| abstract |
Optically active N-substituted phenylalaninols of the formula (I): <IMAGE> (I) wherein R is isopropyl, 1-ethylpropyl, cyclopentyl, cyclohexyl, cycloheptyl, 4-methylbenzyl, 4-methoxybenzyl, or 3,4-methylenedioxybenzyl; and acid addition salts thereof which are useful as a resolving agent, and a process for preparing D-3-acetylthio-2-methylpropionic acid which comprises reacting DL-3-acetylthio-2-methylpropionic acid with an optically active N-substituted phenylalaninol of the formula (I) to form diastereomeric salts, subjecting the formed diastereomeric salts to a fractional crystallization from a solvent to separate the D-acid salt from the L-acid salt, and then decomposing the D-acid salt with a mineral acid to give D-3-acetylthio-2-methylpropionic acid. |