The resolution of trans-2,2-dichloro-3-methylcyclopropanecarboxylic acid via crystallization of its salts with (+)- and (−)-α-phenylethylamine, and the transformation of the resulting enantiomers into (R)- and (S)-dimethyl 2-methylsuccinates
摘要:
The resolution of trans-2,2-dichloro-3-methylcyclopropanecarboxylic acid trans-1 was achieved by crystallization of its salts with (+)- and (-)-alpha-phenylethylamine. The chiral acids were converted into methyl esters 9, which upon reaction with sodium methoxide in methanol underwent a three-carbon ring cleavage, leading to the corresponding mono-orthoester derivatives 10. Acidic hydrolysis then gave the known (R)- and (S)-dimethyl 2-methylsuccinates 12. (C) 2011 Elsevier Ltd. All rights reserved.