Dynamic Kinetic Resolution of N-Protected Amino Acid Esters via Phase-Transfer Catalytic Base Hydrolysis

Eiji Yamamoto; Kodai Wakafuji; Yuho Furutachi; Kaoru Kobayashi; Takashi Kamachi; Makoto Tokunaga

doi:10.1021/acscatal.8b00693

Dynamic Kinetic Resolution of N-Protected Amino Acid Esters via Phase-Transfer Catalytic Base Hydrolysis

Eiji Yamamoto, Kodai Wakafuji, Yuho Furutachi, Kaoru Kobayashi, Takashi Kamachi, Makoto Tokunaga

Multidisciplinary chemistry

Research output: Contribution to journal › Article › peer-review

15 Citations (Scopus)

Abstract

Asymmetric base hydrolysis of α-chiral esters with synthetic small-molecule catalysts is described. Quaternary ammonium salts derived from quinine were used as chiral phase-transfer catalysts to promote the base hydrolysis of N-protected amino acid hexafluoroisopropyl esters in a CHCl₃/NaOH (aq) via dynamic kinetic resolution, providing the corresponding products in moderate to good yields (up to 99%) with up to 96:4 er. Experimental and computational mechanistic studies using DFT calculation and pseudotransition state (pseudo-TS) conformational search afforded a TS model accounting for the origin of the stereoselectivity. The model suggested π-stacking and H-bonding interactions play essential roles in stabilizing the TS structures.

Original language	English
Pages (from-to)	5708-5713
Number of pages	6
Journal	ACS Catalysis
Volume	8
Issue number	7
DOIs	https://doi.org/10.1021/acscatal.8b00693
Publication status	Published - Jul 6 2018

All Science Journal Classification (ASJC) codes

Catalysis
Chemistry(all)

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title = "Dynamic Kinetic Resolution of N-Protected Amino Acid Esters via Phase-Transfer Catalytic Base Hydrolysis",

abstract = "Asymmetric base hydrolysis of α-chiral esters with synthetic small-molecule catalysts is described. Quaternary ammonium salts derived from quinine were used as chiral phase-transfer catalysts to promote the base hydrolysis of N-protected amino acid hexafluoroisopropyl esters in a CHCl3/NaOH (aq) via dynamic kinetic resolution, providing the corresponding products in moderate to good yields (up to 99%) with up to 96:4 er. Experimental and computational mechanistic studies using DFT calculation and pseudotransition state (pseudo-TS) conformational search afforded a TS model accounting for the origin of the stereoselectivity. The model suggested π-stacking and H-bonding interactions play essential roles in stabilizing the TS structures.",

author = "Eiji Yamamoto and Kodai Wakafuji and Yuho Furutachi and Kaoru Kobayashi and Takashi Kamachi and Makoto Tokunaga",

note = "Funding Information: This work was supported by JSPS KAKENHI Grant Nos. 16H07042, 15K05431, and 23655087, and a Grant-in-Aid for Scientific Research on Innovative Areas “Advanced Molecular Transformations by Organocatalysts” from The Ministry of Education, Culture, Sports, Science and Technology, Japan (Nos. 24105524 and 26105744). Computations were partially carried out using the computer facilities at the Research Institute for Information Technology, Kyushu University. We appreciate the reviewer for the valuable suggestions in the peer-review process. Publisher Copyright: Copyright {\textcopyright} 2018 American Chemical Society.",

year = "2018",

month = jul,

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doi = "10.1021/acscatal.8b00693",

language = "English",

volume = "8",

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journal = "ACS Catalysis",

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T1 - Dynamic Kinetic Resolution of N-Protected Amino Acid Esters via Phase-Transfer Catalytic Base Hydrolysis

AU - Yamamoto, Eiji

AU - Wakafuji, Kodai

AU - Furutachi, Yuho

AU - Kobayashi, Kaoru

AU - Kamachi, Takashi

AU - Tokunaga, Makoto

N1 - Funding Information: This work was supported by JSPS KAKENHI Grant Nos. 16H07042, 15K05431, and 23655087, and a Grant-in-Aid for Scientific Research on Innovative Areas “Advanced Molecular Transformations by Organocatalysts” from The Ministry of Education, Culture, Sports, Science and Technology, Japan (Nos. 24105524 and 26105744). Computations were partially carried out using the computer facilities at the Research Institute for Information Technology, Kyushu University. We appreciate the reviewer for the valuable suggestions in the peer-review process. Publisher Copyright: Copyright © 2018 American Chemical Society.

PY - 2018/7/6

Y1 - 2018/7/6

N2 - Asymmetric base hydrolysis of α-chiral esters with synthetic small-molecule catalysts is described. Quaternary ammonium salts derived from quinine were used as chiral phase-transfer catalysts to promote the base hydrolysis of N-protected amino acid hexafluoroisopropyl esters in a CHCl3/NaOH (aq) via dynamic kinetic resolution, providing the corresponding products in moderate to good yields (up to 99%) with up to 96:4 er. Experimental and computational mechanistic studies using DFT calculation and pseudotransition state (pseudo-TS) conformational search afforded a TS model accounting for the origin of the stereoselectivity. The model suggested π-stacking and H-bonding interactions play essential roles in stabilizing the TS structures.

AB - Asymmetric base hydrolysis of α-chiral esters with synthetic small-molecule catalysts is described. Quaternary ammonium salts derived from quinine were used as chiral phase-transfer catalysts to promote the base hydrolysis of N-protected amino acid hexafluoroisopropyl esters in a CHCl3/NaOH (aq) via dynamic kinetic resolution, providing the corresponding products in moderate to good yields (up to 99%) with up to 96:4 er. Experimental and computational mechanistic studies using DFT calculation and pseudotransition state (pseudo-TS) conformational search afforded a TS model accounting for the origin of the stereoselectivity. The model suggested π-stacking and H-bonding interactions play essential roles in stabilizing the TS structures.

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Dynamic Kinetic Resolution of N-Protected Amino Acid Esters via Phase-Transfer Catalytic Base Hydrolysis

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