Synthesis and reactions of the optically active dialkyl diselenides from the pinane group

Article abstract of DOI:10.2174/157017809788489846

A convenient method of synthesis of the optically active dialkyl diselenides from the pinane group is described. The 3-hydroxy and 3-alkoxy derivatives of bis(cis-myrtanyl) diselenide have been obtained. The influence of a structure of the resulting disel

Full text of DOI:10.2174/157017809788489846

Letters in Organic Chemistry, 2009, 6, 321-328
321
Synthesis and Reactions of the Optically Active Dialkyl Diselenides from
the Pinane Group
Zbigniew Rafiꢀski, Jacek ꢁcianowski* and Andrzej Wojtczak
Department of Chemistry, Nicolaus Copernicus University, Torun, Poland
Received July 18, 2008: Revised April 20, 2009: Accepted April 20, 2009
Abstract: A convenient method of synthesis of the optically active dialkyl diselenides from the pinane group is described.
The 3-hydroxy and 3-alkoxy derivatives of bis(cis-myrtanyl) diselenide have been obtained. The influence of a structure
of the resulting diselenides on the diastereomeric excess of the methoxyselenenylation reaction and the selenocyclization
have been investigated.
Keywords: Asymmetric synthesis, Diselenides, Selenium, Terpenoids.
INTRODUCTION
Hitherto, only the functionalized terpene diselenides
being derivatives of camphor have been described [9].
Diselenides are a class of organic compounds with a
great synthetic importance. Depending on the reaction condi-
tions they can be employed both as precursors for synthesis
of nucleophilic, radical or electrophilic reagents [1]. Dise-
lenides are also investigated because of their biological and
pharmacological functions. Especially interesting are results
concerning antioxidizing, antimicrobial, antiviral, and anti-
tumor properties [2].
In the present paper we describe our investigations con-
cerning the synthesis of the dialkyl diselenides from the
pinane group functionalized with hydroxy or alkoxy groups,
derivatives of bis(cis-myrtanyl) diselenide 1. The use of the
obtained diselenides in the methoxyselenenylation reaction
of styrene and selenocyclization with the use of
o-allylphenol is also reported.
In recent years, diselenides are frequently employed as
precursors for an asymmetric synthesis. For example the
optically active diselenides have been used in synthesis in
the new asymmetric carbon-carbon and carbon-heteroatom
coupling [3]. The investigation on the use of the optically
active diselenides as catalysts in asymmetric reactions was
also conducted [4].
RESULTS AND DISCUSSION
We started our investigations on the functionalized opti-
cally active diselenides from pinane group with the synthesis
of the bis(3-trans-hydroxy-cis-myrtanyl) diselenide
(Scheme 2). Myrtenyl chloride 3 was obtained in a reaction
of (-)-myrtenol 2 with triphenylphosphine in carbon tetra-
chloride [10]. It was subsequently transformed into 10-
chloroisopinocampheol 4 by the hydroboration oxidation
reaction [11]. Diselenide 5 was obtained in a reaction of
chloride 4 with sodium diselenide generated in situ (Se,
NaOH, N2H4ꢂH2O).
5
Recently, we have described a method for the preparation
of terpene-derived dialkyl diselenides, which was based on a
reaction of sodium diselenide with alkyl tosylates and chlo-
rides [5,6].
We have obtained non-functionalized diselenides from
p-menthane, pinane, carane and bornane groups [5-7]. For
example, we have obtained bis(cis-myrtanyl) diselenide 1 in
a reaction of sodium diselenide with cis-myrtanyl tosylate
(Scheme 1) [5]. The obtained diselenide has been employed
in the asymmetric methoxyselenenylation [6] and seleno-
cyclization [8].
Cl
OH
i
3
2
OH
OTs
Se)2
ii
Cl
Se)2
i
ii
OH
OH
iii
1
Scheme 1. Reagents and conditions: i) TsCl, pyridine, 0 °C, 30 min,
then RT, 24 h, 87%; ii) Se, NaOH, N2H4ꢂH2O, 100 °C, 1 h, 91%.
4
5
Scheme 2. Reagents and conditions: i) PPh3, CCl4, reflux, 24 h,
80%; ii) BMS, H2O2/NaOH, 65%; iii) Se, NaOH, N2H4ꢂH2O, 50
°C, 20 h, 54%.
*Address correspondence to this author at the Department of Chemistry,
Nicolaus Copernicus University, 7 Gagarin Street, 87-100 Torun, Poland;
Fax: +48(56) 6542477; E-mail: jsch@chem.uni.torun.pl
1570-1786/09 $55.00+.00
© 2009 Bentham Science Publishers Ltd.

322 Letters in Organic Chemistry, 2009, Vol. 6, No. 4
Rafiꢀski et al.
The structure of obtained diselenide 5 was confirmed by
pinane moieties is typical for that ring system. The Se-Se
distances are 2.3140(9) and 2.2978(9) Å for Se1-Se2 and
Se3-Se4, respectively, and are similar to that of 2.3182(11)
reported for dineomenthyl diselenide [6]. The C-Se distances
vary between 1.941(8) and 1.984(7) Å and are similar to
those reported for other terpene selenides [6,8]. The C-Se-Se
angles range from 99.3(2)° for C10-Se1-Se2 to 102.7(2)° for
C40-Se4-Se3. Two molecules reveal significant differences
in the diselenide bridge conformation. The C-Se-Se-C tor-
sion angles for the diselenide bridges are -90.9(3)° and
-87.5(3)° for C10-Se1-Se2-C20 and C30-Se3-Se4-C40, re-
spectively. These values are significantly lower than that of
-112.1(4)°, reported for (+)-dineomenthyl diselenide [6]. The
orientation of pinane moieties relative to the diselenide
bridges, described with the C-C-Se-Se torsion angles, reveal
even larger differences between two molecules. In molecule
1 the C2-C10 Se1-Se2 and Se1-Se2-C20-C12 torsion angles
are -163.5(4)° and -76.2(5)°, while in the second molecule
the equivalent torsion angles are C22-C30-Se3-Se4 83.6(5)°
and Se3-Se4-C40-C32 118.2(5)°. The absolute configuration
of the chiral centers in all cis-pinane moieties is 1S,2S,3S,5R.
