Dicarbaporphyrinoid systems. Synthesis of oxo-adj-dibenziphlorins.
A series of diformylbenzophenones were generated by sequentially reacting protected bromobenzaldehydes with n-butyllithium and ethyl N,N-dimethylcarbamate. The acetal protective groups were cleaved with refluxing formic acid. Vilsmeier-Haack formylation of 2,2',4,4'-tetramethoxybenzophenone also afforded a related dialdehyde. MacDonald "2 + 2" condensation of three benzophenone dialdehydes with a dipyrrylmethane gave oxophlorin analogues constructed from two benzene and two pyrrole rings. The free base oxodibenziphlorins were rather unstable in solution, and in most cases these porphyrinoids were isolated as the corresponding trifluoroacetate salts. The spectroscopic properties of 6-oxo-adj-dibenziphlorins are consistent with a nonaromatic ring system. DFT calculations indicated that the macrocycles considerably diverge from planarity, particularly when methoxy substituents are present on the arene rings.
Department of Chemistry, Illinois State University , Normal, Illinois 61790-4160, United States.
Deyaa I
DI
AbuSalim
Michelle L
ML
Merfeld
Timothy D
TD
Lash