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The reaction of a dipyrromethanedicarbinol with 2,2′-bipyrrole leading to meso-substituted [34]- octaphyrin(1.1.1.0.1.1.1.0) and/or corrole was investigated to determine the effect of key reaction parameters on the distribution of the two macrocycles. Solvent, acid catalyst, acid quantity, oxidant, oxidant quantity, and reaction time were surveyed for a model reaction affording 5,10,19,24,29,- 38-hexaphenyl[34]octaphyrin(1.1.1.0.1.1.1.0) (HPO) and/or meso-triphenylcorrole (TPC). HPO was found to be a fairly ubiquitous product, produced in yields as high as 23% (UV-vis), while TPC was observed infrequently, in yields up to 10% (UV-vis). A preparative-scale reaction provided HPO in an isolated yield of 25%. The methodology was extended to the synthesis of an octaphyrin bearing two different substituents in defined locations and to an octaphyrin possessing electron- withdrawing pentafluorophenyl substituents. Preferential formation of octaphyrin instead of corrole suggests that the anti conformation of 2,2′-bipyrrole is the relevant form under the reaction conditions surveyed. The spectral properties of the novel meso-substituted [34]octaphyrin- (1.1.1.0.1.1.1.0) species are similar to those of the known β-substituted analogue, including spectra consistent with the absence of macrocycle aromaticity despite a main conjugation path of 34 π-electrons. Key to the overall study was the development of a refined synthesis of 2,2′-bipyrrole. [ABSTRACT FROM AUTHOR]

The reaction of dipyrromethanedicarbinols with pyrrole leading to meso-substituted corroles was investigated to determine whether mild acid catalysts [Dy(OTf)3, Yb(OTf)3, Sc(OTf)3, and InCl3] known to provide porphyrins from dipyrromethanecarbinol species while suppressing undesired reversibility (resulting in scrambling) are applicable to reactions affording corrole, and to explore the requirements of the oxidation step. We examined a model reaction leading to mesotriphenylcorrole (TPC) to survey the effect of acid catalyst, acid concentration, ratio of pyrrole to dipyrromethanedicarbinol, oxidant, oxidant quantity, and reaction time on the yield of TPC (by UV-vis) in reactions performed at room temperature in CH2Cl2. Key to this survey was a modification of the well-known spectrophotometric method for monitoring reactions leading to porphyrin. The survey revealed that TPC could be prepared via a subset of the mild acid catalysts [Dy(OTf)3 and Yb(OTf)3], and a preparative-scale reaction afforded an isolated yield of TPC of 49%, devoid of porphyrin. Suppression of reversible processes was further demonstrated by the synthesis of three corroles bearing different meso substituents in defined locations in isolated yields ranging from 50% to 80%. The reaction conditions were applicable to a dipyrromethanedicarbinol bearing electron-withdrawing pentafluorophenyl substituents-provided that the reaction time of the condensation step was increased. We identified circumstances under which DDQ can cause severe interference with the detection and isolation of some corroles, we found that the yield and purity of the corrole depend on judicious selection of oxidation conditions, and we assessed the sensitivity toward light of dilute solutions of the corroles prepared in this study. [ABSTRACT FROM AUTHOR]

Examines the yields of tetraphenylporphyrin (TPP), N-confused tetraphenylporphyrin (NC-TPP) and tetraphenylsapphyrin (TPS) under diverse conditions in the one-flask room-temperature reaction of pyrrole and benzaldehyde. Chromatographic properties of NC-TPP and TPS; Observation of additional pigments; Survey of NC-TPP and TPS in the Adler reaction.