Non-symmetric bispyrrolotetrathiafulvalene building blocks

The use of redox-responsive compounds has received a lot of research attention in the field of molecular nanotechnology. Tetrathiafulvalene (TTF) is one of the key redox units that has been used to construct redox-active materials. A wide variety of TTF derivatives has been reported including the monopyrroloTTF (MPTTF) and the bispyrroloTTF (BPTTF) derivatives. However, the use of BPTTF as a building block is still limited, despite several favorable properties of its highly π-extended structure. Herein, the synthesis and functionalization of two novel non-symmetric BPTTF building blocks are reported. The key intermediates in these new synthetic protocols are 4,6-dimethyl-5-tosyl-5H-[1,3]dithiolo[4,5-c]pyrrole-2-thione and 5-(4-iodophenyl)-4,6-dimethyl-[1,3]dithiolo[4,5-c]pyrrole-2-thione, which can be obtained in moderate to high yields in a two- or three-step synthetic procedure from 2,5-dimethyl-3,4-dithiocyanato-1-tosyl-1H-pyrrole and 1-(4-iodophenyl)-2,5-dimethyl-1H-pyrrole, respectively.