First synthesis and stereochemistry of enantiomerically pure spiroselenurane and spirotellurane using the 2-exo-hydroxy-10-bornyl group as a chiral ligand

Article abstract of DOI:10.1016/S0957-4166(98)00352-8

The first synthesis of enantiomerically pure spiroselenuranes 8a-d and spirotelluranes 12a,b, using the 2-exo-hydroxy-10-bornyl group as a chiral ligand, has been developed and proceeds in good yield and with excellent diastereoselectivity. The X-ray analysis of spirotellurane 12a indicated that the spirochalcogenuranes have a trigonal bipyramidal (TBP) structure around the chalcogenium atom. A comparison of the spectroscopic properties of spirochalcogenuranes is also discussed.

Full text of DOI:10.1016/S0957-4166(98)00352-8

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 9 (1998) 3303–3317
First synthesis and stereochemistry of enantiomerically pure
spiroselenurane and spirotellurane using the 2-exo-hydroxy-
10-bornyl group as a chiral ligand
Jian Zhang,∗,† Shigemasa Takahashi, Shinichi Saito and Toru Koizumi ∗,‡
Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-01, Japan
Received 10 August 1998; accepted 31 August 1998
Abstract
The first synthesis of enantiomerically pure spiroselenuranes 8a–d and spirotelluranes 12a,b, using the 2-exo-
hydroxy-10-bornyl group as a chiral ligand, has been developed and proceeds in good yield and with excellent
diastereoselectivity. The X-ray analysis of spirotellurane 12a indicated that the spirochalcogenuranes have a
trigonal bipyramidal (TBP) structure around the chalcogenium atom. A comparison of the spectroscopic properties
of spirochalcogenuranes is also discussed. © 1998 Elsevier Science Ltd. All rights reserved.
1. Introduction
Chalcogenuranes have been regarded as intermediates in many organic reactions involving the
chalcogenonium(IV) compounds, such as Swern oxidation and Pummerer rearrangement.1 Much atten-
tion has been centred on the study of the synthesis and isolation of achiral spirochalcogenuranes.2
Since the first synthesis of stable spirosulfurane by Kapovits et al., some spirosulfuranes have been
synthesized or separated, and the structure as well as the hydrolysis of these compounds has been
reported.3 A recent study on spiroselenuranes and spirotelluranes has indicated that they are more stable
than their sulfur analogues.4 On the other hand, much attention has been devoted to the discovery of
chalcogenonium compounds that mimic the properties of the selenium-containing enzyme (GSH-Px) and
other enzymes which play important roles in the human body.5 The formation of chalcogenonium(IV)
species, chalcogenuranes, has been proposed as the key process in some of the reactions. Additionally,
recent research has shown that some organotellurium(IV) compounds with the spirocyclic structure
∗
†
Corresponding author. E-mail: zhang@selen.c.u-tokyo.ac.jp
Present address: Department of Life and Environmental Sciences, Graduate School of Arts and Sciences, The University of
Tokyo, Komaba, Meguro, Tokyo 153-0041.
‡
Deceased on 12 January 1998.
0957-4166/98/$ - see front matter © 1998 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(98)00352-8

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possess different levels of immunomodulating activity and could act as a potent immunomodulator
with a variety of potential therapeutic applications.5k Therefore, the synthesis and isolation of chiral
spirochalcogenuranes is important in order to investigate the stereochemical features of the reactions as
well as their role in the biomimic reactions.
Although there have been several examples of the synthesis and isolation of the optically active
spirosulfuranes 1a–d (Scheme 1),6 there is only one report on the isolation of the optically active
spiroselenurane 2 via the resolution,7 however, the stereochemistry and the enantiopurity of 2 were not
clear. To the best of our knowledge, there is no report on the synthesis or the isolation of the chiral
spirotelluranes; and consequently, very little is known on the systematic comparison of the properties of
spirochalcogenuranes.
Scheme 1.
Due to our interest regarding the mechanism and stereochemistry of the reaction of hypervalent
chalcogenium compounds, we have reported the synthesis and reaction of the halooxachalcogenuranes
3a–c8 (Scheme 1) and spirosulfurane 49 (Scheme 2) by using the 2-exo-hydroxy-10-bornyl group as a
chiral ligand.
Scheme 2.
Nucleophilic reactions of halooxachalcogenuranes 3a–c provided an excellent method for the asym-
metric synthesis of enantiomerically pure chalcogenonium(IV) compounds, especially the chiral seleno-
nium(IV) and telluronium(IV) compounds, such as selenoxides,8a,g selenonium ylides8b and telluronium
salts.8h,j Hydrolysis of enantiomerically pure alkoxyacyloxyspirosulfurane 4a under different conditions
gave, diastereospecifically, corresponding sulfoxides 5aa and 5ab with the opposite absolute configura-
tion at the sulfur atom (Scheme 2). The different reactivity of the two apical S–O bonds under various
conditions has been considered as the most important reason to account for the high diastereoselectivity
of the hydrolysis.9 Herein, we report our recent result on the asymmetric synthesis and the structure

J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
3305
determination of the title compounds and a comparison of the stability and spectral characteristics of
spirochalcogenuranes.
2. Results and discussion
The spiroselenuranes 8a–d were prepared as shown in Scheme 3. Reaction of (1S)-10-iodo-2-exo-
methoxymethoxy-borneol with 2,20-diselenobisethylbenzoate in abs. EtOH in the presence of NaBH4
followed by deprotection with conc. HCl in MeOH and alkaline hydrolysis of the ester gave selenide
6a as a white solid (Eq. 1). Selenide 6b was prepared by the 1,4-addition of methyl propiolate with
the selenolate anion, which was generated in situ from di-(2-exo-hydroxy-10-bornyl) diselenide and
sodium borohydride, followed by alkaline hydrolysis (Eq. 2). Selenide 6c was also prepared from
di-(2-exo-hydroxy-10-bornyl) diselenide 7 (Eq. 3), and selenide 6d was obtained by the reaction of
di-(3-hydroxy)propyl diselenide with (1S)-10-iodo-2-exo-borneol (Eq. 4). Treatment of the selenides
6a–d with t-BuOCl in a CH2Cl2 solution followed by reaction with NEt3 afforded the corresponding
enantiomerically pure spiroselenuranes 8a–d in high yields as single diastereoisomers, respectively, and
no other epimeric compound could be detected.10 The reactions were believed to proceed through the
diastereoselective generation of the intermediates of chloroselenuranes similar in structure to 3b followed
by intramolecular cyclization under the basic conditions.
(1)
(2)

