HETEROCYCLES

Paper | Special issue | Vol. 82, No. 1, 2010, pp. 441-447
Received, 17th March, 2010, Accepted, 23rd April, 2010, Published online, 27th April, 2010.
DOI: 10.3987/COM-10-S(E)15

■ Tin-Tellurium Exchange Reaction in Tin-Containing Heterocycles: A New Entry for the Preparation of Tellurium Heterocycles

Haruki Sashida,* Mamoru Kaname, and Kazuo Ohyanagi

Faculty of Pharmaceutical Sciences, Hokuriku University, 3-Ho, Kanagawa machi, Kanazawa 920-1181, Japan

Abstract

An alternative, simple and practical preparation of benzo[b]tellurophene, 1H-isotellurochromene, and 1-benzo- and 3-benzotellurepines by taking advantage of the tin-tellurium replacement reaction from the corresponding five-, six- and seven-membered tin-containing heterocycles was achieved.

Much attention has focused on the chemistry of not only aromatic, but also non-aromatic heterocycles containing a heavier element, and many results about their syntheses, chemical properties and applications have been reported. It is well known that five-,2 six-3 and seven-membered4 tin-containing vinyl compounds are excellent precursors of tin-metal exchange reactions5 for the preparation of the corresponding heterocycles containing a heavier element, i.e., boron,2a-d,3a,3b,3p,4a-h phosphorus,2e, 3d,3g,3i,3l arsenic,2e,3c,3d,3g,3i,3j,3l,3m antimony3e,3h,3i,3l,3n,3o,4i and bismuth3f,3i,3k,3l,3o elements. Thus, the synthesis of the parent tin containing heterocycles seemed extremely desirable.
Previously, we succeeded in the preparation of the 1-benzotellurepines (1),6 which are novel seven- membered conjugated heterocycles containing a tellurium element, via the successive intramolecular cyclization of tellurols into an acetylene moiety (Scheme 1, path a).7 Moreover, we have focused on the Synthesis of various tellurium-containing heterocyclic ring systems using efficient similar intramolecular cyclization reactions involving an acetylene group. The 1-benzostannepine skeleton (2)8 has also been constructed by this intramolecular cyclization methodology (path b).

Furthermore, the 1-benzostannepines (2) have previously been prepared through dilithium intermediates (3),9 which were generated by the treatment of the 1-benzotellurepines (1) with tert-BuLi in the presence of TMEDA. In this paper, we describe an alternative route for the preparation of the several heterocycles containing of a tellurium element by the novel replacement reaction of the tin-tellurium element.10

The treatment of the 2-tert-butyl and 2-n-butyl-1-benzostannepines (2a, b)8 with 1.0 equivalent of TeCl4 in CHCl3 at 0 ˚C resulted in the tin-tellurium exchange reaction to give the corresponding 1,1-dichlorotellurepines (4a, b) in 82 and 77% yields, respectively. Compounds 4a and b were obtained as thermally stable yellow and pale yellow crystals at room temperature under an inert atmosphere. The 1,1-dichlorotellurepines (4a, b) were dechlorinated upon treatment with a 2% aqueous Na2S solution reverting to the tellurepines (1)6 in almost quantitative yield.

3,3-Dichloro-3-benzotellurepine (6) was also synthesized by the reaction of the 3-benzostannepine (5)11 with TeCl4 in 78% yield. A five-membered tin heterocycle, the stannaindole (8),12 can be readily transformed into the benzo[b]tellurophene (9) based on this telluration in 80% yield. Compounds 6 and 9 were also treated with Na2S to give the known parent tellurium heterocycles (7, 10).13,14
In addition, the six-membered 2-stannanaphthalene (12)15 similarly reacted with TeCl4 to afford the dichloroisotellurochromene (14, 80% yield), which was quantitatively dechlorinated upon treatment with Na2S, reverting to 11.16 (E)-o-(2’-Lithiovinyl)benzyllithium (13), generated by the tellurium-lithium exchange of 3-tert-butyl-1H-isotellurochromene (11) with BuLi, reacted with an electrophile and a metal reagent to afford the stylene derivatives and 1,2-dihydro-2-metalanaphthalenes involving the 1,2-dihydro-2-stannanaphthalene (12) in good yields, respectively. Very recently, we reported17 that the 2,2-dichloroisotellurochromene (14) was obtained by the treatment of 11 with SO2Cl2 in high yield and has the tellurane structure of the hypervalent tellulium compound. Thus, the mutual transformation between the 1H-isotellurochromene (11) and 1,2-dihydro-2-stannanaphthalene (12) has been accomplished.

