The dithianyl group as a synthon in porphyrin chemistry: condensation reactions and preparation of formylporphyrins under basic conditions.
Vilsmeier formylation is one of the most widely used substitution reactions for the functionalization of porphyrins. However, its utility is limited by the electrophilic/acidic reaction conditions, deactivation of the aromatic system and regiochemical problems, the requirement for metal complexes and necessity for subsequent demetalation under harsh conditions, and low functional group tolerance. To overcome these limitations, the dithianyl group has been utilized as a latent formyl synthon in porphyrin chemistry. 2-Formyl-1,3-dithiane can be used directly in pyrrole condensation reactions to regioselectively yield porphyrins with up to four dithianyl residues. Likewise, 5-dithianyldipyrromethane could be prepared quantitatively as a key building block for various porphyrin condensation reactions yielding the respective free base formylporphyrins after deprotection. Additionally, dithianyllithium can be used as a reagent for the direct aromatic substitution of metallo- and free base porphyrins under nucleophilic conditions.
Senge
Mathias O
MO
Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Golm, Germany. mosenge@chem.uni-potsdam.de
Hatscher
Sabine S
SS
Wiehe
Arno
A
Dahms
Katja
K
Kelling
Andrea
A
D005561:Formates / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D016877:Oxidants / Q000737:chemistry; D011166:Porphyrins / Q000138:chemical synthesis* / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry*
D005561:Formates; D016877:Oxidants; D011166:Porphyrins; D013440:Sulfides