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J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
(3)
(4)
The formation of the five-membered spiroselenurane structure was confirmed by spectroscopic tech-
1
niques. In the H NMR spectra of spiroselenuranes, the chemical shift of protons (Ha, Hb) on the
methylene bound to the selenium atom is shifted considerably downfield compared with that of their
selenide analogues. In the 13C NMR spectra, the chemical shift of the carbon (C1) bound to the alkoxy
oxygen at the bornyl group of spiroselenuranes 8a–d is at about 90 ppm whereas the shift of the
corresponding carbon atom of selenides is 77 ppm. In the 77Se NMR spectra, the chemical shift of
selenurane is between 844 and 949 ppm, while that of selenides are smaller than 200 ppm. These spectral
features could be considered characteristic of compounds with a trigonal bipyramidal (TBP) structure.8
Scheme 3.
Spiroselenuranes 8a–d obtained here are considerably more stable than their sulfur analogues. For
example, 8c or 8d could be obtained by extraction of the reaction mixture from water, while the
spirosulfurane 4c with the same structure of 8c was sensitive to moisture and was readily hydrolyzed to
give the sulfoxide. Thus, the structure of 4c could only be detected by the 1H NMR of the crude product.
Attempts to synthesize the spirosulfurane with the same structure as 8d only led to the formation of the
sulfoxide.

J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
3307
The synthesis of chiral spirotelluranes were carried out as illustrated in Scheme 4. (1S)-10-Iodo-2-
exo-hydroxy-borneol was converted to the corresponding di-(2-exo-hydroxy-10-bornyl) ditelluride 9 in
42% yield.11 Addition of tellurolate anion, which was prepared in situ from ditelluride 9 and sodium
borohydride, to methyl propiolate or ethyl-3-propyl propiolate produced the corresponding tellurides
10a and 10b as red oil. Separation of the E- and Z-isomers of 10a,b followed by treatment with t-BuOCl
in CH2Cl2 solution afforded the enantiomerically pure chlorotelluranes 11a and 11b, respectively, in high
yields as the sole product. Hydrolysis of the Z-isomers of the chlorotelluranes 11a and 11b under basic
conditions gave the corresponding spirotelluranes 12a and 12b as colorless crystals in good yields as a
single diastereoisomer.10
Scheme 4.
The structure of 12a and 12b was determined by the spectroscopy as well as an X-ray analysis of
12a (Scheme 4). As with that of spiroselenuranes and selenides, a similar tendency of the downfield
1
shift of the protons (Ha, Hb, Hc) and the carbon (C1) were observed in the H and 13C NMR of the
spirotelluranes 12a,b compared with that of the corresponding tellurides. The 125Te NMR chemical shift
of 12a appears at 1894 ppm, which is consistent with the value of halooxatelluranes but lower than that
of 1,10spirobi(3H-2,1-benzoxatellurole)-3-one reported by Furukawa et al.4d
The X-ray analysis of 12a indicated that the spirotellurane 12a has a slightly distorted trigonal
bipyramidal (TBP) geometry around the central tellurium atom as shown in Scheme 4. As expected,
the two electronegative oxygen atoms bound to the tellurium atom occupy apical positions, while two
carbon atoms and the lone electron pair occupy equatorial positions. The O–Te–O moiety with the
angle of 177.1° in 12a is almost linear. Similar to the alkoxyacyloxyspirosulfuranes,9,12 the length
of Te–O(acyloxy) [2.20(7) Å] is longer than that of the Te–O(alkoxy) [2.02(7) Å] in this alkoxy-
acyloxyspirotellurane which reflects the polarized nature of the hypervalent O–Te–O bond resulting
from the difference in the electronegativities of the apical ligands. The formation of the spirotellurane

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J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
Table 1
was considered through the following reactions: successive hydrolysis of the ester followed by the
dissociation of the Te–Cl bond and the attack of the carboxylate anion at the resulting telluronium cation.
The geometry of the double bond was found to play an important role in this reaction, only the Z-isomers
of 11a,b could be converted to the corresponding spirotelluranes 12a,b, the similar hydrolysis of the
E-chlorotelluranes (E-11a,b) gave only the decomposition of the starting materials.
The chemical shift of the quaternary carbon in the alkoxy ligands of spirosulfuranes of type 1 was
found to be very responsive to the change of the nature of trans apical substitutes. In the 13C NMR
spectrum, the chemical shift of this carbon moved to a markedly lower field, which indicated the higher
polarization of the hypervalent O–S–O bond, with increasing electronegativities of the trans apical
ligands.
With the spirochalcogenuranes in hand, we then compared the spectroscopic characteristics of these
compounds having the same structure but with a different chalcogenium atom at the centre of the spiro
1
ring (Table 1). In the H NMR spectra, the methylene protons (Ha, Hb) as well as the proton (Hc) of
the alkoxy ligand in the bornyl group are shifted upfield when the chalcogenium changes from S to
Se, or Se to Te. The same properties were obtained for the carbon (C1) in the 13C NMR spectrum of
these compounds. In contrast, the alkene protons (Hd, He) are shifted downfield when the chalcogenium
changes from S to Se, or Se to Te. Although reasons to account for these results are not clear at present,
the changing of the central chalcogenium atom would result in a different extent of polarization of the
O–Y–O bonds and distribution of electrons which might finally appear as a variance of the chemical shift
in the NMR spectra.
In conclusion, the enantiomerically pure spiroselenuranes 8a–d and spirotellurane 12a,b have been
synthesized in good yields and with excellent diastereoselectivity, by using the 2-exo-hydroxy-10-bornyl
group as a chiral ligand. The structure and the stereochemistry of the spirochalcogenuranes have been
studied by spectroscopy and X-ray analysis. The comparison of the spectroscopic characteristics of these
compounds clearly indicated that the central chalcogenium atom plays an important role in the properties
of these compounds.
3. Experimental
3.1. General methods
Melting points were recorded with a Yanaco micro melting point apparatus and are uncorrected. Micro-
analyses were performed by the Microanalysis Center of Toyama Medical and Pharmaceutical University.

