Direct synthesis of variously substituted negative photochromes of hydroxytricyanopyrrole (HTCP) series

Synthetic approaches for modification of negative photochromes of hydroxytricyanopyrrole (HTCP) series were described for the first time. The first and fifth positions of the pyrrole ring were directly functionalized but hydroxyl group of the 2-vinyl-phenol fragment and the butadienetricarbonitrile (BDTC) moiety, which are necessary for the photochromic reaction were untouched. These results are the starting point for wide research in the field of directed synthesis of nitrile rich negative photochromes with tunable physicochemical characteristics.