Stereospecific formation of optically active trialkylsilyllithiums and their configurational stability

Evaluation of absolute configuration of naphthylphenyl‐substituted oligosilanes by CD exciton chirality method

“…The naphthylphenyl-substituted oligosilanes (R)-1-(1-naphthyl)-1-phenyl-1,2,2,2-tetramethyldisilane (R)-2 and (R)-1-(1-naphthyl)-1-phenyl-1,2,2,3,3,3-hexamethyltrisilane (R)-5 were synthesized by the reaction of trimethylchlorosilane or pentamethylchlorodisilane 14 with (S)-methyl(1-naphthyl)phenylsilyllithium 15 by configurationally controlled reaction as shown in Scheme 1. Disilanes, (R)-1-(1-naphthyl)-1,2-diphenyl-1,2,2-trimethyldisilane (R)-3 and (R)-1-(1-naphthyl)-1,2,2-triphenyl-1,2-dimethyldisilane (R)-4 were synthesized by the reaction of (S)-methyl(1-naphthyl)phenylchlorosilane 16 and dimethylphenylsilyllithium or diphenylmethylsilyllithium 17 obtained by cleavage reaction of arylsilanes.…”

“…We chose (S)-1 as reference compound for the naphthylphenyl-substituted oligosilanes because it has the same configuration of asymmetric silicon center with (R)-2 and (R)-3 based on the reaction mechanism. 15,16 The longitudinally polarized Sakurai and Gilman. 13,17 In the case of the naphthylsubstituted oligosilane reported by Pitt et al, 19 the spectral shift of UV absorption maximum was relatively insignificant compared with the phenyl-substituted oligosilanes.…”

“…(15 ml) and THF (15 ml) solution of methyllithium (1.77 mmol) at −78°C under argon atmosphere. 15 To the solution, trimethylchlorosilane (2.20 mmol) in toluene (5 ml) was added. Purification by silicagel column chromatography (8:2 hexane-toluene) afforded (R)-2 (83% ee, 54.4% yield).…”

“…30, 137.11, 136.14, 135.30, 135.25, 135.08, 134.65, 133.42, 130.12, 129.34, 128.90, 128.80, 128.74, 127.81, 127.78, 125.40, 125.14 (aromatic) The preparation of optically active (S)-methyl(1-naphthyl)phenylsilyllithium was prepared from (R)-SiSn (86% ee, 1.0 mmol) in toluene (10 ml) and THF (10 ml) solution of methyllithium (1.14 mmol) at −78°C under argon atmosphere. 15 To the solution, a pentamethylchlorodisilane 14 (1.2 mmol) in toluene (3 ml) was added. Purification by silica-gel column chromatography (8:2 hexane-toluene) afforded (R)-5 (82% ee, 51.1% yield).…”

Exciton coupling effects and conformational change of perhexyloligosilanes with optically active methyl(1‐naphthyl)phenylsilyl terminals

“…TfO(Hex 2 Si) m OTf was prepared by the dearylation reaction 15 of 2b, 4b, and 6b with trifluoromethane sulfonic acid (TfOH) in toluene, and (S)-MeNpPhSi*Li was prepared by the same procedure as the reference literature. 16 The products 4a, 6a, and 8a were purified by column chromatography, preparative GPC, and preparative HPLC and characterized by 1 H, 13 C, 29 Si, and FT-MS. The oligosilanes 4a, 6a, and 8a were proved to have optical purities above 99% by HPLC with a Daicel CHIRALCEL OD column.…”