Cristina M. A. Alonso

A New Synthetic Approach to N-Arylquinolino[2,3,4-at]porphyrins from β-Arylaminoporphyrins

A new reaction leading to porphyrins bearing fused rings is described. Novel N-arylquinolino[2,3,4-at]porphyrins 2 were obtained by thermal oxidative cyclization of beta-arylaminoporphyrins 1. The starting beta-arylaminoporphyrins were prepared by two routes: (i) nucleophilic displacement of the nitro group from 2-nitro-5,10,15,20-tetraphenylporphyrin by anilines and (ii) palladium-catalyzed amination of bromobenzene derivatives with (2-amino-5,10,15,20-tetraphenylporphyrinato)nickel(II). The N-arylquinolino[2,3,4-at]porphyrins show interesting UV-vis spectra with strong absorption bands in the red region.

Synthesis and Diels–Alder reactions of 2-(buta-1,3-dien-2-yl)-5,10,15,20-tetraphenylporphyrin

Abstract A new method for the introduction of a buta-1,3-dien-2-yl group in a β-position of a porphyrin is described. The new β-dienic porphyrin was used in Diels–Alder reactions with several dienophiles giving the corresponding adducts in good yields.

Unexpected fragmentation of β-substituted meso-tetraphenylporphyrins induced by high-energy collisional activation

The protonated molecules and radical cations of meso-tetraphenylporphyrins with β-pyrrolic substituents, when formed by fast atom bombardment (FAB) and subjected to high-energy collisions, give rise to unexpected fragment ions. The reaction involves hydrogen migration from the ortho position of the phenyl ring to the α atom of the substituent, with formation of an intramolecular, six-membered ring. The process is analogous to condensed-phase cyclizations described for the same type of compounds. The fragmentation requires the presence of a double bond in the substituent group attached to the pyrrolic ring. A rearrangement process involving anchimeric assistance by the phenyl group (analogous to an ortho effect) is proposed for the formation of these ions.

Reaction of β-amino-meso-tetraphenylporphyrin with α,β-unsaturated carbonyl compounds: An approach to fused pyridinoporphyrins

Abstract Fused pyridinoporphyrins (3a and 3b) were obtained from the reaction of nickel (II) β-amino-meso-tetraphenylporphyrin with propenal or methyl vinyl ketone.

Meso-Tetraarylporphyrins Bearing Nitro or Amino Groups: Synthetic Strategies and Reactivity Profiles

Porphyrins bearing nitro and amino substituents have been used as excellent synthons for further functionalization in order to obtain new compounds with adequate features for a wide range of applications. This chapter brings an update on the effort of several research groups to study the synthesis and reactivity features of meso-tetraarylporphyrins bearing those functionalities.

Hetero-Diels–Alder reactions of β-imino-meso-tetraphenylporphyrin derivatives: a new approach to pyrido[2,3-b]porphyrins

Abstract The title compounds were prepared from hetero-Diels–Alder reactions of β-imino- meso -tetraphenylporphyrin derivatives with 3,4-dihydro-2 H -pyran or 2,3-dihydrofuran catalysed by lanthanum triflate.

Reduction and adduct formation from electrosprayed solutions of porphyrin salts

The solutions of four meso-tetrakis(N-alkylpyridinium-4-yl)porphyrin salts and of the p-toluenesulfonate salt of meso-tetrakis(4-trimethylammoniumphenyl)porphyrin, in methanol, were studied by electrospray mass spectrometry, in order to investigate the influence of the type of counter ion, the length of the substituent N-alkyl groups of the four (N-alkylpyridinium-4-yl)porphyrins and the presence of an aromatic (alkylpyridinium) or aliphatic (trimethylammonium) nitrogen, in ion formation. In our experimental conditions, adducts with the counter ions were formed only for the meso-tetrakis(4-trimethylammoniumphenyl)porphyrin and were not observed for the other porphyrins, even when the counter ion was the same. In contrast, formation of reduced species, such as the [M(4+) + e(-)]3+, [M(4+) + 2e(-)]2+, [M(4+) + 4e(-) + 2H(+)]2+, and [M(4+) + 5e(-) + 2H(+)]+ ions was observed only for the (N-alkylpyridinium-4-yl)porphyrins and the appearance of these species is apparently solvent related and may occur via counter ion/solvent adducts.