Porphyrin analogues have been attracting considerable attention not only from the interest of annulenic chemistry but also from their use in a variety of applications. [1] Recently, reinvestigation of the Rothemund-type pyrrole ± aryl aldehyde condensation [2] has revealed the concurrent formation of a porphyrin isomer, the N-confused porphyrin (NCP), [3] and expanded porphyrins such as sapphyrin [4] and hexaphyrin [5] .We have also reported a new analogue, the N-fused porphyrin (NFP), in which a unique fused tri-pentacyclic ring exists in the porphyrin core as the result of an inversion of the confused ring in NCP. [6] Herein we report the first example of a normal-type of fused expanded porphyrin, N-fused pentaphyrin (NFP 5 ), which contains a fused tri-pentacyclic ring in the core.The title compound was synthesized under similar Rothemund-type conditions, namely, the acid-catalyzed condensation of pentafluorobenzaldehyde and unsubstituted pyrrole, followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Along with the meso-pentafluorophenylporphyrin (12 %), meso-pentafluorophenylhexaphyrin [5] (20 %), and other higher homologues of meso-aryl type (around 13 %), [7] yellowish (1-Y) and reddish (1-R) products, both of which show parent mass peaks in the fast atom bombardment (FAB) mass spectra corresponding to the pentapyrrolic macrocycle, could be isolated in a total yield of approximately 15 %. The ratio of the two products 1-R and 1-Y changed greatly according to the amounts of oxidant used and converged to 1-R when DDQ was used in excess (2.5 equiv). The similar products 2 and 3 were also obtained, in yields of 19 and 2 %, respectively, from the analogous reactions with 2,6-dichloro-and 2,4,6-trimethylbenzaldehyde. [8] Although the reaction is not optimized yet, the relatively high concentration of reactants (b 50 mm) seems effective for the formation of products.The structure of the N-fused product 1-Y was revealed by X-ray analysis on a single crystal (Figure 1). [9] A fused tripentacyclic ring with inward-and outward-pointing nitrogen atoms was found in a pentapyrrolic core. The inner nitrogen atom N(27) of the fused ring was connected to the b-carbon atom C(3) of the neighboring pyrrole ring. One of the pyrrole rings was canted significantly: the tilting angles of each ring, clockwise from the fused ring, were 24. 96, 15.32, 22.46, and 99.188 to the mean plane of the 30 core atoms. Two of the Figure 1. Top: X-ray crystal structure of meso-pentafluorophenyl N-fused pentaphyrin (1-Y). Bottom: Schematic representation of NFP 5 -Y showing the numbering scheme.[8] For Pd 0 -catalyzed reactions of alkadienols with aryl halides, see: K.