J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
3309
Spectroscopic measurements were carried out with the following instruments: optical rotations, JASCO
DIP-1000 digital polarimeter; IR, Perkin–Elmer 1600 Series FTIR; mass (MS) and high resolution mass
1
spectra (HRMS), JMS-AX 505H; H NMR, Varian Gemini-300 (300 MHz) for solutions in CDCl3 (or
other solvent as mentioned) with Me4Si (0 ppm) as an internal standard, J values in hertz; 13C NMR,
Varian Gemini-300 (75 MHz) for solutions in CDCl3 (or other solvent as mentioned) with CDCl3 (77
ppm) as an internal standard; 77Se NMR, Varian Unity 500 (95.4 MHz) for solutions in CDCl3 with
Me2Se (281 ppm) as an external standard; 125Te NMR, Varian Unity 500 (157.9 MHz) for solutions
in CDCl3 with Ph2Te2 (0.5 M in CH2Cl2, 422 ppm) as an external standard. The crystallographic data
were collected on a Rigaku AFC7R diffractometer with graphite monochromated Mo-Kα radiation and a
rotating anode generator, and the structure was solved by direct methods; all data reduction and structural
refinements were performed with the teXsan crystal structure analysis package provided by Molecular
Structure Corporation. All reactions were carried out in dried glassware under N2 atmosphere. Dry
CH2Cl2 was distilled from P2O5 and stored over 4 Å molecular sieves. Anhydrous EtOH was distilled
from CaH2 and stored over 4 Å molecular sieves. Column chromatography and TLC were performed on
Kiesel gel 60 (Merck, 230–400 mesh) or Kiesel gel 60 (Merck, Art. 7734 and Art. 5715, respectively).
3.2. Ethyl-2-({(1S,2R,4R)-2-methoxymethoxy-7,7-dimethylbicyclo[2.2.1]-heptan-1-yl}methylseleno)-
benzoate
To a solution of 2,20-diselenobisethylbenzoate (37.5 mg, 0.082 mmol) and (1S)-10-iodo-2-exo-
methoxymethoxy-borneol (53 mg, 0.16 mmol) in abs. EtOH (3 ml) was added NaBH4 (38 mg, 1
mmol) under an N2 atmosphere at 0°C, the mixture was stirred until the yellow color of the diselenide
disappeared (ca. 10 min). The whole solution was heated at reflux for 5 h and cooled to rt. The reaction
was quenched with NH4Cl (5 ml) and the mixture was extracted with CH2Cl2 (3×15 ml). The organic
layer was washed with H2O (2×5 ml), followed by brine (5 ml) and dried over MgSO4. Removal of the
solvent under reduced pressure gave the crude product which was purified by column chromatography
26
(hexane:EtOAc=20:1) to give the title product (17 mg, 25%) as a yellow oil. [α]D −4.37 (c 1.27,
1
CHCl3); IR (neat) 2952, 1707, 1456, 1388, 1045, 1009, 739 cm−1; H NMR δ: 0.93 (s, 3H), 1.11 (s,
3H), 1.3–1.47 (m, 2H), 1.4 (t, J=7.1, 3H), 1.6–1.93 (m, 5H), 2.81 (d, J=9.9, 1H), 3.17 (d, J=9.9, 1H),
3.33 (s, 3H), 3.74 (dd, J=3.8, 7.7, 1H), 4.38 (q, J=7.1, 2H), 4.59 (d, J=6.6, 1H), 4.67 (d, J=6.6, 1H), 7.18
(t, J=7.7, 1H), 7.4 (t, J=7.1, 1H), 7.52 (d, J=7.1, 1H), 7.99 (d, J=7.7, 1H); 13C NMR δ: 14.7, 20.6, 20.9,
25.3, 27.4, 33.2, 39.6, 45.5, 48.7, 52.5, 56.0, 61.4, 83.1, 97.0, 124.2, 128.4, 129.1, 131.4, 132.3, 138.7,
166.9; m/z: 426 (M+, 80Se), 424 (M+, 78Se), 274, 272, 229, 227, 201, 199, 184, 182, 93. HRMS calcd for
C21H30O4Se: 426.1309 (M+, 80Se). Found: 426.1311.
3.3. Ethyl-2-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-benzoate
To a solution of ethyl-2-({(1S,2R,4R)-2-methoxymethoxy-7,7-dimethylbicyclo[2.2.1]-heptan-1-
yl}methylseleno)-benzoate (59 mg, 0.14 mmol) in MeOH (3 ml) was added conc. HCl (2 drops) under
an N2 atmosphere at rt. The whole solution was heated at reflux for 3 h and cooled to rt. Removal of the
solvent under reduced pressure gave the crude product which was purified by column chromatography
26
(hexane:EtOAc=30:1–5:1) to give the desired product (45 mg, 85%) as a yellow oil. [α]D −36.93
1
(c 2.90, CHCl3); IR (neat) 3512, 2952, 1704, 1457, 1250, 1034, 738 cm−1; H NMR δ: 0.93 (s, 3H),
1.13 (s, 3H), 1.0–1.2 (m, 1H), 1.22–1.38 (m, 1H), 1.41(t, J=7.1, 3H), 1.59–1.83 (m, 5H), 2.35–2.43 (br
d, 1H), 2.86 (d, J=9.3, 1H), 3.11 (d, J=9.3, 1H), 4.0 (dd, J=3.8, 7.7, 1H), 4.39 (q, J=7.1, 2H), 7.23 (t,
J=7.7, 1H), 7.44 (t, J=7.7, 1H), 7.51 (d, J=8.2, 1H), 8.03 (d, J=7.7, 1H); 13C NMR δ: 14.6, 20.2, 21.0,

