Author Topic: Tosylation of alcohols using ZrCl4 -Zinc Bromide  (Read 1571 times)

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lutesium

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Tosylation of alcohols using ZrCl4 -Zinc Bromide
« on: October 06, 2004, 10:48:00 PM »



ZrCl4 as an Efficient Catalyst for Selective Tosylation of Alcohols with p-Toluenesulfonic Acid

 Tosylation of alcohols has directly been carried out with p-toluenesulfonic acid in methylene chloride under reflux using ZrCl4 as a catalyst. Primary alcohols were found to be tosylated chemoselectively over secondary alcohols



 Chemistry Letters
Vol. 33 (2004) , No. 11 p.1428
 
ZrCl4 as an Efficient Catalyst for Selective Tosylation of Alcohols with p-Toluenesulfonic Acid
 
Biswanath Das and Vtukuri Saidi Reddy
 

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References
1) Part 54 in the series, “Studies on Novel Synthetic Methodologies.”
 
 
2) T. W. Greene and P. G. M. Wuts, “Protecting Groups in Organic Synthesis,” 3rd ed., Wiley, New York (1999).
 
 
3) a) G. W. Kabalka, M. Varma, R. S. Varma, P. C. Srivastava, and F. F. Knapp, Jr., J. Org. Chem., 51, 2386 (1986).
 
 
 b) J. Hartung, S. Honig, R. Kneuer, and H. Wenner, Synthesis, 1997, 1433.
 
 
 c) Y. Yoshida, Y. Sakakura, N. Aso, S. Okada, and Y. Tanabe, Tetrahedron, 55, 2183 (1999).
 
 
 d) Y. Yoshida, K. Shimomishi, Y. Sakakura, S. Okada, N. Aso, and Y. Tanabe, Synthesis, 1999, 1633.
 
 
4) Y. Nitta and Y. Arakawa, Chem. Pharm. Bull., 33, 1380 (1985).
 
 
5) a) B. M. Choudary, N. S. Chowdari, and M. L. Kantam, Tetrahedron, 56, 7291 (2000).
 
 
 b) S. Velusamy, J. S. K. Kumar, and T. Punniyamurthy, Tetrahedron Lett., 45, 203 (2004).
 
 
6) K. Ishihara, S. Ohara, and H. Yamamoto, Science, 290, 1140 (2000).
 
 
7) Note without reference.

java

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Reduction of Tosylates and Similar Compounds
« Reply #1 on: October 07, 2004, 02:35:00 AM »
Reduction of Tosylates and Similar Compounds

(Reference : March's 5th edition text pg.526)

RCH2OTs  + LiAlH4------------->RCH3

Tosylates and other sulfonatescan be reduced with LiAlH4

Ref .- J.AM.Chem. Soc. 73,2872,1951
          Helv. Chim. Acta. 35,1660, 1952
          Aus. J. Chem. 35, 1895, 1982
Note: when the reagent is LiAlH4 , alky tosyolates are reduced more rapidly than I, Br, if the solvent is Et2O, but the order reversed in diglyme.

......also with NaBH4 in a dipolar aprotic solvent

Ref.-Tetrahedral Lett. 3495,1969

.......with LiEt3BH withi- Bu2AlH (DIBAL-H-diisobutyl-aluminum hydride)

Ref.-Recl. Trav. Chim. Pays-Bas 103, 220, 1984

.......also with Bu3SnH-NaI

Ref.-Chem.Lett. 795, 1983


lutesium

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Zinc Bromide-Promoted Tosylation of Alcohols...
« Reply #2 on: October 07, 2004, 03:08:00 AM »



Zinc Bromide-Promoted Tosylation of Alcohols
 
 



The combination of zinc bromide with tosyl chloride promoted sulfonylation, allowing temperature-controlled regioselective sulfonylation of carbohydrates which possess both primary and secondary hydroxy groups.

Chemistry Letters
Vol. 30 (2001) , No. 7 p.706
 
Zinc Bromide-Promoted Tosylation of Alcohols Allows Efficient Temperature-Controlled Primary Hydroxy Sulfonylation
 
Hatsuo Yamamura, Jyumpei Kawasaki, Hirokazu Saito, Shuki Araki and Masao Kawai
 

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References

1) W. S. Johnson, J. C. Collins, Jr., R. Pappo, M. B. Rubin, P. J. Kropp, W. F. Johns, J. E. Pike, and W. Bartmann, J. Am. Chem. Soc., 85, 1409 (1963).
 
 
2) Y. Tsuda, M. Nishimura, T. Kobayashi, Y. Sato, and K. Kanemitsu, Chem. Pharm. Bull., 39, 2883 (1991).
 
 
3) H. Yamamura and K. Fujita, Chem. Pharm. Bull., 39, 2505 (1991).
 
 
4) Note without reference.
 
 
5) B. L. May, S. D. Kean, C. J. Easton and S. F. Lincoln, J. Chem. Soc., Perkin Trans 1, 1997, 3157.
 
 
6) Note without reference.

no2meth

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ZrCl4?
« Reply #3 on: October 08, 2004, 06:20:00 PM »
The ZrCl4 procedure looks teasy; contrary to the CoCl2-catalyzed process primary alcs tosylate faster! Now, the only question I see is: how the hell do you pull of ZrCl4? It doesn't exactly seem to be lying on hardware store's shelves, many chem suppliers don't have it also :( Say one has access to ZrO2, the oxychloride or some Zr(II) salts. Any idea to make ZrCl4 other than chlorine-CCl4 at 500-800 deg C?

lutesium

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The oxide can be converted to the halide but...
« Reply #4 on: October 08, 2004, 08:07:00 PM »
The oxide can be converted to the halide but neeed to research.

Use the Zinc Bromide method if you want to. Its easier to access