN2003 and
FIRB2001, and Consorzio CINMPIS is gratefully acknowledged.
[12]
a) M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, F. Marini,
L. Bagnoli, A. Temperini, Angew. Chem. Int. Ed. 2003, 42,
3131; b) M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, F.
Marini, L. Bagnoli, A. Temperini, Chem. Eur. J. 2002, 8, 1118;
c) M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, R. Bonini,
F. Marini, L. Bagnoli, A. Temperini, Org. Lett. 2004, 6, 4751.
M. Tiecco, L. Testaferri, L. Bagnoli, F. Marini, A. Temperini,
C. Tomassini, C. Santi, Tetrahedron Lett. 2000, 41, 3241.
Single crystal diffraction data collection for 2 and 3 was carried
out with an XCALIBUR Oxford Instruments diffractometer
equipped with a CCD detector, with graphite monochromated
Mo-Kα radiation and operating at 50 kV and 30 mA. To max-
imize the reciprocal space coverage, a combination of ω and φ
scans was used with a step-size of 0.5° and a time of 30 s/
frame. The distance between the crystal and the detector was
60.4 mm. Data were corrected for absorption with the SAD-
ABS program.[20] The structure was solved by direct methods
(SIR 97 program[21]) and refined by full-matrix least-squares
against F2 with the use of all data and with the use of the
SHELXTL software package.[22] Non-H atoms were refined
anisotropically; H atoms were placed in calculated positions.
Absolute structure configuration for both structures was tested
with the Flack test and the Flack parameters were 0.01(1) and
0.02(1) for 2 and 3, respectively.[23] Crystallographic data (ex-
cluding structure factors) for the structure in this paper have
been deposited with the Cambridge Crystallographic Data
Centre. CCDC-294258 and -294259 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif. Crystal data
for 2: C9H10 Br1 S1 Se1, FW = 309.10, monoclinic, space group
P21 (no. 4), Z = 2, a = 11.048(2), b = 9.118(1), c = 11.081(2) Å,
β = 92.440(3)°, V = 1115.2(9) Å3, ρcalcd. = 1.84 gcm–3, µ(Mo-
Kα) = 7.084 mm–1, F(000) = 752; 5764 data (2θmax = 50°) of
which 4254 unique, Rinct = 0.017; 213 parameters, awR2 = 0.055,
bS = 1.016 (all data), R1 [2866 with IϾ2σ(I)] = 0.029, largest
final difference peak/hole +0.38/–0.31 e·Å–3.
[1] a) G. A. Jeffrey, An Introduction to Hydrogen Bonding, Oxford
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Recent Theoretical and Experimental Advances in Hydrogen
bonded Clusters (Ed.: S. S. Xantheas), Kluwer, Dordrecht,
2000; c) J. Emsley, Structure and Bonding, Springer, Berlin,
1984.
[2] a) M. J. Frisch, A. C. Scheiner, H. F. Schaefer III, J. S. Binkley,
J. Chem. Phys. 1985, 82, 4194; b) F. Sim, A. St-Amant, I. Papai,
D. R. Salahub, J. Am. Chem. Soc. 1992, 114, 4391; c) Z. La-
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Mulhearn, S. Bachrach, J. Org. Chem. 1995, 60, 7110; e) V.
Barone, C. Adamo, J. Chem. Phys. 1996, 105, 11007; f) P. Sanz,
M. Ynez, O. Mò, Chem. Eur. J. 2003, 9, 4548.
[3] a) M. Iwaoka, H. Komatsu, T. Katsuda, S. Tomoda, J. Am.
Chem. Soc. 2004, 126, 5309.
[4] a) B. M. Goldstein, S. D. Kennedy, W. J. Hemnen, J. Am.
Chem. Soc. 1990, 112, 8285; b) D. H. R. Barton, M. B. Hall,
Z. Lin, S. I. Pareck, J. Reibenspies, J. Am. Chem. Soc. 1993,
115, 5056; c) V. N. Ramasubbu, R. Parthasarathy, Phosphorus
Sulfur 1987, 31, 221.
[5] I. Hargittai, B. Rozsondai, “Structural Chemistry of Organic
Compounds Containing Selenium or Tellurium” in The Chem-
istry of Organic Selenium and Tellurium Compounds (Eds.: S.
Patai, Z. Rappoport), John Wiley & Sons, New York, 1986,
vol. 1.
[6] a) M. Baiwir, G. Llabres, O. Dideberg, L. Dupont, J.-L. Piette,
Acta Crystallogr., Sect. B 1975, 31, 2188; b) H. W. Roesky, K.-
L. Weber, U. Seseke, W. Pinkert, M. Noltemeyer, W. Clegg,
G. M. Sheldrick, J. Chem. Soc., Dalton Trans. 1985, 565; c) S.
Tomoda, M. Iwaoka, K. Yakushi, A. Kawamoto, J. Tanaka, J.
Phys. Org. Chem. 1988, 1, 179; d) S. Tomoda, M. Iwaoka, J.
Chem. Soc., Chem. Commun. 1990, 231; e) S. Kubiniok, W.-W.
[13]
[14]
4872
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 4867–4873

Intramolecular Nonbonding Interactions between Selenium and Sulfur
FULL PAPER
[15] Crystal Data for 3: C9H10 Cl1 S1 Se1, FW = 264.64, orthorhom-
bic, space group P 212121 (no. 19), Z = 4, a = 8.391(1), b =
[19] M. Tiecco, L. Testaferri, L. Bagnoli, F. Marini, A. Temperini,
C. Tomassini, C. Santi, Tetrahedron Lett. 2000, 41, 3241.
[20] G. M. Sheldrick, Program for Empirical Absorption Correction
of Area Detector Data, University of Göttingen, Göttingen,
Germany, 1996b.
[21] A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C.
Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R.
Spagna, J. Appl. Crystallogr. 1999, 32, 115.
[22] G. M. Sheldrick, SHELXL-97 – Program for Refinement of
Crystal Structures, University of Göttingen, Göttingen, Ger-
many, 1997.
[23] H. D. Flack, Acta Crystallogr. Sect. A 1983, 39, 876.
Received: May 9, 2006
10.849(1),
c = 11.011(1) Å, V = =
1002.4(9) Å3, ρcalcd.
1.75 gcm–3, µ(Mo-Kα) = 4.162 mm–1, F(000) = 524; 4360 data
(2θmax = 50°), of which 1742 unique, Rint = 0.021; 109 param-
eters, wR2 = 0.049, S = 1.001 (all data), R1 [1610 with IϾ2σ(I)]
= 0.023, largest final difference peak/hole +0.29/–0.30 e·Å–3.
[16] A. Bondi, J. Phys. Chem. 1964, 68, 441.
[17] The covalency factor χ for the intramolecular Se–S interaction
can be estimated by the following equation: χ = [(RSe
+
RS)vdW – dSeS]/[(RSe +RS)vdW – (rSe +rS)cov] where R and r are
the van der Waals and the covalent radii, respectively, and d
the distance between the two interacting atoms.
[18] a) G. R. Van Hecke, W. D. Horrocks, Inorg. Chem. 1966, 5,
Published Online: August 24, 2006
1968; b) G. S. Reddy, W. Tam, Organometallics 1984, 3, 630.
Eur. J. Org. Chem. 2006, 4867–4873
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4873