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J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
25.7, 27.6, 31.7, 39.6, 45.2, 48.5, 52.1, 61.4, 77.1, 124.8, 128.5, 129.1, 131.4, 132.6, 137.5, 166.9; 77Se
NMR δ: 266; m/z: 382 (M+, 80Se), 380 (M+, 78Se), 364, 362, 230, 228, 184, 135, 93. HRMS calcd for
C19H26O3Se: 382.1046 (M+, 80Se). Found: 382.1046.
3.4. 2-({(1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-benzoic acid 6a
To a solution of ethyl-2-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methyl-
seleno)-benzoate (282 mg, 0.74 mmol) in THF:H2O:EtOH (1:1:1, 9 ml) was added a solution of 1N
aqueous NaOH (3 ml, 3 mmol), and the reaction mixture was stirred under an N2 atmosphere at rt
overnight. After acidification with 1N HCl, the reaction mixture was extracted with CH2Cl2 (3×50 ml).
The combined organic layer was then washed with H2O (2×10 ml), followed by brine (10 ml) and dried
over MgSO4. Evaporation of the solvent under reduced pressure afforded the product 6a (261 mg) in
26
quantative yield as a white solid. Mp 219–220°C; [α]D −42.57 (c 0.65, CHCl3); IR (KBr) 3433, 2951,
1674, 1462, 1257, 1036, 740 cm−1; 1H NMR δ: 0.94 (s, 3H), 1.14 (s, 3H), 1.02–1.21 (m, 1H), 1.3–1.41
(m, 1H), 1.59–1.92 (m, 7H), 2.88 (d, J=9.3, 1H), 3.13 (d, J=9.3, 1H), 4.03 (dd, J=3.3, 7.7, 1H), 7.24 (t,
J=7.7, 1H), 7.42–7.59 (m, 2H), 8.14 (d, J=7.7, 1H); 13C NMR δ: 20.3, 21.0, 25.8, 27.6, 31.8, 39.7, 45.2,
48.6, 52.1, 77.2, 124.9, 127.9, 128.8, 132.6, 133.3, 138.5, 171.1; m/z: 354 (M+, 80Se), 352 (M+, 78Se),
336, 334, 321, 318, 202, 200, 184, 182, 153, 135, 93. HRMS calcd for C17H22O3Se: 354.0733 (M+,
80Se), 352.0742 (M+, 78Se). Found: 354.0706, 352.0741.
3.5. Methyl-3-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-acrylate
To a solution of di-(2-exo-hydroxy-10-bornyl) diselenide 7 (188 mg, 0.41 mmol) and methyl propiolate
(0.09 ml, 1 mmol) in abs. EtOH (6 ml) was added NaBH4 (38 mg, 1 mmol) under an N2 atmosphere at
0°C, and the mixture was stirred for 40 min at 0°C. The reaction was quenched with NH4Cl (5 ml) and
the mixture was extracted with EtOAc (2×50 ml). The organic layer was washed with H2O (2×5 ml),
followed by brine (5 ml) and dried over MgSO4. Removal of the solvent under reduced pressure gave the
product (270 mg, 100%) as a yellow oil. (Z:E=ca. 4:1). 1H NMR for Z-isomer, δ: 0.87 (s, 3H), 1.0–1.27
(m, 1H), 1.08 (s, 3H), 1.2–1.8 (m, 8H), 2.79 (d, J=11.5, 1H), 3.08 (d, J=11.5, 1H), 3.76 (s, 3H), 3.91 (dd,
J=3.7, 7.7, 1H), 6.32 (d, J=9.9, 1H), 7.8 (d, J=9.9, 1H); for E-isomer, δ: 0.89 (s, 3H), 1.0–1.27 (m, 1H),
1.09 (s, 3H), 1.2–1.8 (m, 8H), 2.87 (d, J=11.0, 1H), 3.17 (d, J=11.0, 1H), 3.73 (s, 3H), 3.81 (dd, J=3.7,
7.7, 1H), 6.08 (d, J=15.4, 1H), 8.16 (d, J=15.4, 1H).
3.6. 3-({(1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-acrylic acid 6b
The hydrolysis procedure described in the preparation of 6a was followed to prepare 6b (248 mg,
100%) from methyl-3-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-
acrylate (Z:E=ca. 4:1) (270 mg, 0.82 mmol) as a yellow oil. (Z:E=ca. 4:1). 1H NMR for Z-6b, δ: 0.87 (s,
3H), 1.0–1.25 (m, 1H), 1.08 (s, 3H), 1.2–1.9 (m, 8H), 2.78 (d, J=11.5, 1H), 3.11 (d, J=11.5, 1H), 3.91
(dd, J=3.8, 7.1, 1H), 6.33 (d, J=9.9, 1H), 7.96 (d, J=9.9, 1H); for E-6b, δ: 0.9 (s, 3H), 1.0–1.25 (m, 1H),
1.09 (s, 3H), 1.2–1.9 (m, 8H), 2.89 (d, J=11.0, 1H), 3.2 (d, J=11.0, 1H), 3.8 (dd, J=3.7, 7.7, 1H), 6.08
(d, J=15.9, 1H), 8.34 (d, J=15.9, 1H).

J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
3311
3.7. Ethyl-3-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-propionate
To a solution of di-(2-exo-hydroxy-10-bornyl) diselenide 7 (340 mg, 0.73 mmol) and ethyl-3-
bromopropionate (0.28 ml, 2.2 mmol) in abs. EtOH (20 ml) was added NaBH4 (84 mg, 2.2 mmol) under
an N2 atmosphere at 0°C, and the mixture was stirred until the yellow color of the diselenide disappeared
(ca. 10 min). The whole solution was stirred at rt for 4 h, then quenched with NH4Cl (10 ml) and the
mixture was extracted with EtOAc (3×50 ml). The organic layer was washed with H2O (2×10 ml),
followed by brine (10 ml) and dried over MgSO4. Removal of the solvent under reduced pressure gave
the crude product which was purified by column chromatography (hexane:EtOAc=15:1) to give product
(485 mg, 100%) as a yellow oil. [α]D −34.12 (c 1.88, CHCl3); IR (neat) 2951, 1735, 1228 cm−1; 1H
26
NMR δ: 0.81 (s, 3H), 1.03 (s, 3H), 0.98–1.18 (m, 2H), 1.25 (t, J=7.1, 3H), 1.42–1.57 (m, 1H), 1.61–1.81
(m, 4H), 2.6–2.83 (m, 7H), 3.81 (dd, J=3.4, 7.7, 1H), 4.14 (q, J=7.1, 2H); 13C NMR δ: 14.5, 18.9, 20.2,
20.9, 24.9, 27.3, 31.8, 35.7, 39.5, 45.4, 47.9, 52.6, 60.9, 77.2, 172.4; 77Se NMR δ: 119; m/z: 334 (M+,
80Se), 332 (M+, 78Se), 289, 287, 182, 180, 153, 135, 109, 93. HRMS calcd for C15H26O3Se: 334.1047
(M+, 80Se), 332.1056 (M+, 78Se). Found: 334.1045, 332.1039.
3.8. 3-({(1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-propionic acid 6c
The hydrolysis procedure described in the preparation of 6a was followed to prepare 6c (249 mg, 97%)
from ethyl-3-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-propionate
26
(281 mg, 0.84 mmol) as a yellow oil. [α]D −15.78 (c 1.28, CHCl3); IR (neat) 2952, 1711, 1070,
756 cm−1; 1H NMR δ: 0.82 (s, 3H), 1.03 (s, 3H), 0.96–1.28 (m, 2H), 1.42–1.58 (m, 1H), 1.61–1.82 (m,
5H), 2.68–2.82 (m, 7H), 3.86 (dd, J=3.8, 8.2, 1H); 13C NMR δ: 18.6, 20.2, 20.9, 25.1, 27.3, 31.9, 35.5,
39.3, 45.4, 48.1, 52.7, 77.4, 177.3; 77Se NMR δ: 120; m/z: 306 (M+, 80Se), 304 (M+, 78Se), 182, 180,
153, 135, 109, 93. HRMS calcd for C13H22O3Se: 306.0734 (M+, 80Se), 304.0743 (M+, 78Se). Found:
306.0771, 304.0800.
3.9. 3-({(1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylseleno)-propanol 6d
To a solution of di-(3-hydroxy)propyl diselenide (295 mg, 1.07 mmol) and (1S)-10-iodo-2-exo-borneol
(600 mg, 2.13 mmol) in abs. EtOH (15 ml) was added NaBH4 (125 mg, 3.29 mmol) under an N2
atmosphere at 0°C. The whole solution was heated at reflux for 3 h and cooled to rt. The reaction was
quenched with NH4Cl (10 ml) and the mixture was extracted with EtOAc (3×50 ml). The organic layer
was washed with H2O (2×10 ml), followed by brine (10 ml) and dried over MgSO4. Removal of the
solvent under reduced pressure gave the crude product which was purified by column chromatography
26
(hexane:EtOAc=5:1) to give 6d (545 mg, 88%) as a yellow oil. [α]D −23.14 (c 1.56, CHCl3); IR (neat)
2951, 1454, 1070, 756 cm−1; 1H NMR δ: 0.83 (s, 3H), 1.05 (s, 3H), 0.98–1.21 (m, 3H), 1.43–1.59 (m,
1H), 1.62–2.0 (m, 6H), 2.58–2.78 (m, 3H), 2.66 (d, J=11.0, 1H), 2.8 (d, J=11.0, 1H), 3.76–3.86 (m, 3H);
13C NMR δ: 20.1, 20.8, 21.6, 24.5, 27.2, 31.9, 32.9, 39.6, 45.3, 47.8, 52.6, 62.1, 77.2; 77Se NMR δ: 97;
m/z: 292 (M+, 80Se), 290 (M+, 78Se), 275, 273, 204, 160, 91. HRMS calcd for C13H24O2Se: 292.0942
(M+, 80Se), 290.0951 (M+, 78Se). Found: 292.0957, 290.0969.
3.10. General procedure for preparation of spiroselenuranes 8a–d
To a solution of selenide 6a–d (1.10 mmol) in CH2Cl2 (25 ml) was added t-BuOCl (0.14 ml, 1.16
mmol) dropwise at 0°C under an N2 atmosphere. The mixture was stirred at 0°C for 30 min followed by