Analysis of the intermolecular interactions revealed the net-
work of H-bonds involving three out of four hydroxyl
groups, with the O···O distances being O1-H1O···O3 [x+1, y-
1, z] 2.630 Å, O3-H3O···O4 [x+1, y, z] 2.636 Å and O4-
H4O···O1 [x-1, y+1, z] 2.727 Å. The O2-H group is buried
between the pinane moieties and does not form any H-bond.
1H, 13C, 77Se NMR and X-ray analyses.
Fig. (1). X-ray structure of diselenide 5.
The structure of 5 contains two diselenide molecules in
the asymmetric unit Fig. (1) [12-14]. The geometry of cis-
We have also synthesized the diselenides containing the
alkoxy groups. We obtained (+)-bis(trans-3-methoxy-cis-
OH
Br
Br
Br
Se)2
OMe
OH
OMe
i
iv
ii
iii
7
8
2
6
9
Scheme 3. Reagents and conditions: i) PBr3, hexane, -20 °C, 30 min, then RT, 5 h, 59%; ii) BMS, H2O2/NaOH, 46%; iii) 60% NaH, MeI,
RT, 24 h, 92%; iv) Se, NaOH, N2H4ꢀH2O, 50 °C, 20 h, 76%.
Fig. (2). X-ray structure of diselenide 9.

Synthesis and Reactions of the Optically Active Dialkyl Diselenides
Cl
Cl
Letters in Organic Chemistry, 2009, Vol. 6, No. 4
323
Se)2
OBn
x+1, -y, z] -89.5(3)° have either the opposite sign or have a
much smaller absolute value than those reported for 5.
OH
OBn
The methoxy groups are buried between the methoxy
groups and gem-dimethyl groups of the pinane moieties of
the surrounding diselenide molecules. Their conformation is
trans with the torsion angles being C(2)-C(3)-O(1)-C(11)
-165.0(3)° and C(22)-C(23)-O(2)-C(31) -163.3(3)°. The ab-
solute configuration of the chiral centers in all cis-pinane
moieties is 1S,2S,3S,5R.
ii
i
11
4
10
Scheme 4. Reagents and conditions: i) 60% NaH, BnCl, RT, 48 h,
66%; ii) Se, NaOH, N2H4ꢁH2O, 50 °C, 20 h, 42%.
The diselenide 11 containing a benzyloxy groups has
been obtained in a reaction of sodium diselenide with the
chloride 10, formed as a result of a reaction of 10-
chloroisopinocampheol 4 with sodium hydride and benzyl
chloride (Scheme 4).
myrtanyl) diselenide 9 as a result of the hydroboration oxida-
tion of the myrtenyl bromide 6, subsequent protection of the
hydroxy group in the resulted 10-bromoisopinocampheol 7
with the methyl group and final reaction of
10-bromoisopinocampheyl methyl ether 8 with sodium dise-
lenide (Scheme 3).
Many literature reports concerning an influence of het-
eroatoms in diselenide molecules on the increase of the di-
astereomeric excesses in the methoxyselenenylation reaction
and selenocyclization [3] prompted us to the use of obtained
diselenides in the methoxyselenenylation of styrene (route
A) and selenocyclization with the use of o-allylphenol (route
B) (Scheme 5). Treatment of diselenides 1, 5, 9 and 11 with
1M solution of bromine and then silver triflate gave the cor-
responding triflate precursors. The resulting salts 1a, 5a, 9a,
11a, have not been isolated from the reaction mixture but
used directly in a reaction with styrene [6] or o-allylphenol
[8] to give the respective methoxy selenides 12-15 and se-
lenides being derivatives of dihydrobenzofuran 16-19.
The structure of the obtained diselenide was confirmed
by the X-ray analysis Fig. (2) [12-14].
Structure 9 is formed by the two halves of different dise-
lenide molecules positioned in the asymmetric unit. The two-
fold axis parallel to crystallographic z dissects the diselenide
bonds of the two molecules, relating each half of the dise-
lenide to its symmetry equivalent counterpart. The Se-Se
bond distances are Se1-Se1 [-x, -y, z] 2.3229(7) Å and Se2-
Se2 [-x+1, -y, z] 2.3205(8) Å, and are significantly longer
than those reported for the 3-hydroxy compound 5. The C10-
Se1 and C30-Se2 distances of 1.955(3) and 1.958(3) Å, as
well as the C-Se-Se angles are mimilar to those found in 5 or
dineomenthyl diselenide [6]. However, the angles C2-C10-
Se1 117.1(2) deg and C22-C30-Se2 117.4(2) deg are larger
than the corresponding angles reported for 5.
The yields and the diastereomeric ratios have been
presented in Tables 1 and 2. The diastereomeric ratios for the
addition and selenocyclization products were similar both for
non-functionalized diselenide 1 and the functionalized dise-
lenides 5, 9, 11. The slight increase of the diastereomeric
ratio has been observed for the diselenide 9 containing the
methoxy groups.
Conformation of the diselenide bridges described with
the torsion angles C10-Se1-Se1 [-x, -y, z]-C10 [-x, -y, z] -
64.3(2)° and C30-Se2-Se2 [-x+1, -y, z]-C30 [-x+1, -y, z] -
66.3(2)° is similar in both molecules, although the difference
close to 10ꢀ is statistically significant. The observed value is
different from that of -90 deg reported for 5. Also the orien-
tation of the pinane moiety relative to the diselenide bridge
in 9 is different from that found in 5. The torsion angles C2-
C10-Se1-Se1 [-x, -y, z] -92.3(2) and C22-C30-Se2-Se2 [-
In conclusion, the new unknown functionalized
diselenides from the pinane group have been obtained. It has
been demonstrated that the elaborated methodology of
synthesis of the optically active dialkyl diselenides based on
OMe
Se
*
X
iii
route A
Se)2
Se OTf
SeBr
X
12-15
X
X
i
ii
Se
*
O
1, 5, 9, 11
X = H, OH, OMe, OBn
1a, 5a, 9a, 11a
X
iv
route B
16-19
Scheme 5. Reagents and conditions: i) 1M Br2 in CCl4, -78 °C, 15 min; ii) AgOTf in MeOH, -78 °C, 15 min; iii) styrene, -78 °C, 5 h; iv) o-
allylphenol, -78 °C, 5 h.

