The aldol adduct between the anion of 4-isopropyl-2-oxazolin-5-one with racemic N-(tert-butoxycarbonyl)-phenylglycinal underwent concomitant isomerization and ring cleavage under mild basic conditions producing the racemic dipeptide N-Boc-phenylisoserine-valine methyl ester, which after acid hydrolysis followed by sequential esterification and N-benzoylation, gave a separable 1:4 syn/anti diasteroisomeric mixture of N-benzoyl-3-phenylisoserine methyl esters, the predominant anti racemate being resolved by lipase from Pseudomonas fluorescens (P) using vinyl acetate as the acyl donor leading to the corresponding chiral phenylisoserine derivatives.
A chemoenzymatic approach to chiral phenylisoserinates using 4-isopropyl-2-oxazolin-5-one as masked umpoled synthon for hydroxycarbonyl anion
BARCO, Achille;BENETTI, Simonetta;DE RISI, Carmela;POLLINI, Gian Piero;ROMAGNOLI, Romeo;ZANIRATO, Vinicio
1994
Abstract
The aldol adduct between the anion of 4-isopropyl-2-oxazolin-5-one with racemic N-(tert-butoxycarbonyl)-phenylglycinal underwent concomitant isomerization and ring cleavage under mild basic conditions producing the racemic dipeptide N-Boc-phenylisoserine-valine methyl ester, which after acid hydrolysis followed by sequential esterification and N-benzoylation, gave a separable 1:4 syn/anti diasteroisomeric mixture of N-benzoyl-3-phenylisoserine methyl esters, the predominant anti racemate being resolved by lipase from Pseudomonas fluorescens (P) using vinyl acetate as the acyl donor leading to the corresponding chiral phenylisoserine derivatives.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
