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lutesium
(Hive Bee)
10-06-04 22:48
No 534728
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Tosylation of alcohols using ZrCl4 -Zinc Bromide
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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
![](../picproxie_imgs/pdf.gif)
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.
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java
(Hive Addict)
10-07-04 02:35
No 534760
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Reduction of Tosylates and Similar Compounds
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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
It is better to die on your feet than to live on your knees...Emiliano Zapata
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lutesium
(Hive Bee)
10-07-04 03:08
No 534765
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Zinc Bromide-Promoted Tosylation of Alcohols...
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Zinc Bromide-Promoted Tosylation of Alcohols ![](../picproxie_imgs/pdf.gif)
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.
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no2meth
(Stranger)
10-08-04 18:20
No 534964
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ZrCl4?
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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?
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lutesium
(Hive Bee)
10-08-04 20:07
No 534974
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The oxide can be converted to the halide but...
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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
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