In conclusion, the tin-tellurium exchange reaction was found to be a unique and useful tool for the preparation of tellurium-containing heterocycles from the vinylic tin heterocycles. Thus, the 1-benzotellurepines, 3-benzotellurepine, isotellurochromene and benzo[b]tellurophene were obtained from the tin-containing heterocycles in high yields.

EXPERIMENTAL
Melting points were measured on a Yanagimoto micro melting point hot stage apparatus and are uncorrected. IR spectra were determined with a Horiba FT-720 spectrometer. Mass spectra (MS) and HRMS were recorded on a JEOL JMS-DX300 instrument. NMR spectra were determined with a JEOL EX-90A (90 MHz) or a JEOL JNM-GSX 400 (400 MHz) spectrometer in CDCl3 using tetramethylsilane as internal standard and J values are given in Hz. Microanalyses were performed in the Microanalytical Laboratory in this Faculty.

Starting Tin-Containing Heterocycles
1-Benzostannepines (2),8 3-benzostannepine (5),11 1-stannaindole (8)12 and 1,2-dihydro-2-stanna- naphthalenes (12)15 were prepared by the reported methods.

General Procedure for the Sn-Te Exchange Reaction
TeCl4 (135 mg, 0.5 mmol) was added in one portion to a solution of tin heterocycle 2 (0.5 mmol) in benzene (5 mL) under an argon at 5 ˚C. The reaction mixture was vigorously stirred at r.t. for 30 min. Hexane (ca. 15 mL) was added to the mixture, the resulting precipitate was filtered off, and washed with hexane. The crude products were recrystallized from CH2Cl2-hexane or benzene-hexane.
2-tert-Butyl-1,1-dichloro-1-benzotellurepine (4a)
82% yield, pale yellow prisms, mp 156-158 °C (decomp.), (lit.,6b mp 155-158 ˚C).
2-n-Butyl-1,1-dichloro-1-benzotellurepine (4b)
77% yield, yellow needles, mp 113-116 °C (decomp.). MS (EI) m/z (%): 384(M+, 1), 349 (1), 314 (7), 184 (40), 141 (100). 1H-NMR (400 MHz, CDCl3) 1.00, 1.48-1.53, 1.73-1.80, 3.00 (3H, t, J = 7.3 Hz, 2H, m, 2H, m, 2H, t, J = 7.5 Hz, n-Bu), 6.30 (1H, dd, J = 7.7 and 13.6 Hz, 4-H), 6.68 (1H, d, J = 13.6 Hz, 5-H), 6.97 (1H, d, J = 7.7 Hz, 3-H), 7.46-7.55, 8.05 (3H, m, 1H, dd, J = 6.6 and 2.6 Hz, Ph-H). 13C-NMR (100 MHz, CDCl3) 13.8 (q), 21.9 (t), 31.4 (t), 38.5 (t), 125.1 (d), 128.7 (s), 130.2 (d), 131.8 (d), 133.7 (d), 133.9 (d), 134.5 (d), 136.1 (d), 139.6 (s), 140.3 (s). HRMS m/z: C14H16 35Cl2130Te: 383.9691. Found: 383.9749.
3,3- Dichloro-3-benzotellurepine (6)
77% yield, colorless prisms, mp 45-47 ˚C (decomp), (lit.,13 mp 45-48 ˚C).
1,1-Dichloro-2-(trimethylsilyl)benzo[b]tellurophene (9)
88% yield, pale yellow prisms, mp 197-200 ˚C. MS (EI) m/z (%): 376, 374, 372 (M+, 2, 4, 3), 339 (15), 337 (13), 304 (80), 289 (90), 159 (100). 1H-NMR (400 MHz, CDCl3) 0.46 (9H, s, SiMe3), 7.44, 7.50-7.64, 7.84 (1H, ddd, J = 7.7, 7.4 and 1.8 Hz, 2H, m, 1H, d, J = 7.7 Hz, Ph-H), 7.96 (1H, s, 3-H). 13C-NMR (100 MHz, CDCl3) -0.03 (q), 129.4 (d), 129.5 (d), 130.2 (d), 132.3 (d), 148.9 (s), 151.0 (s), 152.5 (d), 159.8 (s). HRMS m/z: C11H14 35Cl2Si130Te: 373.9304. Found: 373.9276.
3-tert-Butyl-2,2-dichloroisotellurochlomene (14)
80% yield, colorless prisms, mp 188-189 ˚C, (lit.,17 mp 188-190 ˚C).

