S- - -a-MeTPA

Methyl 2-pyridyl ketoxime. A solution of 2-acetylpyridine (3, Acros, 27.2 g, 0.225 mole) and hydroxylamine hydrochloride (18.0 g, 0.259 mole) in 100 mL of pyridine is stirred magnetically and heated to reflux in a 250-mL, round-bottomed flask fitted with a water-cooled reflux condenser for 6 h. After removing the solvent on a rotary evaporator, 400 mL of HzO is added, resulting in precipitation of the oxime in the form of a white precipitate which is isolated by vacuum filtration. The filtrate is extracted three times with 100 mL of ether. The white solid is dissolved in ether and combined with the extracts, and then dried with Na2S04. The solvent is evaporated using a rotary evaporator. The crude product (30.0 g, 97%) is used directly in the next step without further purification. 

S-( )-l-(2-pyridyl)ethyl amine. In a 2-L, three-necked reaction flask equipped with overhead mechanical stirring, the oxime (30.0 g, 0.220 mole) and acetic acid (270 mL) are dissolved in 400 mL of 95% EtOH. Zinc dust (270 g) is added in 10 g increments over 2 h. The reaction mixture is stirred with an overhead mechanical stirrer at ambient temperature for 12 h. The 

S-(—)-l-(2-Pyridyl)ethylamine.22 To a 1-L Erlenmeyer flask 34.5 g (0.230 mole) of L-(+)-tartaric acid in 220 mL of boiling 95% EtOH is added 23.6 g (0.193 mole) of racemic l-(2-pyridyl)ethylamine in 300 mL of hot 95% EtOH. As the solution cools to ambient temperature and is allowed to sit for several hours, a white precipitate forms. Four recrystallizations of this precipitate from 100 mL of 95% EtOH gives 12.9 g of the (+)-acid tartrate salt of S-( —) amine ( 99% ee). The salt is neutralized by dissolving in 250 mL of 2 NNaOH and extracting with four 150-mL portions of ether. The organic layer is dried over solid NaOH and then concentrated by rotary evaporation. 

The % ee of the tartrate salt of the amine may be determined by HPLC using a CROWNPAK CR column (Chiral Technologies, Inc. ) The eluent is pH 1.0 HC104, and the flow rate is 0.6 mL/min. 

Caution Perchlorate salts or metal complexes with organic ligands are potentially explosive. They should be handled in small quantities (e.g., 100 mg) and with caution. Chem. Eng. News, 61, 4 (1983). 

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