[7751-38-4]  · C6H14Cl2Si  · Dichlorodiisopropylsilane  · (MW 185.17)

(nucleoside 3,5-hydroxy protection; component in Peterson alkenation reaction)

Physical Data: bp 50-55 °C/5 mmHg.1,2

Solubility: sol most organic solvents.

Preparative Method: conveniently prepared by the reaction of diisopropylsilane in carbon tetrachloride with Palladium(II) Chloride at 140 °C for 8 h in a steel bomb. Washing the residue with ether and removing the ether by rotary evaporation yields the product which is purified by distillation to yield a clear colorless oil.

Handling, Storage, and Precautions: special care should be used when handling since the reagent is corrosive.

Nucleoside-protecting Group.

The use of silicon groups as protection for hydroxy groups has been widely exploited.3 One potentially useful way to protect a nucleoside is by using a protecting group which spans the 3- and 5-hydroxy groups. One of the useful groups which can be used as a bifunctional protecting group in nucleosides is the diisopropylsilyl group. Reaction of the nucleoside with dichlorodiisopropylsilane and Imidazole in DMF gives the protected nucleoside (eq 1).4 This method has not been widely used; the more common 3,5-hydroxy-bridging protecting group is a tetraisopropyldisiloxy group.5

Nucleosides are generally linked together through phosphate linkages. Studies are being directed toward synthesizing alternative linkages that will impart different solubilities to oligonucleotides. A diisopropylsilyl protecting group has also been used as a phosphate linker isostere (eq 2).1

A diisopropylsilyl group has also been used as a linker in a radical cyclization reaction to form eight-membered rings (eq 3).6

Modified Peterson Alkenation.

The Peterson alkenation is a useful method for the alkenation of carbonyl compounds. Dichlorodiisopropylsilane has been used in a Peterson alkenation modification (eq 4).7

Related Reagents.

Di-t-butyldichlorosilane; Di-t-butylmethylsilyl Trifluoromethanesulfonate; Di-t-butylsilyl Bis(trifluoromethanesulfonate); Dichlorodimethylsilane; Diisopropylsilyl Bis(trifluoromethanesulfonate).

1. Cormier, J. F.; Ogilvie, K. K. Nucleic Acid Res. 1988, 16, 4583.
2. Hurd, C. D.; Yarnall, W. A. JACS 1949, 71, 755.
3. For reviews on silylations see: (a) Klebe, J. F. ACR 1970, 3, 299. (b) Cooper, B. E. CI(L) 1978, 794.
4. Furusawa, K.; Katsura, T. TL 1985, 26, 887.
5. Markiewicz, W. T. JCR(S) 1979, 24.
6. Hutchinson, J. H.; Daynard, T. S.; Gilliard, J. W. TL 1991, 32, 573.
7. Couret, C.; Escudie, J.; Delpon-Lacaze, G.; Satge, J JOM 1992, 440, 233.

Janet Wisniewski Grissom

University of Utah, Salt Lake City, UT, USA

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.