2,3,9,10-Tetrahydrodiindeno[5,4-b:4',5'-d]thiophen-1,11-dione is an helical diketone that can be used to create novel chiral ligands capable of forming interesting coordination complexes with metals. This dione is one of three possible products of the condensation reaction of 3,3'-(dibenzo[b,d]thiophene-2,8-diyl)dipropanoic acid. Synthesis begins with bromination of commercially available dibenzothiophene in chloroform to give 2,8-dibromodibenzothiophene. Tandem Heck coupling with methyl acrylate, followed by hydrogenation with Pd/C and hydrolysis in base affords the desired dicarboxylic acid. Cyclization in polyphosphoric acid leads to a mixture of helical, bent and linear diones. The effect of temperature on the product distribution of the PPA cyclization was studied. This presentation will describe the optimization of the synthetic route, the results of modeling studies aimed at trying to understand kinetic and thermodynamic factors affecting the cyclization, and our efforts to elaborate the helical dione into stable chiral ligands.

Synthesis and characterization of novel helical, bent, and linear dibenzothiophene dione derivatives

245th National Meeting (2013)

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