324 Letters in Organic Chemistry, 2009, Vol. 6, No. 4
Rafiꢀski et al.
Table 1. Metoxyselenenylation of Styrene Prompted by the Monoterpene Diselenides
Entry
Diselenide
Product
OMe
D.r.a
Isolated Yield (%)
Se)2
Se
*
1
51:49b
64b
20
58
82
1
12
OMe
*
Se)2
OH
Se
Se
Se
2
3
4
52:48
64:36
52:48
OH
5
13
OMe
*
Se)2
OMe
OMe
9
14
OMe
Se)2
*
OBn
OBn
11
15
aDiastereomeric ratios were established on the basis of 1H NMR and 77Se NMR spectra.
bLit. [6a].
Table 2. Cyclization of o-allylphenol with Use of Monoterpene Diselenides
Entry
Diselenide
Product
D.r.a
Isolated Yield (%)
Se)2
Se
*
O
1
52:48b
83b
1
16
Se)2
OH
Se
O
*
2
52:48
74
OH
5
17

Synthesis and Reactions of the Optically Active Dialkyl Diselenides
Letters in Organic Chemistry, 2009, Vol. 6, No. 4
325
(Table 2). Contd…..
Isolated Yield (%)
Entry
Diselenide
Product
D.r.a
Se)2
Se
O
*
OMe
3
62:38
31
OMe
9
18
Se)2
Se
O
*
OBn
4
57:43
38
OBn
11
19
aDiastereomeric ratios were established on the basis of 1H NMR and 77Se NMR spectra.
bLit. [7].
a reaction of alkyl halides with sodium diselenide can be an
efficient method for the functionalized dialkyl diselenides.
The obtained functionalized diselenides have been success-
fully used in reactions of addition to the double bonds and
selenocyclization. The best diastereoselection has been
observed for a diselenide containing a methoxy groups. The
developed methodology can be considered as a good base for
further research on a synthesis and use of the functionalized
optically active diselenides.
trated by means of a rotary evaporator. The product was iso-
lated by the distillation under reduced pressure.
Yield: 80%. Colorless liquid. B.p. 44-46 °C (0.15 Torr).
19
1
[ꢁ]D -42.0 (c 10.46, CHCl3). H NMR (200 MHz, CDCl3):
0.83 (s, 3H, CH3), 1.18 (d, J=9.9 Hz, 1H, CHH), 1.31 (s, 3H,
CH3), 2.06-2.17 (m, 1H), 2.21-2.33 (m, 3H), 2.38-2.47 (m,
1H), 3.94-4.05 (m, 2H), 5.56-5.64 (m, 1H). 13C NMR (50
MHz, CDCl3): 21.1 (CH3), 26.0 (CH3), 31.2 (CH2), 31.5
(CH2), 38.0 (C), 40.4 (CH), 44.2 (CH), 48.6 (CH2), 122.4
(CH=), 144.1 (C=). Anal. Calcd for C10H15Cl: C, 70.37; H,
8.86. Found: C, 70.32; H, 8.81
EXPERIMENTAL
General
(-)-Myrtenyl Bromide (6)
To a solution of (-)-myrtenol (30.4 g, 200 mmol) in hex-
ane (60 mL) PBr3 (21.6 g, 80 mmol) was added at -20 °C,
and the mixture was stirred for 30 min and then at r.t. for 5 h.
Saturated aqueous NaHCO3 was added and the product ex-
tracted with diethyl ether. The extracts were washed with
brine, dried (MgSO4), and evaporated. The crude product
was purified by the distillation under reduced pressure.
(1R)-(-)-Myrtenol (95%, 94 ee) was purchased from Ald-
rich. Dichloromethane and N,N-dimethylformamide were
distilled from CaH2 and stored over molecular sieves 4Å.
Methanol was distilled from magnesium turns and stored
1
over molecular sieves 4Å. H, 13C and 77Se NMR spectra
were measured in CDCl3 on a Bruker AM-300 or Varian
1
Gemini 200 spectrometer (300 MHz or 200 MHz for H and
75.5 MHz or 50.3 MHz for 13C). Chemical shifts (ꢀ) are
given in ppm relative to TMS and coupling constants (J) are
given in Hz. 77Se NMR spectra were recorded on Varian
Gemini 200, with diphenyl diselenide as the internal stan-
dard. Elemental analyses were performed on a Vario
MACRO CHN analyzer. Column chromatography was
carried out using MERCK Silica gel 60 (70-230 mesh) with
the indicated solvents (petroleum ether (Pet ether):
40-60 °C). All reaction requiring anhydrous conditions were
conducted in a flame-dried apparatus.
Yield: 59%. Colorless liquid. B.p. 48-50 °C (0.15 Torr).
24
1
[ꢁ]D -22.0 (c 14.88, CHCl3). H NMR (200 MHz, CDCl3):
0.83 (s, 3H, CH3), 1.18 (d, J=9.9 Hz, 1H, CHH), 1.31 (s, 3H,
CH3), 2.06-2.17 (m, 1H), 2.21-2.33 (m, 3H), 2.38-2.47 (m,
1H), 4.00 (m, 2H), 5.63-5.70 (m, 1H). 13C NMR (50 MHz,
CDCl3): 21.1 (CH3), 26.0 (CH3), 31.3 (CH2), 31.5 (CH2),
37.0 (CH2), 37.9 (C), 40.3 (CH), 44.8 (CH), 123.1 (CH=),
144.1 (C=). Anal. Calcd for C10H15Br: C, 55.83; H, 7.03.