General Procedure for the Dechlorination with Sodium Sulfide
A 2% aqueous Na2S solution (5 mL) was added to a solution of 4a (0.2 mmol) in hexane (5 mL) with vigorous stirring in ice-bath for 10 min. Water (10 mL) was added to the reaction mixture, and the whole was extracted with CH2Cl2 (20 mL x 3). The combined extract was dried (MgSO4) and evaporated in vacuo. The residue was chromatographed on silica gel with hexane to give the tellurium heterocycles. The obtained compounds were identical with the authentic samples prepared in our previous paper.
2-tert-Butyl-1-benzotellurepine (1a): 92%.6
2-n-Butyl-1-benzotellurepine (1b): 89%.6
3-Benzotellurepine (7): 91%.13
2-(Trimethylsilyl)benzo[b]tellurophene (10): 95%.14
3-tert-Butylisotellurochlomene (11): 88%.16

ACKNOWLEDGEMENT
This work was supported in part by a Grant-in Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan (19590022). The authors wish to express to Mrs. Koichi Itoh and Atsuhiro Kuroda (Hokuriku University) for their technical assistances.

References

1. Studies on tellurium-containing heterocycles. Part 29. Part 28: see H. Sashida, H. Satoh, K. Ohyanagi, and M. Kaname, Molecules, 2010, 15, 1466. CrossRef
2. (a) J. J. Eisch, N. K. Hota, and S. Kozima, J. Am. Chem. Soc., 1969, 91, 4575; CrossRef (b) G. E. Herberich, B. Buller, B. Hessner, and W. Oschmann, J. Organometal. Chem., 1980, 195, 253; (c) J. J. Eisch, J. E. Galle, and S. Kozima, J. Am. Chem. Soc., 1986, 108, 379; CrossRef (d) J. Ashe, III, X. Fang, and J. W. Kampf, Organometallics, 1999, 18, 1821; CrossRef (e) A. J. Ashe, III and X. Fang, Chem. Commun., 1999, 1283. CrossRef
3. (a) P. Jutzi, J. Organometal. Chem., 1969, 19, 1; (b) A. J. Ashe, III and P. Shu, J. Am. Chem. Soc., 1971, 93, 1804; CrossRef (c) P. Jutzi and K. Deuchert, Angew. Chem., Int. Ed., 1969, 8, 991; CrossRef (d) A. J. Ashe, III, J. Am. Chem. Soc., 1971, 93, 3293; CrossRef (e) A. J. Ashe, III, J. Am. Chem. Soc., 1971, 93, 6690; CrossRef (f) A. J. Ashe, III and M. D. Gordon, J. Am. Chem. Soc., 1972, 94, 7596; CrossRef (g) G. Märkl and F. Kneidl, Angew. Chem., Int. Ed., 1973, 11, 931; CrossRef (h) A. Meinema, C. J. R. Crispim Romão, and J. G. Noltes, J. Organometal. Chem., 1973, 55, 139; (i) P. Jutzi, Angew. Chem., Int. Ed., 1975, 14, 232; CrossRef (j) G. Märkl, H. Kellerer, and F. Kneidl, Tetrahedron Lett., 1975, 2411; CrossRef (k) A. J. Ashe, III, Tetrahedron Lett., 1976, 415; CrossRef (l) A. J. Ashe, III, Acc. Chem. Res., 1978, 11, 153; CrossRef (m) A. J. Ashe, III, D. J. Bellville, and H. S. Freidman, J. Chem. Soc., Chem. Commun., 1979, 880; CrossRef (n) F. Bickelhaupt, R. Lourens, H. Vermeer, and R. J. M. Weustink, Recl. Trav. Chim. Pays-Bas, 1979, 98, 3; (o) A. J. Ashe, III, T. R. Diephouse, and M. Y. El-Sheikh, J. Am. Chem. Soc., 1982, 104, 5693; CrossRef (p) A. J. Ashe, III, X. Fang, and J. W. Kampf, Organometallics, 1999, 18, 466. CrossRef