3312
J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
dropwise addition of Et3N (0.17 ml, 1.21 mmol), then the reaction was stirred for 1.5 h at 0°C to rt. The
reaction mixture was worked up by removal of the solvent and excess reagents followed by diluting with
H2O (5 ml), the aqueous layer was extracted with EtOAc (3×50 ml), and the combined organic layer
was washed with H2O (3×10 ml) followed by brine (10 ml) and dried over MgSO4. Evaporation of the
solvent under reduced pressure afforded the crude product which was purified by recrystallization from
hexane and CH2Cl2 to give the product 8a–d as colorless crystals.
3.10.1. Spiro[4H-3a,6-methano-3H-1,2-benzoxasulfole-2,20 λ4-[5H-1,2]benzoxaselenol]-50 -one,5,6,7,
7a-tetrahydro-8,8-dimethyl-[2R-(2α,3aα,6α,7aβ)]-8a
From 6a (177 mg, 0.5 mmol), t-BuOCl (0.063 ml, 0.53 mmol) and Et3N (0.77 ml, 0.55 mmol) was
obtained spiroselenurane 8a (175 mg, 100%) as colorless crystals. Mp 168–169°C; [α]D26 +81.0 (c 1.00,
1
CHCl3); IR (KBr) 2958, 1668, 1319, 1292, 1050, 763 cm−1; H NMR δ: 0.93 (s, 3H), 1.21 (s, 3H),
1.0–1.08 (m, 1H), 1.12–1.24 (m, 1H), 1.7–1.95 (m, 4H), 2.1–2.21 (m, 1H), 3.14 (d, J=13.2, 1H), 4.16
(d, J=13.2, 1H), 4.37 (dd, J=2.8, 7.1, 1H), 7.66–7.79 (m, 2H), 7.81–7.87 (m, 1H), 8.21–8.24 (m, 1H);
13C NMR δ: 20.6, 20.7, 27.0, 29.4, 39.8, 45.5, 46.6, 55.1, 56.3, 93.3, 126.3, 131.1, 132.6, 132.7, 133.5,
137.4, 169.2; 77Se NMR δ: 887; m/z: 354 (M++2, 80Se), 352 (M++2, 78Se and/or M+, 80Se), 350 (M+,
78Se), 308, 306, 200, 198, 151, 109, 107, 93. Anal. calcd for C17H20O3Se: C, 58.12; H, 5.74. Found: C,
58.28; H, 5.56.
3.10.2. Spiro[4H-3a,6-methano-3H-1,2-benzoxasulfole-2,20 λ4-[5H-1,2]oxaselenol]-50 -one,5,6,7,7a-
tetrahydro-8,8-dimethyl-[2R-(2α,3aα,6α,7aβ)] 8b
From 6b (Z:E=ca. 4:1, 267 mg, 0.88 mmol), t-BuOCl (0.11 ml, 0.92 mmol) and Et3N (0.14 ml, 0.1
26
mmol) was obtained spiroselenurane 8b (212 mg, 79%) as colorless crystals. Mp 126–127°C; [α]D
−189.41 (c 0.95, CHCl3); IR (KBr) 2957, 2875, 1674, 1592, 1323, 104.8 cm−1; H NMR δ: 0.92 (s,
1
3H), 1.07 (s, 3H), 1.18–1.3 (m, 2H), 1.73–2.08 (m, 5H), 3.06 (d, J=12.7, 1H), 4.18 (d, J=13.2, 1H), 4.26
(dd, J=3.3, 7.1, 1H), 7.02 (d, J=6.0, 1H) 7.24 (d, J=6.0, 1H); 13C NMR δ: 20.3, 20.6, 26.9, 29.8, 39.7,
45.8, 46.5, 55.6, 55.7, 94.9, 111.5, 136.8, 144.1; 77Se NMR δ: 919; m/z: 302 (M+, 80Se), 300 (M+, 78Se),
258, 256, 178, 138, 136, 91, 65. Anal. calcd for C13H18O3Se: C, 51.83; H, 6.02. Found: C, 51.65; H,
5.99.
3.10.3. Spiro[4H-3a,6-methano-3H-1,2-benzoxasulfole-2,20 λ4-30,40-dihydro-[5H-1,2]oxaselenol]-50 -
one,5,6,7,7a-tetrahydro-8,8-dimethyl-[2R-(2α,3aα,6α,7aβ)] 8c
From 6c (116 mg, 0.38 mmol), t-BuOCl (0.05 ml, 0.42 mmol) and Et3N (0.06 ml, 0.46 mmol) was
obtained spiroselenurane 8c (110 mg, 95%) as colorless crystals. Mp 137–139°C; [α]D26 +85.74 (c 0.96,
CHCl3); IR (KBr) 2954, 1674, 1355, 629 cm−1; 1H NMR δ: 0.91 (s, 3H), 1.05 (s, 3H), 1.0–1.32 (m, 2H),
1.63–2.04 (m, 5H), 2.85–3.19 (m, 2H), 3.4 (d, J=13.2, 1H), 3.42–3.61 (m, 2H), 3.85 (d, J=13.2, 1H),
4.27 (dd, J=3.3, 7.1, 1H); 13C NMR δ: 20.3, 20.5, 27.0, 29.9, 31.3, 39.6, 43.5, 45.6, 46.6, 49.6, 56.5,
93.6, 175.3; 77Se NMR δ: 913; m/z: 306 (M++2, 80Se), 304 (M++2, 78Se or M+, 80Se), 302 (M+, 78Se),
260, 258, 232, 230, 189, 187, 152, 150, 135, 108, 93, 79. HRMS calcd for C13H20O3Se: 304.0578 (M+,
80Se), 302.0587 (M+, 78Se). Found: 304.0624, 302.0595.
3.10.4. Spiro[4H-3a,6-methano-3H-1,2-benzoxasulfole-2,20 λ4-30,40-dihydro-[5H-1,2]oxaselenol]-5,6,
7,7a-tetrahydro-8,8-dimethyl-[2R-(2α,3aα,6α,7aβ)] 8d
From 6d (46 mg, 0.16 mmol), t-BuOCl (0.022 ml, 0.18 mmol) and Et3N (0.027 ml, 0.19 mmol) was
26
obtained spiroselenurane 8d (34 mg, 74%) as colorless crystals. Mp 80–82°C; [α]D +76.45 (c 0.74,
1
CHCl3); IR (KBr) 2948, 1385, 1012 cm−1; H NMR δ: 0.88 (s, 3H), 1.07 (s, 3H), 1.02–1.22 (m, 2H),