Found: C, 55.68; H, 6.92.
(-)-10-Chloroisopinocampheol (4)
(-)-Myrtenyl Chloride (3)
Yield: 65%. Colorless oil. B.p. 60–62 °C (0.15 Torr).
20
1
The solution of (-)-myrtenol (30.4 g, 200 mmol) and
triphenylphosphine (57.7 g, 220 mmol) in carbon tetrachlo-
ride (500 mL) was refluxed for 24 h. Then it was cooled and
petroleum ether (600 mL) was added. The formed precipitate
was filtered off under vacuum, and the filtrate was concen-
[ꢁ]D -55.8 (c 9.35, CHCl3). H NMR (300 MHz, CDCl3):
0.88 (s, 3H, CH3), 1.14 (d, J=9.9 Hz, 1H, CHH), 1.22 (s, 3H,
CH3), 1.78 (ddd, J=14.1, 4.2, 2.4 Hz, 1H, CH), 1.94-2.02 (m,
2H), 2.10 (bs, 1H, OH), 2.23-2.31 (m, 1H), 2.39-2.58 (m,
2H), 3.54 (dd, J=10.5, 6.3 Hz, 1H, CHH), 3.65 (dd, J=10.5,
10.5 Hz, 1 H, CHH), 4.27 (qui, J=4.8 Hz, 1H, CH). 13C

326 Letters in Organic Chemistry, 2009, Vol. 6, No. 4
Rafiꢀski et al.
NMR (50 MHz, CDCl3): 23.8 (CH3), 27.1 (CH3), 33.1
(CH2), 37.5 (CH2), 37.8 (C), 41.4 (CH), 44.5 (CH), 48.6
(CH2), 55.6 (CH), 68.1 (CH). Anal. Calcd for C10H17ClO: C,
63.65; H, 9.08. Found: C, 63.58; H, 8.98.
solved in dry DMF (5 mL) under argon and added to the
solution. The mixture was heated at 50 °C for 20 h. The reac-
tion mixture was cooled, poured into water (30 mL), and
extracted with diethyl ether (3ꢁ20 mL). The combined ethe-
real layers were washed with water (2ꢁ20 mL), dried with
anhydrous MgSO4, and the solvent was evaporated. Crude
product was purified by chromatography on a silica gel col-
umn. The diselenides were obtained as yellow solids.
(-)-10-Bromoisopinocampheol (7)
Yield: 46%. Colorless oil. B.p. 92-94 °C (0.8 Torr);
21
1
[ꢀ]D -21.6 (c 3.18, CHCl3). H NMR (200 MHz, CDCl3):
0.88 (s, 3H, CH3), 1.17 (d, J=9.9 Hz, 1H, CHH), 1.22 (s, 3H,
CH3), 1.80 (ddd, J=14.2, 4.6, 2.4 Hz, 1H), 1.90–2.07 (m,
2H), 2.21 (bs, 1H, OH), 2.28–2.62 (m, 3H), 3.42 (dd, J=14.9,
9.6 Hz, 1H, CHH), 3.53 (dd, J=15.9, 14.9 Hz, 1H, CHH),
4.25 (qui, J=6.9 Hz, 1H, CH). 13C NMR (50 MHz, CDCl3):
23.7 (CH3), 27.0 (CH3), 33.0 (CH2), 37.4 (CH2), 37.6 (CH2),
37.7 (C), 41.4 (CH), 45.4 (CH), 55.5 (CH), 68.7 (CH). Anal.
Calcd for C10H17BrO: C, 51.52; H, 7.35. Found: C, 51.61; H,
7.28.
(-)-Bis(trans-3-hydroxy-cis-myrtanyl) Diselenide (5)
Yield: 54%. Yellow crystals. M.p. 127-128 °C. Column
chromatography (70-230 mesh silica gel, CH2Cl2/EtOAc,
22
1
80:20). [ꢀ]D -38.4 (c 1.98, CHCl3). H NMR (300 MHz,
CDCl3): ꢂ = 0.89 (s, 3H, CH3), 1.17 (d, J= 9.9 Hz, 1H,
CHH), 1.22 (s, 3H, CH3), 1.76 (ddd, J=14.1, 4.2, 2.7 Hz, 1H,
CH), 1.93-2.04 (m, 2H), 2.22-2.30 (m, 1H), 2.37-2.43 (m,
2H), 2.47-2.54 (m, 1H), 2.99 (dd, J=12.0, 6.9 Hz, 1H, CHH),
3.16 (dd, J=12.0, 9.0 Hz, 1 H, CHH), 4.15-4.23 (m, 1H). 13C
NMR (50 MHz, CDCl3): ꢂ = 23.8 (CH3), 27.3 (CH3), 33.4
(CH2), 35.8 (CH2), 38.0 (CH2), 38.1 (C), 41.5 (CH), 46.2
(CH), 53.6 (CH), 69.9 (CH). 77Se NMR (38 MHz, CDCl3): ꢂ
= 303.0. Anal. Calcd for C20H34O2Se2: C, 51.73; H, 7.38.
Found: C, 51.65; H, 7.34.
Synthesis of Compounds (8, 10); General Procedure
NaH (60% in mineral oil, 11 mmol) was added to a solu-
tion of monoterpene alcohol (10 mmol) in dry THF (10 mL).
The suspension was stirred at room temperature for 20 min,
and then alkyl iodide (30 mmol) was added, and the mixture
was stirred at room temperature from 24 h to 48 h. The reac-
tion mixture was poured onto ice and extracted with ether;
the combined ethereal layers were washed with saturated
aqueous sodium chloride, dried over anhydrous magnesium
sulfate, and evaporated. The crude product was purified by
the column chromatography or by distillation under reduced
pressure.
