Synthesis and characterization of cage and bicyclic silsesquioxanes via dehydration of silanols

✍ Scribed by Masafumi Unno; Shamsul Bahri Alias; Miwako Arai; Keisuke Takada; Ryoji Tanaka; Hideyuki Matsumoto

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 98 KB
• Volume: 13
• Category: Article
• ISSN: 0268-2605
• DOI: 10.1002/(sici)1099-0739(199904)13:4<303::aid-aoc846>3.0.co;2-#

✦ Synopsis

Synthesis of cage and ladder silsesquioxanes by the dehydration of silanols using dicyclohexylcarbodiimide (DCC) is described. The reaction of 1,3-dicyclohexyldisiloxane-1,1,3,3-tetraol with DCC gave octa(cyclohexylsilsesquioxane) in 13% yield. The bicyclic ladder siloxane 3 (Ph 8 Thex 2 Si 6 O 7 ) was prepared from 1,1,3,3tetraphenyldisiloxane-1,3-diol and 1,3-dithexyldisiloxane-1,1,3,3-tetraol (Thex or thexyl denotes 1,1,2-trimethylpropy) at 80 °C. In this reaction, the propellane-type cage siloxane 2 (Ph 6 Thex 2 Si 5 O 6 ) was generated also. Upon reaction completion at 120 °C, only 2 was obtained. The reaction from the same starting compounds with diisopropylcarbodiimide at 80 °C resulted in another caged siloxane, Ph 4 Thex 4 Si 6 O 8 (5). The structures of 2, 3 and 5 were determined by X-ray crystallography.