Pressure and Temperature-Controlled Enantiodifferentiating [4+4] Photocyclodimerization of 2-Anthracenecarboxylate Mediated by Secondary Face- and Skeleton-Modified γ-Cyclodextrins

• Published in: Journal of organic chemistry 2006-04, Vol.71 (8), p.3126-3136
• Main Authors: Yang, Cheng, Nakamura, Asao, Fukuhara, Gaku, Origane, Yumi, Mori, Tadashi, Wada, Takehiko, Inoue, Yoshihisa
• Format: Article
• Language: English
• Subjects: Chemistry; Coordination compounds; Exact sciences and technology; Inorganic chemistry and origins of life; Organic chemistry; Preparations and properties
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo0601718

A series of secondary-face-substituted and skeleton-modified γ-cyclodextrins (γ-CDs) were prepared as chiral hosts for enantiodifferentiating [4+4] photocyclodimerization reactions of 2-anthracenecarboxylic acid (AC). These γ-CD derivatives form stable ternary complexes with ACs, with altroside-bearing γ-CDs undergoing induced-fit conformational changes upon complexation, and the photocyclodimerization of AC was, thus, dramatically accelerated. The enantiomeric excess (ee) of anti-head-to-head cyclodimer 3 was greatly enhanced in general with altroside-bearing γ-CDs 7−9. Although mono-altro-γ-CD 9 and 3A-azido-3A-deoxy-altro-γ-CD 7 gave 2 in ee's smaller than those obtained with native γ-CD, 3A-amino-3A-deoxy-altro-γ-CD 8 yielded 2 in much higher ee's, which is likely to be ascribed to the combined effects of the less-symmetric cavity and the electrostatic interactions. The influence of temperature and high pressure on the supramolecular photochirogenic reaction has been investigated in depth. An ee as high as 71% was obtained for cyclodimer 2 in the photocyclodimerization of AC mediated by 8 at 210 MPa and −21.5 °C.