J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
3313
1.69–2.18 (m, 7H), 3.18 (d, J=13.2, 1H), 3.25 (d, J=13.2, 1H), 3.23–3.4 (m, 2H), 3.82–3.96 (m, 1H),
3.99–4.06 (m, 2H); 13C NMR δ: 20.6, 20.9, 27.5, 28.1, 30.9, 40.7, 43.7, 45.4, 46.1, 46.5, 55.1, 66.2,
87.2; 77Se NMR δ: 844; m/z: 290 (M+, 80Se), 288 (M+, 78Se), 274, 272, 232, 230, 189, 187, 138, 136,
108, 93, 79. HRMS calcd for C13H22O2Se: 290.0785 (M+, 80Se), 288.0794 (M+, 78Se). Found: 290.0865,
288.0813.
3.11. Di-(2-exo-hydroxy-10-bornyl) ditelluride 9
The ditelluride was synthesized according to the procedure reported in the literature.11 From tellurium
powder (461 mg, 3.6 mmol), thioureadioxide (390 mg, 3.6 mmol), CTAB (10 mg) and (1S)-10-iodo-2-
exo-borneol (100 mg, 0.36 mmol) was obtained ditelluride 9 (43 mg, 42%) as a red oil. [α]D26 +101.6 (c
1.12, CHCl3); IR (neat) 3454, 2949, 2876, 1453, 1168, 1069, 757 cm−1; 1H NMR δ: 0.85 (s, 6H), 1.07
(s, 6H), 1.08–1.92 (m, 14H), 2.55 (brs, 2H), 3.41 (d, J=11.5, 2H), 3.60 (d, J=11.5, 2H), 3.87 (dd, J=3.8,
7.1, 2H); 13C NMR δ: 8.5, 20.3, 20.9, 27.0, 33.4, 39.5, 46.4, 47.2, 53.9, 77.9; 125Te NMR δ: 660; m/z:
566 (M+, 130Te), 564 (M+, 128Te), 562 (M+, 126Te). HRMS calcd for C16H22OTe: 360.0739 (M+, 130Te),
356.0710 (M+, 126Te). Found: 360.0738, 356.0710.
3.12. General procedure for the synthesis of tellurides 10a,b
To a solution of di-(2-exo-hydroxy-10-bornyl) ditelluride 9 (498 mg, 0.89 mmol) in abs. EtOH (20
ml) was added NaBH4 (101 mg, 2.66 mmol) under an N2 atmosphere at 0°C and the mixture was stirred
until the red color of the ditelluride disappeared (ca. 10 min). Methyl propiolate (0.24 ml, 2.66 mmol)
was added and the whole solution was stirred at 0°C for 15 min. Removal of the solvent under reduced
pressure was followed by addition of saturated NH4Cl solution (15 ml). The mixture was extracted with
CH2Cl2 (3×50 ml) and the organic layer was washed with H2O (10 ml), followed by brine (10 ml) and
dried over MgSO4. Removal of the solvent under reduced pressure gave the crude product which was
purified by column chromatography (hexane:EtOAc=10:1) to give Z-10a (561 mg, 67%) and E-10a (94
mg, 11%) as yellow prisms and an oil, respectively.
3.12.1. Z-Methyl-3-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methyltelluro)-
acrylic acid Z-10a
25
Yellow prisms; mp 75–77°C; [α]D −8.82 (c 1.06, CHCl3); IR (KBr) 3520, 2953, 2879, 1686, 1552,
1340, 1211, 1180 cm−1; 1H NMR δ: 0.87 (s, 3H), 1.01–1.30 (m, 2H), 1.07 (s, 3H), 1.46–1.90 (m, 6H),
2.69 (d, J=11.3, 1H), 2.85 (d, J=11.3, 1H), 3.79 (s, 3H), 3.86 (ddd, J=3.8, 3.8, 7.7, 1H), 6.92 (d, J=9.9,
1H), 8.59 (d, J=9.9, 1H); 13C NMR δ: 10.5, 20.2, 20.7, 27.0, 33.4, 40.4, 45.8, 47.7, 52.0, 52.9, 78.3,
122.9, 137.6, 169.4; m/z: 368 (M+, 130Te), 366 (M+, 128Te), 364 (M+, 126Te). Anal. calcd for C14H22O3Te:
C, 45.95; H, 5.78. Found: C, 46.03; H, 5.94.
3.12.2. E-Methyl-3-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methyltelluro)-
acrylic acid E-10a
26
Yellow oil; [α]D −17.6 (c 2.11, CHCl3); IR (neat) 3482, 2950, 2878, 1716, 1570, 1259, 1150 cm−1
;
1H NMR δ: 0.90 (s, 3H), 0.85–1.30 (m, 2H), 1.09 (s, 3H), 1.51–1.91 (m, 6H), 2.92 (d, J=10.7, 1H), 3.09
(d, J=10.7, 1H), 3.73 (s, 3H), 3.78 (ddd, J=3.6, 3.6, 7.2, 1H), 6.40 (d, J=16.5, 1H), 8.64 (d, J=16.5, 1H);
13C NMR δ: 9.2, 20.3, 20.8, 27.0, 33.7, 40.5, 46.0, 47.9, 51.8, 52.8, 78.5, 127.8, 128.0, 165.0; m/z: 368
(M+, 130Te), 366 (M+, 128Te), 364 (M+, 126Te). HRMS calcd for C14H22O3Te: 368.0638 (M+, 130Te),
366.0624 (M+, 128Te), 364.0608 (M+, 126Te). Found: 368.0627, 366.0590, 364.0590.

