Aromaticity control via modifications of a macrocyclic frame: 5,6-dimethoxyphenanthriporphyrin and 5,6-dioxophenanthriporphyrin

Abstract

Antiaromatic phenanthriporphyrin and nonaromatic 5,6-dioxophenanthriporphyrin reveal specific reactivity toward protic and Lewis acids yielding respectively nonaromatic and aromatic macrocycles.

A meso‐Tetraaryl‐21‐carbaporphyrin: Incorporation of a Cyclopentadiene Unit into a Porphyrin Architecture

“…[33] Thesubsequent protonation involves the C(21) position as confirmed by NMR experiments (Scheme 5). [33] Thesubsequent protonation involves the C(21) position as confirmed by NMR experiments (Scheme 5).…”

“…Zuschriften 6152 www.angewandte.de three monocationic derivatives.Similar behavior in course of titration with HBF 4 ·Et 2 Ow as demonstrated recently for 5,6dioxaphenanthriporphyrin. [33] Thesubsequent protonation involves the C(21) position as confirmed by NMR experiments (Scheme 5). Thus the C(21)H 2 resonance with the intensity of two hydrogens, scalarly coupled to H(2,3) as shown by COSY,h as been identified at d = À6.26 ppm.…”

Three‐Stage Aromaticity Switching in Boron(III) and Phosphorus(V) N‐Fused p‐Benziporphyrin

“…A reaction of 6‐P dissolved in [D 2 ]dichloromethane with tetrafluoroboric acid in diethyl ether has been followed by 1 H NMR spectroscopy (Figure S6 in the Supporting Information). Of particular importance is the observation that 6‐P is susceptible to the protonation at the meso ‐position; such a reaction is rarely encountered for meso ‐arylated porphyrinoids . Two non‐aromatic stereoisomers of phosphorus(V) N‐fused p ‐benziphlorin 7 ‐ P ‐ syn and 7 ‐ P ‐ anti have been differentiated by orientation of meso ‐phenyl with respect to the PO unit (Scheme S12).…”

“…[9,10] In several processes at emplatef actor introduced by coordination of metal or nonmetal cations has been recognized as acommon driving force behind the fusion. [11,12] Significantly,i nsertion of phosphorus(V) into 21-telluraporphyrin promptedt he inversion of the tellurophene ring and triggered the inner-core fusion, yielding contracted[ CNN]-typec arbaporphyrinoids 2-P. [13] Such N-fusion rearrangements have been subsequently reported for expanded (hetero)porphyrinsa s shown for phosphorus(V) complexes of at riply-fused [24]pentaphyrin 3-P. [14] In general the listed examples (1-3)e ncompassed at riphyrin(n.1.1)-likee nvironment, exemplified by archetypal oxatriphyrin(3.1.1) 4 (Scheme 1), appropriately match-ing the cationic radii of central ions. [15] Thus the introduction of fused rings into the macrocyclic core can be treated as an important way to generaten ew classes of ligands that can adaptt os pecific ions and form B/P-X (X = N, O, C) bonds and thus influencingt he properties of such molecules.…”

“…Of particular importance is the observation that 6-P is susceptible to the protonation at the meso-position;s uch ar eaction is rarely encountered for meso-arylated porphyrinoids. [23,24] Twon on-aromatic stereoisomers of phosphorus(V) N-fused p-benziphlorin 7-P-syn and 7-P-anti have been differentiatedb yo rientation of meso-phenyl with respect to the PO unit (Scheme S12). In analogy to the boron(III) N-fused p-benziphlorin, 7-B the protonation has been tentatively localized at C(5) position (C(5) d = 49.8 and5 0.9 ppm, and H(5) d = 6.33, 6.06 ppm) for two diastereoisomers (Figure S7), albeit the specific assignment to 7-P-syn and 7-P-anti has not been feasible.…”