Terpenyl selenides: Synthesis and application in asymmetric epoxidation

Article abstract of DOI:10.1002/ejoc.201500211

Abstract Synthesis of terpenyl selenides derived from limonene, menthol, caranol, and myrtanol is described. Three methodologies for the synthesis of terpenyl selenonium salts are compared. The results of selenium-mediated epoxidation through the use of isoselenocineole derived from limonene and methyl terpenyl, phenyl terpenyl, diterpenyl selenides, and selenonium salts are presented. The influence of solvent, counteranion, and diastereomeric purity of selenonium salt on the enantioselectivity of the epoxidation reaction is discussed. Selenium-mediated asymmetric epoxidation through the use isoselenocineole, and methyl terpenyl, phenyl terpenyl, and diterpenyl selenides is presented. The influence of reaction conditions, counteranion, and purity of selenonium salt on the reaction of asymmetric epoxidation is described.

Full text of DOI:10.1002/ejoc.201500211

FULL PAPER
DOI: 10.1002/ejoc.201500211
Terpenyl Selenides: Synthesis and Application in Asymmetric Epoxidation
[a]
[a]
[a]
´
Anna Banach, Jacek Scianowski,* Magdalena Uzarewicz-Baig, and
Andrzej Wojtczak[a]
Keywords: Synthetic methods / Diastereoselective synthesis / Selenium / Epoxidation / Terpenoids
Synthesis of terpenyl selenides derived from limonene,
menthol, caranol, and myrtanol is described. Three method-
ologies for the synthesis of terpenyl selenonium salts are
compared. The results of selenium-mediated epoxidation
through the use of isoselenocineole derived from limonene
and methyl terpenyl, phenyl terpenyl, diterpenyl selenides,
and selenonium salts are presented. The influence of solvent,
counteranion, and diastereomeric purity of selenonium salt
on the enantioselectivity of the epoxidation reaction is dis-
cussed.
nonium ylides for asymmetric epoxidation was described
quite recently. (2R,5R)-2,5-Dimethyltetrahydroselenophene
(4) was used as an efficient catalyst (0.2 equiv.) for the benz-
ylidenation of aromatic aldehydes with high enantiomeric
excess (Ͼ 90%ee).[7] Recently, exo-α-methylseleno-iso
borneol (5), and exo-α-phenylseleno-isoborneol (6) were
converted into the corresponding selenonium salts by reac-
tion with benzyl bromide and silver tetrafluoroborate,
which were used for asymmetric synthesis of chiral epoxides
with good yields and good stereoselectivities (50–81%ee).[8]
Selenides 4–5 and 7–8 were the first chiral selenides applied
in the asymmetric cyclopropanation with good yields, excel-
lent diastereoselectivities, and high enantioselectivities, up
to 99%ee[9] (Figure 1).
Introduction
Phosphonium ylides are very important intermediates in
modern organic chemistry, especially because of their use
in the formation of C=C bonds in Wittig-type reactions.
Another important group are sulfonium ylides, which are
used for the synthesis of epoxides, substituted aziridines,
and cyclopropanes.[1] Chiral sulfonium ylides have been ap-
plied in asymmetric synthesis with good yield, and high dia-
stereo- and enantioselectivities.[2] Selenonium ylides are less
common and, until now, only a few examples of their appli-
cations have been reported.[3] They have similar reactivity
to sulfonium analogues and can be easily formed by the
reaction of selenonium salts with bases. For example, non-
enolizable carbonyl compounds 1 were used for selenium-
mediated epoxidation by the reaction of selenonium salts 2
and tBuOK (Scheme 1).[4]
Figure 1. Chiral selenides used for asymmetric epoxidation and
cyclopropanation.
Well-known sulfonium ylides have found interesting ap-
plications in asymmetric synthesis. For example, isothio-
cineole 9 (Figure 2), derived from limonene, was used for
asymmetric epoxidation and aziridination with high en-
antio- and diastereoselectivities,[2] and it was used in the key
step of the quinine and quinidine synthesis.[10]
Scheme 1. Application of selenonium salts in epoxidation reactions.
Selenonium ylides were also used for the synthesis of
cyclopropane derivatives. They were generated by the reac-
tion of selenonium salt with sodium hydroxide[5] or selenide
with carbene.[6] The first example of the use of chiral sele-
Here, we report the synthesis of the selenium analogue
10 of sulfide 9 (Figure 2), and compare their reactivity in
sulfur- and selenium-mediated asymmetric epoxidation.
Recently, we presented our results on asymmetric epoxid-
ation through the use of methyl terpenyl, phenyl terpenyl,
and diterpenyl sulfides derived from monoterpenes from p-
[a] Department of Organic Chemistry, Faculty of Chemistry,
Nicolaus Copernicus University in Torun´,
7 Gagarin Street, 87-100 Torun, Poland
E-mail: jsch@chem.umk.pl
http://www.chem.umk.pl/
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201500211.
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CSD.[13] The C12–Se6–C7 angle was 104.8(2)°, and the
C10–C7–Se6–C12 torsion angle was –8.2(5)°. Although the
accessible surface of C12 is limited by the C10 methyl, the
phenyl ring, as well as a fragment of the terpenyl moiety,
electrophilic attack on C12 in the ylide should be easier
than for the sulfur analogue.[2]
Figure 2. Structures of isothiocineole 9 and isoselenocineole 10.
menthane, carane, and pinane group.[11] We therefore de-
cided to prepare the selenium analogues and to compare
their reactivity in selenium-mediated asymmetric epoxid-
ation.
Results and Discussion
The first goal of our investigation was the synthesis of
the selenium analogue of isothiocineole 9. Selenide 10 has
been prepared by a methodology similar to that of its sulfur
analogue (Scheme 2).[2] The reaction of limonene with sel-
enium in the presence of γ-terpinene at 130 °C gave iso-
selenocineole 10 with 68% yield.
Scheme 3. Synthesis of selenonium salts 11 and 12.
Scheme 2. Synthesis of isoselenocineole 10.
Selenide 10 was used for the synthesis of triflane salt 11
by application of Aggarwal’s methodology,[2] and tetra-
fluoroborate salt 12 was prepared by stirring selenide 10
with benzyl bromide in the presence of AgBF4 (Scheme 3).
The structure of selenonium salt 12 was confirmed by X-
ray analysis (Figure 3). The asymmetric part of the crystal
–
Figure 3. X-ray structure of selenonium salt 12. The BF4 anion
reveals significant rotational disorder in the crystal lattice.
–
structure (ASU) contains a selenonium cation and a BF4
anion. The absolute configuration (1R,4R,5R,6R) was de-
Selenonium salts 11 and 12 were used for the asymmetric
termined by the Flack method.[12] A tetrahedral geometry synthesis of epoxystilbene (Table 1). Aggarwal obtained the
around Se atom was found, with the Se distance between triflate sulfonium salt from isothiocineole, benzyl bromide,
the plane defined by three C atoms being 0.955(3) Å. The and AgOTf, and they used it to synthesize trans-epoxystil-
observed Se6–C7 and Se6–C12 distances (2.038(5) and bene with good yield with high diastereoselectivity and
1.956(5) Å), are approximately 0.15–0.2 Å longer than enantioselectivity (entry 1).[2] Under the same reaction con-
those of S–C bonds in similar compounds as verified with ditions, triflate selenonium salt 11 gave the product with
Table 1. Asymmetric epoxidation with isothiocineole and isoselenocineole salts.
Entry
X
Y–
Base
Solvent
Reaction conditions
Yield [%]
cis/trans[a]
er (SS/RR)[b]
1
2
3
4
S
OTf–
OTf–
OTf–
KOH
KOH
NaOH
NaOH
MeCN/H2O (9:1) 24 h, 0 °C
MeCN/H2O (9:1) 24 h, 0 °C
77
11
31
45
5:95
71:29
40:60
38:62
99:1
52:48
84:16
84:16
Se
Se
Se
MeCN
MeCN
3 d, room temp.
3 d, room temp.
–
BF4
[a] Determined on the basis of 1H NMR spectroscopy. [b] Determined on the basis of HPLC analysis using a Chiralcel Daicel OD-H
column.
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Terpenyl Selenides in Asymmetric Epoxidation
only 11% yield, and the major product was the cis-com- methyl iodide or benzyl bromide (Scheme 5, Path a,
pound. Lack of enantioselectivity for the trans product was Method a).
observed (entry 2). Under anhydrous conditions, used for
Phenyl terpenyl selenides were prepared by using sodium
sulfur compounds in our previous work (entries 3 and 4),[11] phenyl selenolate with terpenyl tosylates, chlorides, or epox-
an increase in the diastereoselectivity and enantioselectivity ides (Scheme 5, Path b). Diterpenyl selenides were obtained
–
was observed. The best yield was obtained when BF4
counteranion was chosen.
in the reaction of terpenylsodium selenolates with terpenyl
tosylates or in the reaction of sodium diselenide with epox-
We also assessed the use of isoselenocineole 10 for the ides (Scheme 5, Path c).
one-pot synthesis of epoxy stilbene without isolating the
Alternatively, methyl terpenyl selenides were synthesized
selenonium salt (Scheme 4). Similar diastereoselectivity and in the one-pot reaction of diselenides with NaBH4 and
enantioselectivity were obtained, but a decrease in the yield methyl iodide (Scheme 6, Method b).
was observed.
