Reaction of Dimethyldichlorosilane, Phenylmethyldichlorosilane, or Diphenyldichlorosilane with Dimethyl Sulfoxide. Evidence for Silanone and Cyclodisiloxane Intermediates

Dimethyldichlorosilane reacts with dimethyl sulfoxide (DMSO) in the presence of 2,2,5,5-tetramethyl-1-oxa-2,5-disilacyclopentane (I) to yield 2,2,4,4,7,7-hexamethyl-1,3-dioxa-2,4,7-trisilacycloheptane (Si-7), 2,2,4,4,6,6,9,9-octamethyl-1,3,5-trioxa-2,4,6,9-tetrasilacyclononane (Si-9), octamethylcyclotetrasiloxane (D 4 ), and decamethylcyclopentasiloxane (D 5 ). Similar reaction with phenylmethyldichlorosilane with DMSO and I yields 2,4,4,7,7-pentamethyl-2-phenyl-1,3-dioxa-2,4,7-trisilacycloheptane ( Ph Si-7), as well as an approximately 1:1 mixture of cis - and trans -2,4,6,6,9,9-hexamethyl-2,4-diphenyl-1,3,5-trioxa-2,4,6,9-tetrasilacyclononane ( Ph Si-9) and both 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane ( Ph D 3 ) and 2,4,6,8-tetramethyl-2,4,6,8-tetraphenylcyclotetrasiloxane ( Ph D 4 ). Likewise reaction of diphenyldichlorosilane with DMSO and I yields 4,4,7,7-tetramethyl-1,3-dioxa-2,2-diphenyl-2,4,7-trisilacycloheptane ( PhPh Si-7), 6,6,9,9-tetramethyl-1,3,5-trioxa-2,2,4,4-tetraphenyl-2,4,6,9-tetrasilacyclononane ( PhPh Si-9), and hexaphenylcyclotrisiloxane ( PhPh D 3 ).