# meso-Tetrahexyl-7,8-dihydroxychlorin and Its Conversion to ß-Modified Derivatives

## TL;DR

This paper describes the synthesis and functionalization of a new type of chlorin compound with potential for various chemical modifications.

## Contribution

The study introduces a new class of versatile chlorins based on meso-tetrahexyl-7,8-dihydroxychlorin and their functionalization capabilities.

## Key findings

- The diol chlorin can be oxidized to form a chlorin dione and porpholactone.
- The diol chlorin undergoes dehydration to form a porphyrin enol in equilibrium with its keto-chlorin form.
- The meso-hexylchlorin dione can be reduced and methylated using various reagents.

## Abstract

meso-Tetrahexylporphyrin was converted to its corresponding 7,8-dihydroxychlorin using an osmium tetroxide-mediated dihydroxylation strategy. Its diol moiety was shown to be able to undergo a number of subsequent oxidation reactions to form a chlorin dione and porpholactone, the first meso-alkylporphyrin-based porphyrinoid containing a non-pyrrolic building block. Further, the diol chlorin was shown to be susceptible to dehydration, forming the porphyrin enol that is in equilibrium with its keto-chlorin form. The meso-hexylchlorin dione could be reduced and it underwent mono- and bis-methylation reactions using methyl-Grignard reagents, and trifluoromethylation using the Ruppert-Prakash reagent. The optical and spectroscopic properties of the products are discussed and contrasted to their corresponding meso-aryl derivatives (where known). This contribution establishes meso-tetrahexyl-7,8-dihydroxychlorins as a new and versatile class of chlorins that is susceptible to a broad range of conversions to generate functionalized chlorins and a pyrrole-modified chlorin analogue.