Scheme 4. One-pot synthesis of epoxy stilbene.
Scheme 6. One-pot synthesis of methyl terpenyl selenides.
In the second step of our investigation, we prepared a
series of methyl terpenyl 13–19, benzyl terpenyl 20, 21,
Terpenyl tosylates, chlorides, and epoxides have been pre-
phenyl terpenyl 22–28, and diterpenyl selenides 29–34. Rep- pared according to methodologies described in our previous
resentative examples of the synthesis of the p-menthane works.[14] Using these paths, we have also prepared selenides
group are presented in Scheme 5.
from carane and pinane systems (Figure 4).
Methyl and benzyl terpenyl selenides were prepared in
Encouraged by the asymmetric epoxidation with iso-
the reaction of terpenyl selenols with sodium hydride and selenocineole salts, we prepared benzyl methyl menthyl and
Scheme 5. Synthesis of methyl terpenyl 13, 14, benzyl terpenyl 20, 21, phenyl terpenyl 22, 23, and diterpenyl selenides 29.
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Scheme 7. Synthesis of selenonium salts 35 and 36.
Table 2. Results of the epoxidation reactions.
Entry[a] Salt/selenide Yield [%] Ratio cis/trans[a] Ratio trans (SS/RR)[b]
1
2
3
4
5
6
7
8
35
36
35
13
14
15
16
17
18
19
22
23
24
25
26
27
28
29
30
31
32
33
34
89
32
85
22
70
8
45:55
50:50
43:57
55:45
58:42
54:46
70:30
51:49
60:40
54:46
58:42
4:96
53:47
52:48
77:23
44:56
64:36
58:42
58:42
58:42
65:35
58:42
11:89
53:47
50:50
30:70
–
6
10
12
56
20
55
10
12
0
0
13
7
10
10
11
12
40
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Figure 4. Selenides from carane and pinane groups. [a] Prepared by
Method a. [b] Prepared by Method b.
36:64
36:64
–
benzyl methyl neomenthyl selenonium salts 35 and 36. We
tested three methodologies for their synthesis: (a) the reac-
tion of methyl menthyl selenide with benzyl bromide in the
presence of AgBF4; (b) the reaction of benzyl menthyl
selenide with Meerwein’s reagent, and (c) the reaction of
benzyl menthyl selenide with methyl iodide in the presence
of AgBF4. The results are presented in Scheme 7. In the
case of 36, the product was an almost equimolar mixture
of two diastereoisomers. The selenonium salt 35 was ob-
tained as an approximate 70:30 mixture of two diastereoiso-
mers. The main diastereoisomer was isolated by column
–
–
38:62
16:84
52:48
33:67
58:42
50:50
53:47
42:58
51:49
59:41
60:40
13:87
61:49
45:55
[a] Determined on the basis of 1H NMR spectroscopy. [b] Deter-
mined on the basis of HPLC analysis using a Chiralcel Daicel OD-
H column.
chromatography (silica gel; CH2Cl2/MeOH, 90:10). How- selenides 13–19 (entries 4–10), the best diastereoselectivity
ever, attempts at crystallization from CH2Cl2/heptane at was observed for methyl isocaranyl selenide 16 (entry 7).
room temperature led back to the initial mixture.
Introduction of a hydroxyl group into this system (selenide
Selenonium salts 35 and 36 were used for the asymmetric 18) led to an increase in enantioselectivity and gave the best
epoxidation by reaction with benzaldehyde and sodium result (entry 9). Similar enantioselectivity was observed for
hydroxide (Table 2, entries 1 and 2); however, a lack of dia- methyl neomenthyl selenide 14 with the dominating S,S-
stereoselectivity and enantioselectivity was observed. Sig- enantiomer (entry 5).
nificant increase of enantioselectivity was observed when
Interestingly, the epimeric methyl menthyl selenide 13
one isolated diastereomer of 35 was used (entry 3).
gave the opposite enantiomer predominantly (Table 2, en-
The use of selenides 13–19 and 22–34 for the one-pot try 4). A similar dependence for phenyl neomenthyl 23 and
synthesis of epoxystilbene without isolation of the sele- phenyl menthyl selenides 22 was observed (entries 11 and
nonium salt resulted in higher diastereo- and enantio- 12). Among all tested compounds, selenide 23 gave the
selectivities (Table 2, entry 3–22). Among methyl terpenyl highest diastereoselectivity 96:4 (trans/cis), whereas selenide
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Terpenyl Selenides in Asymmetric Epoxidation
isolated by distillation under reduced pressure and purified by dis-
tillation (60–62 °C/0.5 Torr), yield 18.268 g (68%); yellow liquid;
22 gave the best enantioselectivity (11:89). Very high
enantioselectivity was also observed for symmetric selenides
32 from the carane group, containing a hydroxyl group (en-
try 21). For selenides 26 and 27 we could not isolate the
product (entries 15 and 16). Comparison of the diastereo-
selectivity and enantioselectivity of the epoxidation reaction
of terpenyl sulfides obtained in our previous work[11] with
these terpenyl selenides, reveal that sulfides in general led
to high diastereoselectivities but low enantioselectivities,
1
[α]2D2 = +55.51 (c = 0.41, CHCl3). H NMR (700 MHz, CDCl3): δ
= 1.14 (d, J = 7.7 Hz, 3 H, CH3), 1.23 (dq, J = 1.4, 14.0 Hz, 1 H),
1.53–1.57 (m, 1 H), 1.58 (s, 3 H, CH3), 1.64–1.67 (m, 1 H), 1.68 (s,
3 H, CH3), 1.83 (d, J = 2.8 Hz, 1 H), 1.99–2.05 (m, 1 H), 2.15 (dq,
J = 2.8, 13.3 Hz, 1 H), 2.37 (dt, J = 1.4, 12.6 Hz, 1 H), 2.43–2.50
(m, 1 H), 3.72 (s, 1 H) ppm. 13C NMR (100.6, CDCl3): δ = 18.7
(CH3), 23.7 (CH2), 24.5 (CH2), 27.0 (CH3), 35.4 (CH), 35.6 (CH3),
36.1 (CH2), 48.8 (CH), 49.9 (CH), 50.2 (C) ppm. 77Se NMR
whereas terpenyl selenides gave low to moderate diastereo- (76.3 MHz, CDCl ): δ = 481.70 ppm. IR (film): ν = 2937, 1457,
˜
3
1379, 1130, 1083, 1037 cm–1. C10H18Se (217.21): calcd. C 55.30, H
selectivities but, in some cases, very good enantioselectivit-
ies. Introduction of the phenyl group instead of the methyl
8.35; found C 55.54, H 8.27.
group led to higher enantioselectivities for both sulfides and
selenides.
Synthesis of Methyl Terpenyl Selenides; General Procedure
(Method a): A solution of selenol (2.5 mmol) in anhydrous petro-
leum ether (5 mL) was carefully added to a suspension of NaH
(0.121 g, 5.0 mmol) in anhydrous petroleum ether (5 mL). The mix-
ture was kept for 0.5 h at ambient temperature under an argon
atmosphere. Methyl iodide (160 μL, 2.6 mmol) was added and the
mixture was stirred for 24 h, then poured into water (75 mL) and
extracted with diethyl ether (3ϫ 50 mL). The combined ethereal
layers were dried with anhydrous MgSO4, and the solvent was evap-
orated. A crude product was purified by the column chromatog-
raphy (petroleum ether) to give the pure methyl terpenyl selenide.
Conclusions
Convenient methodologies for the synthesis of selenides
and selenonium salts derived from p-menthane, carane, and
pinane groups have been proposed. Both selenides and
selenonium salts were successfully used for selenium-medi-
ated asymmetric epoxidation. Comparison of results of
epoxidation obtained through the use of cyclic sulfide and
selenide – isothiocineole and isoselenocineole, revealed bet-
ter diastereo- and enantioselectivities for the sulfide. Our
results reveal that the nature of the solvent (more polar
solvents decrease stereoselectivity of reaction) and
counteranion are important factors affecting the yield, dia-
stereoselectivity, and enantioselectivity. Furthermore, the
use of selenonium salt with a significant excess of one dia-
stereoisomer resulted in better enantioselectivity of the
epoxidation reaction. The use of pure diastereoisomer pro-
vided higher enantioselectivity. On the other hand, probable
isomerization during the epoxidation can decrease the
enantioselectivity of the reaction.
