Synthesis And Properties Of 2,6-Dichlorotripyrroles And Tetrapyrroles

Oligopyrroles, such as tripyrroles and tetrapyrroles, are versatile precursors for the synthesis of porphyrinoids. Their synthesis generally involves transition-metal catalyzed coupling reactions, such as Ullmann coupling, and has limited versatilities. It is highly desirable for the development of a new synthetic strategy toward tripyrroles and tetrapyrroles.Previously, our group has developed a stepwise synthetic method for the BF2 complexes of tripyrrole and tetrapyrroles via the condensation between pyrroles and aromatic aldehydes in CH2Cl2 using POCl3 as a catalyst, and the subsequent BF2 complexation. In Chapter 2, we described a stepwise and regioselective aromatic substitution reaction on2,3,5,6-tetrachloroBODIPYs with pyrroles under no acid or metal catalyzed conditions. These resultant BF2 complexes 3aa-4ab are interesting near-infrared(NIR) fluorescent dyes with absorption maximum up to 690 nm and were further functionalized at the unoccupied 3(5)-position to achieve the desired properfies, like the targeting properties.Previously, we have achieved a series of free-base tripyrroles and teterpyrroles from the removal of the BF2 unit from their corresponding BF2 complexes. Considering that this procedure involves the BF2 complexation and the subsequent removal of this BF2 unit, in Chapter 4,we presented a stepwise and regioselective aromatic substitution reaction on 1,9-dihalogenateddipyrrins with pyrroles, from which a series of free-base tripyrroles and tetrapyrroles were selectively obtained in high yields via the variation of temperature and solvents.