(+)-Bis(trans-3-methoxy-cis-myrtanyl) Diselenide (9)
Yield: 76%. Yellow crystals. M.p. 47-49 °C. Column
chromatography (70-230 mesh silica gel, Pet ether/EtOAc,
22
1
95:5). [ꢀ]D +40.7 (c 3.28, CHCl3). H NMR (200 MHz,
CDCl3): ꢂ = 0.89 (s, 3H, CH3), 1.05 (d, J=9.6 Hz, 1H, CHH),
1.21 (s, 3H, CH3), 1.72-1.84 (m, 1H), 1.90-1.98 (m, 1H),
2.08-2.24 (m, 2H), 2.28-2.47 (m, 2H), 3.11 (dd, J=10.2, 8.8
Hz, 1H, CHH), 3.17 (dd, J=10.2, 7.2 Hz, 1H, CHH), 3.32 (s,
3H, CH3), 3.56 (m, 1H). 13C NMR (50 MHz, CDCl3): ꢂ =
23.7 (CH3), 27.2 (CH3), 32.6 (CH2), 35.0 (CH2), 36.0 (CH2),
38.2 (C), 41.3 (CH), 44.7 (CH), 50.7 (CH), 56.1 (OCH3),
78.8 (CH). 77Se NMR (38 MHz, CDCl3): ꢂ = 300.5. Anal.
Calcd for C22H38O2Se2: C, 53.66; H, 7.78. Found: C, 53.70;
H, 7.74.
(+)-10-Bromoisopinocampheyl Methyl Ether (8)
Yield: 92%. Colorless oil. Column chromatography (70-
20
230 mesh silica gel, Pet ether/EtOAc, 95:5). [ꢀ]D +14.2 (c
1
6.02, CHCl3). H NMR (200 MHz, CDCl3): 0.87 (s, 3H,
CH3), 0.88-0.98 (m, 1H), 1.08 (d, J=9.6 Hz, 1H, CHH), 1.24
(s, 3H, CH3), 1.68-1.80 (m, 1H), 1.81-2.00 (m, 1H), 2.17-
2.47 (m, 4H), 3.34 (s, 3H, CH3), 3.39-3.60 (m, 2H). 13C
NMR (50 MHz, CDCl3): 23.5 (CH3), 27.1 (CH3), 32.2
(CH2), 34.8 (CH2), 36.9 (CH2), 38.1 (C), 41.1 (CH), 43.4
(CH), 52.6 (CH), 56.3 (OCH3), 77.5 (CH). Anal. Calcd for
C11H19BrO: C, 53.45; H, 7.75. Found: C, 53.38; H, 7.74.
(+)-Bis(trans-3-benzyloxy-cis-myrtanyl) Diselenide (11)
Yield: 42%. Yellow solid. M.p. 51-53 °C. Column chro-
matography (70-230 mesh silica gel, Pet ether/CH2Cl2/
22
1
EtOAc, 68:31:1). [ꢀ]D +51.2 (c 2.33, CHCl3). H NMR
(200 MHz, CDCl3): ꢂ = 0.89 (s, 3H, CH3), 1.18 (d, J=9.9 Hz,
1H, CHH), 1.22 (s, 3H, CH3), 1.82-2.03 (m, 2H), 2.08-2.18
(m, 1H), 2.25-2.58 (m, 3H), 3.06 (dd, J=10.5, 9.6 Hz, 1H,
CHH), 3.20 (dd, J=10.5, 6.3 Hz, 1H, CHH), 3.75-3.84 (m,
1H), 4.42-4.50 (m, 2H), 7.21-7.40 (m, 5H, 5ꢁCH). 13C NMR
(50 MHz, CDCl3): ꢂ =23.7 (CH3), 27.2 (CH3), 32.6 (CH2),
35.4 (CH2), 35.8 (CH2), 38.2 (C), 41.3 (CH), 44.8 (CH), 50.8
(CH), 70.4 (CH2), 76.8 (CH), 127.3 (CH), 127.7 (2ꢁCH),
128.2 (2ꢁCH), 138.7 (C). 77Se NMR (38 MHz, CDCl3): ꢂ =
303.5. Anal. Calcd for C34H46O2Se2: C, 63.35; H, 7.19.
Found: C, 63.24; H, 7.11.
(+)-Benzyl 10-chloroisopinocampheyl Ether (10)
Yield: 66%. Colorless oil. B.p. 107–109 °C (0.15 Torr).
21
1
[ꢀ]D +38.8 (c 4.37, CHCl3). H NMR (300 MHz, CDCl3):
0.86 (s, 3H, CH3), 1.17 (d, J =9.9 Hz, 1H, CHH), 1.24 (s, 3H,
CH3), 1.87-2.05 (m, 2H), 2.20-2.25 (m, 1H), 2.35-2.50 (m,
3H), 3.46 (dd, J=10.5, 9.6 Hz, 1H, CHH), 3.62 (dd, J=10.5,
6.3 Hz, 1H, CHH), 3.68-3.76 (m, 1H), 4.45 (d, J=11.4 Hz,
1H, CHH), 4.62 (d, J=11.4 Hz, 1H, CHH), 7.29-7.39 (m, 5H,
5ꢁCH). 13C NMR (50 MHz, CDCl3): ꢂ = 23.5 (CH3), 27.2
(CH3), 32.2 (CH2), 35.2 (CH2), 38.2 (C), 41.4 (CH), 42.7
(CH), 47.6 (CH2), 52.7 (CH), 70.6 (CH2), 74.3 (CH), 127.5
(CH), 127.8 (2ꢁCH), 128.3 (2ꢁCH), 138.5 (C). Anal. Calcd
for C17H23ClO: C, 73.23; H, 8.31. Found: C, 73.30; H, 8.34.
(1S,2S,3S,5R)-2-[(2-Methoxy-2-phenylethylselanyl)
methyl]-6,6-dimethylbicyclo[3.1.1]heptan-3-ol (13)
Yield: 20%. Light yellow oil. D.r. 52:48. Column chro-
matography (70-230 mesh silica gel, CH2Cl2/EtOAc, 95:5).