Method b: NaBH4 (0.40 g, 10.7 mmol) was carefully added to the
diselenide (1.64 mmol) in methanol (15 mL) under an argon atmo-
sphere. Methyl iodide (1.15 g, 8.1 mmol) was added and the mix-
ture was stirred for 24 h. The solution was poured into water
(8 mL) and extracted with diethyl ether (3ϫ 5 mL). The combined
ethereal layers were dried with anhydrous MgSO4, and the solvent
was evaporated. The crude product was purified by column
chromatography to give pure methyl terpenyl selenide.
(1R,2S,5R)-(–)-Menthyl Methyl Selenide (13): Purification by col-
umn chromatography on silica gel (PE), yield 0.292 g (50%;
Method a), 0.756 g (99%, Method b); yellow liquid; [α]2D6 = –72.26
1
(c = 0.91, CHCl3). H NMR (700 MHz, CDCl3): δ = 0.75 (d, J =
6.3 Hz, 3 H, CH3), 0.88 (d, J = 6.3 Hz, 3 H, CH3), 0.90 (d, J =
7.0 Hz, 3 H, CH3), 1.03 (ddd, J = 3.5, 12.6, 21.7 Hz, 1 H), 1.18–
1.28 (m, 2 H), 1.33–1.41 (m, 1 H), 1.69 (dq, J = 3.5, 13.3 Hz, 1 H),
1.72–1.76 (m, 1 H), 1.91 (s, 3 H, CH3), 2.16 (dq, J = 2.1, 12.6 Hz,
1 H), 2.27–2.32 (m, 1 H), 2.67 (dt, J = 4.2, 11.9 Hz, 1 H) ppm. 13
C
NMR (176.1, CDCl3): δ = 2.7 (CH3), 16.5 (CH3), 22.9 (CH3), 23.6
(CH3), 26.2 (CH2), 30.3 (CH), 35.6 (CH), 36.2 (CH2), 44.6 (CH),
45.6 (CH2), 48.7 (CH) ppm. 77Se NMR (76.3 MHz, CDCl3): δ =
Experimental Section
General: Melting points were measured with a Büchi Tottoli SPM-
20 heating unit and are uncorrected. NMR spectra were recorded
with a Bruker Avance III (400 MHz) or Bruker Avance III
(700 MHz) for 1H and 176.1 MHz or 100.6 MHz for 13C. Chemical
shifts are expressed in parts per million (ppm) relative to TMS. 77Se
NMR spectra were recorded with a Bruker Avance III/ 400 or
Bruker Avance III/ 700 with diphenyl diselenide as an external stan-
dard. Elemental analyses were performed with a Vario MACRO
CHN analyzer. TLC was conducted on precoated silica gel plates
(Merck 60F254) and the spots were visualized under UV light. Col-
umn chromatography was carried out with column using Silica Gel
60 Merck (70–230 mesh). All reactions requiring anhydrous condi-
tions were conducted in flame-dried apparatus.
148.76 ppm. IR (film): ν = 2925, 1455, 1385, 1368, 1180, 897 cm–1.
˜
C11H22Se (233.25): calcd. C 56.64, H 9.51; found C 56.38, H 9.58.
(1S,2S,5R)-(+)-Methyl Neomenthyl Selenide (14): Purification by
the column chromatography on silica gel (PE), yield 0.554 g (95%;
Method a), 0.749 g (98%; Method b); yellow liquid; [α]2D3 = +94.47
1
(c = 0.48, CHCl3). H NMR (700 MHz, CDCl3): δ = 0.89 (d, J =
7.0 Hz, 3 H, CH3), 0.91 (d, J = 6.3 Hz, 3 H, CH3), 0.94 (d, J =
6.3 Hz, 3 H, CH3), 1.05–1.12 (m, 1 H), 1.30 (ddd, J = 2.8, 11.2,
13.3 Hz, 1 H), 1.56–1.62 (m, 1 H), 1.70–1.76 (m, 2 H), 1.85–1.94
(m, 1 H), 1.95 (s, 3 H, CH3), 2.00 (dq, J = 2.1, 13.3 Hz, 1 H), 3.26
(t, J = 2.5 Hz, 1 H) ppm. 13C NMR (176.1, CDCl3): δ = 5.4 (CH3),
22.2 (CH3), 22.4 (CH3), 23.5 (CH3), 28.3 (CH2), 29.1 (CH), 32.7
(CH), 36.7 (CH2), 42.7 (CH2), 48.2 (CH), 50.8 (CH) ppm. 77Se
Isoselenocineole (10): Selenium was added to a mixture of limonene
(20 mL, 124.0 mmol) and γ-terpinene (19.85 mL, 124.0 mmol), and
the reaction mixture was stirred and heated at 130 °C for 8 h. An
additional portion of selenium (7.777 g, 99.2 mmol) and γ-terpin-
ene (21.85 mL, 136.0 mmol) was added and the solution was stirred
for 16 h at 130 °C. The solution was cooled and the product was
NMR (76.3 MHz, CDCl ): δ = 64.67 ppm. IR (film): ν = 2920,
˜
3
1474, 1455, 1383, 1272, 1230, 1184, 891 cm–1. C11H22Se (233.25):
calcd. C 56.64, H 9.51; found C 56.88, H 9.47.
(1S,3R,4S,6R)-(+)-4-Caranyl Methyl Selenide (15): Purification by
the column chromatography on silica gel (PE), yield 0.318 g (55%;
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Method a); yellow liquid; [α]2D3 = +18.78 (c = 1.45, CHCl3). 1H
(CH3), 33.4 (CH2), 33.7 (CH2), 38.6 (C), 41.3 (CH), 41.6 (CH),
NMR (700 MHz, CDCl3): δ = 0.55 (ddd, J = 5.6, 8.4, 8.4 Hz, 1
46.3 (CH) ppm. 77Se NMR (133.6 MHz, CDCl3): δ = 62.23 ppm.
H), 0.65 (ddd, J = 6.3, 8.4, 8.4 Hz, 1 H), 0.80–0.86 (m, 1 H), 0.93 IR (film): ν = 2919, 1467, 1422, 1383, 1366, 1274, 1210 cm–1.
˜
(d, J = 7.0 Hz, 3 H, CH3), 0.96 (s, 3 H, CH3), 0.97 (s, 3 H, CH3),
1.41 (ddd, J = 6.3, 8.4, 14.7 Hz, 1 H), 1.78–1.88 (m, 2 H), 1.94 (s,
3 H, CH3), 2.26 (ddd, J = 7.0, 9.1, 15.4 Hz, 1 H), 3.03 (q, J =
8.4 Hz, 1 H) ppm. 13C NMR (176.1, CDCl3): δ = 6.0 (CH3), 17.2
(CH3), 19.0 (C), 21.5 (CH3), 22.8 (CH), 22.8 (CH), 27.0 (CH2),
29.9 (CH3), 31.1 (CH2), 32.6 (CH), 45.5 (CH) ppm. 77Se NMR
C11H20Se (231.24): calcd. C 57.14, H 8.72; found C 57.37, H 8.65.
Synthesis of Benzyl Terpenyl Selenides; General Procedure: A solu-
tion of selenol (4.6 mmol) in anhydrous petroleum ether (3 mL)
was carefully added to a suspension of NaH (0.250 g, 10.4 mmol)
in anhydrous petroleum ether (3 mL). The mixture was kept for
0.5 h at ambient temperature under an argon atmosphere. Benzyl
bromide (0.750 g, 4.4 mmol) was added and the mixture was stirred
for 3 h. The solution was poured into water (30 mL) and extracted
with diethyl ether (3ϫ 30 mL). The combined ethereal layers were
dried with anhydrous MgSO4, and the solvent was evaporated. A
crude product was purified by the column chromatography to give
pure benzyl terpenyl selenide.
(76.3 MHz, CDCl ): δ = 123.66 ppm. IR (film): ν = 2924, 2863,
˜
3
1455, 1375, 1273, 1195, 1129, 898 cm–1. C11H20Se (231.24): calcd.
C 57.14, H 8.72; found C 57.51, H 8.61.
(1S,3R,4R,6R)-(+)-4-Isocaranyl Methyl Selenide (16): Purification
by the column chromatography on silica gel (PE), yield 0.254 g
(44%; Method a); yellow liquid; [α]2D3 = –60.48 (c = 1.45, CHCl3).
