Synthesis, structure, and thermolysis of a novel spirotellurane bearing two 1,2-oxatelluretane rings, 1,5-dioxa-4λ4-telluraspiro[3.3]heptane: Oxirane and olefin formation reactions

Article abstract of DOI:10.1016/S0040-4039(02)01527-7

The first 1,5-dioxa-4λ⁴-telluraspiro[3.3]heptane was synthesized and its structure was determined by X-ray analysis. This tellurane gave the corresponding oxirane and olefin, as well as alcohol, upon heating, which were shown to be formed via a radical pathway.

Full text of DOI:10.1016/S0040-4039(02)01527-7

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 43 (2002) 6775–6778
Synthesis, structure, and thermolysis of a novel spirotellurane
bearing two 1,2-oxatelluretane rings,
1,5-dioxa-4l4-telluraspiro[3.3]heptane: oxirane and olefin
formation reactions
Naokazu Kano, Tatsuhisa Takahashi and Takayuki Kawashima*
Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033,
Japan
Received 10 June 2002; revised 12 July 2002; accepted 19 July 2002
Abstract—The first 1,5-dioxa-4l4-telluraspiro[3.3]heptane was synthesized and its structure was determined by X-ray analysis. This
tellurane gave the corresponding oxirane and olefin, as well as alcohol, upon heating, which were shown to be formed via a radical
pathway. © 2002 Elsevier Science Ltd. All rights reserved.
As part of our study on the intermediates of the Wittig
and Peterson-type olefin formation reactions,1,2 we have
reported the syntheses and isolations of oxetanes bear-
ing highly coordinate main group elements at the posi-
tion adjacent to the oxygen atom, which give the
corresponding olefins on thermolyses.3 Meanwhile, we
have found that highly coordinate group 16 element
analogues of 1,2-heteraoxetanes bearing the Martin lig-
and, that is, pentacoordinate 1,2l6-oxathietanes 1 and
tetracoordinate 1,2l4-oxaselenetanes 2, yield not the
olefins but the oxiranes with retention of configura-
tion,4 indicating the deep relationship with the Corey–
Chaykovsky reaction.5 We have also investigated the
synthesis, crystal structure, and unique thermal behav-
ior of the first 1,5-dioxa-4l4-telluraspiro[3.3]heptane 4.
The first trial for the synthesis of 4 by oxidative cycliza-
tion of the corresponding bis(b-hydroxyalkyl) tellurides,
which was effective for the synthesis of its selenium
analogue 3, failed due to photo instability of the syn-
synthesis
of
tetracoordinate
1,5-dioxa-4l4-sele-
naspiro[3.3]heptanes 36 bearing two oxaselenetane rings
to elucidate the influence of the ring size of the spiro-
ring system on the reactivity of 1,2-oxachalcogenetanes
and found that these compounds undergo double oxi-
rane extrusion. Such an oxirane formation from highly
coordinate 1,2-oxachalcogenetanes would proceed
regardless of the central chalcogen atom. The chemistry
of a 1,2-oxatelluretane, however, has not been explored
in detail; there has been only one report on the isola-
tion of a 2-chloro derivative whose thermal reactivity
has not yet been investigated.7 We report here the
thetic
intermediates,
dibenzyl
telluride
and
bis(phenylthiomethyl) telluride. Thus, we took advan-
tage of the direct substitution of tellurium tetrachloride
with LiCHPhC(CF3)2OLi (5) generated by Yus’
method.8 Successive treatment of b-hydroxyalkyl
phenyl sulfide 6 with n-BuLi and excess amount of
lithium in the presence of catalytic amount of 4,4%-di-t-
butylbiphenyl (DTBB) in THF at −78°C afforded 5
(Scheme 1). Adding an excess amount of TeCl4 to 5 at
−78°C and further warming the reaction mixture to the
room temperature gave a single isomer of 1,5-dioxa-
4l4-telluraspiro[3.3]heptane 4 in 13% yield as a stable
solid in the air.9 We think the low yield of tellurane 4 is
caused by the following reasons: (i) the amount of
TeCl4 for reaction may be insufficient, as the excess
amount of lithium, necessary for the lithiation of 6,
reduced and consumed TeCl4, (ii) benzenethiolato
Keywords: tellurane; tellurium; 1,5-dioxa-4l4-telluraspiro[3.3]heptane;
X-ray analysis; thermolysis.
