Andrzej Zarecki

FACILE SYNTHESIS OF ENANTIOMERICALLY PURE TERT-BUTYL(METHYL)PHENYLSILANES

Abstract A method for the preparation of both enantiomers of tert-butyl(methyl)phenylsilane 2 is presented. Racemic tert-butyl(methyl)phenylsilyl chloride 3 was allowed to react with (R)-(−)-2-amino-1-butanol 4 to give hydrochloride 5. Diastereomer separation via treatment of the respective free amine 6 with 0.5 mol equivalent of HCl in hexane-2-propanol yielded crystalline diastereomerically pure hydrochloride (R)Si-5. The corresponding free amine (R)Si-6 was reduced with LiAlH4 to give (S)-2. The mother liquors obtained after separation of (R)Si-5 on treatment with oxalic acid provided a crystalline salt that eventually afforded (R)-2. The optical purity of (S)-2 (98% ee) was documented by its reaction (hydrosilylation) with propargylic alcohol derivative 10 and HPLC analysis of product 11 using a chiral column.

Migration of aryl groups from silicon to carbon in α,β-epoxysilanes. A new model for hypervalent silicon study

Abstract The reaction of (2 R ,3 R )-3-(triphenylsilyl)glycidol ( 1 ) with n -Bu 4 NF·3H 2 O in THF, followed by treatment of the product with p -nitrobenzoyl chloride yields (2 S )-glycidol p -nitrobenzoate ( 4 ) and trans -cinnamyl p -nitrobenzoate ( 6 ) in a ratio of 1:1.5. The reaction of ( R )Si-( 2R,3R )- or ( R )Si-( 2S, 3 S )-3-[(methyl)(phenyl)(1-naphthyl)silyl]-glycidols, 7 or 8 respectively, with n -Bu 4 NF·3H 2 O affords mixtures of the respective glycidol, trans -cinnamyl alcohol and 3-(1-naphthyl)allyl alcohol. No significant difference in the product distribution in reaction of these two diasteromers was observed.

Preparation of optically activen-butyl(methyl)phenyl-, tert-butyl(methyl)phenyl- andisopropyl(methyl)phenylsilanes from the corresponding silyl chlorides using2,2′-dihydroxy-1,1′-binaphthyls as resolving agents

Enantiomeric silanes 4a, 4b and 4c were obtained from the corresponding racemic silyl chlorides via diastereomeric derivatives with (R)-[1,1′]binaphthalenyl-2,2′-diol; the optical purity of silanes 4a and 4c was determined (>98% ee) by HPLC using a chiral cyclodextrin-based column.