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<strong>Fluka</strong> Chemika [106] M. Schorr and W. Schmitt, Phosphorus, Sulfur and Silicon, 68, 25 (1992) [107] J. R. Babu, G. Sanai-Zingde, J. S. Riffle, J. Polymer Sci. 31, 1645 (1993) [108] H. Appler J. Organomet. Chem. 350, 217 (1988) [109] L. M. Markovskii et al., Zh. Organ. Khim. 28, 1388 (1992) [110] M. Müller et al., Liebigs Ann. Chem. 975 (1989) [111] R. Hoffmann, R. Brückner, Chem. Ber. 125,1471 (1992) [112] D. L. J. Clive, C. Zhang, J. Chem. Soc., Chem. Commun. 647 (1993) [113] K. K. Murthi, R. G. Salomon, Tetrahedron Lett. 35, 517 (1994) [114] N. Kuhn, S. Stubenrauch, J. Prakt. Chem. 335, 285 (1993) [115] V. N. Sergeev, E. P. Shapovalenko, Y. I. Baukov, Zh. Obshch. Khim. 57, 1315 (1987) [116] H. Oshita, Y. Mizobe, M. Hidai, J. Organomet. Chem. 456, 213 (1993) [117] K. Hattori, H. Yamamoto, Tetrahedron 50, 3099 (1994) [118] B. J. Bunn, N. S. Simpkins, J. Org. Chem. 58, 533 (1993) [119] P. Duhamel et al., J. Chem. Soc., Perkin Trans. 1, 387 (1992) [120] P. Cazeau, F. Duboudin, F. Moulines, O. Babot, J. Dunogues, Tetrahedron 43, 2075 (1987) [121] T. Thiemann, S. Kohlstruk, G. Schwär, A. de Meijere, Tetrahedron Lett. 32, 3483 (1991) [122] P. A. McCarthy, M. Kageyama, J. Org. Chem. 52, 4681 (1987) [123] F. L. Koerwitz, G. B. Hammond, D. F. Wiemer, J. Org. Chem. 54, 738 (1989) [124] B. Caron, P. Brassard, Tetrahedron 47, 4287 (1991) [125] G. A. Olah, T. Bach, G. K. S. Prakash, New J. Chem., 15, 571 (1991) 3.1.26 Trimethyliodosilane, TMIS Trimethyliodosilane is one of the most reactive silylating agents, particularly useful for synthetic purposes. Although it has been known for many years, its chemical potential was discovered mainly in the last decade [1–3]. It has been used e.g. for the cleavage of ethers, esters, carbamates and ketals, for the synthesis of iodides, and as electrophilic catalyst in different reactions [1–3]. R. D. Miller and D. R. McKean were the first to use TMIS as silylating agent [4]. Later on, other authors showed its high silylating power by comparison with other silylating agents [5, 6]. Trimethyliodosilane is a clear, colourless liquid which is extremely sensitive to light and moisture. Analytical applications M. Donike and co-workers [7] found that trimethyliodosilane is by far the best catalyst for the quantitative silylation of hydroxyketosteroids with MSTFA. Hydroxyl groups are silylated immediately, keto groups yield the pure silyl enol ether within a few min (TMCS and potassium acetate are much less reactive; TMBS, although an excellent catalyst, needs longer reaction times and isomer formation is possible). The drawback with this application of TMIS is the formation of dehydrated products. This can be avoided by using only very small amounts of catalyst, by protecting from light and by addition of a 34 [126] S. Bauermeister, T. A. Modro, Phosphorus, Sulfur and Silicon 72, 201 (1992) [127] T. Hayashi et al., Tetrahedron Lett. 29, 4147 (1988) [128] T. Makaiyama et al., Chemistry Lett. 2239 (1990) [129] S. Czernecki, T. Le Diguarher, Synthesis 683 (1991) [130] G. A. Olah, T. Bach, G. K. S. Prakash, J. Org. Chem. 54, 3770 (1989) [131] P. J. Beswick et al., Tetrahedron 44, 7325 (1988) [132] M. Bordeau et al., J. Org. Chem. 57, 4705 (1992) [133] M. Uemura et al., Tetrahedron Lett. 27, 2479 (1986) [134] U. Gross, D. Kaufmann, Chem. Ber. 120, 991 (1987) [135] M. S. Loft, D. A. Widdowson, T. J. Mowlem, Synlett, 135 (1992) [136] D. L. Comins, Y. C. Myoung, J. Org. Chem. 55, 292 (1990) [137] J. Yoshida et al., J. Org. Chem. 51, 3996 (1986) [138] T. Ohno et al., Tetrahedron Lett. 33, 5515 (1992) [139] A. J. Stern, J. S. Swenton, J. Org. Chem. 54, 2953 (1989) [140] A. A. Krolevets et al., Zh. Obshch. Khim. 58, 2274 (1988) [141] E. P. Kramarova et al., Zh. Obshch. Khim. 61, 1406 (1991) [142] S. F. Karaev et al., Zh. Obshch. Khim. 62, 2709 (1992) [143] W. Amberg, D. Seebach, Chem. Ber. 123, 2439 (1990) [144] M. Grignon-Dubois, M. Fialeix, J.