51615-30-6Relevant articles and documents
Preparation of enantiopure pregabalin intermediate using cross linked enzyme aggregates (CLEAs) in basket reactor
Basetty, Shalini,Kumaraguru, Thenkrishnan
, (2022/02/11)
Route to the synthesis of enantiomerically pure ethyl (S)-3-cyano-5-methylhexanoate, (S)-5, a key chiral intermediate for Pregabalin has been improved. The racemic β-cyano diester, 3 was prepared in 98% purity via gelatine catalysed Knoevenagel condensation of diethylmalonate with isovaleraldehyde followed by hydrocyantion of α,β-unsaturated diester 14 using acetone cyanohydrin and K2CO3. Racemic diethyl 2-(1-cyano-3-methylbutyl)malonate, rac-3, has been resolved using lipase from Thermomyces lanuginosus immobilised in form of crosslinked enzyme aggregates, CLEAs. The CLEAs were made by employing commercial soymilk as an additional protein source and a reaction was carried out in a moving basket reactor. The immobilised enzyme was found to be stable in many organic solvents and temperature up to 50 °C. The resolution reaction was studied in a basket reactor at 50% substrate loading in calcium acetate buffer, pH 7.5 at 30 °C by using 20% w/w enzyme loading. The apparent kinetic parameters were V max,app = (8.74 ± 0.43) mM/h/g and K m,app = (1.5 ± 0.07) M (correlation coeff. r = 0.98). The desired ethyl (S)-3-cyano-5-methylhexanoate, (S)-5 is obtained in 90-92% theoretical yield and e.e > 99%. The advantages of this improved process are mild reaction conditions; an alternate method for hydrocyanation step avoiding the use of highly toxic potassium cyanide at large scale operation and an immobilised enzyme that can be reused for at least 11 recycles.
Divergent Rearrangements of Vinylcyclopropane into Skipped Diene and Cyclopentene: Mechanism, Scope, and Limitations
Delbrassinne, Arnaud,Richald, Maximilien,Janssens, Julien,Robiette, Rapha?l
supporting information, p. 2862 - 2868 (2021/06/11)
Vinylcyclopropanes are versatile intermediates in organic synthesis which undergo various rearrangements. We report a new rearrangement of vinylcyclopropane into skipped diene. A detailed mechanistic study revealed that this transformation involves regioselective ring-opening of the cyclopropane ring followed by 1,2-migration of one of the cyclopropane substituents. Interestingly, our investigations showed that skipped diene is the kinetic product of the process but formation of a more stable cyclopentene is also accessible. The fundamental understanding of the processes involved enabled the development of divergent methodologies allowing to obtain cyclopentene or skipped diene from vinylcyclopropane in a selective and controlled manner.
Method for preparing pregabalin by photocatalysis (by machine translation)
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Paragraph 0004, (2020/06/05)
The preparation method is characterized by comprising the 3S following -3 - steps:5 - 1) dissolving the compound I and a certain amount of alkali in an organic solvent, adding the compound II, heating the reaction, obtaining the compound III, 2) preparing the compound V; 3) preparing the compound V through deprotection, ring opening, chiral resolution, and recrystallization to obtain pregabalin. The preparation method comprises the following steps: 1) dissolving compound III, compound IV and photocatalyst in an organic solvent. The raw materials used in the invention are cheap and easily available, the reaction conditions of the photocatalytic oxidation method are mild, reagents are environmentally friendly, green and environment-friendly, and the method is an ideal industrial production process. (by machine translation)
