Vol. 26, No. 5, 2015
Princival et al.
835
were placed elemental tellurium (200 mesh) previously
dried overnight in an oven at 100 oC (63.8 g, 0.5 mol) and
SO2Cl2 (250 mL, 3.0 mol). The mixture was refluxed for
72 h until all the tellurium powder was consumed. After
this time, the excess of SO2Cl2 was removed by distillation
under vacuum. A white solid was obtained, which was
submitted to high vacuum under a water bath heating to
remove any trace of SO2Cl2 and then used without further
purification. Yield: 119.8 g (89%).
added p-methoxyphenyltellurium trichloride prepared
as described for 2 (15 mmol), the alkyne (15 mmol) and
benzene (50 mL). The mixture was heated under reflux for
8 h and the reaction was monitored by TLC eluting with a
mixture of hexane:ethyl acetate (4:1). After all the alkyne
was consumed, the mixture was treated with methanol:
water (1:1) (3 × 30 mL) and extracted with ethyl acetate
(3 × 25 mL). The organic phases were dried with MgSO4
and the solvent was evaporated. The residue was filtered
through silica gel eluting with ethyl acetate. After drying,
filtering and evaporating the solvent, the residue was
dissolved in chloroform and precipitated with hexane (for
yields see Table 1).
Reaction under microwave irradiation
In a 50 mL round bottomed flask equipped with
a Vigreux column (25 cm), a reflux condenser and a
drying tube, were placed elemental tellurium (200 mesh)
o
previously dried overnight in an oven at 100 C (3.82 g,
Reaction under microwave irradiation - general procedure
To a glass pressure resistant tube (10 mL) equipped with
a magnetic stirring bar were added the alkyne (1 mmol) and
p-methoxyphenyltellurium trichloride (1 mmol). The tube
was then placed in the oven of a microwave apparatus and
irradiated. Temperature and irradiation time being modified
depending on the used alkyne. After that, the tube was
opened and the residue was dissolved in chloroform and
precipitated with hexane.
30 mmol) and SO2Cl2 (7.5 mL, 90 mmol). The system was
placed into the oven of a microwave apparatus and then it
was irradiated for 4 h at 65 ºC and at 100 W. After this time
all the tellurium powder was consumed and the excess of
SO2Cl2 was removed by distillation under vacuum, leaving
behind a white solid which was submitted to high vacuum
and heating as described above and then used for further
reactions without purification. Yield: 7.59 g (94%).
Preparation of p-methoxyphenyltellurium trichloride (2)
Supplementary Information
Reaction under conventional heating
Supplementary data are available free of charge at
The procedure described by Cunha et al.16 was employed
using the tellurium tetrachloride prepared as described for 1
(26.9 g, 100 mmol) and neat anisole (10.8 mL, 100 mmol).
The yellow solid obtained was recrystallized from acetic
acid. Yield: 24.2 g (71%); m.p.: 181-182 oC, literature:2,17
182 oC.
Acknowledgements
The authors thank FAPESP, CNPq, CAPES and the
University of São Paulo (NAP-CatSinQ) for financial
support.
Reaction under microwave irradiation
In a glass pressure resistant tube (35 mL) equipped with
a magnetic stirring bar were placed tellurium tetrachloride
prepared as described for 1 (1.02 g, 8 mmol) and neat
anisole (0.87 mL, 8 mmol). The tube was closed and
placed in the oven of a microwave apparatus and then
References
1. Zade, S. S.; Singh, H. B. In The Chemistry of Organic Selenium
and Tellurium Compounds, vol. 4; Rappoport, Z., ed.; John
Wiley & Sons: Chichester, 2013, ch. 7.
o
irradiated for 3 min at 50 C and at 100 W, after cooling
2. Petragnani, N.; Stefani, H. A.; Tellurium in Organic Synthesis,
2nd ed.; Elsevier: Amsterdam, 2007.
to room temperature. The solid was washed with ethyl
acetate (3 × 2 mL) and dried under reduced pressure.Yield:
2.34 g (86%); m.p.: 181-182 oC, literature:2,17 182 oC.
3. Comasseto, V. J.; Clososki, C. G.; Cunha, R. L. O. R. In
Tellurium in Comprehensive Organometallic Chemistry III,
vol. 9; Mingos, D. M. P.; Crabtree, R. H., eds.; Elsevier:
Amsterdam, 2007, ch. 9.13.
Addition of p-methoxyphenyltelluriumtrichloride to alkynes,
typical procedure
4. Princival, J. L.; Dos Santos, A. A.; Comasseto, J. V.; J. Braz.
Chem. Soc. 2010, 21, 2042.
Reaction under conventional heating - general procedure
To a 100 mL round bottomed flask equipped with
a reflux condenser and a magnetic stirring bar were
5. Irgolic, K. J. In Organotellurium Compounds, Methods of
Organic Chemistry (Houben Weyl), vol. E12b; Klamann, D.,
ed.; Georg Thieme Verlag: Stuttgart, 1990.