[7751-38-4] · C6H14Cl2Si · Dichlorodiisopropylsilane · (MW 185.17)
(nucleoside 3´,5´-hydroxy protection; component in Peterson alkenation reaction)
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.
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
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
Janet Wisniewski Grissom
University of Utah, Salt Lake City, UT, USA