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Synlett 2013; 24(16): 2061-2066
DOI: 10.1055/s-0033-1339495
letter
© Georg Thieme Verlag Stuttgart · New York

2,4,6-Tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine as a New Recyclable Hypervalent Iodine(III) Reagent for Chlorination and Oxidation Reactions

Prerana B. Thorat
Department of Chemistry, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, Maharashtra 440 033, India   Fax: +91(2462)29245   Email: nnkarade@gmail.com
,
Bhagyashree Y. Bhong
Department of Chemistry, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, Maharashtra 440 033, India   Fax: +91(2462)29245   Email: nnkarade@gmail.com
,
Nandkishor N. Karade*
Department of Chemistry, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, Maharashtra 440 033, India   Fax: +91(2462)29245   Email: nnkarade@gmail.com
› Author Affiliations
Further Information

Publication History

Received: 14 June 2013

Accepted after revision: 09 July 2013

Publication Date:
14 August 2013 (online)

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Abstract

The synthesis of 2,4,6-tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine, as a new recyclable nonpolymeric analogue of (dichloroiodo)benzene, is achieved in two steps using 2,4,6-trichloro-1,3,5-triazine and 4-iodophenol. The application of 2,4,6-tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine for the chlorination reaction of various activated arenes, olefin, and 1,3-diketone is demonstrated. The reagent 2,4,6-tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine can be applied also for the oxidative synthesis of 1,3,4-oxadiazoles and 1,2,4-thiadiazoles under mild conditions in excellent yields. The recyclability of the 2,4,6-tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine was possible owing to the facile recovery and reuse of the coproduced 2,4,6-tris(4-iodophenoxy)-1,3,5-triazine from the reaction mixture due to its practical insolubility in methanol.

Key words

oxidation - hypervalent iodine reagent - (dichloro­iodo)benzene - 1,3,5-triazine - chlorination

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    for this article is available online at http://www.thieme-connect.com/ejournals/toc/synlett.
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  • References and Notes

