Photooxidation of Dithiaethyneporphyrin

Abstract

The oxidative degradation of the contracted carbaporphyrinoid 3,8,13,18-tetraphenyldithiaethyneporphyrin, which contains an acetylene moiety embedded in the macrocyclic framework, was investigated. The light-induced, regioselective cleavage of the macrocyclic ring was observed during exposure to dioxygen affording four open-chain diastereomers terminated by carbonyl groups. Studies on the regioselectivity of the process showed that the thiophene was cleft together with the 8-aryl substituent, which proved the primary attack of dioxygen at the C8-C9 bond. Diastereomers {4Z,10E}, {4Z,10Z}, {4E,10E}, and {4E,10Z} [the arrangement with respect to C4-C5 and C10···C13 conjugated bonds given] differ by the orientation of the terminal pyrro-

The Synthesis and Properties of Free‐Base [14]Triphyrin(2.1.1) Compounds and the Formation of Subporphyrinoid Metal Complexes

“…The spectra of the free‐base [14]triphyrin(2.1.1) compounds are dominated by an intense band between 350 and 450 nm and weaker bands in the 500–650 nm region, which have been assigned as allowed and forbidden B and Q bands, respectively, by analogy with Gouterman’s four‐orbital model for tetrapyrrole porphyrinoids 24. Similar band assignments were recently made by the Kobayashi and Latos‐Grażyński groups for boron subporphyrins[4] and [18]dithiatriphyrin(4.1.1) 5f–i. When fused benzene and naphthalene rings are added to the [14]triphyrin(2.1.1) π system, the Q and B bands shift to the red and the Q band intensifies significantly (Figure 5, left).…”

“…In contrast with the vacataporphyrin9d, 25 and subpyriporphyrin5j compounds reported by Latos‐Grażyński and co‐workers, there is no evident scope for switching the aromaticity properties of the π system to another form. As was the case with [18]dithiatriphyrins(4.1.1),5f–i the analysis of the electronic structure is relatively straightforward, since the π system consistently displays standard 4 N+2 Hückel aromaticity. The potential effect of NH tautomerism was investigated and found to be relatively minor.…”

“…Subsequently a [15]triphyrin(3.1.1) compound was reported by Krivokapić et al 5e. and Latos‐Grażyński and co‐workers have reported heteroaromatic core modified [18]dithiatriphyrin(4.1.1)5f–i and dithiaethyneazuliporphyrin5h,i compounds with four atom bridges containing a triple bond.…”

Iridium Complex of N‐Fused Bilatrienone: Oxidative Cleavage of N‐Fused Porphyrin Induced by Iridium‐Cyclooctadiene Complexation

“…For example, N‐confused porphyrin ( 6 ) [13–15] underwent oxidative ring cleavage to yield an N‐confused bilatrienone derivative ( 7 ) in an air‐saturated solution under photoirradiation (Figure 1b) [16] . Similarly, photooxidation of dithiaethyneporphyrin gave a ring‐opened product possessing a cumulene moiety [17] . In addition to photooxidation, metalation‐induced oxidative ring cleavage during aerobic copper insertion of 6 afforded a linear tripyrrinone analog ( 8 ) [18] .…”

Synthesis and Characterization of Triphyrins: A New Family of Porphyrinoids

“…Cyclic monoanionic tridentate ligands have been extensively studied in the field of coordination-chemistry. The typical examples are subpyriporphyrin, 11 vacataporphyrin, [13][14][15][16] thiaethyneporphyrins, [25][26][27][28][29] [15]triphyrin(3.1.1) 30 and N-fused porphyrins (NFPs) (Scheme 16). 38 The coordination abilities and properties of their metal complexes except for NFPs have been described above.…”