Tellurium (Te) in Organic Synthesis
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Tellurium (Te) in organic synthesis Reporter: Lin Deng Supervisor: Guangbin Dong Date: Jan 28. 2014 Petragnani, N.; Stefani, H. A. Tellurium in Organic Synthesis, 2nd ed.; Academic Press: London, 2007. Else_TOS-PETRAGNANI_ch001.qxd 12/4/2006 5:46 PM Page 1 – 1 – Introduction 1.1 SOME PHYSICAL PROPERTIES OF TELLURIUM The Pauling electronegativities of carbon and tellurium are, respectively, 2.5 and 2.1. This, in addition to the large volume of the tellurium atom (atomic radius 1.37, ionic radius 2.21), promotes easy polarization of Te–C bonds. The ionic character of the bonds increases in the order C(sp3)ϪTeϾC(sp2)ϪTeϾC(sp)ϪTe, in accordance with the elec- tronegativity of carbon accompanying the s character (Table 1.1). BriefThe TeϪC bondintroduction therefore exhibits a high reactivity, to Tellurium as demonstrated typically (Te by )the easy heterolytic cleavage towards nucleophilic reagents. 1.2 RELEVANT MONOGRAPHS AND REVIEW ARTICLES 1. Rheinboldt, H. in Houben-Weyl-Methoden der Organischen Chemie (ed. E. Muller). 4th edn, Vol. IX. Georg Thieme, Stuttgart, 1955. 2. Petragnani, N.; Moura Campos, M. Organomet. Chem. Rev. 1967, 2, 61. 3. Cooper, W. C. (ed.). Tellurium. Van Nostrand Rheinhold, New York, 1971. 4. Irgolic, K. J.; Zingaro, R. in Organometallic Reactions (eds. E. Becker; M. Tsutsui). Wiley, New York, 1971. 5. Irgolic, K. J. The Organic Chemistry of Tellurium. Gordon and Breach, New York, 1974. 6. Irgolic, K. J. J. Organomet. Chem. 1975, 103, 91. lrgolic, K. J. J. Organomet. Chem. 1977, 130, 411. Irgolic, K. J. J. Organomet. Chem. 1978, 158, 235; Irgolic, K. J. J. Organomet. Chem. 1980, 189, 65. Irgolic, K. J. J. Organomet. Chem. 1980, 203, 368. Table 1.1 Some physical properties of the VIA family of elements Element Atomic Atomic Electronic Pauling Ionization Ionic Atomic number mass configuration electronegativity potential radius radius O 8 15.99 1s22s22p4 3.5 13.61 1.40 0.66 S 16 32.06 2s22p63s23p4 2.5 10.36 1.84 1.04 Se 34 78.96 3s23p63d104s24p4 2.4 9.75 1.98 1.17 Te 52 127.6 4s24p64d105s25p4 2.1 9.01 2.21 1.37 • 2.5 for carbon & 1large volume atom • easily polarize Te-C bonds • Highly reactive 2 Tellurium (Te) in organic synthesis • Several important types of reactions • Reductions • Tellurium-Mediated Formation of anion species and their reactions with electrophiles • Organotellurium-based ring closure reactions • Remove the Tellurium • With formation of new C-C bonds • With formation of other functionalities • Application of Tellurium chemistry • Vinylic tellurides • Free radical chemistry 3 with deuterium, 100%PhCHDOD is Reductions observed aliphatic ketones and esters are not • Reduction of carbonyl compounds applicable • Using hydrogen telluride Kambe, N.; Kondo, K.; Morita, S.; Murai, S.; Sonoda, N. Angew. Chem. 1980, 92, 1009. • Using phenyl telluride (1) Akiba, M.; Cava, M. P. Synth. Commun. 1984, 12, 1119. (2) Aso, Y.; Ogura, F. et al. Nippon Kagaku Kashi 1987, 1490. Aliphatic ketones and esters are not applicable 4 Reductions • Using phenyl telluride Q1: Why the reaction will give ether instead of alcohol as product in the presence of zinc iodide? Nagakawa, K.; Osuka, M.; Sasaki, K.; Aso, Y.; Otsubo, T.; Ogura, F. Chem. Lett. 1987, 1331. 