Synthesis of 2-Alkynyl-Tellurophene Derivatives via Palladium-Catalyzed Cross-Coupling

Abstract

We present herein our results on the palladium-catalyzed cross-coupling of 2-halotellurophene with several terminal alkynes to give the 2-alkynyl-tellurophene derivatives in excellent yields. The reaction proceeded cleanly under mild conditions and was performed with propargyl alcohols, propargyl amines, propiolate, as well as alkyl and aryl alkynes, in the presence of PdCl₂(PPh₃)₂, Et₃N, THF and CuI.

Key words

vinylic tellurides - palladium - cross-coupling - telluro­phene - Sonogashira

References and Notes

• 1a Zeni G. Braga AL. Stefani HA. Acc. Chem. Res.  2003,  36:  731 
• 1b Silveira CC. Braga AL. Vieira AS. Zeni G. J. Org. Chem.  2003,  68:  662 
• 1c Zeni G. Panatieri RB. Lissner E. Menezes PH. Braga AL. Stefani HA. Org. Lett.  2001,  3:  819 
• 2a Petragnani N. Stefani HA. Tetrahedron  2005,  61:  1613 
• 2b Organoselenium Chemistry, In Topics in Current Chemistry   Vol. 208:  Wirth T. Springer-Verlag; Heidelberg: 2000. 
• 2c Krief A. In Comprehensive Organometallic Chemistry II   Vol. 11:  Abel EV. Stone FGA. Wilkinson G. Pergamon Press; New York: 1995.  Chap. 13.
• 2d Paulmier C. Selenium Reagents and Intermediates in Organic Synthesis, In Organic Chemistry Series 4   Baldwin JE. Pergamon Press; Oxford: 1986. 
• 2e Petragnani N. Tellurium in Organic Synthesis   Academic Press; London: 1994. 
• 3 Nogueira CW. Zeni G. Rocha JBT. Chem. Rev.  2004,  104:  6255 
• 4 Sonogashira K. Tohda Y. Hagihara N. Tetrahedron Lett.  1975,  16:  4467 
• 5a Masui K. Ikegami H. Mori A. J. Am. Chem. Soc.  2004,  126:  5074 
• 5b Zeni G. Nogueira CW. Panatieri RB. Silva DO. Menezes PH. Braga AL. Silveira CC. Stefani HA. Rocha JBT. Tetrahedron Lett.  2001,  42:  7921 
• 5c Zeni G. Lüdtke DS. Nogueira CW. Panatieri RB. Braga AL. Silveira CC. Stefani HA. Rocha JBT. Tetrahedron Lett.  2001,  42:  8927 
• 5d Parrish JP. Jung YC. Floyd RJ. Jung KW. Tetrahedron Lett.  2002,  43:  7899 
• 6 The tellurophene derivatives were prepared according to: Barton TJ. Roth RW. J. Organomet. Chem.  1972,  39:  C66 
• 7 Inoue S. Jigami T. Nozoe H. Aso Y. Ogura F. Otsubo T. Heterocycles  2000,  52:  159 

8

Typical Procedure for Cross-Coupling Reaction.
A 25-mL, two-necked, round-bottom flask equipped with a magnetic stir bar and argon was charged sequentially with Pd(PPh₃)₂Cl₂ (10 mol%), CuI (10 mol%), THF (2.5 mL), 2-iodotellurophene (0.25 mmol), alkyne (0.75 mmol) and Et₃N (0.5 mL). The mixture was stirred at r.t. for 12 h. After this time, the mixture was filtered through a pad of alumina eluting with 50 mL of EtOAc. The organic phase was concentrated under vacuum and the residue was purified by flash chromatography. Selected Spectral Data for 1-(5-Butyltellurophen-2-yl)pent-1-yn-3-ol.
¹H NMR (400 MHz, CDCl₃): δ = 7.54 (d, 1 H, J = 4.08 Hz), 7.17 (d, 1 H, J = 4.06 Hz), 4.5 (t, 1 H, 6.3 Hz), 2.84 (t, 2 H, 7.4 Hz), 2.30-2.15 (m, 1 H), 1.79 (quint, 2 H, J = 7.08 Hz), 1.60 (quint, 2 H, J = 7.8 Hz), 1.40 (sext, 2 H, J = 7.05), 1.03 (t, 3 H, J = 7.4 Hz), 0.92 (t, 3 H, J = 7.17 Hz). ¹³C NMR (100 MHz, CDCl₃): δ = 156.63, 142.05, 133.60, 118.87, 95.97, 85.07, 64.47, 36.66, 36.37, 22.03, 13.74, 9.46.