1H NMR (700 MHz, CDCl3): δ = 0.57 (ddd, J = 2.1, 8.4, 9.8 Hz,
1 H), 0.75 (ddd, J = 4.9, 9.8, 9.8 Hz, 1 H), 0.83 (ddd, J = 5.6, 11.9,
14.7 Hz, 1 H), 0.95 (s, 3 H, CH3), 0.96 (s, 3 H, CH3), 1.00 (d, J =
7.0 Hz, 3 H, CH3), 1.29–1.37 (m, 1 H), 1.92 (s, 3 H, CH3), 1.97–
2.02 (m, 2 H), 2.15 (ddd, J = 1.4, 6.3, 14.7 Hz, 1 H), 2.24 (dt, J =
6.3, 10.5 Hz, 1 H) ppm. 13C NMR (176.1, CDCl3): δ = 2.2 (CH3),
15.6 (CH3), 17.5 (C), 20.6 (CH), 20.7 (CH), 21.6 (CH3), 28.9 (CH3),
29.2 (CH2), 29.4 (CH2), 34.5 (CH), 44.5 (CH) ppm. 77Se NMR
(1R,2S,5R)-(–)-Benzyl Menthyl Selenide (20): Purification by the
column chromatography on silica gel (PE/EtOAc, 90:10), yield
1
0.299 g (22%); yellow liquid; [α]2D5 = –69.52 (c = 1.66, CHCl3). H
NMR (700 MHz, CDCl3): δ = 0.66 (d, J = 6.8 Hz, 3 H, CH3), 0.89
(d, J = 7.2 Hz, 3 H, CH3), 0.92 (d, J = 6.4 Hz, 3 H, CH3), 1.23–
1.33 (m, 3 H), 1.33–1.41 (m, 2 H), 1.67–1.79 (m, 2 H), 2.24 (dq, J
= 2.0, 9.2 Hz, 1 H), 2.27–2.36 (m, 1 H), 2.71 (ddd, J = 4.0, 12.0,
12.0 Hz, 1 H), 3.82 (s, 2 H, CH2), 7.18–7.24 (m, 1 H, ArH), 7.27–
7.36 (m, 4 H, ArH) ppm. 13C NMR (176.1, CDCl3): δ = 15.0
(CH3), 21.5 (CH3), 22.3 (CH3), 25.0 (CH2), 25.5 (CH2), 29.0 (CH),
34.3 (CH), 34.9 (CH2), 44.0 (CH), 45.2 (CH2), 47.5 (CH), 126.5
(CHAr), 128.4 (2ϫCHAr), 129.0 (2ϫCHAr), 140.0 (CAr) ppm. 77Se
(76.3 MHz, CDCl ): δ = 175.85 ppm. IR (film): ν = 2924, 2864,
˜
3
1455, 1375, 898 cm–1. C11H20Se (231.24): calcd. C 57.14, H 8.72;
found C 56.92, H 8.77.
(1S,3R)-(–)-trans-3-Hydroxy-4-caranyl Methyl Selenide (17): Purifi-
cation by the column chromatography on silica gel (dichlorometh-
ane/ethyl acetate, 80:20), yield 0.292 g (36%; Method b); yellow
liquid; [α]2D0 = –70.80 (c = 1.50, CHCl3). 1H NMR (700 MHz,
CDCl3): δ = 0.53 (t, J = 9.1 Hz, 1 H), 0.77 (ddd, J = 4.9, 9.1,
9.8 Hz, 1 H), 0.95 (s, 3 H, CH3), 0.98 (s, 3 H, CH3), 1.19 (s, 3 H,
CH3), 1.27 (ddd, J = 1.4, 4.9, 14.7 Hz, 1 H), 2.00 (s, 3 H, CH3),
2.01–2.09 (m, 2 H), 2.28 (dd, J = 7.7, 15.4 Hz, 1 H), 2.53 (dd, J =
7.0, 12.6 Hz, 1 H) ppm. 13C NMR (CDCl3): δ = 5.5 (CH3), 15.3
(CH3), 17.7 (C), 20.3 (CH), 20.5 (CH), 23.1 (CH3), 28.8 (CH3),
29.0 (CH2), 33.4 (CH2), 53.7 (CH), 71.9 (C) ppm. 77Se NMR
NMR (133.5 MHz, CDCl ): δ = 519.33 ppm. IR (film): ν = 2929,
˜
3
1676, 1487, 1455, 1246, 1181, 1022, 736 cm–1. C17H26Se (309.35):
calcd. C 66.00, H 8.47; found C 66.17, H 8.40.
(1S,2S,5R)-(+)-Benzyl Neomenthyl Selenide (21): Purification by
the column chromatography on silica gel (PE/EtOAc, 90:10), yield
1.010 g (73%); yellow liquid; [α]2D3 = +114.51 (c = 0.55, CHCl3). 1H
NMR (700 MHz, CDCl3): δ = 0.72 (d, J = 7.0 Hz, 3 H, CH3), 0.87
(d, J = 6.3 Hz, 3 H, CH3), 0.89 (d, J = 6.3 Hz, 3 H, CH3), 1.01–
1.05 (m, 1 H), 1.26–1.32 (m, 2 H), 1.52–1.57 (m, 1 H), 1.70–1.77
(m, 2 H), 1.90–1.95 (m, 2 H), 3.27 (t, J = 2.1 Hz, 1 H), 3.73 (d, J
= 11.9 Hz, 1 H), 3.78 (d, J = 11.9 Hz, 1 H), 7.17–7.20 (m, 1 H,
(76.3 MHz, CDCl ): δ = 91.07 ppm. IR (film): ν = 3391, 2925,
˜
3
2349, 1454, 1372, 1130, 922 cm–1. C11H20OSe (247.24): calcd. C
ArH), 7.22–7.28 (m, 2 H, ArH), 7.28–7.33 (m, 2 H, ArH) ppm. 13
C
53.44, H 8.15; found C 53.38, H 8.23.
NMR (176.1, CDCl3): δ = 20.6 (CH3), 21.2 (CH3), 22.4 (CH3), 27.0
(CH2), 27.6 (CH), 28.1 (CH2), 31.3 (CH), 35.5 (CH2), 42.0 (CH2),
45.3 (CH), 49.6 (CH), 126.7 (CHAr),128.5 (2ϫCHAr), 129.1
(2ϫCHAr), 140.0 (CAr) ppm. 77Se NMR (76.3 MHz, CDCl3): δ =
(1S,3S)-(+)-cis-3-Hydroxy-4-isocaranyl Methyl Selenide (18): Puri-
fication by the column chromatography on silica gel (dichlorometh-
ane/ethyl acetate, 95:5), yield 0.349 g (43%; Method b); yellow li-
quid; [α]2D2 = +57.10 (c = 1.41, CHCl3). 1H NMR (700 MHz,
CDCl3): δ = 0.67–0.77 (m, 2 H), 0.94 (s, 3 H, CH3), 0.97 (s, 3 H,
CH3), 1.22 (s, 3 H, CH3), 1.28 (dd, J = 7.0, 16.1 Hz, 1 H), 1.94
(dd, J = 8.4, 15.4 Hz, 1 H), 1.98 (s, 3 H, CH3), 2.29 (ddd, J = 5.6,
8.4, 14.7 Hz, 2 H), 2.85 (q, J = 5.6 Hz, 1 H) ppm. 13C NMR
(CDCl3): δ = 6.4 (CH3), 16.8 (CH3), 19.9 (CH), 20.0 (C), 24.3 (CH),
27.7 (CH2), 29.6 (CH3), 29.7 (CH3), 34.1 (CH2), 52.2 (CH), 74.1
(C) ppm. 77Se NMR (76.3 MHz, CDCl3): δ = 124.66 ppm. IR
243.07 ppm. IR (film): ν = 3070, 2933, 1576, 1465, 1448, 1376,
˜
1234, 1022, 856, 739 cm–1. C17H26Se (309.35): calcd. C 66.00, H
8.47; found C 66.15, H 8.41.
Synthesis of Phenyl Terpenyl Selenides; General Procedure: NaBH4
(0.3 g, 8.0 mmol) was carefully added to a solution of diphenyl di-
selenide (0.605 g, 1.9 mmol) in methanol (30 mL) under an argon
atmosphere. Tosylate (3.9 mmol) in methanol (20 mL) was added
and the mixture was stirred for 24 h at 50 °C. Methanol was evapo-
rated, water (100 mL) was added, and the product was extracted
with petroleum ether (3ϫ 100 mL). The combined ethereal layers
were dried with anhydrous MgSO4, and the solvent was evaporated.
A crude product was purified by column chromatography (petro-
leum ether) to give pure phenyl terpenyl selenide.
(film): ν = 3429, 2926, 2864, 2359, 1456, 1375, 1131, 919 cm–1.
˜
C11H20OSe (247.24): calcd. C 53.44, H 8.15; found C 53.51, H 8.13.
