Rhodium-Catalyzed Enantioselective Synthesis, Crystal Structures, and Photophysical Properties of Helically Chiral 1,1′-Bitriphenylenes

Abstract

The highly enantioselective synthesis of helically chiral 1,1'-bitriphenylenes has been achieved via rhodium-catalyzed double [2 + 2 + 2] cycloaddition of biaryl-linked tetraynes with 1,4-diynes (up to 93% ee). Crystal structures and photophysical properties of these helically chiral 1,1'-bitriphenylenes have also been studied.

Self-assembled organic and polymer photonic crystals for laser applications

“…In contrast, the chiroptical properties of CPL emission at the excited state cannot be generated in straightforward ways. Intriguing attempts have been made to increase the degree of CPL emission by synthesizing p-conjugated polymers with chiral side chains, [45][46][47][48][49] chiral metal complexes, [50][51][52][53] and helicene derivatives with steric hindrance 54,55 On the other hand, CLC materials are readily available to efficiently generate CPL emission. When a fluorescent dye is dissolved in the CLC material, the selective reflection band superimposes on the broad fluorescence band emitted from the guest dye.…”

Enantioselective Helicene Synthesis by Rhodium-Catalyzed [2+2+2] Cycloadditions

“…25 It was anticipated that the regioand enantioselective intermolecular double [2+2+2] cycloaddition of biaryl-linked tetrayne 18 with dialkynyl ketones 9 would proceed to afford fully conjugated [7]helicenes, contain- (47) 40 (39) 53 (18) 56 ( (26) 58 (32) 61 (31) 32 ( ing triphenylene and fluorene cores (Scheme 12). 26 Pleasingly, the desired reactions between 18 and 9 proceeded at room temperature in the presence of the cationic rhodium(I)/(S)-xylSegphos catalyst to furnish the corresponding [7]helicenes 19 in good yield with high ee values (Scheme 12). 26 The catalyst loading could be reduced to 10 mol % without erosion of the product ee value, although the product yield decreased.…”

“…26 Pleasingly, the desired reactions between 18 and 9 proceeded at room temperature in the presence of the cationic rhodium(I)/(S)-xylSegphos catalyst to furnish the corresponding [7]helicenes 19 in good yield with high ee values (Scheme 12). 26 The catalyst loading could be reduced to 10 mol % without erosion of the product ee value, although the product yield decreased.…”

“…26 Not only dialkynyl ketones 9 but also dialkynylphosphine oxides 16 reacted with tetrayne 18 in the presence of a cationic rhodium(I)/(S)-Segphos catalyst to give the corresponding phosphafluorene-based [7]helicenes 22 in moderate yields and ee values (Scheme 14). 26 Fluorenone 19a could be readily derivatized into highly emissive fluorene derivatives without erosion of its ee value as shown in Scheme 15. 26 …”

“…26 Fluorenone 19a could be readily derivatized into highly emissive fluorene derivatives without erosion of its ee value as shown in Scheme 15. 26 …”