4. (a) J. Leusink, W. Drenth, J. G. Noltes, and G. J. M. van der Kerk, Tetrahedron Lett., 1967, 1263; CrossRef (b) G. Axelrad and D. Halpern, Chem. Commun., 1971, 291; CrossRef (c) A. J. Ashe, III, J. W. Kampf, C. M. Kausch, H. Konishi, M. O. Kristen, and J. Kroker, Organometallics, 1990, 9, 2944; CrossRef (d) A. J. Ashe, III, J. W. Kampf, Y. Nakadaira, and J. M. Pace, Angew. Chem., Int. Ed., 1992, 31, 1255; CrossRef (e) Y. Sugihara, T. Yagi, I. Murata, and A. Imamura, J. Am. Chem. Soc., 1992, 114, 1479; CrossRef (f) Y. Sugihara, R. Miyatake, and T. Yagi, Chem. Lett., 1993, 933; CrossRef (g) Y. Sugihara, R. Miyatake, T. Yagi, and I. Murata, Tetrahedron, 1994, 50, 6495; CrossRef (h) Y. Sugihara, R. Miyatake, I. Murata, and A. Imamura, J. Chem. Soc., Chem. Commun., 1995, 1249; CrossRef (i) A. J. Ashe III, L. Goossen, J. W. Kampf, and H. Konishi, Angew. Chem., Int. Ed., 1992, 31, 1642. CrossRef
5. L. Maier, D. Seyferth, F. G. A. Stone, and E. G. Rochow, J. Am. Chem. Soc., 1957, 79, 5884. CrossRef
6. (a) H. Sashida, K. Ito, and T. Tsuchiya, J. Chem. Soc., Chem. Commun., 1993, 1493; CrossRef (b) H. Sashida, K. Ito, and T. Tsuchiya, Chem. Pharm. Bull., 1995, 43, 19.
7. (a) H. Sashida, Rev. on Heteroatom Chemistry, 2001, 22, 59; (b) H. Sashida, J. Synth. Org. Chem. Jpn., 2001, 59, 355.
8. H. Sashida and A. Kuroda, J. Chem. Soc., Perkin Trans. 1, 2000, 1965. CrossRef
9. H. Sashida, Heterocycles, 2000, 53, 49. CrossRef
10. A part of this work has been appeared in a preliminary communication: H. Sashida, A. Kuroda, and T. Tsuchiya, Chem. Commun., 1998, 767. CrossRef
11. A. J. Leusink, J. G. Noltes, H. A. Budding, and G. J. M. van der Kerk, Recl. Trav. Chim. Pays-Bas, 1964, 83, 1036.
12. J. Kurita, M. Ishii, S. Yasuike, and T. Tsuchiya, J. Chem. Soc., Chem. Commun., 1993, 1309. CrossRef
13. H. Sashida, H. Kurahashi, and T. Tsuchiya, J. Chem. Soc., Chem. Commun., 1991, 802. CrossRef
14. H. Sashida, K. Sadamori, and T. Tsuchiya, Synth. Commun., 1998, 28, 713. CrossRef
15. H. Sashida, Synthesis, 1999, 1866. CrossRef
16. (a) H. Sashida and K. Ohyanagi, J. Chem. Soc., Perkin Trans. 1, 1998, 2123; CrossRef (b) H. Sashida, K. Ohyanagi, M. Minoura, and K.-y. Akiba, J. Chem. Soc., Perkin Trans. 1, 2002, 606. CrossRef
17. H. Sashida, S. Nakabayashi, M. Kaname, and M. Minoura, Heterocycles, 2010, 80, 1339. CrossRef