  • 4 Poliakoff M, Fitzpatrick JM, Farren TR, Anastas PT. Science 2002; 297: 807; and references cited therein
    CrossrefSearch in Google Scholar
    • 9a Richardson RD, Wirth T. Angew. Chem. Int. Ed. 2006; 45: 4402
      CrossrefPubMedSearch in Google Scholar
    • 9b Ochiai M, Miyamoto K. Eur. J. Org. Chem. 2008; 4229
    • 9c Dohi T, Kita Y. Chem. Commun. 2009; 2073
    • 9d Uyanik M, Ishihara K. Chem. Commun. 2009; 208
  • 11 Podgorsek A, Jurisch V, Stavber S, Zupan M, Iskra J, Gladysz JA. J. Org. Chem. 2009; 74: 3133
    CrossrefSearch in Google Scholar
  • 13 Steffensen MB, Hollink E, Kuschel F, Bauer M, Simanek EE. J. Polym. Sci., Part A: Polym. Chem. 2006; 44: 3411
    CrossrefSearch in Google Scholar
  • 15 Preparation of 2,4,6-Tris(4-iodophenoxy)-1,3,5-triazine (11) KOH (20 mmol, 1.12 g) was added to acetone (150 mL) and stirred for 45 min. 4-Iodophenol (20 mmol, 4.4 g) was then added to this solution and again stirred for 30 min. The resulting mixture was cooled to 0 °C, cyanuric chloride (5 mmol, 0.92 g) was added, and the mixture stirred for a further 1 h at 0 °C. The reaction mixture was allowed to stir for 48 h at r.t., poured into crushed ice, the resulting white precipitate was filtered with suction and then washed with MeOH to furnish 11 in 93% yield. White solid, mp 236–238 °C. 1H NMR 400 MHz (CDCl3): δ = 6.88 (2 H, d, J = 8.6 Hz, ArH), 7.66 (2 H, d, J = 8.6 Hz, ArH) ppm. 13C NMR 100 MHz (CDCl3): δ = 90.54, 123.56, 138.65, 151.26, 173.40 ppm. IR (neat): ν = 1589, 1562, 1480, 1378, 1358, 1204, 1172, 1055, 1008, 820, 803, 704 cm–1. ESI-MS: m/z [M + H]+ calcd for C21H12I3N3O3: 735.05; found: 735.75.
  • 16 Synthesis of 2,4,6-Tris(4-dichloroiodophenoxy)-1,3,5-triazine (8) 2,4,6-Tris(4-iodophenoxy)-1,3,5-triazine was dissolved in CHCl3, and chlorine gas was passed through this solution at 0 °C with stirring for 2 h. 2,4,6-Tris(4-dichloroiodophenoxy)-1,3,5-triazine precipitated out as yellow, stable, micro-crystalline solid. The reaction mixture was kept under refrigeration for 24 h, then filtered and washed with CHCl3 to produce 8 in 94% yield. Yellow solid, mp 232–234 °C. IR (neat): ν = 1586, 1561, 1479, 1380, 1360, 1212, 1176, 1002, 838, 807, 749 cm–1.
  • 17 General Procedure for Nuclear Chlorination of Arenes Reagent 8 (0.5 mmol) was added to a stirred solution of the appropiate activated arene (1 mmol) in CH2Cl2 (3 mL). The reaction mixture was stirred at r.t. for the period of time given in Table 1, and progress of reaction was monitored by TLC. When the substrate was consumed, the CH2Cl2 was evaporated under reduced pressure. MeOH was added to the reaction mass, and the white precipitate was isolated by filtration. The residue was washed several times with small aliquote of MeOH and air-dried to recover 2,4,6-tris(4-iodophenoxy)-1,3,5-triazine in 93% yield. The filtrate was concentrated in vacuo to afford the crude product which was purified by column chromatography on silica gel using PE–EtOAc (9:1) as eluent to give the chlorinated product in excellent purity.
  • 21 General Experimental Procedure for the Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazoles 15 from Aldehyde N-Acylhydrazones 14 2,4,6-Tris(4-dichloroiodophenoxy)-1,3,5-triazine (8, 0.4 mmol) was added to a stirred solution of the appropriate aldehyde N-acylhydrazone (1 mmol) in CH2Cl2 at r.t. The progress of the reaction was monitored by TLC, and the reaction was complete within 2–6 h. After completion, the solvent was removed in vacuo followed by addition of MeOH to precipitate out triiodide 11. The resulting heterogeneous solution was filtered to recover 11 which was subsequently subjected to chlorination at 0 °C in CHCl3 to form 8. The filtrate, meanwhile, was concentrated in vacuo to afford the crude product which was purified by column chromatography on silica gel using PE–EtOAc (9:1) as eluent to give 2,5-disubstituted 1,3,4-oxadiazoles in excellent purity.
  • 23 The same reaction in CH2Cl2 resulted in the formation of few other side products as revealed by TLC.
  • 24 General Procedure for 1,2,4-Thiazoles 17 2,4,6-Tris(4-dichloroiodophenoxy)-1,3,5-triazine (8, 0.947 g, 1 mmol) was added to a stirred solution of appropriate thiobenzamide (3 mmol) in MeOH at r.t. The progress of the reaction was monitored by TLC, and the reaction was complete within 2 h. After completion of reaction, the mixture was filtered, and the resulting white precipitate was washed several times with MeOH to recover 11 which was subsequently subjected to chlorination at 0 °C in CHCl3 to form 8. The original filtrate was concentrated in vacuo to afford the crude product which was purified by column chromatography on silica gel using PE–EtOAc (9:1) as eluent to give the substituted 1,2,4-thiazole in excellent purity.
  • 25 The measured solubilities of the coproduced triiodide 11, a reduced form of the 2,4,6-tris[(4-dichloroiodo)phenoxy]-1,3,5-triazine (8) reagent, in several (mixed) solvents at 25 °C are as follows: 0.02 mg·mL–1 (MeOH); 0.02 mg·mL–1 (i-PrOH); 0.2 mg·mL–1 (MeCN); 4.1 mg·mL–1 (EtOAc); 4.3 mg·mL–1 (acetone); 0.04 mg·mL–1 (MeOH–EtOAc = 10:1); 0.06 mg·mL–1 (MeOH–EtOAc = 5:1); 0.6 mg·mL–1 (MeOH–EtOAc = 1:1).