* Corresponding author. Tel./fax: +81-3-5800-6899; e-mail: takayuki
@chem.s.u-tokyo.ac.jp
0040-4039/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(02)01527-7

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N. Kano et al. / Tetrahedron Letters 43 (2002) 6775–6778
1) n-BuLi (1.1 eq)
F3C
F3C
2) Li (5.5 eq),
O
Te
OH
OLi
Ph
H
Ph
H
TeCl4 (4.0 eq)
THF, –78 ºC
DTBB (0.11 eq)
THF, –78 ºC
SPh
Li
F3C
F3C
F3C
F3C
CF3
CF3
O
Ph
Ph
6
5
4 (13%)
Scheme 1.
,
anions, which are inevitably generated in the reaction,
also consumed TeCl4, and (iii) the formation of 4
involves formation of four bonds in a one-pot reaction
with overcoming ring strain of the four-membered
rings.
3.676(2) A, respectively] in contrast to oxathietanes and
oxaselenetanes (Fig. 1B).4,6,12,14 This is the first example
of the synthesis and structural analysis of a 1,5-dioxa-
4l4-telluraspiro[3.3]heptane derivative.
Thermolysis (toluene-d8, 200°C, 180 h in a degassed
sealed tube) of 4 gave the corresponding oxirane 7
(135%) and olefin 815 (7%), together with deuterated
alcohol 96 (56%) (Scheme 2).16 Judging from 19F NMR
spectra, the ratio of the products, 7, 8 and 9, has not
been changed during the reaction. The black precipi-
tates indicate the formation of elemental tellurium or
tellurium oxide. This is the first example of oxetanes
giving both the corresponding olefin and oxirane in
marked contrast to other oxetane analogues with highly
coordinate main group elements.1,3,4,13,17 The yield of 7,
exceeding 100%, indicates the double oxirane formation
from the single molecule of 4. Although the oxetanes
containing a pentacoordinate group 14 or 15 element
gave the corresponding olefin,3 the oxachalcogenetanes
in the spiro ring systems did not yield the olefins but
the oxiranes regardless of the ring size (five- or four-
membered ring) of the other ring except for 4.4,6 These
results have showed an interesting difference in the
reactivity between oxetanes with a tetracoordinate sul-
fur, selenium, and tellurium. Dicoordinate 1,2-oxatel-
luretane to be formed in the first step was not observed
1
In the H, 13C, and 19F NMR spectra of 4, two 1,2-
oxatelluretane rings were observed equivalently. In the
125Te NMR spectra, a signal of 4 (lTe 1207 in CDCl3)
was observed as a multiplet due to long-range coupling
with 19F nuclei. The signal in the extremely low-field
region unambiguously supports its tellurane structure.10
The molecular structure of 4 was finally determined by
X-ray crystallographic analysis.11 It was revealed that
there are two independent molecules of 4 in the unit
cell. Both molecules are very similar to each other. Both
phenyl groups at the 3- and 3%-positions are cis to the
lone pair of the tellurium (Fig. 1A). The apical OꢀTeꢀO
bond angle (148.08(10)°), which is much smaller than
that (160.53(7)°) of a tellurane bearing two Martin
ligands,12 is considerably deviated from linearity,
although the deviation is a common structural feature
of the hypervalent species containing a four-membered
ring.3,4,6,13 Thus, the structure of 4 is intermediate
between pseudo trigonal-bipyramidal structure and
square-pyramidal structure. The bond lengths in the
four-membered rings are almost similar to the previ-
ously reported 2-chloro-1,2-oxatelluretane.7 Both two
four-membered rings in 4 are slightly puckered, judging
from the torsion angles of Te1ꢀC1ꢀC2ꢀO1 (12.0(3)°)
and Te1ꢀC3ꢀC4ꢀO2 (10.7(2)°) and from the sum of the
angles of the four-membered rings [358.2(8)° and
358.6(8)°, respectively]. Interestingly, it forms a dimer
with intermolecular contacts between Te1···O2% and
Te1%···O2 of two independent molecules [3.195(3) and
Scheme 2.
