Chiral Symmetry Breaking of Spiropyrans and Spirooxazines by Dynamic Enantioselective Crystallization

Hiroki Ishikawa; Naohiro Uemura; Rei Saito; Yasushi Yoshida; Takashi Mino; Yoshio Kasashima; Masami Sakamoto

doi:10.1002/chem.201901889

Chiral Symmetry Breaking of Spiropyrans and Spirooxazines by Dynamic Enantioselective Crystallization

Chemistry. 2019 Jul 22;25(41):9758-9763. doi: 10.1002/chem.201901889. Epub 2019 Jun 27.

Authors

Hiroki Ishikawa¹, Naohiro Uemura¹, Rei Saito¹, Yasushi Yoshida^{1

2}, Takashi Mino^{1

2}, Yoshio Kasashima³, Masami Sakamoto^{1

2}

Affiliations

¹ Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
² Molecular Chirality Research Center, Chiba University, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
³ Education Center, Faculty of Creative Engineering, Chiba Institute of Technology, Shibazono, Narashino, Chiba, 275-0023, Japan.

PMID: 31063242
DOI: 10.1002/chem.201901889

Abstract

Dynamic enantioselective crystallization enabled the chiral symmetry breaking of two spiropyrans and one spirooxazine. The three spiro compounds afforded racemic conglomerate crystals, and easily racemized in alcoholic solution without irradiation. Optically pure enantiomorphic crystals were obtained by vapor-diffusion crystallization or attrition-enhanced deracemization (Viedma ripening). Their absolute configurations were determined by single-crystal X-ray analysis and each enantiomorphic crystal was correlated with its solid-state circular dichroism (CD) spectrum.

Keywords: chiral symmetry breaking; deracemization; dynamic crystallization; spirooxazines; spiropyrans.

Abstract

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