(1S,2R,5S)-(–)-Methyl Myrtanyl Selenide (19): Purification by the
column chromatography on silica gel (PE), yield 0.335 g (58%;
Method a); yellow liquid; [α]2D5 = –36.01 (c = 1.55, CHCl3). 1H
NMR (700 MHz, CDCl3): δ = 0.87 (d, J = 9.8 Hz, 1 H, CH), 0.98 (1R,2S,5R)-(–)-Menthyl Phenyl Selenide (22): Purification by col-
(s, 3 H, CH3), 1.17 (s, 3 H, CH3), 1.47–1.52 (m, 1 H), 1.81–1.86 umn chromatography on silica gel (PE), yield 0.067 g (6%); yellow
(m, 1 H), 1.86–1.89 (m, 1 H), 1.90–1.94 (m, 1 H), 1.94 (s, 3 H,
CH3), 1.99–2.04 (m, 2 H), 2.22–2.27 (m, 1 H), 2.31–2.35 (m, 1 H),
liquid; [α]2D5 = –62.59 (c = 0.95, CHCl3). 1H NMR (700 MHz,
CDCl3): δ = 0.80 (d, J = 6.3 Hz, 3 H, CH3), 0.85 (d, J = 6.3 Hz, 3
2.62 (ddd, J = 7.7, 11.9, 26.6 Hz, 2 H) ppm. 13C NMR (176.1, H, CH3), 0.88–0.94 (m, 1 H), 0.95 (d, J = 7.0 Hz, 3 H, CH3), 1.06–
CDCl3): δ = 4.1 (CH3), 23.0 (CH2), 23.3 (CH3), 26.2 (CH2), 28.0 1.12 (m, 1 H), 1.25–1.37 (m, 3 H), 1.72–1.78 (m, 2 H), 2.10 (dq, J
3482
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© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 3477–3485

Terpenyl Selenides in Asymmetric Epoxidation
= 2.1, 13.3 Hz, 1 H), 2.41–2.49 (m, 1 H), 3.10 (dt, J = 7.0, 11.9 Hz,
(100.6 MHz, CDCl3): δ = 15.4 (CH3), 18.3 (CH), 18.8 (C), 22.8
1 H), 7.28–7.32 (m, 3 H, ArH), 7.57–7.61 (m, 2 H, ArH) ppm. 13C (CH), 26.6 (CH2), 28.3 (CH3), 28.6 (CH3), 33.0 (CH2), 54.2 (CH),
NMR (176.1 MHz, CDCl3): δ = 16.1 (CH3), 22.4 (CH3), 23.1 72.7 (CH), 127.3 (CHAr), 129.1 (2ϫCHAr), 130.3 (CAr), 134.0
(CH3), 26.0 (CH2), 30.1 (CH), 35.3 (CH), 35.7 (CH2), 45.9 (CH2), (2ϫCHAr) ppm. 77Se NMR (76.3 MHz, CDCl3): δ = 342.42
48.7 (CH), 49.4 (CH), 128.3 (CHAr), 129.8 (2ϫCHAr), 130.0 (CAr), (Se) ppm. IR (film): ν = 3435, 2942, 2346, 1579, 1477, 1437, 1375,
˜
136.5 (2ϫCHAr) ppm. 77Se NMR (76.3 MHz, CDCl3):
δ
=
1130, 920, 870, 836 cm–1. C16H22OSe (309.31): calcd. C 62.13, H
377.33 ppm. IR (film): ν = 2925, 1653, 1540, 1507, 1457, 1178, 7.17; found C 62.34, H 7.11.
˜
1022, 735 cm–1. C16H24Se (295.32): calcd. C 65.07, H 8.19; found
C 64.91, H 8.25.
(1S,3R)-(–)-(cis)-3-Hydroxy-4-isocaranyl Phenyl Selenide (27): Puri-
fication by the column chromatography on silica gel (PE), yield
0.693 g (59%); yellow liquid; [α]2D0 = –80.96 (c = 0.52, CHCl3). H
1
(1S,2S,5R)-(+)-Neomenthyl Phenyl Selenide (23): Purification by
the column chromatography on silica gel (PE), yield 0.236 g (21%);
yellow liquid; [α]2D5 = +100.04 (c = 0.65, CHCl3). 1H NMR
(700 MHz, CDCl3): δ = 0.85 (d, J = 7.0 Hz, 3 H, CH3), 0.87 (d, J
NMR (700 MHz, CDCl3): δ = 0.63 (t, J = 8.4 Hz, 1 H), 0.85 (ddd,
J = 4.9, 9.8, 9.8 Hz, 1 H), 1.00 (s, 3 H, CH3), 1.01 (s, 3 H, CH3),
1.32 (s, 3 H, CH3), 1.38 (ddd, J = 4.2, 4.9, 13.3 Hz, 1 H), 2.17 (dd,
= 7.0 Hz, 3 H, CH3), 0.87–0.90 (m, 1 H), 0.91 (d, J = 7.0 Hz, 3 H, J = 10.5, 14.7 Hz, 1 H), 2.25 (ddd, J = 4.9, 6.3, 14.7 Hz, 1 H), 2.42
CH3), 0.99–1.02 (m, 1 H), 1.12 (ddd, J = 3.5, 12.6, 25.2 Hz, 1 H),
(dd, J = 7.0, 14.7 Hz, 1 H), 3.08 (dd, J = 7.7, 12.6 Hz, 1 H), 7.27–
1.30 (ddd, J = 3.5, 12.6, 14.7 Hz, 1 H), 1.63–1.69 (m, 1 H), 1.73– 7.30 (m, 3 H, ArH), 7.58–7.60 (m, 2 H, ArH) ppm. 13C NMR
1.77 (m, 1 H), 1.77–1.81 (m, 1 H), 1.94–1.99 (m, 2 H), 3.69 (t, J = (100.6 MHz, CDCl3): δ = 16.4 (CH3), 18.8 (C), 21.4 (CH), 21.7
2.8 Hz, 1 H), 7.21–7.24 (m, 3 H, ArH), 7.53–7.54 (m, 2 H,
(CH), 24.5 (CH3), 29.7 (CH3), 30.9 (CH2), 34.5 (CH2), 59.0 (CH),
72.7 (CH), 128.3 (CHAr), 130.2 (2ϫCHAr), 131.3 (CAr), 134.6
ArH) ppm. 13C NMR (176.1, CDCl3): δ = 20.7 (CH3), 21.0 (CH3),
22.1 (CH3), 27.2 (CH2), 27.8 (CH), 31.4 (CH), 35.3 (CH2), 41.9 (2ϫCHAr) ppm. 77Se NMR (76.3 MHz, CDCl3): δ = 316.10
(CH2), 49.6 (CH), 50.5 (CH), 126.9 (CHAr),128.9 (2ϫCHAr), 130.8 (Se) ppm. IR (film): ν = 3448, 2937, 2864, 2346, 1578, 1477, 1438,
˜
(CAr), 134.2 (2ϫCHAr) ppm. 77Se NMR (133.5 MHz, CDCl3): δ =
1375, 1217, 1114, 927, 756 cm–1. C16H22OSe (309.31): calcd. C
288.89 ppm. IR (film): ν = 3071, 2922, 1580, 1476, 1455, 1384, 62.13, H 7.17; found C 61.97, H 7.20.
˜
1278, 1230, 1182, 1022, 857, 738 cm–1. C16H24Se (295.32): calcd. C
65.07, H 8.19; found C 65.28, H 8.05.