-M. Leger, Can. J. Chem. 71, 754 (1993) [145] M. Grignon-Dubois et al., J. Org. Chem. 58, 1926 (1993) [146] P.-P. Picard et al., J. Organomet. Chem. 419, C1-C4, (1991) [147] M. Pietsch, M. Walter, K. Buchholz, Carbohydrate Res. 254, 183 (1994) very small amount of a reduction agent (e.g. cysteine or 1,4-dithioerythritol). M. Donike introduced this method for the determination of conjugated steroids in the routine urine analysis of anabolica [8]. Synthetic applications R. D. Miller and D. R. McKean [4] found a mixture of HMDS/TMIS (1.1:1) to be a very efficient silylating agent for aldehydes and ketones. The thermodynamically controlled mixtures of trimethylsilyl enol ethers are generated at room temperature in very good yields. All �- and �-ketoesters (the ester groups are not affected!) [4], other ketoesters [18, 20], ketoamides [19] and �-halogenketones [9] can also be transformed regioselectively by this method to the corresponding silyl enol ethers. The utility of this method has also been described by other authors [10, 11]. H. H. Hergott and G. Simchen [5] compared the reactivity of ten electrophilic silylation agents in a system consisting of triethylamine and 1,2-dichloroethane for the silylation of ketones: trimethyliodosilane (together with TMS triflate) gave by far the highest reaction rates. Similar results on the silylating reactivity of TMIS were found by A. R. Bassindale and T. Stout [6]. N-(Trifluoroacetyl)lactams have also been shown to yield trimethylsilyl enol ethers by silylation with TMIS/Et 3N [15]. The preparation of trimethylsilylesters of acetate derivatives from the silver salt and TMIS in ether is possible in 29% yield [16].The bis-silylation
<strong>Fluka</strong> Chemika of primary amines, especially N,N-bis-(trimethylsilyl)-cyclohexylamine was prepared by reaction of TMIS with the primary amine and Et 3N in different solvents. The best solvent with the highest yield is chloroform (65% yield). Benzylamine and diisopropylamine are bis-silylated by this method as well. The authors describe the bis-silylated amine to be stable to water and alcohols in neutral and basic conditions and Grignard reactions [17]. D. Seebach and co-workers [12] described the mixture of TMIS/HMDS (2:1) in pyridine as a potent silylating agent for hindered hydroxyl groups (without base, alcohol reacts with TMIS to form the corresponding iodides by cleavage of the silyl ether intermediates! [1–3]). Transformation of a protected alcohol group (protected with tert-butyldimethylsilyl) to the corresponding iodine derivative was described in [21]. K. Kato and co-workers [13] prepared trimethylsilyl dithiocarboxylates by the reaction of an alkali dithiocarboxylate with a trimethylhalogensilane and found that the Cs-salt together with TMIS gave the highest reaction rates. Besides its catalytic activity in the silylation of ketosteroids with MSTFA [7, 8], TMIS acts also as catalyst for the silylation with allyltrimethylsilane [14]. Special reactions with trimethyliodosilane are the preparation of mono and bis-silylated propynes from 1,3-bistrialkylstannylpropynes [22], the silylation of ketene diethylacetal with TMSI and Et 3N to trimethylsilylketene diethylacetal [23], the synthesis of (1-(trimethylsilyl)-alkylidene)triphenylphosphoranes [24], and the glycosylation of 5-substituted 6-azauracils with TMIS [25]. Typical procedures Bis-silylation of amines [17]: