Zur weiteren kenntnis des chlorophylls und des hämins XV umwandlung des octaäthylporphins in octaäthyl-geminiporphyrin-polyketone

Synthesis and Stereochemistry of Hydroporphyrins

“…The structure proposed was based on the absorption spectrum, and this assignment is supported by the chlorin-type spectra observed for geminiporphin triketones, namely, 41. 118 Similar products are encountered in other studies on the photoreduction of metalloporphyrins, but their instability has precluded thus far a more detailed investigation.…”

Surprising Outcomes of Classic Ring‐Expansion Conditions Applied to Octaethyloxochlorin, 2. Beckmann‐Rearrangement Conditions

“…Materials and Instrumentation: Solvents and reagents were used as received. OEP ( 1 ) was converted to oxochlorin 7 by using either the procedures described by Chang et al or Inhoffen et al[11a], [11b] Analytical TLC plates (aluminum‐backed, silica gel 60, 250 µm thickness), preparative TLC plates (20 × 20 cm, glass‐backed, silica gel 60, 500 µm thickness), and flash column chromatography with silica gel (standard grade, 60 Å, 32–63 µm) were used. Alternatively, flash column chromatography was performed on an automated chromatography system with normal‐phase silica gel columns.…”

“…An OEP‐derived ketone is known, octaethyloxochlorin 7M ; it is accessible along two complementary routes, and its regular ketone reactivity was demonstrated. [11c], We therefore identified 7M as potentially susceptible to the formation of oxime 8M and its subsequent Beckmann rearrangement to the lactam isomers 9M or 10M (Scheme ). Given the higher migratory aptitude of benzyl moieties over aryl moieties, the formation of lactam 10M was expected to be more probable.…”

Surprising Outcomes of Classic Ring‐Expansion Conditions Applied to Octaethyloxochlorin, 3. Schmidt‐Reaction Conditions

“…Materials and Instrumentation: Solvents and reagents were used as received. OEP ( 1 ) was converted to oxochlorin 6 by using either the procedures described by Chang et al or Inhoffen et al[13a], [13b] Analytical TLC plates (aluminum‐backed, silica gel 60, 250 µm thickness), preparative TLC plates (20 × 20 cm, glass‐backed, silica gel 60, 500 µm thickness), and flash column chromatography with silica gel (standard grade, 60 Å, 32–63 µm) were used. Alternatively, flash column chromatography was performed on an automated chromatography system with normal‐phase silica gel columns.…”

“…The well‐known OEP‐derived ketone 6 is readily accessible through two complimentary routes, and its regular ketone reactivity was demonstrated. [13c], We thus identified oxochlorin 6 as potentially susceptible to a ring‐expansion reaction under Schmidt‐reaction conditions (Scheme ). Parallel to the mechanistic considerations controlling the Beckmann reactions,[1a] product 8 is also the more likely product of a Schmidt‐reaction pathway in comparison to 7 .…”