(1S,2R,5S)-(–)-Myrtanyl Phenyl Selenide (28): Purification by the
column chromatography on silica gel (PE), yield 0.613 g (55%);
(1S,3R,4S,6R)-(+)-4-Caranyl Phenyl Selenide (24): Purification by
yellow liquid; [α]2D3 = –40.69 (c = 1.76, CHCl3). 1H NMR
the column chromatography on silica gel (PE), yield 0.379 g (34%); (700 MHz, CDCl3): δ = 0.86 (d, J = 9.8 Hz, 1 H), 1.00 (s, 3 H,
yellow liquid; [α]2D3 = +49.09 (c = 1.65, CHCl3). 1H NMR
(700 MHz, CDCl3): δ = 0.55 (ddd, J = 6.3, 9.1, 9.1 Hz, 1 H), 0.67
(ddd, J = 7.0, 9.1, 9.1 Hz, 1 H), 0.89 (ddd, J = 7.0, 9.8, 14.7 Hz, 1
H), 0.97 (s, 3 H, CH3), 0.98 (d, J = 7.0 Hz, 3 H, CH3), 1.02 (s, 3
H, CH3), 1.50 (ddd, J = 6.3, 8.4, 15.4 Hz, 1 H), 1.87 (ddd, J = 5.6,
CH3), 1.16 (s, 3 H, CH3), 1.52–1.58 (m, 1 H), 1.81–1.93 (m, 3 H),
2.01–2.07 (m, 1 H), 2.28–2.34 (m, 2 H), 2.98 (dd, J = 8.4, 11.9 Hz,
1 H), 3.05 (dd, J = 7.0, 11.9 Hz, 1 H), 7.19–7.21 (m, 1 H, ArH),
7.22–7.25 (m, 2 H, ArH), 7.45–7.48 (m, 2 H, ArH) ppm. 13C NMR
(176.1, CDCl3): δ = 23.0 (CH2), 23.3 (CH3), 26.2 (CH2), 28.0
8.4, 14.7 Hz, 1 H), 1.95–1.99 (m, 1 H), 2.22 (ddd, J = 7.0, 9.1, (CH3), 33.4 (CH2), 35.9 (CH2), 38.7 (C), 41.3 (CH), 41.5 (CH),
15.4 Hz, 1 H), 3.58 (dt, J = 6.3, 8.4 Hz, 1 H), 7.23–7.26 (m, 3 H, 46.3 (CH), 126.5 (CHAr), 129.0 (2ϫCHAr), 131.0 (CAr), 132.4
ArH), 7.52–7.55 (m, 2 H, ArH) ppm. 13C NMR (176.1, CDCl3): δ (2ϫCHAr) ppm. 77Se NMR (133.5 MHz, CDCl3): δ = 276.17 ppm.
= 15.9 (CH3), 17.8 (C), 20.4 (CH3), 21.3 (CH), 21.6 (CH), 25.7 IR (film): ν = 2918, 1580, 1477, 1437, 1382, 1023, 733 cm–1.
˜
(CH2), 26.0 (CH2), 28.5 (CH3), 31.0 (CH), 47.2 (CH), 126.8 C16H22Se (293.31): calcd. C 65.52, H 7.56; found C 65.36, H 7.62.
(CHAr), 128.9 (2ϫCHAr), 131.2 (CAr), 133.8 (2ϫCHAr) ppm. 77Se
Synthesis of Diterpene Selenides; General Procedure: To a mixture
NMR (76.3 MHz, CDCl ): δ = 343.72 ppm. IR (film): ν = 3070,
˜
3
of NaBH4 (0.132 g, 3.5 mmol) and selenium (0.131 g, 1.7 mmol),
anhydrous ethanol (5 mL) was carefully added at ambient tempera-
ture under an argon atmosphere. Anhydrous DMF (5 mL) was
added and the mixture was warmed to 60 °C for 10 min. The dark
brownish solution was decolorized, the reaction mixture was then
cooled to ca. 20 °C and tosylate (3.3 mmol) in DMF (2 mL) was
2925, 2863, 1579, 1477, 1454, 1437, 1376, 1023, 738 cm–1. C16H22Se
(293.31): calcd. C 65.52, H 7.56; found C 65.78, H 7.50.
(1S,3R,4R,6R)-(+)-4-Isocaranyl Phenyl Selenide (25): Purification
by the column chromatography on silica gel (PE), yield 0.212 g
1
(19%); yellow liquid; [α]2D0 = –102.72 (c = 0.69, CHCl3). H NMR
(700 MHz, CDCl3): δ = 0.55–0.58 (m, 1 H), 0.74 (ddd, J = 4.9, 9.1, added. The reaction mixture was stirred and kept at 50 °C for 3 d.
9.1 Hz, 1 H), 0.85 (ddd, J = 5.6, 12.6, 15.4 Hz, 1 H), 0.95 (s, 6 H,
2ϫCH3), 1.03 (d, J = 6.3 Hz, 3 H), 1.40–1.47 (m, 1 H), 1.98–2.04
(m, 3 H), 2.75 (dt, J = 7.7, 10.5 Hz, 1 H), 7.24–7.27 (m, 3 H, ArH),
The solution was poured into water (100 mL) and extracted with
petroleum ether (3ϫ 75 mL). The combined ethereal layers were
washed with water (50 mL), brine (50 mL), dried with anhydrous
7.52–7.55 (m, 2 H, ArH) ppm. 13C NMR (176.1, CDCl3): δ = 15.6 MgSO4, and the solvent was evaporated. The crude product was
(CH3), 17.5 (C), 20.6 (CH), 20.7 (CH), 21.8 (CH3), 28.8 (CH3), purified by the column chromatography (petroleum ether) to give
29.3 (CH2), 29.5 (CH2), 34.7 (CH), 49.1 (CH), 127.2 (CHAr), 128.8
pure diterpene selenide.
(2ϫCHAr), 129.7 (CAr), 134.9 (2ϫCHAr) ppm. 77Se NMR
(1S,2S,5R)-(+)-Dineomenthyl Selenide (29): Purification by column
chromatography on silica gel (PE), yield 0.123 g (21%); yellow li-
quid; [α]2D4 = +106.96 (c = 0.48, CHCl3). 1H NMR (400 MHz,
CDCl3): δ = 0.90 (d, J = 6.4 Hz, 6 H, 2ϫCH3), 0.92 (d, J = 6.8 Hz,
6 H, 2ϫCH3), 0.94 (d, J = 6.8 Hz, 6 H, 2ϫCH3), 0.95–1.00 (m, 4
H), 1.07–1.17 (m, 2 H), 1.23–1.31 (m, 2 H), 1.61–1.70 (m, 2 H),
1.70–1.78 (m, 4 H), 1.99 (dq, J = 2.4, 13.6 Hz, 2 H), 2.02–2.12 (m,
2 H), 3.28 (t, J = 2.8 Hz, 2 H) ppm. 13C NMR (100.6, CDCl3): δ
(76.3 MHz, CDCl ): δ = 397.57 ppm. IR (film): ν = 3070, 2923,
˜
3
1579, 1476, 1437, 1375, 1022, 738 cm–1. C16H22Se (293.31): calcd.
C 65.52, H 7.56; found C 65.40, H 7.64.
(1S,3S)-(+)-(trans)-3-Hydroxy-4-caranyl Phenyl Selenide (26): Puri-
fication by the column chromatography on silica gel (PE), yield
1
1.010 g (86%); yellow liquid; [α]2D0 = +82.86 (c = 0.85, CHCl3). H
NMR (400 MHz, CDCl3): δ = 0.73–0.79 (m, 2 H), 1.02 (s, 6 H,
2ϫCH3), 1.32 (s, 3 H, CH3), 1.33–1.40 (m, 2 H), 2.00–2.09 (m, 1 = 20.4 (2ϫCH3), 21.1 (2ϫCH3), 22.1 (2ϫCH3), 27.3 (2ϫCH2),
H), 2.27–2.36 (m, 2 H), 3.42 (dd, J = 5.6, 10.4 Hz, 1 H), 7.27–7.30 27.7 (2ϫCH), 31.0 (2ϫCH), 35.5 (2ϫCH2), 41.6 (2ϫCH2), 43.3
(m, 3 H, ArH), 7.57–7.62 (m, 2 H, ArH) ppm. 13C NMR (2ϫCH), 49.6 (2ϫCH) ppm; 77Se NMR (76.3 MHz, CDCl3): δ =
Eur. J. Org. Chem. 2015, 3477–3485
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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3483

´
J. Scianowski et al.
FULL PAPER
128.90 ppm. IR (film): ν = 2921, 1455, 1366, 1277, 1229, 1178, (m, 2 H), 2.30–2.34 (m, 2 H), 2.60 (ddd, J = 7.0, 9.8, 25.2 Hz, 4
˜
761 cm–1. C20H36Se (355.46): calcd. C 67.58, H 10.21; found C H) ppm. 13C NMR (176.1, CDCl3): δ = 23.1 (2ϫCH2), 23.3
67.49, H 10.20.
(2ϫCH3), 26.2 (2ϫCH2), 28.1 (2ϫCH3), 32.1 (2ϫCH2), 33.5
(2ϫCH2), 38.6 (2ϫC), 41.3 (2ϫCH), 42.1 (2ϫCH), 46.4
(2ϫCH) ppm. 77Se NMR (76.3 MHz, CDCl3): δ = 129.97 ppm.
(1S,3R,4S,6R)-(+)-Bis(4-caranyl) Selenide (30): Purification by col-
umn chromatography on silica gel (PE), yield 0.152 g (26%); yellow
liquid; [α]2D3 = +69.73 (c = 1.50, CHCl3). 1H NMR (400 MHz,
CDCl3): δ = 0.60 (ddd, J = 5.6, 8.4, 8.4 Hz, 2 H), 0.67 (ddd, J =
6.8, 8.8, 8.8 Hz, 2 H), 0.82–0.91 (m, 2 H), 0.98 (d, J = 6.8 Hz, 6
H, 2ϫCH3), 1.00 (s, 6 H, 2ϫCH3), 1.02 (s, 6 H, 2ϫCH3), 1.52
(ddd, J = 5.6, 8.0, 15.2 Hz, 2 H), 1.82–1.89 (m, 4 H), 2.30 (ddd, J
= 6.8, 8.4, 15.2 Hz, 2 H), 3.03 (dt, J = 6.3, 7.7 Hz, 2 H) ppm.
