A Facile Strategy to a New Fluorous-Tagged, Immobilized TEMPO Catalyst Using a Click Reaction, and Its Catalytic Activity

Abstract

A new fluorous-tagged TEMPO catalyst was prepared by a facile approach using the copper-catalyzed azide-alkyne cycloaddition as the ligation method. A fluorous F₁₇-CLICK-TEMPO showed excellent activity and selectivity in the oxidation of alcohols to aldehydes using bleach as the terminal oxidant. Moreover, the catalyst could be easily recovered using silica gel 60 and recycled in four cycles without loss of activity.

catalyst immobilization - fluorous - oxidation - click chemistry - TEMPO

References and Notes

1a Zhang W. Chem. Rev.  2004,  104:  2531 

1b Tzschucke CC. Markert C. Bannwarth W. Roller S. Heber A. Haag R. Angew. Chem. Int. Ed.  2002,  41:  3964 

1c Curran DP. Angew. Chem. Int. Ed.  1998,  37:  1174 

2a Dihn LV. Gladysz JA. Angew. Chem. Int. Ed.  2005,  44:  4095 

2b Matsugi M. Curran DP. J. Org. Chem.  2005,  70:  1636 

2c Contel M. Izuel C. Laguna M. Villuendas PR. Alonso PJ. Fisch RH. Chem. Eur. J.  2003,  9:  3077 

2d Tzschucke CC. Markert C. Glatz H. Bannwarth W. Angew. Chem. Int. Ed.  2002,  41:  4500 

3a Zu L. Wang J. Li H. Wang W. Org. Lett.  2006,  8:  3077 

3b Dalicsek Z. Pollreisz F. Gomory A. Soos T. Org. Lett.  2005,  7:  3243 

4 Chen W. Xu L. Hu Y. Banet-Osuna AM. Xiao J. Tetrahedron  2002,  58:  3889 

5a Rostovtsev VV. Green LC. Fokin VV. Sharpless KB. Angew. Chem. Int. Ed.  2002,  41:  2596 

5b For a recent review of the click reaction, see: Bock DP. Hiniestra H. Maarseveen JH. Eur. J. Org. Chem.  2006,  51 

6a Ryu EM. Zhao Y. Org. Lett.  2005,  7:  1035 

6b Kolb HC. Sharpless KB. Drug Discov. Today  2003,  8:  1128 

7a Lee JW. Kim BK. Kim HJ. Han SC. Shim WS. Jin SH. J. Org. Chem.  2006,  71:  4988 

7b Fernandez-Megia E. Correa J. Rodriguez-Meizoso I. Riguera R. Macromolecules  2006,  39:  2113 

7c Wu P. Malkoch M. Hunt JN. Vestberg R. Kaltgrad E. Finn MG. Fokin VV. Sharpless KB. Hawker CJ. Chem. Commun.  2005,  5775 

8a Font D. Jimeno C. Pericas MA. Org. Lett.  2006,  ASAP 

8b Opsteen JA. van Hest JCM. Chem. Commun.  2005,  57 

8c Parrish B. Breitenkamp RB. Emrick T. J. Am. Chem. Soc.  2005,  127:  7404 

8d Dolle RE. MacLeod C. Martinez-Teipel B. Barker W. Seida PR. Hebert T. Angew. Chem. Int. Ed.  2005,  44:  5830 

8e Bettinewtti L. Lober S. Hubner H. Gmeiner P. J. Comb. Chem.  2005,  7:  309 

8f Jang H. Fafarman A. Holub JM. Kirshenbaum K. Org. Lett.  2005,  7:  1951 

8g Lober S. Rodriguez-Loaiza P. Gmeiner P. Org. Lett.  2003,  5:  1753 

9 Gissibl A. Finn MG. Reiser O. Org. Lett.  2005,  7:  2325 

10 Gheorghe A. Matsuno A. Reiser O. Adv. Synth. Catal.  2006,  348:  1016 

11 Wu YM. Deng J. Fang X. Chen QY. J. Fluorine Chem.  2004,  125:  1415 

12 Kaleta Z. Egyed O. Soos T. Org. Biomol. Chem.  2005,  3:  2228 

For examples of immobilized TEMPO reagents, see:

13a Bolm C. Fey T. Chem. Commun.  1999,  1795 

13b Fey T. Fischer H. Bachmann S. Albert K. Bolm C. J. Org. Chem.  2001,  66:  8154 

13c Brunel D. Fajula F. Nagy JB. Deroide B. Verhoef MJ. Veum L. Peters JA. van Bekkum H. Appl. Catal. A  2001,  213:  73 

13d Ciriminna R. Blum J. Avnir D. Pagliaro M. Chem. Commun.  2000,  1441 

13e Ciriminna R. Bolm C. Fey T. Pagliaro M. Adv. Synth. Catal.  2002,  344:  159 

13f Ferreira P. Hayes W. Phillips E. Rippon D. Tsang SC. Green Chem.  2004,  6:  310 

13g Benaglia M. Puglisi A. Holczknecht O. Quici S. Pozzi G. Tetrahedron  2005,  61:  12058 

13h Tanyeli C. Gümüş A. Tetrahedron Lett.  2003,  44:  1639 

13i Pozzi G. Cavazzini M. Holczknecht O. Quici S. Shepperson I. Tetrahedron Lett.  2004,  45:  424 

13j Pozzi G. Cavazzini M. Quici S. Benaglia M. Dell′Anna G. Org. Lett.  2004,  6:  441 