N,N-Bis(trimethylsilyl)cyclohexylamine: Dissolve N-trimethylsilylcyclohexylamine (0.1 mol) and Et 3N (0.1 mol) in 75 ml 1,2dimethoxyethane. Then add TMIS (0.1 mol) dropwise under nitrogen. After stirring at 80°C for 6 h, evaporate the solvent in vacuo and treat the residue with ether (100 ml), 50 ml saturated NaHCO 3 solution and 50 ml water. Wash the ether phase with water, dry over Na 2SO 4 and distill. Yield: 40% 35 Trimethylsilyl enol ethers [18]: Add HMDS (1.6 mmol) and TMIS (1.3 mmol) at –20°C under nitrogen to a stirred solution of the ketone (0.4 mmol) in dichloromethane (2 ml), containing one piece of molecular sieve 4 Å. Stir the mixture under nitrogen for 15 min at –20°C and for 1 h at room temperature. After the reaction has come to completion, extract the reaction mixture with dry diethyl ether. Wash the extract with ice cooled saturated aqueous sodium hydrogen carbonate, dry over MgSO 4 and then concentrate. Elute the residue rapidly through a short alumina column with 4 drops of triethylamine in dry diethyl ether as eluant to obtain the pure silyl enol ether. References [1] A. H. Schmidt, Chemiker-Ztg. 104, 253 (1980) [2] G. A. Olah, S. C. Narang, Tetrahedron 38, 2225 (1982) [3] W. P. Weber, “Silicon Reagents for Organic Synthesis”, Springer Verlag (1983) [4] R. D. Miller, D. R. McKean, Synthesis 730 (1979) [5] H. H. Hergott, G. Simchen, Liebigs Ann. Chem. 1718 (1980) [6] A. R. Bassindale, T. Stout, Tetrahedron Lett. 26, 3403 (1985) [7] M. Donike, J. Zimmermann, J. Chromatogr. 202, 483 (1980) [8] M. Donike et al., Dtsch. Z. Sportmed. 14 (1984) [9] R. D. Miller, D. R. McKean, Synth. Commun. 12, 319 (1982) [10] J. P. McCormick et al., Tetrahedron Lett. 22, 607 (1981) [11] T. Cohen et al., J. Org. Chem. 50, 4596 (1985) [12] R. Hässig et al., Chem. Ber. 115, 1990 (1982) [13] S. Kato et al., Synthesis 457 (1982) [14] A. Hosomi, H. Sakurai, Chem. Lett. 85 (1981) [15] E. P. Kramarova et al., Zh. Obshch. Khim. 54, 1921 (1984) [16] R. J. Terjeson et al., J. Fluorine Chem. 42,187 (1989) [17] M. Schorr, W. Schmitt, Phosphorus, Sulfur, and Silicon 68, 25 (1992) [18] T. Suzuki, E. Sato, K. Unno, J. Chem. Soc. Perkin Trans. I. 2263 (1986) [19] G. A. Kraus, D. Bougie, Synlett 279 (1992) [20] M. Ihara, T. Taniguchi, K. Fukumoto, Tetrahedron Lett. 35, 1901 (1994) [21] G. A. Kraus, D. Bougie, Tetrahedron 50, 2681 (1994) [22] E. T. Bogoradovskii et al., Zh. Obshch. Khim. 58, 1167 (1988) [23] G. S. Zaitseva et al., Zh. Obshch. Khim. 58, 714 (1988) [24] H. J. Bestmann et al., Synthesis 787 (1992) [25] V. I. Kobylinskaya et al., Zh. Obshch. Khim. 62, 1115 (1992)
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Page 4 and 5: Fluka Chemika Dr. Gert van Look Flu
Page 6 and 7: Fluka Chemika Preface The field of
Page 8 and 9: Fluka Chemika T. K. Sarkar, “Meth
Page 10 and 11: Fluka Chemika SEM-Cl 2-(Trimethylsi
Page 12 and 13: Fluka Chemika 2. Comparison of the
Page 14 and 15: Fluka Chemika 3. Reagents for the I
Page 16 and 17: Fluka Chemika [3] D. R. Knapp, “H
Page 18 and 19: Fluka Chemika BSA. Y. Tanabe et al.
Page 20 and 21: Fluka Chemika 3.1.5 N,N-Bis(trimeth
Page 22 and 23: Fluka Chemika [15c] D. J. Harvey,
Page 24 and 25: Fluka Chemika - it reacts more sele
Page 26 and 27: Fluka Chemika [35] L. M. Henriksen,
Page 28 and 29: Fluka Chemika alcohols need no cata
Page 30 and 31: Fluka Chemika acid bis(trimethylsil
Page 32 and 33: Fluka Chemika [10] A. R. Bassindale
Page 34 and 35: Fluka Chemika “Kinetic”silyl en
Page 38 and 39: Fluka Chemika 3.1.27 4-Trimethylsil
Page 40 and 41: Fluka Chemika Silylation of amino a
Page 42 and 43: Fluka Chemika [6] R. L. Ostrozynski
Page 44 and 45: Fluka Chemika [22] A. B. Benkö, V.

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