32659-49-7Relevant articles and documents
Enoate reductase-mediated preparation of methyl (S)-2-bromobutanoate, a useful key intermediate for the synthesis of chiral active pharmaceutical ingredients
Brenna, Elisabetta,Gatti, Francesco G.,Manfredi, Alessia,Monti, Daniela,Parmeggiani, Fabio
experimental part, p. 262 - 268 (2012/06/18)
Enoate reductases belonging to the Old Yellow Enzyme (OYE) family were employed to develop a biocatalysed approach to methyl (S)-2-bromobutanoate, a key intermediate for the introduction of a particular stereogenic unit into the molecular skeleton of a certain class of chiral drugs. Methyl (Z)-2-bromocrotonate afforded, respectively, (S)-2-bromobutanoic acid (ee = 97%) and methyl (S)-2-bromobutanoate (ee = 97%) by baker's yeast fermentation and by OYE1-3 biotransformations. The bioreductions of other methyl 2-haloalkenoates were also considered. It was observed that the (Z)- and (E)-diastereoisomers of α-bromo unsaturated esters afforded the same enantiomer of the corresponding reduced product.
A synthesis of levetiracetam based on (S)-N-phenylpantolactam as a chiral auxiliary
Boschi, Francesca,Camps, Pelayo,Comes-Franchini, Mauro,Munoz-Torrero, Diego,Ricci, Alfredo,Sanchez, Laura
, p. 3739 - 3745 (2007/10/03)
The synthesis of levetiracetam and its enantiomer by deracemization of (±)-2-bromobutyric acid using either (S)- or (R)-N-phenylpantolactam as chiral auxiliaries, followed by SN2 substitution of the bromine atom by a 2-oxopyrrolidin-1-yl group and amidation of the carboxylic acid, is described.
Chirospecific Synthesis of (+)-Pilocarpine
Compagnone, Reinaldo S.,Rapoport, Henry
, p. 1713 - 1719 (2007/10/02)
An efficient chirospecific synthesis for (+)-pilocarpine (1a) using D-methionine or D-2-aminobutanol as chiral educt is described.Formation of the C3-C4 carbon bond at an early stage gave the key intermediate diethyl phosphonate.Wittig coupling of this phosphonate with 1-methyl-5-imidazolecarboxaldehyde introduced the imidazole moiety of the pilocarpine skeleton.Selective reduction of an α,β-unsaturated nitrile to the corresponding allylic alcohol, stereocontrolled hydrogenation of the olefin, and epimerization of (+)-isopilocarpine to (+)-pilocarpine via kinetic protonation led to formation of the natural alkaloid.This methodology allows chirospecific syntheses of the four possible stereoisomers of pilocarpine.A short and convenient route to (+/-)-pilocarpine based on the key intermediate phosphonate is also described.