5 Reductions • Using other tellurides Ti (III) as reducing reagent; DCM Coupling mechanism is unclear Suzuki, S. H.; Manabe, H.; Enokiya, R.; Hanazaki, Y. Chem. Lett. 1986, 1339.; Suzuki, H.; Hanazaki, Y. Chem. Lett. 1986, 549. Me N O H NMP Suzuki, H.; Nakamura, T. J. Org. Chem. 1993, 58, 241. • Deuterium experiments • Mechanism involves radical intermediate generate Ti(III) to reduce the carbonyl group 6 Reductions • Selective Reduction of α,β-unsaturated carbonyl compounds Kambe, N.; Kondo, K.; Morita, S.; Murai, S.; Sonoda, N. Angew. Chem. 1980, 92, 1009.; Akiba, M.; Cava, M. P. Synth. Commun. 1984, 12, 1119 • Reduction of conjugated arylalkenes and arylalkynes • Works well with terminal alkenes acceptable yield (1) Akiba, M.; Cava, M. P. Synth. Commun. 1984, 12, 1119. (2) Aso, Y.; Ogura, F. et al. Nippon Kagaku Kashi 1987, 1490. 7 Reductions • Reduction of imines and enamines Kambe, N.; Inagaki, T.; Miyoshi, N.; Ogawa, A.; Sonoda, N. Chem. Lett. 1987, 7, 1275. • Reductive desulphuration and reduction of nitro groups Suzuki, H.; Manabe, H.; Kawaguchi, T.; Inouye, M. Bull. Chem. Soc. Jpn. 1987, 60, 771 8 Reductions • Reductive desulphuration and reduction of nitro groups • Protic solvent — higher reducing ability • Aprotic solvent — Azo compounds • Steric hindered nitro compounds are easier to be reduced • More practical condition Suzuki, H.; Manabe, H.; Inouye, M. Chem. Lett. 1985, 1671. Osuka, A.; Shimizu, H.; Suzuki, H. Chem. Lett. 1983, 1373. Akiba, M.; Cava, M. P. Synth. Commun. 1984, 14, 1119. Uchida, S.; Yanada; K.; Yamaguchi, H.; Meguri, H. Chem. Lett. 1986, 1069. 9 Reductions • Debromination • Application of this reactions Kambe, N.; Tsukamoto, T.; Miyoshi, N.; Murai, S.; Sonoda, N. Bull. Chem. Soc. Jpn. 1986, 59, 3013. 10 Else_TOS-PETRAGNANI_Ch004.qxd 12/12/2006 6:51 PM Page 147 4.2 TELLURIUM-MEDIATED FORMATION OF ANIONIC SPECIES 147 Chemistry.p. 309. Plenum Press, London, 1973. Mathai, I. M.; Schug, K.; Miller, S. I. J. Org. Chem. 1970, 35, 1733. Gordon, J. E.; Chang, V. S. K. J. Org. Chem. 1973, 38, 3062 and references therein. 42. Moura Campos, M.; Petragnani, N. Tetrahedron Lett. 1960, 5. 43. Suzuki, H.; Kondo, A.; Osuka, A. Bull. Chem. Soc. Jpn. 1985, 58, 1335. 44. Butcher, T. S.; Detty, M. R. J. Org. Chem. 1998, 63, 177. 45. Leonard, K. A.; Zhou, F.; Detty, M. R. Organometallics 1996, 15, 4285. 46. Petragnani, N.; Moura Campos, M. Chem. Ber. 1961, 94, 1759. 47. Ramasamy, K.; Kalyanasundaram, S. K.; Shanmugam, P. Synthesis 1978, 311. 48. Suzuki, S.; Inouye, M. Chem. Lett. 1985, 225. 49. Huang, K.; Hou, Y. Q. Synth. Commun. 1988, 18, 2201. 50. Engman, L. Tetrahedron Lett. 1982, 23, 3601. 51. Li, C. J.; Harp, D. N. Tetrahedron Lett. 1990, 31, 6291. 52. Einstein, F. B. W.; Jones, C. H. W.; Jones, T.; Sharma, R. D. Can. J. Chem. 1983, 61, 2611. 53. Engman, L.; Bystrom, S. E. J. Org. Chem. 1985, 50, 3170. 54. Kambe, N.; Tsukamoto, T.; Miyoshi, N.; Murai, S.; Sonoda, N. Bull. Chem. Soc. Jpn. 1986, 59, 3013. 55. Bargues, V.; Blay, G.; Fernandez, J.; Pedro, J. R. Synlett 1996, 655. 56. See methods reported in refs. 57–60. 57. Osuka, A.; Suzuki, H. Chem. Lett. 1983, 119. 