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J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
3.12.3. Z-Ethyl-3-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methyltelluro)-3-
propyl-acrylic acid Z-10b
The procedure described in the preparation of 10a was followed to prepare Z-10b (374 mg, 52%) and
E-10b (223 mg, 31%) from di-(2-exo-hydroxy-10-bornyl) ditelluride 9 (498 mg, 0.86 mmol) and ethyl-3-
26
propyl propiolate (360 mg, 2.57 mmol) as a red oil. [α]D −28.55 (c 1.67, CHCl3); IR (neat) 3520, 2954,
1676, 1570, 1325, 1188 cm−1; 1H NMR δ: 0.87 (s, 3H), 0.99 (t, J=7.7, 3H), 1.01–1.22 (m, 2H), 1.07 (s,
3H), 1.3 (t, J=7.1, 3H), 1.52–1.82 (m, 9H), 2.11 (m, 1H), 2.54 (dt, J=1.1, 8.0, 2H), 3.86 (dd, J=3.8, 7.7,
1H), 4.21 (q, J=7.1, 2H), 6.57 (d, J=1.1, 1H); 13C NMR δ: 5.6, 13.5, 14.5, 20.0, 20.7, 23.8, 27.3, 33.0,
39.9, 41.8, 45.1, 48.1, 52.6, 60.6, 77.9, 120.2, 153.1, 168.5; m/z: 424 (M+, 130Te), 422 (M+, 128Te), 420
(M+, 126Te), 272, 270, 268, 226, 224, 222, 135, 93, 79. HRMS calcd for C18H30O3Te: 424.1264 (M+,
130Te), 422.1250 (M+, 128Te), 420.1234 (M+, 126Te). Found: 424.1280, 422.1277, 420.1201.
3.12.4. E-Ethyl-3-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methyltelluro)-3-
propyl-acrylic acid E-10b
Red oil; [α]D −19.62 (c 1.16, CHCl3); IR (neat) 3521, 2955, 1712, 1588, 1367, 1177 cm−1; H
NMR δ: 0.90 (s, 3H), 0.99 (t, J=7.1, 3H), 1.0–1.18 (m, 2H), 1.09 (s, 3H), 1.29 (t, J=7.1, 3H), 1.6–1.9
(m, 8H), 2.01 (d, J=3.8, 1H), 2.89 (dt, J=1.1, 7.1, 1H), 2.9 (d, J=10.4, 1H), 3.0 (d, J=10.4, 1H), 3.75 (dd,
J=3.8, 7.6, 1H), 4.15 (q, J=7.1, 2H), 6.08 (s, 1H).
26
1
3.12.5. General procedure for synthesis of chlorotelluranes 11a,b
To a solution of telluride 10 (1 mmol) in dry CH2Cl2 (8 ml) was added t-BuOCl (0.13 ml, 1.05 mmol)
under an N2 atmosphere at 0°C. Then, the whole mixture was stirred at 0°C for 20 min. Removal of the
solvent under reduced pressure gave the crude product as a white solid. Purification of the residue by
recrystallization from hexane and CH2Cl2 afforded the desired product as colorless crystals.
3.12.6. Z-5-Chloro-10,10-dimethyl-5-(2-methoxycarbonylethenyl)-5λ4-tellura-4-oxatricyclo[5.2.1.03,7
]
decane Z-11a
27
Yield 86%; colorless prisms; mp 163–165°C; [α]D +129.6 (c 1.03, CHCl3); IR (KBr) 2954, 2883,
1
1706, 1427, 1352, 1340, 1227, 1177, 1046, 987, 819 cm−1; H NMR δ: 0.92 (s, 3H), 1.08–1.23 (m,
2H), 1.06 (s, 3H), 1.60–1.96 (m, 5H), 3.32 (d, J=13.7, 1H), 3.46 (d, J=13.7, 1H), 3.91 (s, 3H), 4.02 (dd,
J=4.4, 4.4, 1H), 6.71 (d, J=9.3, 1H), 7.96 (d, J=9.3, 1H); 13C NMR δ: 20.4, 20.5, 26.9, 31.8, 40.0, 42.2,
45.5, 46.7, 53.4, 55.9, 94.2, 127.3, 143.9, 167.1; m/z: 402 (M+, 130Te, 35Cl/128Te, 37Cl), 400 (M+, 128Te,
35Cl/126Te, 37Cl), 398 (M+, 126Te, 35Cl). Anal. calcd for C14H21O3ClTe: C, 42.00; H, 5.29. Found: C,
41.95; H, 5.19.
3.12.7. E-5-Chloro-10,10-dimethyl-5-(2-methoxycarbonylethenyl)-5λ4-tellura-4-oxatricyclo[5.2.1.03,7
]
decane E-11a
25
Yield 97%; colorless prisms; mp 120–122°C; [α]D +82.8 (c 1.16, CHCl3); IR (KBr) 2950, 2881,
2848, 1728, 1604, 1303, 1218, 1140, 1045, 988, 975, 867, 596 cm−1; 1H NMR δ: 0.91 (s, 3H), 0.86–1.28
(m, 2H), 1.07 (s, 3H), 1.60–1.94 (m, 5H), 3.50 (s, 2H), 3.83 (s, 3H), 4.15 (dd, J=5.1, 5.1, 1H), 6.93 (d,
J=16.1, 1H), 7.94 (d, J=16.1, 1H); 13C NMR δ: 20.2, 20.5, 26.6, 31.1, 41.6, 42.7, 45.3, 46.5, 52.5, 55.3,
93.4, 136.0, 141.4, 163.6; m/z: 404 (M+, 130Te, 37Cl), 402 (M+, 130Te, 35Cl/128Te, 37Cl), 400 (M+, 128Te,
35Cl/126Te, 37Cl), 398 (M+, 126Te, 35Cl). Anal. calcd for C14H21O3ClTe: C, 42.00; H, 5.29. Found: C,
41.93; H, 5.31.

