April 2022

Thermodynamic-Dominated Stereoselective Gridization of Molecular Nanolinkage Based on Fluorenes

The path-selectivity and stereoselectivity of gridization pathways into fluorene-based drawing hand grids (DHGs-F) are precisely modulated through tuning acid conditions and side-chain effects. BF3·OEt2 supports the realization of the gridization path (rac-DHG1-F, yield: 82%, meso-DHG1-F, yield: 11%). On the contrary, CF3SO3H will lead to the enhancements in polymerization pathways (about 85% yield). When the side chain is a methoxyl group, rac-DHG1-F and meso-DHG1-F will be obtained. However, when the side chain is a group without an oxygen atom, only rac-DHGs-F can be obtained (de = 100%). Moreover, through excitonic physical properties, rac-DHGs-F exhibits a more π-electronic delocalization, potentially serving as the intriguing tactic strategy to modulate the optoelectronic properties.

By Li, Xiao-Yan, ago

Expedient Access to Indolyl-Substituted Tri- and Diarylmethanes and (±)-Colletotryptin E by Silica Sulfuric Acid Catalyzed Transindolylation

An expedient access to a series of nonsymmetrical bis(indolyl)methanes (BIMs) through transindolylation of readily available symmetrical 3,3′-BIMs with various indoles catalyzed by silica-supported sulfuric acid has been established. This approach not only provides a useful strategy for the synthesis of structurally diverse BIMs, but also provides examples of nucleophilic substitution of BIMs with aromatic and nonaromatic π-systems, leading to a library of indolyl-substituted tri- and diarylmethanes. Moreover, this method was successfully applied in the first total synthesis of the 2,3′-BIM alkaloid (±)-colletotryptin E in three steps with an overall yield of 46%. The features of this procedure include a metal-free process, an inexpensive and environmentally friendly catalyst, mild reaction conditions, broad functional-group tolerance, good yields, and gram-scalable preparations.

By Yimyaem, Jirapat, ago