Cap in hand: Combined use of diamino‐γ‐cyclodextrin (CD) and Cu(ClO4)2 resulted in the first catalytic supramolecularphotochirogenesis in the photocyclodimerization of 2‐anthracenecarboxylic acid. The anti‐head‐to‐head cyclodimer formed in 64–70 % enantiomeric excess and about 50 % yield; these values are the highest ever reported for CD‐mediated photochirogenesis.
found to stepwise form 1:1 and 1:2 complexes, having a large K 1 and a relatively small K 2 values. Photocyclodimerization of AC within the pillar[6]arene improved the yield of the head-to-head photodimers. Up to 4.97 HH/HT ratio has been reached by optimizing the reaction conditions.
摘要通过1 H NMR,UV-vis和ITC方法研究了蒽羧酸与水溶性阳离子柱芳烃的络合行为。发现阳离子柱[6]芳烃逐步形成1:1和1:2的配合物,具有较大的K 1和相对较小的K 2值。柱[6]芳烃中AC的光环二聚化提高了头对头光二聚体的收率。通过优化反应条件,最高可达到4.97 HH / HT比率。
Chiral ionic liquid-mediated photochirogenesis. Enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid
Enantiodifferentiatingphotocyclodimerization of 2-anthracenecarboxylic acid (AC-H) and its lithium salt (AC-Li) in chiral ionic liquid (CIL), (R)-1-(2,3-dihydroxypropyl)-3-methylimidazolium acetate [(R)-GLYMI][AcO]}, gave a mixture of two head-to-tail (HT) and two head-to-head (HH) cyclodimers in HT/HH ratios of 1.3–1.7 (for AC-H) and 2.2–4.3 (for AC-Li) with low enantiomeric excesses (ee) of 0–3%
Stereochemistry of the major photocyclodimer is switched from 52% anti-head-to-head to 51% anti-head-to-tail among the four stereoisomers produced upon irradiation of 2-anthracenecarboxylic acid at low temperatures by changing the solvent from dichloromethane to methanol, through a critical control of the hydrogen bonding and dipole–dipole interactions.
A remarkable stereoselectivity switching upon solid-state versus solution-phase enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid mediated by native and 3,6-anhydro-γ-cyclodextrins
The enantiodifferentiating [4+4] photocyclodimerization of anthracenecarboxylic acid (AC) mediated by native, mono- and di-3,6-anhydro-γ-cyclodextrins was investigated in both aqueous solution and solid-state. The solid-state photolyses gave inherently disfavored head-to-head photodimers in much higher chemical and optical yields than in the aqueous solution.