Expanded Bacteriochlorins

Abstract

Ruffled rings: Both pyrrolidine moieties in meso‐tetraaryl‐7,8,17,18‐tetrahydroxybacteriochlorins can be sequentially expanded into morpholine rings to give the first bacteriochlorin‐like derivatives containing two non‐pyrrolic heterocycles. These porphyrioids are characterized by nonplanar conformations and significantly red‐shifted optical spectra, both of which can be modulated by the introduction of linkages between β and o‐phenyl positions.

Indachlorins: Nonplanar Indanone‐Annulated Chlorin Analogues with Panchromatic Absorption Spectra between 300 and 900 nm

“…For instance, the expansion of a dihydroxypyrroline in indachlorin 13 to a dialkoxy‐substituted morpholine building block in 14 was accomplished by using standard reaction conditions 18a. 20b, 24b, 29 Product 14 possessed the expected alcohol‐dependent compositions (from HRMS). The diagnostic signals in the 1 H NMR spectrum of 14 b include the signals for the indanone moiety and the morpholine moiety (s at δ =6.05 ppm for OC H (OEt) and two dq at both δ =3.60 and 3.18 ppm for the two diastereotopic methylene protons of the ethoxy side chains) 18a.…”

“…The diagnostic signals in the 1 H NMR spectrum of 14 b include the signals for the indanone moiety and the morpholine moiety (s at δ =6.05 ppm for OC H (OEt) and two dq at both δ =3.60 and 3.18 ppm for the two diastereotopic methylene protons of the ethoxy side chains) 18a. 20b, 24 The presence of only one diastereomer (from 1 H and 13 C NMR spectroscopy) suggests that the three stereoelements (the helix of the indaphyrin framework and the two sp 3 ‐carbons on the morpholine ring) are similarly coupled as in the free base and Ni II morpholinochlorins,24b, 29b thus forming only two enantiomers with the alkoxy substituents arranged trans to each other (Figure 1). Single‐crystal X‐ray diffractometry provided the final confirmation for the connectivity of 14 b , including the presence of only one racemic pair (Figure 3).…”

“…In parallel to the generation of secochlorin bisaldehyde 8 by oxidative cleavage of diol 6 (Scheme ),21, 33 the application of these oxidation conditions to tetraolbacteriochlorin 7 ought to generate secobacteriochlorin tetraaldehyde 17 (that was also surmised to be the intermediate in the formation of bismorpholinobacteriochlorin 11 from tetraol 7 ) 20b. Indeed, treatment of tetraol 7 with periodate under mildly basic conditions generated a nonpolar, fragile compound of the expected composition of tetraaldehyde 17 (from HRMS).…”

“… Syntheses of free base chlorin diol 6 ,18a bacteriochlorin tetraol 7 ,18b bisaldehyde intermediate 8 ,21 indaphyrin 9 ,22b morpholinochlorin 10 ,24a and bismorpholinobacteriochlorin 11 20b. …”

Synthesis and evaluation of cationic bacteriochlorin amphiphiles with effective in vitro photodynamic activity against cancer cells at low nanomolar concentration

“…The synthesis of bacteriochlorins has been the subject of a number of reviews over the past decade [8–11]. Notable recent advances include (1) Brückner's two-fold OsO 4 -mediated dihydroxylation of meso -tetraarylporphyrins followed by ring-expansion of the resulting tetrahydroxybacteriochlorins to give morpholinobacteriochlorins [12], and (2) Pereira's scalable diimide-mediated reduction of meso -tetraarylporphyrins to give the corresponding bacteriochlorins [13]. Our own contribution in this area entails a de novo synthetic pathway to bacteriochlorins wherein a geminal dimethyl group is located in each reduced pyrrole ring [14, 15].…”