title: Preferential geminal bis-silylation of 3,4-benzothiophane is caused by the dominance of electron withdrawal by R3Si over steric shielding effects.
abstract: Benzylic C-H lithiation of 3,4-benzothiophane and subsequent treatment with triphenyl- or trimethylchlorosilane under a variety of conditions leads to α,α- rather than α,α'-bis-silylation products as a consequence of anion stabilization by R3Si and very fast deprotonation of the intermediate monosilylated product, even with a sterically bulky base such as lithium diisopropylamide.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Han
authors.forename: Yun
authors.initials: Y
authors.lastname: Ma
authors.forename: Ivan
authors.initials: I
authors.lastname: Keresztes
authors.forename: David B
authors.initials: DB
authors.lastname: Collum
authors.forename: E J
authors.initials: EJ
authors.lastname: Corey
mesh_terms: D004583:Electrons; D008094:Lithium / Q000737:chemistry*; D015394:Molecular Structure; D012821:Silanes / Q000737:chemistry*; D013237:Stereoisomerism; D013876:Thiophenes / Q000737:chemistry*
chemical_list: C000598266:3,4-benzothiophane; D012821:Silanes; D013876:Thiophenes; D008094:Lithium