Ring-Opening Reactions of α,β-Epoxy Silanes with Organocopper Reagents:  Reaction at Carbon or Silicon?

Synthesis of a 35-Member Stereoisomer Library of Bistramide A: Evaluation of Effects on actin State, Cell Cycle and Tumor Cell Growth

“…Several explanations have been put forth on the selective opening of epoxysilanes. 29,43 One interesting hypothesis includes a prior coordination of nucleophile with both the α-carbon and silicon functionality, 44 though more recent studies using allyl cuprates do not support this pathway. 43 Alternatively, formation of a pentacoordinated silicon followed by 1,2-migration was also postulated.…”

“…29,43 One interesting hypothesis includes a prior coordination of nucleophile with both the α-carbon and silicon functionality, 44 though more recent studies using allyl cuprates do not support this pathway. 43 Alternatively, formation of a pentacoordinated silicon followed by 1,2-migration was also postulated. 45 Lastly, X-ray crystal structure 46 and gas phase and theoretical studies 47 showed the α C-O bond (adjacent to the Si) to be longer and weaker than the β C-O bond.…”

Regiochemical Effect of an α-Trimethylsilyl Group on Epoxide Reactions with Non-nucleophilic Bases

“…Ring opening reactions of α,β-epoxysilanes show a strong preference for cleavage of the C−O bond α to silicon by a wide variety of nucleophilic reagents, and a number of years ago, we introduced a synthesis of olefins and heteroatom-substituted olefins based on these reactions 2d, In order to broaden our understanding of the regiochemistry of the reactions of α,β-epoxysilanes, we have studied the influence of an α-silyl group on the reactions of epoxides with non-nucleophilic bases, in which prior coordination with silicon would not be expected. …”

1,4-bis[2,2-bis(trimethylsilyl)ethenyl]benzene: Regioselective ring opening of its α,β-epoxybis(silane) with some nucleophiles

“…Surprisingly, in the reaction of epoxybis(silane) 2 with methylcopper reagent (MeLi/ CuI 2:1), the iodovinylsilane 8 was the major product (Scheme 3). This is in contrast to the results of a,b-epoxysilanes with organocuprate reagents [18]. FT-IR, NMR ( 1 H and 13 C), and mass spectrometry data has confirmed the formation of the iodovinylsilane 8 [8].…”

“…It has also been reported [18] that reaction of a,b-epoxysilanes with organocuprate reagents result in regiospecific opening of the epoxide ring to form b-hydroxyalkylsilanes. Surprisingly, in the reaction of epoxybis(silane) 2 with methylcopper reagent (MeLi/ CuI 2:1), the iodovinylsilane 8 was the major product (Scheme 3).…”