13C NMR (100.6, CDCl3): δ = 16.0 (2ϫCH3), 17.6 (2ϫC), 20.4
(2ϫCH3), 21.3 (2ϫCH), 21.8 (2ϫCH), 25.8 (2ϫCH2), 26.4
(2ϫCH2), 28.6 (2ϫCH3), 31.2 (2ϫCH), 42.4 (2ϫCH) ppm. 77Se
IR (film): ν = 2913, 1466, 1382, 1365, 1232, 1201 cm–1. C H Se
˜
20 34
(353.44): calcd. C 67.96, H 9.70; found C 67.92, H 9.71.
Synthesis of Selenonium Salts; Method a: The selenide (2.23 mmol)
was dissolved in dichloromethane (1 mL), then benzyl bromide
(0.763 g, 4.46 mmol) and a solution of silver triflate (0.572 g,
2.23 mmol) in water (2 mL) were added. The resulting biphasic
mixture was stirred at room temp. for 1 d. Water (5 mL) and di-
chloromethane (5 mL) were added and the layers were separated.
The aqueous organic layer was extracted with dichloromethane
(3ϫ 3 mL). The combined organic layers were dried with MgSO4
and the solvent was removed under reduced pressure. The crude
product was dissolved in the minimal amount of dichloromethane
and added dropwise to rapidly stirred diethyl ether (10 mL). The
precipitate was filtered and washed several times with diethyl ether.
NMR (133.5 MHz, CDCl ): δ = 268.00 ppm. IR (film): ν = 2924,
˜
3
2863, 1454, 1376, 1330, 1129 cm–1. C20H34Se (353.44): calcd. C
67.96, H 9.70; found C 68.15, H 9.63.
(1S,3R,4R,6R)-(+)-Bis(4-isocaranyl) Selenide (31): Purification by
the column chromatography on silica gel (PE), yield 0.070 g (12%);
yellow liquid; [α]2D3 = –103.92 (c = 0.54, CHCl3). 1H NMR
(700 MHz, CDCl3): δ = 0.54 (ddd, J = 1.4, 7.7, 9.1 Hz, 2 H), 0.73
(ddd, J = 5.6, 9.8, 9.8 Hz, 2 H), 0.77–0.86 (m, 4 H), 0.93 (s, 6 H,
2ϫCH3), 0.94 (s, 6 H, 2ϫCH3), 0.97 (d, J = 7.0 Hz, 6 H, 2ϫCH3),
1.29–1.36 (m, 2 H), 1.91–2.00 (m, 4 H), 2.14 (ddd, J = 2.1, 6.3,
15.4 Hz, 2 H), 2.33 (ddd, J = 6.3, 10.5, 10.5 Hz, 2 H) ppm. 13C
NMR (176.1, CDCl3): δ = 15.5 (2ϫCH3), 17.5 (2ϫC), 20.5
(2ϫCH), 20.7 (2ϫCH), 21.6 (2ϫCH3), 28.9 (2ϫCH3), 29.7
(2ϫCH2), 29.9 (2ϫCH2), 35.6 (2ϫCH), 43.9 (2ϫCH) ppm. 77Se
Method b: AgBF4 (0.443 g, 2.27 mmol) was carefully added to a
mixture of selenide (2.26 mmol) and benzyl bromide (0.963 g,
5.63 mmol) at 0 °C, under an argon atmosphere. The resulting mix-
ture was stirred at room temp. for 4 h. The crude product was dis-
solved in dichloromethane (10 mL) and filtered through Celite. The
solvent was removed under reduced pressure, diethyl ether (10 mL)
was added and the mixture was decanted. The precipitate was
washed several times with diethyl ether.
Method c: Meerwein reagent (0.09 g, 0.64 mmol) was added to the
solution of selenide (0.32 mmol) in dichloromethane (3 mL) under
an argon atmosphere. The mixture was stirred at room temp. for
1 d. The crude product was dissolved in dichloromethane (5 mL)
and filtered. The solvent was removed under reduced pressure, di-
ethyl ether (5 mL) was added and the mixture was decanted. The
precipitate was washed several times with diethyl ether.
NMR (76.3 MHz, CDCl ): δ = 377.98 ppm. IR (film): ν = 2924,
˜
3
1455, 1374, 1224, 1167, 814 cm–1. C20H34Se (353.44): calcd. C
67.96, H 9.70; found C 68.24, H 9.62.
(1S,3S)-(+)-(trans)-Bis(3-hydroxy-4-caranyl) Selenide (32): Purifica-
tion by the column chromatography on silica gel (dichloromethane/
EtOAc, 90:10), yield 0.433 g (68%); yellow solid; m.p. 97–98 °C;
[α]2D3 = +117.32 (c = 1.50, CHCl3). H NMR (700 MHz, CDCl3):
1
Method d: AgBF4 (0.127 g, 0.65 mmol) was carefully added to the
selenide (0.64 mmol) and methyl iodide (0.230 g, 1.62 mmol) at
0 °C under an argon atmosphere. The resulting mixture was stirred
at room temp. for 4 h. The crude product was dissolved in dichloro-
methane (5 mL) and filtered through Celite. The solvent was re-
moved under the reduced pressure, diethyl ether (5 mL) was added
and the mixture was decanted. The precipitate was washed several
times with diethyl ether.
δ = 0.76–0.79 (m, 2 H), 0.84–0.90 (m, 2 H), 1.01 (s, 6 H, 2ϫCH3),
1.05 (s, 6 H, 2ϫCH3), 1.28 (s, 6 H, 2ϫCH3), 1.29–1.40 (m, 4 H),
2.07 (dd, J = 9.0, 15.6, Hz, 2 H), 2.36–2.43 (m, 2 H), 2.96 (dd, J =
4.8, 10.8 Hz, 2 H) ppm. IR (film): ν = 3441, 2935, 1456, 1373, 1227,
˜
1172, 796 cm–1. C20H34O2Se (385.44): calcd. C 62.32, H 8.89; found
C 62.41, H 8.98.
(1S,3R)-(–)-(cis)-Bis(3-hydroxy-4-isocaranyl) Selenide (33): Purifi-
cation by the column chromatography on silica gel (dichlorometh-
ane/EtOAc, 90:10), yield 0.439 g (69%); yellow solid; m.p. 99–
101 °C; [α]2D3 = –129.42 (c = 0.48, CHCl3). 1H NMR (700 MHz,
CDCl3): δ = 0.56 (t, J = 8.4 Hz, 2 H), 0.81 (ddd, J = 5.2, 10.0,
10.0 Hz, 2 H), 0.98 (s, 6 H, 2ϫCH3), 1.03 (s, 6 H, 2ϫCH3), 1.24
(s, 6 H, 2ϫCH3), 1.30 (ddd, J = 1.2, 5.2, 14.0 Hz, 2 H), 2.01–2.15
(m, 4 H), 2.35 (dd, J = 7.2, 14.8 Hz, 2 H), 2.74 (ddd, J = 7.2,
12.4 Hz, 2 H) ppm. 13C NMR (100.6, CDCl3): δ = 1.0 (2ϫCH3),
15.3 (2ϫCH3), 17.8 (2ϫC), 20.4 (2ϫCH), 20.5 (2ϫCH), 23.1
(2ϫCH3), 28.8 (2ϫCH3), 30.1 (2ϫCH2), 33.4 (2ϫCH2), 55.2
(2ϫCH), 71.4 (2ϫC) ppm. 77Se NMR (76.3 MHz, CDCl3): δ =
(1R,4R,5R,6R)-6-Benzyl-4,7,7-trimethyl-6-seleniabicyclo[3.2.1]oct-
ane Trifluoromethanesulfonate (11): Purification by precipitate,
yield 0.653 g (64%; method a); white solid; m.p. 113–114 °C; [α]2D2
= –215.50 (c = 1.20, CHCl3). 1H NMR (400 MHz, CDCl3): δ =
1.14 (d, J = 7.2 Hz, 3 H, CH3), 1.22–1.36 (m, 1 H), 1.60–1.64 (m,
2 H), 1.72–1.79 (m, 1 H), 1.82 (s, 3 H, CH3), 1.92 (s, 3 H, CH3),
2.15–2.25 (m, 1 H), 2.41 (s, 1 H), 2.50–2.59 (m, 1 H), 2.67 (d, J =
13.6 Hz, 1 H), 3.98 (s, 1 H), 4.32 (d, J = 11.2 Hz, 1 H), 5.06 (d, J
= 11.2 Hz, 1 H), 7.35–7.42 (m, 3 H, ArH), 7.52–7.61 (m, 2 H,
ArH) ppm. 13C NMR (100.6, CDCl3): δ = 17.8 (CH3), 22.7 (CH2),
23.7 (CH3), 26.1 (CH2), 26.3 (CH3), 31.6 (CH), 33.6 (CH2), 41.4
(CH2), 50.8 (CH), 64.5 (CH), 76.5 (C), 129.5 (CHAr), 129.7
(2 ϫ CHAr), 130.3 (CAr), 130.5 (2 ϫ CHAr) ppm; 77Se NMR
206.17 ppm. IR (film): ν = 3448, 2938, 2243, 1448, 1375, 1113, 909,
˜
733 cm–1. C20H34O2Se (385.44): calcd. C 62.32, H 8.89; found C
62.44, H 8.79.