58. Clive, D. L. J.; Beaulieu, P. L. J. Org. Chem. 1982, 47, 1124. 59. Engman, L.; Cava, M. P. J. Org. Chem. 1982, 47, 3946. 60. Li, C. J.; Harp, D. N. Tetrahedron Lett. 1991, 32, 1545. 61. Mack, W. Angew. Chem. 1967, 6, 1083. 62. Luppold, E.; Winter, W. Chem. Ztg. 1977, 101, 303. 63. Osuka, A.; Takechi, K.; Suzuki, H. Bull. Chem. Soc. Jpn. 1984, 57, 303. 64. Suzuki, H.; Takaoka, K.; Ogura, A. Bull. Chem. Soc. Jpn. 1985, 58, 1067. 65. Huang, X.; Pi, J. H. Synth. Commun. 1990, 20, 2297. 66. Huang, X.; Pi, J. H.; Huang, Z. Phosphorus Sulfur Silicon 1992, 67, 177. 67. Padmanabhan, S.; Ogawa, T.; Suzuki, H. J. Chem. Res. (S) 1989, 266. 68. Li, C. J.; Harpp, D. N. Tetrahedron Lett. 1993, 34, 903. 69. Li, C. J.; Harpp, D. N. Tetrahedron Lett. 1992, 33, 7293. 4.2 TELLURIUM-MEDIATED FORMATION OF ANIONIC SPECIES AND THEIR REACTIONS WITH ELECTROPHILES 4.2.1Formation Reformatsky-type of reactionsanion species and their reactions Else_TOS-PETRAGNANI_Ch004.qxd 12/12/2006 6:51 PM Page 148 By treatment with sodium telluride,with bromoacetic electrophiles esters react with aromatic and non-eno- lizable• Reformatsky aldehydes in aprotic-type solvents, reactions giving α,β-unsaturated esters.1,2 Na Te/DMF/THF R 1 2 Br CO2R + RCHO 1 In accordance 148-10°C (37-73%) 4. TELLURIUM IN COORGANICR SYNTHESIS 2 with normal mechanism, 1 O In accordanceR = Me, with Et; Ra =Reformatsky Ph, o -Me, reactionp -Me2N, mechanism, p -Cl, p -FC the6H 4telluride, ion attacks theTe(-2) as bromine atom to generate an ester enolate which reacts in sequence Owith the aldehyde to PhCH = CH, Me2CPh, Me2C=CH(CH2)2CMe=CH anion afford the α,β-unsaturated ester. O- O O- 2- 1 1 Te Br CO2R - R OR -TeBr R1O R O + O H3O R OR1 TeBr- Te + Br- The reaction exhibits the following features: chloroacetates give lower yields than bro- moacetates; the E configuration is observed for the formed CϭC bond; α,β-unsaturated carbonyl compounds• E configuration lead only to 1,2-addition of double products; bond; ketones are unreactive under the described conditions;• for αa ,largeβ-unsaturated excess of the carbonylbromoacetate, only and 1,2-additionsodium telluride is required to assure high conversions.• ketone is not applicable • need large excess of bromoacetate and sodium telluride 1 Reformatsky-type reaction (typical procedure). To a solution of Na2Te (prepared from tel- lurium (0.7 g, 4 mmol), NaH (0.20 g, 8.6 mmol) and DMF (7 mL) by heating at 140°C for 30 min under N , is added dropwise at −20°C a solution of benzaldehyde (0.10 g, 1 mmol) 2 Suzuki, S.; Inouye, M. Chem. Lett. 1986, 403. in THF (1.5 mL) followed by ethyl bromoacetate (0.67 g, 4 mmol) in THF (1.5 mL). 11 Tellurium precipitates instantaneously. After stirring for 1 h, 0.5 M H2SO4 (5 mL) satu- rated with NaCl is added followed by Et2O (10 mL). Excess Na2Te is destroyed by expos- ing the mixture to air and stirring for 1 h. The mixture is filtered through Celite®,the organic phase is separated, and the aqueous layer extracted twice with Et2O. The combined extracts are washed with brine, dried (Na2SO4) and evaporated, leaving a yellow oil, which is purified by Kügelrohr distillation under reduced pressure to give ethyl cinnamate (0.10 g (60%); b.p.