Facile synthesis of enantiomerically pure tert-butyl(methyl)phenylsilanes

A method for the preparation of both enantiomers of tert-butyl(methyl)pheny lsilane 2 is presented. Racemic tert-butyl(methyl)phenylsilyl chloride 3 wa s 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 diaster eomerically 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) w as documented by its reaction (hydrosilylation) with propargylic alcohol de rivative 10 and HPLC analysis of product lr using a chiral column. (C) 1999 Elsevier Science Ltd. All rights reserved.