2683-82-1Relevant articles and documents
Surprising Outcomes of Classic Ring-Expansion Conditions Applied to Octaethyloxochlorin, 3. Schmidt-Reaction Conditions
Li, Ruoshi,Zeller, Mathias,Bruhn, Torsten,Brückner, Christian
, p. 1835 - 1842 (2017/04/21)
The Schmidt reaction (treatment of a ketone with sodium azide and a mineral acid) is an alternative to the Beckmann rearrangement to expand a cyclic ketone to a lactam. However, when applied toward the conversion of a synthetic porphyrin into a derivative containing a nonpyrrolic building block, this approach failed to generate the expected lactam. Instead, by using sulfuric acid as a catalyst, a novel heptaethyl-2-hydroxy-chlorin-3-one was formed, structurally characterized, and its mechanism of formation deduced. The work demonstrates how the extraordinary structural stability of the porphyrin macrocycle redirects the reactivity patterns of classic ring-expansion reactions. By using hydrochloric acid as a catalyst, a somewhat regioselective chlorination of the meso-positions of the oxochlorin was observed. The halogenation sites were determined spectroscopically and by X-ray crystallography of selected derivatives. The regioselectivity of the halogenation was computationally rationalized. This method is superior to alternative halogenation methods for the regioselective generation of 5-chloro-, 10-chloro-, and 5,10-dichlorooxochlorins.
Paley's watchmaker analogy and prebiotic synthetic chemistry in surfactant assemblies. Formaldehyde scavenging by pyrroles leading to porphyrins as a case study
Alexy, Eric J.,Hintz, Carl W.,Hughes, Hubert M.,Taniguchi, Masahiko,Lindsey, Jonathan S.
, p. 10025 - 10031 (2015/10/12)
The formation of elaborate molecules is regarded as an essential first step in prebiotic chemistry, but how such transformations could spontaneously occur, particularly in dilute aqueous conditions, remains poorly understood. Here, micromolar concentrations of a 3,4-dialkylpyrrole and excess formaldehyde in aqueous micellar solution (pH 7) at 25 or 50 °C were found to give good yield (up to 40%) of the lipophilic octaalkylporphyrin. The reaction occurs despite a mean occupancy number of ～0.1 pyrrole molecules/micelle, and 1 of 10 000 micelles initially containing the requisite 4 pyrrole molecules to form the porphyrin assuming a (random) Poisson distribution. Yields of up to 13% were observed in large, unilamellar phosphatidylcholine vesicles, wherein there are ～15 000 pyrrole molecules per vesicle membrane. Double-labeling crossover experiments (of 3,4-diethylpyrrole and 3,4-dimethylpyrrole) examined by mass spectrometry revealed facile exchange processes of reactive constituents among both micelle and vesicle surfactant assemblies. Together, the exchange of pyrrolic reactants among micelles and the thermodynamic driving force for tetrapyrrole formation overcome the apparent statistical odds against reaction. The fruitful exchange, accumulation and reaction of minute quantities of reactants in aqueous-surfactant assemblies suggest a general means for formation of prebiotically valuable constituents, even when the statistical odds at the outset are overwhelmingly improbable.
The exhaustive reduction of formylporphyrins to methylporphyrins using dimethylformamide/water as reductant under microwave irradiation
Fletcher, Sarah J.,Harper, Shannon R.,Arnold, Dennis P.
, p. 200 - 208 (2014/05/20)
The reduction of meso-formyl derivatives of 5,15-diaryl- and 5,10,15-triphenylporphyrin (and their nickel(II) complexes) to the corresponding meso-methyl porphyrins is achieved in high yield by microwave heating of the substrate in dimethylformamide (DMF)
