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Supramolecular Photochirogenesis with Novel Cyclic Tetrasaccharide: Enantiodifferentiating Photoisomerization of ( Z )‐Cyclooctene with Cyclic Nigerosylnigerose‐Based Sensitizers
Author(s) -
Yang Cheng,
Liang Wenting,
Nishijima Masaki,
Fukuhara Gaku,
Mori Tadashi,
Hiramatsu Hiroyuki,
Danoh Yasufumi,
Tsujimoto Kazuo,
Inoue Yoshihisa
Publication year - 2012
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22014
Subject(s) - chemistry , photoisomerization , cyclooctene , supramolecular chemistry , tetrasaccharide , stereochemistry , crystallography , organic chemistry , isomerization , catalysis , crystal structure , polysaccharide
Isophthalic and terephthalic acid monoesters of cyclic nigerosyl‐(1→6)‐nigerose (CNN), a cyclic tetrasaccharide composed of four d ‐glucopyranosyl residues connected by alternating α‐1,3‐ and α‐1,6‐linkages, were synthesized as novel chiral supramolecular sensitizers for enantiodifferentiating photoisomerization of ( Z )‐cyclooctene ( 1Z ) to planar chiral ( E )‐isomer ( 1E ). Despite the saucer‐shaped shallow cavity of CNN that does not immediately guarantee strong ground‐state interactions with 1Z , the sensitizer‐appended CNNs afforded optically active 1E in such enantiomeric excesses that are much improved than those obtained with an α‐cyclodextrin analog and comparable with those obtained with a β‐cyclodextrin analog. Interestingly, the enantiomeric excess values obtained were a critical function of temperature and solvent to show an inversion of the product chirality by changing the environmental variants. Nevertheless, all of the differential activation parameters calculated from the temperature‐dependent enantiomeric excesses gave an excellent compensatory enthalpy–entropy relationship, indicating an operation of a single enantiodifferentiating mechanism in the present chiral photosensitization with modified CNNs. Chirality 24:921–927, 2012 . © 2012 Wiley Periodicals, Inc.