Chemical resolution of spiroindanones and synthesis of chiroptical polymers with circularly polarized luminescence

Herein, the synthesis and chemical resolution of 1,1'-spirobisindane-3,3'-dione have been accomplished utilizing inexpensive and readily available benzaldehyde and acetone as starting materials, and (1R,2R)- or (1S,2S)-1,2-diphenylethane-1,2-diol as a recyclable chiral resolution reagent. The further transformation of R- and S-1,1'-spirobisindane-3,3'-dione into chiral monomers and polymers has been achieved by the reasonable design of the synthetic route and the optimization of the polymerization conditions. The resulting chiroptical polymers exhibit blue emission with thermally activated delayed fluorescence (TADF), excellent optical activities with circular dichroism intensities per molar absorption coefficient (g_abs) of up to 6.4 × 10^-3, and intense circularly polarized luminescence (CPL) with luminescence dissymmetry factor (g_lum) values of up to 2.4 × 10^-3.

Intramolecular Benzannulation of 3-Sulfonyl-2-benzylchromen-4-ones: Synthesis of Sulfonyl Dibenzooxabicyclo[3.3.1]nonanes

In this work, a concise route for the synthesis of sulfonyl dibenzo-oxabicyclo[3.3.1]nonanes by a two-step route is described, including (i) NaBH₄/LiCl-mediated reduction of 3-sulfonyl-2-benzylchromen-4-ones and (ii) sequential BF₃·OEt₂-mediated intramolecular annulation of the resulting 3-sulfonyl-2-benzylchroman-4-ols. A plausible mechanism is proposed and discussed herein. This protocol provides a highly effective stereocontrolled aryl-hydroxyl Friedel-Crafts-type cross-coupling to construct the tetra- or pentacyclic bridged framework. The use of various reaction conditions is investigated for an efficient transformation.