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Stereoselective synthesis of optical isomers of ethyl 4-chloro-3-hydroxybutyrate in a microfluidic chip reactor.

SYSNO ASEP	0507667
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Stereoselective synthesis of optical isomers of ethyl 4-chloro-3-hydroxybutyrate in a microfluidic chip reactor.
Author(s)	Klusoň, Petr (UCHP-M)_{RID, ORCID, SAI} Stavárek, Petr (UCHP-M)_{RID, ORCID, SAI} Pěnkavová, Věra (UCHP-M)_{RID, ORCID, SAI} Vychodilová, Hana (UCHP-M)_{RID, SAI} Hejda, Stanislav (UCHP-M)_{RID, ORCID, SAI} Jaklová, N. (CZ) Cuřínová, Petra (UCHP-M)_{RID, SAI, ORCID}
Source Title	Journal of Flow Chemistry - ISSN 2062-249X Roč. 9, č. 4 (2019), s. 221-230
Number of pages	10 s.
Language	eng - English
Country	US - United States
Keywords	l-carnitine ; microfluidic chip reactor ; optical purity
Subject RIV	CI - Industrial Chemistry, Chemical Engineering
OECD category	Chemical process engineering
R&D Projects	GA15-04790S GA ČR - Czech Science Foundation (CSF)
Method of publishing	Limited access
Institutional support	UCHP-M - RVO:67985858
UT WOS	000517126800003
EID SCOPUS	85069674188
DOI	10.1007/s41981-019-00043-y
Annotation	Ethyl (R)-4-chloro-3-hydroxybutyrate ((R)-CHBE) is a versatile fine chemistry intermediate. It is used as a precursor in the synthesis of several pharmacologically valuable products, including L-carnitine. It is usually produced by means of stereoselective biotechnology methods in enzymatic reactions. An alternative preparation strategy towards ethyl (R)-4-chloro-3-hydroxybutyrate is based on the asymmetric hydrogenation of ethyl 4-chloro-acetoacetate (ECAA) to the optically pure product ((R)-CHBE) over ((S)-Ru-BINAP) catalytic complex. The reaction conditions were optimised first using (R)-Ru-BINAP yielding the (S)-CHBE isomer. All reactions were performed under continuous regime in a microfluidic chip reactor. Three different solvent phases were employed. The methanol/water phase, the ethanol/water phase, and the [N8,222][Tf2N]/methanol/water phase. The attained conversions were total in all cases already at 408 K. The parameter of enantioselectivity ee was 99.4% towards the (S)-CHBE for the system in which (R)-Ru-BINAP was accommodated in [N8,222][Tf2N]/methanol/water phase. In the case of methanol/water experiment the ee parameter reached 92.5%. For ethanol/water ee was 91.8%. The (R)-CHBE isomer over (S)-Ru-BINAP was obtained with ee = 99.3% in the [N8,222][Tf2N]/methanol/water phase at 408 K. For the reactions leading to (S)-CHBE apparent activation energies were evaluated. They were similar for MeOH/water and EtOH/water (110.5 and 110.7 kJ.mol−1). The apparent activation energies corresponding with the [N8,222][Tf2N]/MeOH/water system were much higher (of about 90 kJ.mol−1) reaching the level of 200 kJ.mol−1. The impact of the molecular structure of the main reactant was negligible as appeared from the comparison with hydrogenation of methylacetoacetate (MAA, ~ 200 kJ.mol−1). The effect of the presence of the [N8,222][Tf2N] ionic liquid on the sum of the activation energy dominated. The effectiveness of the enantioselective synthesis was additionally assessed by nuclear magnetic resonance employing the method of enantioselective complexation of the chiral compound with a chiral solvating agent.
Workplace	Institute of Chemical Process Fundamentals
Contact	Eva Jirsová, jirsova@icpf.cas.cz, Tel.: 220 390 227
Year of Publishing	2020
Electronic address	http://hdl.handle.net/11104/0303716

Number of the records: 1