SYNTHESIS OF OPTICALLY ACTIVE 1-AZA-4-OXABICYCLOHEPTAN-5-ONES

Article abstract of DOI:10.1007/BF00472757

The reaction of the methyl ester of 1,2-dibromopropionic acid with chiral β-aminoalcohols under the conditions of the Gabriel-Cromwell reaction gave epimers of methyl 1-(β-hydroxyalkyl)aziridine-2-carboxylates, which were separated by liquid chromatography.NMR spectroscopy and CD were used to determine the absolute configuration of these products.The relative rate of conversion of epimeric esters of trans-1-(β-hydroxyalkyl)aziridine-2-carboxylic acids to 1-aza-4-oxabicyclo<4.1.0>heptan-5-ones is a function of the intramolecular contacts of the reacting OH and CO2Me groups in the lactonization of the cis-isomer.The most favorable conformation of the six-membered ring in 1-aza-4-oxabicyclo<4.1.0>eptan-5-ones in solution is a distorted boat.