1H NMR (200 MHz, CDCl3): major diastereomer ꢂ = 0.86 (s,
3H, CH3), 1.10 (d, J=9.8 Hz, 1H, CHH), 1.20 (s, 3H, CH3),
1.60-2.16 (m, 5H), 2.31–2.62 (m, 4H), 2.65–3.05 (m, 3H),
General Procedure for the Synthesis of Diselenides
Sodium diselenide (10 mmol) was prepared from sodium
hydroxide, hydrazine hydrate and elemental selenium in dry
DMF [6]. The bromo or chloro precursor (5 mmol) was dis-

Synthesis and Reactions of the Optically Active Dialkyl Diselenides
Letters in Organic Chemistry, 2009, Vol. 6, No. 4
327
(1S,2S,3S,5R)-2-{[(2,3-Dihydrobenzofuran-2-yl)methylsela-
nyl]methyl}-6,6-dimethylbicyclo[3.1.1]heptan-3-ol (17)
3.24 (s, 3H; OCH3), 3.65–3.74 (m, 1H), 4.10-4.21 (m, 1H),
4.36 (dd, J=8.0, 5.0 Hz, 1H, CH), 7.35 (m, 5H, 5ꢀCH); mi-
nor diastereomer (distinct signals) ꢁ = 0.85 (s, 3H, CH3),
1.08 (d, J=9.8 Hz, 1H, CHH), 3.25 (s, 3H, OCH3), 4.32 (dd,
J=8.0, 5.0 Hz, 1H, CH). 13C NMR (50 MHz, CDCl3): major
diastereomer ꢁ = 23.8 (CH3), 27.3 (CH3), 30.5 (CH2), 30.9
(CH2), 33.6 (CH2), 37.2 (CH2), 38.0 (C), 41.5 (CH), 47.0
(CH), 52.8 (CH), 56.8 (OCH3), 69.9 (CH), 84.1 (CH), 126.6
(2ꢀCH), 128.1 (CH), 128.6 (2ꢀCH), 141.0 (C); minor di-
astereomer (distinct signals) ꢁ = 27.4 (CH3), 30.7 (CH2), 31.3
(CH2), 33.7 (CH2), 37.3 (CH2), 53.1 (CH), 70.0 (CH2), 84.0
(CH), 128.0 (CH), 128.5 (2ꢀCH). 77Se NMR (38 MHz,
CDCl3): major diastereomer ꢁ = 134.7; minor diastereomer ꢁ
= 131.3. Anal. Calcd for C19H28O2Se: C, 62.12; H, 7.68.
Found: C, 62.10; H, 7.55.
Yield: 74%. Light yellow oil. D.r. 52:48. Column chro-
matography (70-230 mesh silica gel, CH2Cl2/EtOAc, 90:10).
1H NMR (200 MHz, CDCl3): major diastereomer ꢁ = 0.90 (s,
3H, CH3), 1.17 (d, J=9.9 Hz, 1H, CHH), 1.23 (s, 3H, CH3),
1.76 (ddd, J=13.8, 4.6, 2.4 Hz, 1H), 1.89–2.00 (m, 2H),
2.08–2.14 (m, 1H), 2.36–2.60 (m, 3H), 2.71–3.08 (m, 6H),
3.37 (dd, J=15.6, 9.0 Hz; 1H), 4.14–4.26 (m, 1H), 4.93–5.04
(m, 1H), 6.74-6.86 (m, 2H, 2ꢀCH), 7.08-7.18 (m, 2H,
2ꢀCH); minor diastereomer (distinct signal) ꢁ = 0.89 (s, 3H,
CH3). 13C NMR (50 MHz, CDCl3): major diastereomer ꢁ =
23.8 (CH3), 27.4 (CH3), 29.1 (CH2), 30.8 (CH2), 33.6 (CH2),
35.7 (CH2), 37.5 (CH2), 38.0 (C), 41.5 (CH), 46.9 (CH), 53.2
(CH), 70.0 (CH), 82.4 (CH), 109.4 (CH), 120.6 (CH), 125.0
(CH), 126.2 (C), 128.1 (CH), 159.1 (C); minor diastereomer
(distinct signals) ꢁ = 28.6 (CH2), 30.5 (CH2), 33.7 (CH2),
35.9 (CH2), 53.1 (CH), 70.1 (CH), 82.6 (CH), 126.1 (CH).
77Se NMR (38 MHz, CDCl3): major diastereomer ꢁ = 116.9;
minor diastereomer ꢁ = 118.5. Anal. Calcd for C19H26O2Se:
C, 62.46; H, 7.17. Found: C, 62.40; H, 7.08.
(2-Methoxy-2-phenylethyl){[(1S,2S,3S,5R)-3-methoxy-6,6-
dimethylbicyclo[3.1.1]heptan-2-yl]methyl}selane (14)
Yield: 58%. Light yellow oil. D.r. 64:36. Column chro-
matography (70-230 mesh silica gel, Pet ether/EtOAc, 95:5).
1H NMR (200 MHz, CDCl3): major diastereomer ꢁ = 0.85 (s,
3H, CH3), 1.02 (d, J=9.8 Hz, 1H, CHH), 1.20 (s, 3H, CH3),
1.71-1.83 (m, 1H), 1.86–2.12 (m, 3H), 2.27–2.45 (m, 2H),
2.50–2.78 (m, 3H), 2.95 (dd, J=12.2, 8.0 Hz, 1H, CHH),
3.25 (s, 3H, OCH3), 3.31 (s, 3H, OCH3), 3.42–3.59 (m, 1H),
4.28-4.39 (m, 1H), 7.35 (m, 5H, 5ꢀCH); minor diastereomer
(distinct signals) ꢁ = 0.84 (s, 3H, CH3), 3.24 (s, 3H, OCH3),
3.30 (s, 3H, OCH3). 13C NMR (50 MHz, CDCl3): major di-
astereomer ꢁ = 23.6 (CH3), 27.3 (CH3), 30.4 (CH2), 31.2
(CH2), 32.8 (CH2), 35.0 (CH2), 38.2 (C), 41.3 (CH), 44.9
(CH), 50.3 (CH), 56.1 (OCH3), 56.8 (OCH3), 79.0 (CH),
84.3 (CH), 126.6 (2ꢀCH), 127.8 (CH), 128.4 (2ꢀCH), 141.3
(C); minor diastereomer (distinct signals) ꢁ = 30.6 (CH2),
32.7 (CH2), 44.9 (CH), 50.4 (CH), 84.4 (CH), 126.7 (2ꢀCH).
