Oxazolochlorins 21. Most Efficient Access to meso-Tetraphenyl- and meso-Tetrakis(pentafluorophenyl)porpholactones, and Their Zinc(II) and Platinum(II) Complexes.

Damaris Thuita,Christian Brückner,Dinusha Damunupola

doi:10.3390/molecules25184351

Damaris Thuita, Christian Brückner + Show 1 more

Open Access

https://doi.org/10.3390/molecules25184351

Copy DOI

Journal: Molecules (Basel, Switzerland)	Publication Date: Sep 22, 2020
Citations: 4	License type: CC BY 4.0

Affiliation: University of Connecticut

Abstract

meso-Phenyl- and meso-pentafluorophenyl-porpholactones, their metal complexes, as well as porphyrinoids directly derived from them are useful in a number of technical and biomedical applications, and more uses are expected to be discovered. About a dozen competing and complementary pathways toward their synthesis were reported. The suitability of the methods changes with the meso-aryl group and whether the free base or metal derivatives are sought. These circumstances make it hard for anyone outside of the field of synthetic porphyrin chemistry to ascertain which pathway is the best to produce which specific derivative. We report here on what we experimentally evaluated to be the most efficient pathways to generate the six key compounds from the commercially available porphyrins, meso-tetraphenylporphyrin (TPP) and meso-tetrakis(pentafluorophenyl)porphyrin (TFPP): free base meso-tetraphenylporpholactone (TPL) and meso-tetrakis(pentafluorophenyl)porpholactone (TFPL), and their platinum(II) and zinc(II) complexes TPLPt, TFPLPt, TPLZn, and TFPLZn, respectively. Detailed procedures are provided to make these intriguing molecules more readily available for their further study.

Highlights

IntroductionPorpholactones, members members ofofthe thefamily familyof of so-called pyrrole-modified porphyrins [1], Porpholactones, so-called pyrrole-modified porphyrins [1], are are porphyrinoids in which a ß,ß’-bond parent porphyrinwas wasreplaced replacedby byaalactone lactonemoiety. moiety
Since the most efficient pathways toward the meso-phenyl- and meso-pentafluorophenyl-substituted porpholactones vary, we will discuss the syntheses of these two families separately
Among the possible multi-step processes toward TPL (Scheme 1), one process stands out as suitable for its simplicity and high yields: We have reported in detail [51,52], both the OsO4 -mediated cis-vic-dihydroxylation, followed by a diol oxidation of the intermediate dihydroxychlorin [4,17,53,54]

Summary

Introduction

IntroductionPorpholactones, members members ofofthe thefamily familyof of so-called pyrrole-modified porphyrins [1], Porpholactones, so-called pyrrole-modified porphyrins [1], are are porphyrinoids in which a ß,ß’-bond parent porphyrinwas wasreplaced replacedby byaalactone lactonemoiety. moiety. Porpholactones, members members ofofthe thefamily familyof of so-called pyrrole-modified porphyrins [1], Porpholactones, so-called pyrrole-modified porphyrins [1], are are porphyrinoids in which a ß,ß’-bond parent porphyrinwas wasreplaced replacedby byaalactone lactonemoiety. From porphyrinoids in which a ß,ß’-bond of of thethe parent porphyrin building block was replaced by the perspective of of the thetetrapyrrolic tetrapyrrolicstructure structureofofporphyrins, porphyrins,a pyrrolic a pyrrolic building block was replaced an oxazolidone (Scheme 1). Generalized formation formation of of meso-arylporpholactones meso-arylporpholactones from meso-arylporphyrins. The historically first porpholactone, meso-tetraphenylporpholactone (TPL) was derived from meso-tetraphenylporphyrin (TPP) [2]. While several phenyl- and substituted phenyl-derivatives were

Methods

Results

Conclusion