Laurent Jaquinod

Regioselective syntheses and structural characterizations of 2,3-dibromo-and 2,3,7,8,12,13-hexabromo-5,10,15,20-tetraphenylporphyrins

Abstract The title dibromoporphyrins 4 5 and hexabromoporphyrins 11 12 are prepared from H2(2-NO2TPP) 1 and Cu(2-NO2TPP) 8, respectively. The β-nitro group confines the 18-π-annulene system of a tetraphenylporphyrin to its N22H-N24H aromatic delocalization pathway which induces the localization of an antipodal double bond on the porphyrin periphery and enhances its susceptibility to electrophilic attack. Dibromination of H2-NO2TPP) 1 occurs regioselectively affording the 12,13-dibromo-2- nitroporphyrin 2 which, upon Michael addition of NaBH4 and re-aromatization of the resulting nitrochlorin 3, provides an entry to 2,3-dibromoTPP 4 5 as well as an improved route to 2,3- dicyanoporphyrins 6 7 . Perbromination of Cu(2-NO2TPP) 8 and denitration of 9 gave, after demetalation, 2,3,7,8,12,13-hexabromoTPP 12. Both 4 and 12 are structurally characterized by X-ray crystallography.

5,10,15-Triphenylcorrole: a product from a modified Rothemund reaction

One-pot synthesis of 5,10,15-triphenylcorrole has been achieved by reaction of benzaldehyde with an excess of pyrrole; the triphenylphosphinocobalt complex of 5,10,15-triphenylcorrole has been structurally characterized using X-ray crystallography.

SYNTHESIS AND CHEMISTRY OF NEW BENZOPORPHYRINS

Abstract Benzoporphyrins 5 and 6 are the major products obtained from the cycloaddition reactions of β-fused metallo-pyrroloporphyrins 1 and 2 with dimethyl acetylenedicarboxylate. In the presence of excess dienophile a bis-adduct is also obtained which undergoes retro-Diels-Alder reaction to produce 5 . Benzoporphyrin 5 was converted into the first reported β-fused benzochlorins 9–11 , and the free-base benzoporphyrin 12 was regioselectively brominated to afford 13 . Exhaustive bromination also yields hexabromobenzoporphyrin 14 .

Oligomeric porphyrin arrays

The field of synthesis and physical characterization of oligomeric porphyrin arrays has been the subject of intense research in recent years. Some of these systems present unique physical and optical properties which reflect the extent of electronic interaction between the monomers in the array, and determines their potential applications in chemistry, physics, and biology. General synthetic approaches to a multitude of porphyrin arrays, including directly linked meso-meso, meso-β, and β-β compounds, oligoporphyrins with fused π-systems, and arrays bearing rigid or flexible spacers, developed by us and by others, are described. X-Ray structures of representative compounds are presented.

Investigations on the directive effects of a single meso-substituent via nitration of 5,12,13,17,18-pentasubstituted porphyrins: syntheses of conjugated β-nitroporphyrins

Abstract Vilsmeier formylation of 5-substituted 1,9-diunsubstituted dipyrromethanes afforded 1,9-diformyldipyrromethanes in good yields. Their MacDonald condensation with tetra-β-alkyldipyrromethanes produced 5,12,13,17,18-pentasubstituted porphyrins. A meso-electron-donating group, presumably acting by destabilizing the porphyrin a2u ground state, directs the nitrations to the meso-carbons. β-Nitration takes place on porphyrins bearing a meso-electron-withdrawing group. Unhindered β-nitro groups are shown to exert stronger electronic effects relative to meso-nitro groups by conjugating effectively with the porphyrin macrocycle.

β,β′-Fused metallocenoporphyrinsElectronic supplementary information (ESI) available: molecular structure of 10. See http://www.rsc.org/suppdata/cc/b1/b107732e/

The syntheses of a β,β′-fused ruthenocenoporphyrin (9) and a ferrocenoporphyrin dimer (11) are described.

Approaches to β-fused Porphyrinoporphyrins: Pyrrolo- and Dipyrromethaneporphyrins

Reaction of (2-nitro-5,10,15,20-tetraphenylporphyrinato)nickel(II) 3 or its copper(II) complex 4 with α-isocyanoacetic esters in the presence of 1,8-diazabicyclo[5.4.O]undec-7-ene accomplishes the first syntheses of β-fused pyrroloporphyrins (e.g. 5–10). The removal of the fused pyrrole ester protecting groups to give the di-α-free pyrroloporphyrins 2a and 13 is described, as well as some pyrrole-type chemistry. Unsymmetrical fused dipyrromethanoporphyrins (16–18) were synthesized by reacting 5-acetoxymethylpyrrole-2-carboxylates (14,15) with mono-α-free pyrroloporphyrins (5–8) in the presence of Montmorillonite clay. A symmetrical bis-porphyrinyl dipyrromethane 19 was also prepared by condensation of the β-fused methyl ester pyrroloporphyrin 7 with dimethoxymethane in ethanol and concentrated hydrochloric acid.

Metal ion-induced self assembly of open-chain tetrapyrrole derivatives: Double stranded dinuclear complexes from 10-oxo-5,15-biladienes

Abstract Syntheses of double stranded neutral species via the complexation of Zn, Cd, and Hg with 10-oxo-5,15-biladiene LH2 are described. Formation of the single stranded Cd complex indicates that the self assembly process which affords the double stranded system is not simply a consequence of relief of steric strain. The crystal structure of the cadmium(II) double stranded dimer 8 is described. Long contact distances between carbonyl spacers and Cd ions in the crystal structure of 8 complete the coordination sphere of each Cd, concomitantly forming two distorted trigonal bipyramidal metal centers. Fast coordination/decoordination phenomena involving the carbonyl spacers and the two metallic centers in the zinc(II), cadmium(II) and mercury(II) dimeric complexes 7,8 and 9, respectively, are investigated by using variable temperature 1H NMR. A bending/twisting process is proposed, and its associated energy barrier (40–50 kJ mol−1) is determined for the first time.

Coplanar conjugated β-nitroporphyrins and some aspects of nitration of porphyrins with N2O4

Abstract Sterically controlled N 2 O 4 nitration of a meso -2,3-unsubstituted porphyrin or a bis-α-unsubstituted pyrroloporphyrin affords coplanar conjugated β-nitroporphyrins displaying strong electronic interactions.

Syntheses of carboranylpyrroles

Abstract The syntheses of three carboranylpyrroles ( 5 , 10 and 14 ) bearing carborane cages in 3-position and/or 4-position of the pyrrole ring, either directly linked or through a methylene spacer, are described. Tetramerization of two carboranylpyrroles afforded the corresponding β-carboranylporphyrins, as mixtures of type I–IV isomers.