Synthesis of Porphyrins Di‐ and Tetra‐Functionalized with Nucleobases

A library composed of ten porphyrins bearing nucleobases is prepared, following two strategies: substitution or Sonogashira cross‐coupling reactions. The former strategy led to the synthesis of four porphyrins ( T 2 −Po1 , A 2 −Po1 , C 2 −Po1 and P 2 −Po1 ) bearing nucleobases (NBs) at two trans meso ‐positions. These 4 porphyrins were obtained by reacting 5,15‐di(4‐(bromomethyl)phenyl)‐10,20‐dimesitylporphyrin ( Po1 ) with thymine ( T ), adenine ( A ), cytosine ( C ) and 2‐amino‐6‐chloropurine ( P ), a precursor of guanine ( G ), respectively in the presence of a suitable base. A fifth porphyrin, 5,15‐di(N9‐methylphenylguanine)‐10,20‐dimesitylporphyrin ( G 2 −Po1 ) was obtained by hydrolysis of P 2 −Po1 . A thymine tetra‐functionalized porphyrin was also synthesized following the same strategy starting from T and 5,10,15,20‐tetrakis[4‐(bromomethyl)phenyl]porphyrin ( Po2 ). The second strategy based on Sonogashira cross‐coupling reactions between 5,15‐dibromo‐10,20‐dipentylporphyrin ( Po3 ) and ethynyl‐substituted nucleobases resulted in four rigid porphyrins ( U 2 −Po3 , C 2 −ZnPo3 , A 2 −ZnPo3 , and G 2 −ZnPo3 ).