| 摘要 |
Disclosed a process for preparing substantially enantiomerically pure 3-amino-3-cyclopropylpropanoate esters, i.e., esters of 3-amino-3-cyclopropylpropanoic acid (3-cyclopropylalanine esters or 3-CPA esters) by a 5-step process wherein cyclopropanecarboxaldehyde (CPCA) is reacted with malonic acid and a source of ammonia to obtain 3-cyclopropylalanine (3-CPA); esterifying the 3-CPA; contacting the 3-CPA ester with a substantially enantiomerically pure acid selected from tartaric acid, dibenzoyltartaric acid and mandelic acid to obtain a diastereomeric salt of the 3-CPA ester and the acid; recrystallization of the salt to substantial diastereomeric purity; and neutralizing the salt to afford the substantially enantiomerically pure 3-CPA ester.
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