Large scale synthesis of chiral (3Z,5Z)-2,7-dihydro-1H-azepine-derived Hamari ligand for general asymmetric synthesis of tailor-made amino acids.

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(R)-2,2′-bis(bromomethyl)-1,1′-binaphthalene ((R)-17) was prepared in the identical manner and had identical analytical properties to those given here.

¹H NMR (400 MHz, CDCl₃): δ 4.25 (4H, s, 2 × CH₂), 7.07 (2H, dd, J = 8.4, 0.8 Hz, ArH), 7.27 (2H, ddd, J = 8.4, 6.8, 1.2 Hz, ArH), 7.48 (2H, ddd, J = 8.2, 6.8, 1.2 Hz, ArH), 7.74 (2H, d, J = 8.6 Hz, ArH), 7.92 (2H, d, J = 8.2 Hz, ArH), 8.02 (2H, d, J = 8.6 Hz, ArH).

¹³C NMR (100.6 MHz, CDCl₃): δ 32.6 (CH₂), 126.80 (ArCH), 126.82 (ArCH), 126.84 (ArCH), 127.7 (ArCH), 128.0 (ArCH), 129.4 (ArCH), 132.5 (quaternary ArC), 133.3 (quaternary ArC), 134.1 (quaternary ArC), 134.2 (quaternary ArC).

[α]²⁰_D = +173.8° (c = 1.0, CHCl₃).

An advanced process for large scale (500 g) preparation of a (3Z,5Z)-2,7-dihydro-1H-azepine-derived chiral tridentate ligand (Hamari ligand), widely used for asymmetric synthesis of tailor-made α-amino acids via the corresponding glycine Schiff base Ni(II) complex, is disclosed. The process includes amidation, bis-alkylation, and precipitation/purification of the target compound by TFA as a counterion.

Large Scale Synthesis of Chiral (3Z,5Z)-2,7-Dihydro-1H-azepine-Derived Hamari Ligand for General Asymmetric Synthesis of Tailor-Made Amino Acids

Motohiro Takahashi*^† , Hiroki Moriwaki^†, Toshio Miwa^†, Brittanie Hoang^‡, Peng Wang^‡, and Vadim A. Soloshonok*^§∥ 

^† Hamari Chemicals Ltd., 1-4-29 Kunijima, Higashi-Yodogawa-ku, Osaka 533-0024, Japan

^‡ Hamari Chemicals USA, San Diego Research Center, 11494 Sorrento Valley Road, San Diego, California 92121, United States

^§ Department of Organic Chemistry I, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel Lardizábal 3, 20018 San Sebastián, Spain

^∥ IKERBASQUE, Basque Foundation for Science, María Díaz de Haro 3, Plaza Bizkaia, 48013 Bilbao, Spain

Org. Process Res. Dev., Article ASAP

DOI: 10.1021/acs.oprd.8b00406

Publication Date (Web): January 18, 2019

Copyright © 2019 American Chemical Society

*E-mail: motohiro-takahashi@hamari.co.jp., *E-mail: vadym.soloshonok@ehu.es.

This article is part of the Japanese Society for Process Chemistry special issue.

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