77Se NMR (38 MHz, CDCl3): major diastereomer ꢁ = 139.3;
minor diastereomer ꢁ = 137.5. Anal. Calcd for C20H30O2Se:
C, 62.98; H, 7.93. Found: C, 63.92; H, 7.77.
2-({[(1S,2S,3S,5R)-3-Methoxy-6,6-dimethylbicyclo[3.1.1]
heptan-2-yl]methylselanyl}methyl)-2,3-dihydrobenzofuran
(18)
Yield: 31%. Light yellow oil. D.r. 62:38. Column chro-
matography (70-230 mesh silica gel, Pet ether/EtOAc, 95:5).
1H NMR (300 MHz, CDCl3): major diastereomer ꢁ = 0.90 (s,
3H, CH3), 1.05 (d, J=9.9 Hz, 1H, CHH), 1.23 (s, 3H, CH3),
1.76–1.83 (m, 1H), 1.93–1.99 (m, 1H), 2.08–2.14 (m, 2H),
2.33–2.46 (m, 2H), 2.72–3.08 (m, 5H), 3.30 (s, 3H, CH3),
3.38 (dd, J=15.6, 9.0 Hz, 1H), 3.52–3.62 (m, 1H), 4.92–5.03
(m, 1H), 7.5 (d, J=7.5 Hz, 1H, CH), 6.84 (dt, J=7.5, 0.9 Hz,
1H, CH), 7.10 (dt, J=7.5, 0.9 Hz, 1H, CH), 7.15 (d, J=7.5
Hz, 1H, CH); minor diastereomer (distinct signals) ꢁ = 1.22
(s, 3H, CH3), 3.34 (s, 3H, CH3). 13C NMR (75 MHz, CDCl3):
major diastereomer ꢁ = 23.6 (CH3), 27.2 (CH3), 28.8 (CH2),
30.6 (CH2), 32.7 (CH2), 34.9 (CH2), 35.6 (CH2), 38.2 (C),
41.3 (CH), 45.0 (CH), 50.2 (CH), 56.0 (CH3), 78.8 (CH),
82.6 (CH), 109.2 (CH), 120.4 (CH), 124.9 (CH), 126.3 (C),
127.8 (CH), 159.2 (C); minor diastereomer (distinct signals)
ꢁ = 28.7 (CH3), 30.5 (CH3), 32.8 (CH2), 35.7 (CH2), 38.1
(C), 44.9 (CH), 50.3 (CH), 56.1 (CH3), 78.9 (CH), 82.7
(CH), 109.3 (CH), 126.3 (CH), 127.9 (CH), 159.1 (C). 77Se
NMR (38 MHz, CDCl3): major diastereomer ꢁ = 116.1; mi-
nor diastereomer ꢁ = 119.1. Anal. Calcd for C20H28O2Se: C,
63.31; H, 7.44. Found: C, 63.22; H, 7.35.
{[(1S,2S,3S,5R)-3-(Benzyloxy)-6,6-dimethylbicyclo[3.1.1]
heptan-2-yl]methyl}(2-methoxy-2-phenylethyl)selane (15)
Yield: 82%. Light yellow oil. D.r. 52:48. Column chro-
matography (70-230 mesh silica gel, Pet ether/EtOAc, 95:5).
1H NMR (200 MHz, CDCl3): major diastereomer ꢁ = 0.87 (s,
3H, CH3), 1.12 (d, J=9.8 Hz, 1H, CHH), 1.22 (s, 3H, CH3),
1.84-2.03 (m, 2H), 2.04–2.24 (m, 2H), 2.27–2.78 (m, 5H),
2.95 (dd, J=12.2, 8.0 Hz, 1H, CHH), 3.24 (s, 3H, OCH3),
3.70–3.82 (m, 1H), 4.35 (dd, J=8.0, 5.0 Hz, 1H, CH), 4.42-
4.63 (m, 2H), 7.21-7.42 (m, 10H; 10ꢀCH); minor diastereo-
mer (distinct signal) ꢁ = 0.84 (s, 3H, CH3). 13C NMR (50
MHz, CDCl3): major diastereomer ꢁ = 23.7 (CH3), 27.3
(CH3), 30.5 (CH2), 31.3 (CH2), 32.8 (CH2), 35.4 (CH2), 38.3
(C), 41.5 (CH), 45.0 (CH), 50.5 (CH), 56.9 (OCH3), 70.6
(CH), 77.1 (CH2), 84.5 (CH), 126.7 (CH), 127.4 (CH), 127.8
(2ꢀCH), 127.9 (2ꢀCH), 128.3 (2ꢀCH), 128.4 (2ꢀCH), 138.9
(C), 141.3 (C); minor diastereomer (distinct signals) ꢁ = 30.4
(CH2), 44.9 (CH), 50.4 (CH), 84.2 (CH), 126.6 (CH). 77Se
NMR (38 MHz, CDCl3): major diastereomer ꢁ = 140.6; mi-
nor diastereomer ꢁ = 140.1. Anal. Calcd for C26H34O2Se: C,
68.26; H, 7.49. Found: C, 68.15; H, 7.33.
