The SHi Reaction at Silicon—A New Entry into Cyclic Alkoxysilanes

✍ Scribed by Armido Studer; Hanno Steen

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 299 KB
• Volume: 5
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/(sici)1521-3765(19990201)5:2<759::aid-chem759>3.0.co;2-v

✦ Synopsis

A new mild radical method for the preparation of cyclic five-membered alkoxysilanes is reported. This method comprises an intramolecular homolytic substitution reaction at silicon (S H i). Various leaving groups (SiMe 3 , GeMe 3 , SnMe 3 ) were tested in the homolytic substitution reaction. We found that high yields were only obtained for silanes bearing a trimethylstannyl functionality as leaving group in the S H i reaction. Rate constants for the cyclization reaction were estimated by conducting standard competition experiments. Based on the kinetic data, more elaborate reaction sequences such as radical addition reactions with a subsequent S H i step were carried out. Stereoselective cyclization reactions were also investigated. Excellent 1,2 diastereoselectivities were observed. The products of the S H i reaction, cyclic alkoxysilanes, can easily be converted to the corresponding diol derivatives by Tamao ± Fleming oxidation as demonstrated for several examples.