(76.3 MHz, CDCl ): δ = 564.13 ppm. IR (film): ν = 2923, 2854,
˜
3
(1S,2R,5S)-(–)-Dimyrtanyl Selenide (34): Purification by the col-
umn chromatography on silica gel (PE), yield 0.280 g (48%); yellow
liquid; [α]2D2 = –62.33 (c = 1.25, CHCl3). 1H NMR (700 MHz,
CDCl3): δ = 0.86 (d, J = 9.1 Hz, 2 H), 0.98 (s, 6 H, 2ϫCH3), 1.16
1462, 1377, 1256, 1150, 1029 cm–1. C18H25F3O3SSe (457.41): calcd.
C 47.27, H 5.51; found C 47.58, H 5.43.
(1R,4R,5R,6R)-6-Benzyl-4,7,7-trimethyl-6-seleniabicyclo[3.2.1]oct-
(s, 6 H, 2ϫCH3), 1.46–1.51 (m, 2 H), 1.79–1.84 (m, 2 H), 1.85– ane Tetrafluoroborate (12): Purification by precipitate, yield 0.500 g
1.88 (m, 2 H), 1.89–1.94 (m, 2 H), 1.98–2.03 (m, 4 H), 2.18–2.24
(56%; Method b); white solid; m.p. 136–138 °C; [α]2D3 = –292.89 (c
3484
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© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 3477–3485

Terpenyl Selenides in Asymmetric Epoxidation
1
= 0.45, acetone). H NMR (700 MHz, CDCl3): δ = 1.17 (dd, J =
Acknowledgments
4.9, 6.3 Hz, 3 H, CH3), 1.60 (s, 2 H), 1.65 (s, 1 H), 1.78 (s, 1 H),
1.83 (s, 3 H, CH3), 1.93 (s, 3 H, CH3), 2.25 (s, 1 H), 2.43 (s, 1 H),
2.56 (s, 1 H), 2.70 (d, J = 10.5 Hz, 1 H), 4.03 (s, 1 H), 4.29 (s, 1
H), 4.97 (s, 1 H), 7.35–7.42 (m, 3 H, ArH), 7.52–7.61 (m, 2 H,
ArH) ppm. 13C NMR (100.6, CDCl3): δ = 17.9 (CH3), 22.1 (CH2),
23.8 (CH3), 26.1 (CH2), 26.4 (CH3), 31.6 (CH), 33.7 (CH2), 41.4
(CH2), 50.8 (CH), 64.7 (CH), 76.7 (C), 129.6 (CHAr), 129.8
(2ϫCHAr), 130.1 (CAr), 130.6 (2ϫCHAr) ppm. 77Se NMR
The authors thank the Department of Chemistry, Nicolaus Coper-
nicus University in Torun´ for financial support.
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˜
3
1462, 1377 cm–1. C17H25BF4Se (395.14): calcd. C 51.67, H 6.38;
found C 51.36, H 6.45.
(1S,2S,5R)-Benzyl Methyl Mentyl Selenonium Tetrafluoroborate
(35): Purification by the column chromatography on silica gel
(dichloromethane/methanol, 90:10), yield 0.715 g (80%; Method
b), 0.051 g (40%; Method c), 0.053 g (21%; Method d); white solid;
[α]2D2 = –76.85 (c = 1.05, CHCl3). H NMR (700 MHz, CDCl3): δ
1
= 0.59 (d, J = 6.3 Hz, 3 H, CH3), 0.71–0.87 (m, 1 H), 0.90 (d, J =
6.3 Hz, 3 H, CH3), 0.93–0.97 (m, 1 H), 0.99 (d, J = 7.0 Hz, 3 H,
CH3), 1.29–1.39 (m, 1 H), 1.52–1.82 (m, 6 H), 2.17 (d, J = 12.6 Hz,
1 H), 2.54 (s, 3 H, CH3), 4.62 (d, J = 3.5 Hz, 2 H), 7.28–7.38 (m,
3 H, ArH), 7.42–7.50 (m, 2 H, ArH) ppm. 13C NMR (100.6 MHz,
CDCl3): δ = 13.9 (CH3), 15.9 (CH3), 22.4 (CH3), 23.3 (CH3), 26.5
´
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46.6 (CH), 58.2 (CH), 130.6 (CAr), 131.0 (CHAr), 131.1
(CHAr),131.2 (CHAr), 131.6 (CHAr),131.7 (CHAr) ppm. 77Se NMR
(CDCl3): δ = 372. 46 ppm. C18H29BF4Se (411.19): calcd. C 52.58,
H 7.11; found C 52.97, H 7.08.
´
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(1S,2S,5R)-Benzyl Methyl Neomentyl Selenonium Tetrafluoroborate
(36): Method b: mix of salts (48:52); yield: 0.420 g (47%). Method
c: mix of salts (48:52); yield: 0.066 g (52%); Method d: mix of salts
(42:58); yield: 0.089 g (35%). 1H NMR (400 MHz, CDCl3): δ =
0.90–0.93 (m, 2 H), 0.97 (d, J = 6.8 Hz, 3 H, CH3), 0.99 (d, J =
7.2 Hz, 3 H, CH3), 1.05 (d, J = 6.4 Hz, 3 H, CH3), 1.06 (d, J =
6.4 Hz, 3 H, CH3), 1.07–1.15 (m, 4 H), 1.22–1.33 (m, 4 H), 1.38–
1.53 (m, 4 H), 1.68–1.81 (m, 4 H), 1.88–1.97 (m, 2 H), 2.01–2.12
(m, 2 H), 2.41 (d, J = 15.2 Hz, 1 H), 2.52 (d, J = 16.0 Hz, 1 H),
2.59 (s, 3 H, CH3), 2.76 (s, 3 H, CH3), 4.54 (d, J = 10.8 Hz, 1 H),
4.62 (d, J = 11.2 Hz, 1 H), 4.82–4.96 (m, 2 H, CH2), 5.01–5.09 (m,
2 H, CH2), 7.39–7.48 (m, 2ϫ3 H, ArH), 7.49–7.58 (m, 2ϫ2 H,
ArH) ppm. 13C NMR (100.6 MHz, CDCl3): δ = 14.2 (CH3), 19.3
(CH3), 20.7 (CH3), 20.8 (CH3), 21.2 (CH3), 21.3 (CH3), 21.6 (CH3),
21.7 (CH3), 26.5 (CH2), 26.7 (CH2), 29.5 (CH), 29.7 (CH), 31.1
(CH), 31.4 (CH), 34.1 (CH2), 34.3 (CH2), 37.0 (CH2), 37.2 (CH2),
41.2 (CH2), 44.7 (CH2), 48.3 (CH), 49.1 (CH), 63.4 (CH), 66.1
(CH), 129.0 (CAr), 129.3 (CAr), 129.6 (2ϫCHAr), 129.7
(2ϫCHAr),129.8 (CHAr), 130.1 (CHAr), 130.6 (2ϫCHAr), 130.7
(2ϫCHAr) ppm. 77Se NMR (76.3 MHz, CDCl3): δ = 337. 76 (Se),
345.40 (Se) ppm.
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Epoxidation: A mixture of selenide (2.18 mmol), benzyl bromide
(0.749 g, 4.38 mmol), sodium hydroxide (0.088 g, 2.20 mmol) and
benzaldehyde (0.231 g, 2.18 mmol) in acetonitrile (10 mL) was
stirred for 3 d. Acetonitrile was evaporated and water (80 mL) was
added. The mixture was extracted with petroleum ether (3ϫ
75 mL) and the combined ethereal layers were dried with anhy-
drous magnesium sulfate. The solvent was evaporated, and a crude
product was purified by column chromatography (petroleum ether/
EtOAc, 95:5) to give the pure trans-stilbene oxide.
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Received: February 12, 2015
Published Online: April 17, 2015
Eur. J. Org. Chem. 2015, 3477–3485
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3485