Figure 1. (A) ORTEP drawing of 4 with thermal ellipsoid plot (30% probability for all non-hydrogen atoms). Selected bond
,
lengths (A) and bond angles (°): Te1ꢀO1, 2.091(3); Te1ꢀO2, 2.112(3); Te1ꢀC1, 2.160(3); Te1ꢀC3, 2.155(3); C1ꢀC2, 1.567(5);
C2ꢀO1, 1.397(4); C3ꢀC4, 1.562(5); C4ꢀO2, 1.407(4); O1ꢀTe1ꢀO2, 148.08(10); C1ꢀTe1ꢀO1, 67.30(12); Te1ꢀC1ꢀC2, 89.0(2);
C1ꢀC2ꢀO1, 105.2(3); Te1ꢀO1ꢀC2, 96.7(2); C1ꢀTe1ꢀC3, 98.29(14). (B) Intermolecular interaction of 4. Intermolecular distances
,
(A): Te1%ꢀO2, 3.195(3); Te1ꢀO2%, 3.676(2).

N. Kano et al. / Tetrahedron Letters 43 (2002) 6775–6778
6777
in the reaction mixture by NMR spectroscopy, proba-
bly because of its instability under the reaction condi-
tions. The formation of alcohol 9 is reasonably
explained by the generation of the radical species
through homolytic bond cleavage. Thermolysis of 4 in
the presence of cumene (20 equiv.) as a radical trapping
reagent at 220°C for 30 h gave oxirane 7 (120%), olefin
8 (8%), and alcohol 9 (72%). Furthermore, a similar
reaction using cumene as a solvent afforded 7 (20%)
and 9 (180%) without the formation of 8. The loss of 7
and 8 together with the gain of 9 clearly indicates that
7 and 8 were formed mostly via the radical pathway. It
cannot be ruled out that a part of 7 might be formed by
the carbon–oxygen ligand-coupling or heterolytic cleav-
age of the tellurium–oxygen bond and the successive
attack of the oxide anion at carbon, and that a part of
York, 1983; pp. 58–73; (b) Ager, D. J. Org. React. (NY)
1990, 38, 1–223.
3. (a) Kawashima, T.; Okazaki, R. Synlett 1996, 600–608;
(b) Kawashima, T.; Okazaki, R. In Advances in Strained
and Interesting Organic Molecules; Halton, B., Ed.; JAI
Press: Stamford, 1999; Vol. 7, pp. 1–41.
4. (a) Kawashima, T.; Ohno, F.; Okazaki, R.; Ikeda, H.;
Inagaki, S. J. Am. Chem. Soc. 1996, 118, 12455–12456;
(b) Ohno, F.; Kawashima, T.; Okazaki, R. Chem. Com-
mun. 1997, 1671–1672; (c) Kawashima, T.; Ohno, F.;
Okazaki, R. J. Am. Chem. Soc. 1993, 115, 10434–10435.
5. For the Corey–Chaykovsky reactions, see: Aube´, J. In
Comprehensive Organic Synthesis: Selectivity, Strategy,
and Efficiency in Modern Synthetic Chemistry; Trost, B.
M.; Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 1,
pp. 822–825.
8
might be formed by concerted mechanism if
6. Ohno, F.; Kawashima, T.; Okazaki, R. Chem. Commun.
2001, 463–464.
