D a-PHENYLETHYLAMINE

Kobrich et al, were successful in separating the enantiomers of 79 via the dia-stereomeric salts of 79 with D-(+)-a-phenylethylamine by repeated extraction with hot acetone. 

The purity of d-a-phenylethylamine-Z-malate is not readily determined by its melting point or specific rotation, but rather by its massive crystalline form and solubility. The acid and neutral /-base-/-acid salts are much more soluble, and usually do not crystallize at all. 

Other OAP (polymers 2,354,5) may be obtained starting from polystyrene (cross-linked with 2% DVB, bead polymer, grain size 200—400 mesh) followed by chlorosul-phonation [4] resp. chloromethylation [5] and subsequent reaction with D-ephedrine or D-a-phenylethylamine [6]. 

By the method referred to under the benzyl/soquinoline alkaloids (p. 193) Leithe has shown that the configuration of the I- and d-canadines by reference to Z( —)-a-phenylethylamine is l(—) and d(-j-) respectively. 

For racemic resolution of naproxen the use of cinchonidine, A/-alkyl-D-glucamine, dehydroabietylamine or (S)-a-phenylethylamine has been described. 

To resolve pyren-l-yl-L-alanine, the above ester was first saponified with 2M NaOH in EtOH to give, after neutralization, racemic acid 190 (3.6 g, mp 212-213 °C). The latter was suspended in EtOH (300 mL) and (+)-l-phenylethylamine (1.1 g) was added and dissolved with heating. Upon cooling, a precipitate was collected and recrystallized (EtOH) to afford the l-190 diastereomeric complex (1.7 g). The filtrate was neutralized with HC1 to recover D-rich 190 (2g), which was resuspended in EtOH (200mL) and treated with (-)-l-phenylethylamine (0.7 g). Upon cooling, the d-190 diastereomeric complex (1.5 g) was collected and recrystallized (EtOH). The two complexes were dissolved separately in EtOH and 1M HC1 was added to precipitate the desired enantiomerically pure l- and D-A-ben-zoylamino acid 190 [mp 230-234 °C for l-190 [a]D —232.5 (c 0.5, DMF) for d-190 [a]D +233 (c 0.5, DMF)]. Refluxing l-190 with coned HQ in AcOH gave free l-184 mp 240-250°C (dec). 

R)-a-Phenylalkylamines. (R)-a-Phenylethylamine (4) can be prepared in about 97% optical purity by addition of methylmagnesium bromide to the chiral hydrazone obtained from benzaldehyde and the N-amino derivative (1) of D-( —)-ephedrine followed by hydrogenolysis (equation I). Acetophenone is not a suitable starting material because it reacts with 1 to form two isomeric hydrazones. ... 

The 2,4-dihydroxy-3,3-dimethyl-butironitrile was treated hydrochloric acid and D,L-3-hydroxy-4,4-dimethyl-dihydro-furan-2-one (D,L-pantolacton) was obtained. The racemic mixture of D- and L-pantolactons was a division of D-and L- isomers by the adding of a-phenylethylamine. So D-pantolacton was isolated. 

D. Kozma, Z. Bocskei, K. Simon, E. Fogassy, Racemic compound formation-conglomerate formation. Part 1. Structural and thermoanalytical study of hydrogen manonate, hydrogen phthalate, and hydrogen succinate of a-phenylethylamine, J. Chem. Soc. Perkin Trans. 2 (1994) 1883-1886. 

The asymmetric synthesis of optically active oxaziridines was carefully investigated by Belzecki and co-workers. ° Starting with E-benzylidene-JR-a-phenylethylamine, they obtained with w-chloroperbenzoic acid the four isomers 12a-d, in the yields indicated. 

---