The synthesis of gamma-phenyl and gamma-(n-pyridyl)paraconates was accomplished by chemical reduction of their respective ketodiester precursors followed by cyclisation of the resulting hydroxy diester intermediates. The cis- and trans-lactones thus obtained were separated and separately subjected to enzymatic hydrolysis with HLAP. The cis-lactonic esters had enantiomeric excesses ranging from 94% to 99%, while for the trans-isomers the ee’s ranged from 80% to 93%. The same ketodiester precursors were subjected to reduction with a series of yeasts. The absolute configuration of trans-(-)-2-pyridyl paraconic acid was assigned by means of X-ray analysis of its hydrobromide salt, while the absolute configurations of the other lactones were determined via analysis of their respective CD curves.

Chemoenzymatic and yeast-catalysed synthesis of diastereomeric ethyl gamma-phenyl and gamma-(n-pyridyl)paraconates

FORZATO, Cristina;NITTI, PATRIZIA;PITACCO, GIULIANA;VALENTIN, ENNIO;ZANGRANDO, ENNIO;
2008-01-01

Abstract

The synthesis of gamma-phenyl and gamma-(n-pyridyl)paraconates was accomplished by chemical reduction of their respective ketodiester precursors followed by cyclisation of the resulting hydroxy diester intermediates. The cis- and trans-lactones thus obtained were separated and separately subjected to enzymatic hydrolysis with HLAP. The cis-lactonic esters had enantiomeric excesses ranging from 94% to 99%, while for the trans-isomers the ee’s ranged from 80% to 93%. The same ketodiester precursors were subjected to reduction with a series of yeasts. The absolute configuration of trans-(-)-2-pyridyl paraconic acid was assigned by means of X-ray analysis of its hydrobromide salt, while the absolute configurations of the other lactones were determined via analysis of their respective CD curves.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/1847349
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