2-({[(1S,2S,3S,5R)-3-(Benzyloxy)-6,6-dimethylbicyclo[3.1.1]
heptan-2-yl]methylselanyl}methyl)-2,3-dihydrobenzofuran
(19)
Yield: 39%. Light yellow oil. D.r. 57:43. Column chro-
matography (70-230 mesh silica gel, Pet ether/EtOAc,
1
90:10). H NMR (200 MHz, CDCl3): ꢁ = 0.90 (s, 3H, CH3),
1.18 (d, J=9.9 Hz, 1H, CHH), 1.24 (s, 3H, CH3), 1.84-2.06
(m, 2H), 2.08–2.56 (m, 4H), 2.65–3.11 (m, 5H), 3.38 (dd,
J=15.6, 9.0 Hz, 1H), 3.65–3.74 (m, 1H), 4.39-4.63 (m, 2H),
4.93–5.04 (m, 1H), 6.78 (d, J=7.5 Hz, 1H, CH), 7.82 (t,
J=7.5, 1H, CH), 7.05-7.18 (m, 2H, 2ꢀCH), 7.22-7.40 (m, 5H,
5ꢀCH). 13C NMR (50 MHz, CDCl3): major diastereomer ꢁ =

328 Letters in Organic Chemistry, 2009, Vol. 6, No. 4
Rafiꢀski et al.
[7]
[8]
[9]
Rafiꢃski Z.; ꢂcianowski J. Tetrahedron Asymmetry, 2008, 19,
1237.
Rafiꢃski Z.; ꢂcianowski J.; Wojtczak A. Tetrahedron Asymmetry,
2008, 19, 223.
23.8 (CH3), 27.3 (CH3), 28.9 (CH2), 30.5 (CH2), 32.8 (CH2),
35.4 (CH2), 35.8 (CH2), 38.3 (C), 41.5 (CH), 45.1 (CH), 50.4
(CH), 70.5 (CH), 77.0 (CH2), 82.6 (CH), 109.4 (CH), 120.4
(CH), 124.9 (CH), 126.4 (C), 127.4 (CH), 127.8 (2ꢀCH),
128.0 (CH), 128.3 (2ꢀCH), 138.8 (C), 159.1 (C); minor di-
astereomer (distinct signals) = 28.8 (CH2), 30.3 (CH2), 35.7
(CH2), 82.7 (CH). 77Se NMR (38 MHz, CDCl3): major di-
astereomer = 118.4; minor diastereomer = 121.7. Anal.
Calcd for C26H32O2Se: C, 68.56; H, 7.08. Found: C, 68.39;
H, 7.02.
(a) Back, T.G.; Dyck, P.B.; Parvez, M. J. Chem. Soc., Chem.
Commun., 1994, 515. (b) Back, T.G.; Dyck, P.B.; Parvez, M. J.
Org. Chem., 1995, 60, 703. (c) Back, T.G.; Dyck, P.B. J. Chem.
Soc. Chem. Commun., 1996, 2567. (d) Kurose, N.; Takahashi, T.;
Koizumi, T. J. Org. Chem., 1996, 61, 2932. (e) Kurose, N.;
Takahashi, T.; Koizumi, T. Tetrahedron, 1997, 53, 12115. (f)
Tiecco, M.; Tastaferri, L.; Santi, C.; Marini, F.; Bagnoli, L.;
Temperini, A. Tetrahedron Lett., 1998, 39, 2809. (g) Back, T.G.;
Nan, S. J. Chem. Soc. Perkin Trans. 1, 1998, 19, 3123. (h) Zhang,
J.; Takahashi, S.; Saito, S.; Koizumi, T. Tetrahedron Asymmetry,
1998, 18, 3303. (i) Salama, P.; Bernard, C. Tetrahedron Lett, 1998,
39, 745. (j) Tiecco, M.; Testaferri, L.; Marini, F., Santi, C.;
Bagnoli, L.; Temperini, A. Tetrahedron Asymmetry, 1999, 10, 747.
(k) Tiecco, M.; Testaferri, L.; Santi, C.; Tomassini, C.; Marini, F.;
Bagnoli, L.; Temperini, A. Eur. J. Org. Chem., 2000, 3451. (l)
Back, T.G.; Moussa, Z. Org. Lett., 2000, 2, 3007. (m) Back, T.G.;
Moussa, Z.; Parvez, M. J. Org. Chem., 2002, 67, 499. (n) Tiecco,
M.; Testaferri, L.; Bagnoli, L.; Scarponi, C.; Purgatorio, V.;
Temperini, A.; Marini, F.; Santi, C. Tetrahedron Asymmetry, 2005,
16, 2429. (o) Tiecco, M.; Testaferri, L.; Marini, F.; Sternativo, S.;
Santi, C.; Bagnoli, L.; Temperini, A. Eur. J. Org. Chem., 2005,
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Marinetti, A.; Buzin, F-X.; Ricard, L. J. Org. Chem., 1997, 62, 297.
Brown, H.C.; Dhokte, U.P. J. Org. Chem., 1994, 59, 2365.
Crystals of 5 and 9 have been obtained from the n-heptane solution.
The diffraction experiments were performed for 0.63ꢀ0.33ꢀ0.20
mm yellow crystal of 5 and for 0.41ꢀ0.21ꢀ0.10 mm yellow crystal
of 9. The X-ray data were collected at 291(2) K with an Oxford
Sapphire CCD diffractometer using MoKꢄ radiation ꢅ =0.71073 Å
by ꢆ-2ꢇ method. The numerical absorption correction was applied
(CrysAlis171 package of programs, Oxford Diffraction, 2000) with
the maximum and minimum transmissions of 0.5524 and 0.2203
for 5 and 0.7465 and 0.3503 for 9. The structure of 5 was solved in
the triclinic P1 space group and structure of 9 was determined in
the orthorhombic P2(1)2(1)2 space group. The structures were
solved with direct methods and refined with the full-matrix least-
squares method on F2 with the use of SHELX-97 program package
[13]. The hydrogen atoms have been located from the difference
electron density maps and constrained during refinement. The
absolute structure has been determined with the Flack method [14],
the Flack x value being -0.008(13) for 5 and -0.014(11) for 9. The
structural data have been deposited with Cambridge
Crystallographic Data Centre, the CCDC numbers 689256 and
689255, respectively.
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