13k Gilhespy M. Lok M. Baucherel X. Chem. Commun.  2005,  1085 

13l Dijksman A. Arends IWCE. Sheldon RA. Chem. Commun.  2000,  271 

13m Weik S. Nicholson G. Jung G. Rademann J. Angew. Chem. Int. Ed.  2001,  40:  1436 

14 Holczknecht O. Cavazzini M. Quici S. Shepperson I. Pozzi G. Adv. Synth. Catal.  2005,  347:  677 

15

Propargyl Ether TEMPO 2: To a stirring suspension of NaH (60% in mineral oil, 830 mg, 20.75 mmol) in dry DMF (10 mL), 4-hydroxy TEMPO (1, 3.0 g, 17.44 mmol) was added portionwise at 0 °C and stirred at r.t. for 50 min. Propargyl bromide (1.85 mL, 21.0 mmol) was added dropwise at 0 °C over a period of 45 min. The resulting mixture was stirred at r.t. overnight. The reaction mixture was poured into ice water (80 mL) and was extracted with EtOAc (4 × 25 mL). The combined organics were washed with brine (2 × 30 mL), dried over MgSO₄, filtered and evaporated under reduced pressure. The residue was purified by column chromatography (silica gel, hexanes-EtOAc, 9:1) to give the title compound 2 (2.85 g, 78%) as an orange solid. ¹H NMR and ¹³C NMR spectra were identical to those previously reported. [10]

16 Szonyi F. Cambon A. J. Fluorine Chem.  1989,  42:  59 

17

1-Azidoperfluorodecane (4): 2-(n-perfluorooctyl) ethyl iodide (3) was reacted with sodium azide in acetone-H₂O (5:1) under reflux conditions for 7 h, this gave 2-(n-perfluorooctyl) ethyl azide (4) in quantitative yield. ¹H NMR and ¹³C NMR spectra were identical to those previously reported. [16]

18

F ₁₇ -CLICK-TEMPO 6: To a stirred mixture of 1-azido-perfluorodecane (4, 1.19 g, 2.43 mmol) and propargyl ether TEMPO 2 (0.95 g, 4.54 mmol) in degassed THF (15 mL), CuI (27 mg, 6 mol%) was added. The resulting mixture was stirred under a nitrogen atmosphere at r.t. for 1 day. Then, the solvent was removed in vacuo and the residue was purified by column chromatography (silica gel, hexanes-EtOAc, 5:1 → 1:1) to give some of the recovered TEMPO 2 (0.4 g, 42%) and the title compound 6 (1.35 g, 80% based on 4, 73% based on consumed 2) as a light orange solid. Mp 105-107 °C; IR (KBr): 2984, 1468, 1371, 1410, 1177, 1142, 1084, 1045, 989, 957, 661 cm^-1; MS (PI-EI, 70 eV): m/z 699 [M⁺]; HRMS: m/z [M + H⁺] calcd for C₂₂H₂₄F₁₇N₄O₂: 699.1628; found: 699.1620.

19 Anelli PL. Montanari F. Quici S. Org. Synth., Coll. Vol. VIII  1993,  367 

20

General Procedure for the Oxidation of Alcohols by F ₁₇ -CLICK-TEMPO 6/Bleach: Alcohol (1.0 mmol) in 2 mL CH₂Cl₂, KBr (24 mg, 0.2 mmol) in H₂O (2 mL) and
F₁₇-CLICK-TEMPO 6 (7 mg, 1 mol%) were added to a round-bottom flask. The reaction mixture was stirred at 0 °C before addition of NaOCl (0.8 mL, 10%) and NaHCO₃ (40 mg, 50 mg·mL^-1, bleach). The resulting mixture was stirred at 0 °C for 15 min. The reaction was quenched by the addition of H₂O (5 mL) and the organic layer was extracted with CH₂Cl₂ (2 × 5 mL). The combined organic layers were dried over anhydrous Na₂SO₄ and concentrated in vacuo to give crude product, which was placed on a short bed of silica and eluted with CH₂Cl₂ in order to obtain pure aldehyde.

21 Schwinn D. Glatz H. Bannwarth W. Helv. Chim. Acta  2003,  86:  188 

22 Aluey LS. Rutherford D. Juliette JJJ. Gladysz JA. J. Org. Chem.  1998,  63:  6302 

23 Richter B. de Wolf E. van Koten G. Deelman BJ. J. Org. Chem.  2000,  653:  3885 

24

Aerobic Oxidation of 4-Bromobenzyl Alcohol by F ₁₇ -CLICK-TEMPO 6; Recycling Experiments: 4-Bromo-benzyl alcohol (2.0 g, 10.7 mmol) in CH₂Cl₂ (20 mL), KBr (257 mg, 2.16 mmol) in H₂O (2 mL) and F₁₇-CLICK-TEMPO 6 (75 mg, 1 mol%) were added to a round-bottom flask. The reaction mixture was stirred at 0 °C before addition of NaOCl (8.6 mL, 14 mmol), NaHCO₃ (430 mg, 50 mg·mL^-1, bleach), stirring then continued at 0 °C for 15 min. The reaction was quenched by addition of H₂O (10 mL) and the organic layer was extracted with CH₂Cl₂ (2 × 10 mL). The combined organic layers were dried over anhydrous Na₂SO₄ and concentrated to give crude product, which was placed on a short bed of silica (5 g) and eluted with CH₂Cl₂ in order to obtain 4-bromobenzylaldehyde. The catalyst was recovered from the column by elution with Et₂O and used in the next cycle.