J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
3315
3.12.8. Z-5-Chloro-10,10-dimethyl-5-(2-ethoxycarbonyl-1-propylethenyl)-5λ4-tellura-4-oxatricyclo
[5.2.1.03,7]decane Z-11b
Yield 90%; 1H NMR δ: 0.92 (s, 3H), 1.07 (t, J=7.1, 3H), 1.0–1.24 (m, 2H), 1.09 (s, 3H), 1.33 (t, J=7.1,
3H), 1.6–2.0 (m, 7H), 2.59–2.7 (m, 1H), 3.18–3.23 (m, 1H), 3.16 (d, J=14.3, 1H), 3.49 (d, J=14.3, 1H),
3.99 (dd, J=4.9, 7.1, 1H), 4.33 (q, J=7.1, 2H), 6.38 (s, 1H).
3.12.9. E-5-Chloro-10,10-dimethyl-5-(2-ethoxycarbonyl-1-propylethenyl)-5λ4-tellura-4-oxatricyclo
[5.2.1.03,7]decane E-11b
Yield 90%; 1H NMR δ: 0.91 (s, 3H), 1.03 (t, J=7.1, 3H), 1.0–1.2 (m, 2H), 1.06 (s, 3H), 1.33 (t, J=7.1,
3H), 1.6–2.0 (m, 7H), 2.8–2.9 (m, 1H), 3.32 (d, J=13.2, 1H), 3.4–3.53 (m, 1H), 3.58 (d, J=13.2, 1H),
3.93 (dd, J=4.9, 5.5, 1H), 4.22 (q, J=7.2, 2H), 6.84 (s, 1H).
3.13. Spiro[4H-3a,6-methano-3H-1,2-benzoxasulfole-2,20 λ4-[5H-1,2]oxatellurol]-50 -one,5,6,7,7a-
tetrahydro-8,8-dimethyl-[2R-(2α,3aα,6α,7aβ)] 12a
A solution of chlorotellurane Z-11a (50 mg, 0.13 mmol) and saturated NaHCO3 (0.13 ml, 1.05 mmol)
in CH2Cl2 (15 ml) was placed in a separatory funnel. The whole mixture was then shaken for ca. 3 min
at rt. The organic layer was separated, washed with water and dried over MgSO4. Removal of the solvent
under reduced pressure gave the crude product (46.8 mg) which was purified by column chromatography
26
(CHCl3:MeOH=20:1) to afford the product (26.9 mg, 62%) as colorless prisms. Mp 146–147°C; [α]D
−263.6 (c 1.10, CHCl3); IR (KBr) 3500, 2958, 1665, 1642, 1629, 1573, 1323, 1046, 921 cm−1; 1H NMR
δ: 0.91 (s, 3H), 1.04–1.27 (m, 2H), 1.02 (s, 3H), 1.59–1.97 (m, 5H), 2.60 (d, J=13.2, 1H), 3.55 (d, J=13.2,
1H), 4.06 (dd, J=3.3, 6.6, 1H), 7.43 (d, J=7.1, 1H), 7.50 (d, J=7.1, 1H); 13C NMR δ: 20.2, 20.4, 26.7,
31.2, 38.9, 41.4, 45.4, 46.3, 54.8, 93.7, 138.7, 140.6, 170.4; 125Te NMR δ: 1894; m/z: 352 (M+, 130Te),
350 (M+, 128Te), 348 (M+, 126Te). Anal. calcd for C13H18O3Te: C, 44.63; H, 5.19. Found: C, 44.62; H,
5.10.
Recrystallization of 12a from hexane and CH2Cl2 gave a crystal which was suitable for X-ray analysis.
Crystallographic data for 12a: orthorhombic, space group, P212121 (#19) with a=11.8(1) Å, b=32.9(1),
c=7.2(1) Å, V=2781(42) Å3, and Z=8 (dcalcd=1.671 g cm−3), µ (MoKα)=21.34 cm−1 absorption
collected by ω scans; 3647 unique reflections; 2618 with I>3.00σ(I) were used in refinement; R=6.2%,
Rw=7.5%. Further details of the crystal structure investigation are available on request from the Director
of the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ, UK, on quoting
the full journal citation.
3.14. Spiro[4H-3a,6-methano-3H-1,2-benzoxasulfole-2,20 λ4-30-propyl-[5H-1,2]oxatellurol]-50 -one,5,
6,7,7a-tetrahydro-8,8-dimethyl-[2R-(2α,3aα,6α,7aβ)] 12b
The procedure described in the preparation of 12a was generally followed to prepare 12b (59%) from
26
Z-11b as colorless prisms; mp 104–105°C; [α]D −161.17 (c 1.37, CHCl3); IR (KBr) 2956, 1660, 1614,
1313, 1289, 1015, 870 cm−1; 1H NMR δ: 0.92 (s, 3H), 1.03 (t, J=7.1, 3H), 1.06 (s, 3H), 1.08–1.31 (m,
2H), 1.6–2.0 (m, 7H), 2.51 (dt, J=1.8, 8.1, 2H), 2.66 (d, J=13.4, 1H), 3.48 (d, J=13.4, 1H), 3.93 (dd,
J=3.7, 6.4, 1H), 7.08 (s, 1H); 13C NMR δ: 13.7, 20.5, 20.6, 22.8, 26.9, 31.2, 32.8, 37.7, 41.6, 45.2, 46.3,
54.6, 92.7, 132.4, 156.0, 170.0; m/z: 394 (M+, 130Te), 392 (M+, 128Te), 390 (M+, 126Te), 282, 280, 278,
242, 240, 238, 155, 123, 99. Anal. calcd for C16H24O3Te: C, 49.03; H, 6.17. Found: C, 48.92; H, 6.08.

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J. Zhang et al. / Tetrahedron: Asymmetry 9 (1998) 3303–3317
Acknowledgements
This work was supported by Grants-in-Aid for Scientific Research from the Ministry of Education,
Sciences, Sports and Culture, Japan.
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