Lithium borohydride-trimethylsilyl chloride

Phenylstibine [58266-50-5] C H Sb, has been obtained by the reduction of phenyldiio do stihine [68972-61-2] CgH3l2Sb, (73) or phenyldichlorostibine [5035-52-9] 031130.2, (74) with lithium borohydride. It has also been prepared by the hydrolysis or methanolysis of phenylbis(trimethylsilyl)stibine [82363-95-9] C22H23Si2Sb (75). Diphenylstibine [5865-81-6] C22H22Sb, can be prepared by the interaction of diphenylchlorostibine [2629-47-2] C22H2QClSb, with either Hthium borohydride (76) or lithium aluminum hydride (77). It is also formed by hydrolysis or methanolysis of diphenyl (trimethylsilyl)stibine [69561-88-2] C H SbSi (75). Dimesitylstibine [121810-02-4] h.3.s been obtained by the protonation of lithium dimesityl stibide with trimethyl ammonium chloride (78). The x-ray crystal stmcture of this secondary stibine has also been reported. 

To a 0 °C solution of lithium borohydride (1.32 g, 60.54 mmol) in THF (30 mL) was added trimethylsilyl chloride (15.40 mL, 121.1 mmol). The ice-water bath was removed, and the mixture was stirred at room temperature for 15 min. The mixture was cooled to 0 °C and (5)-phenylalanine (5.00 g, 30.27 mmol) was added. The ice-water bath was removed, and the reaction mixture was stirred for 16 h. The mixture was cooled again to 0 °C and methanol (45 mL) was added dropwise followed by a sodium hydroxide solution (2.5 M, 25 mL). The organic solvents were evaporated in vacuo and the residue was extracted with CHCI3 (5 x 50 mL). The combined extracts were dried (Na2SO4), filtered, and evaporated in vacuo to leave 4.55 g (99%) of (5)-phenylalaninol as a white crystalline solid. 

---