7. Zeni, G.; Chieffi, A.; Cunha, R. L. O. R.; Zukerman-Sch-
pector, J.; Stefani, H. A.; Comasseto, J. V. Organometal-
lics 1999, 18, 803–806.
homolytic bond fission of TeꢀC (or TeꢀO) of 4 is
reversible and if this process competes with concerted
and/or ionic stepwise mechanisms.4,6
Depending on the substrates, the reactions of telluro-
nium ylides with carbonyl compounds were reported to
give Wittig type products and/or Corey–Chaykovsky
type products, respectively, while the reaction mecha-
nism has not yet been elucidated.18,19 However, it was
thought that the latter reaction proceeds through the
backside attack of the oxide anion of the betaine, which
was formed by the ring opening of the transient four-
membered ring and successive rotation around carbon–
8. Foubelo, F.; Gutierrez, A.; Yus, M. Synthesis 1999,
503–514.
9. Selected spectral and analytical data of 4: 3,7-diphenyl-
2,2,6,6 - tetrakis(trifluoromethyl) - 1,5 - dioxa - 4l4 - tel-
luraspiro-[3.3]heptane 4: colorless needles (hexane/
CH2Cl2); mp 187.6–192.3°C (dec.); 1H NMR (CDCl3, 500
MHz) l 6.69 (s, 2JTeH=27.6 Hz, 2H, TeCH), 7.27–7.39
(m, 10H); 13C{1H} NMR (CDCl3, 126 MHz) l 70.23 (s,
1JTeC=62.8 Hz, TeCH), 83.08 (sept, 2JCF=29.8 Hz,
C(CF3)2), 122.70 (q, 1JCF=287.6 Hz, CF3), 124.46 (q,
1JCF=286.5 Hz, CF3), 127.82 (s), 129.42 (s), 129.74 (s),
131.25 (s); 19F NMR (CDCl3, 254 MHz) l −73.14 (q,
4JFF=8.8 Hz, 6F), −78.22 (q, 4JFF=8.8 Hz, 6F); 125Te
NMR (CDCl3, 158 MHz) l 1206.5 (m). Anal. Calcd for
[C20H12F12O2Te+1/12C6H14+1/12CH2Cl2]: C, 37.79; H,
2.05. Found: C, 38.13; H, 2.16. FABMS m/z calcd for
C20H13F12O2Te [M+H+] 642.9786, found 642.9773.
10. Sato, S.; Takahashi, O.; Furukawa, N. Coord. Chem.
Rev. 1998, 176, 483–514.
carbon bonds.19 The study on
a tetracoordinate
1,2-oxatelluretane which decomposes under milder con-
ditions, where homolytic bond cleavage does not take
place, would provide any information concerning the
possibility that such a species is an intermediate of the
reaction of a telluronium ylide with a carbonyl com-
pound. In this study, we have demonstrated the
unprecedented formation of the oxirane and olefin from
a 1,5-dioxa-4l4-telluraspiro[3.3]heptane.
11. Crystal data for [4+1/12C6H14+1/12CH2Cl2]: FW=
Acknowledgements
654.15, crystal size 0.30×0.20×0.05 mm; trigonal, space
,
,
group R-3(H), Z=36, a=47.578(1) A, c=10.776(1) A,
3
V=21125(2) A ; zcalcd=1.851
g , T=120 K,
cm−3
,
This work was partially supported by a Grant-in-Aid
from the Ministry of Education, Culture, Sports, Sci-
ence and Technology, Japan. We also thank Central
Glass and Tosoh Finechem Corporation for the gifts of
R1(wR2)=0.047(0.121), GOF=1.052. Crystallographic
data for the structures in this paper have been deposited
with the Cambridge Crystallographic Data Centre as
supplementary publication numbers CCDC 169252.
Copies of the data can be obtained, free of charge, on
application to CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: +44 (0) 1223-336033 or e-mail:
deposit@ccdc.cam.ac.uk).
organofluorine
compounds
and
alkyllithiums,
respectively.
12. Michalak, R. S.; Wilson, S. R.; Martin, J. C. J. Am.
Chem. Soc. 1984, 106, 7529–7539.
References
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N. Kano et al. / Tetrahedron Letters 43 (2002) 6775–6778
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