Porphyrins, carboranylated

Several reports of carboranylated porphyrins have appeared for utilization in the BNCT of cancer.150 The examples include both nido- (126) (Fig. 73) and closo-carborane cluster-containing (124 and 125) (Fig. 73) materials. Metal-free nido-carboranylporphyrins were able to deliver a higher amount of boron to cells than the corresponding zinc complexes. 

Eq. 53) (e) carboranyl substituents [194,195] etc. (Eq. 39). There have also been reports on the incorporation of cyclophosphazenes in macrocycles such as phthalocyanins [268] and porphyrins [269-271],... 

Miura, M. Gabel, D. Oenbrink, G. Fairchild, R.G. Preparation of carboranyl porphyrins for boron neutron capture therapy. Tetrahedron. Lett. 31,2247-50,1990. 

Boron-containing nucleosides, carboranyl-substituted nucleotides, porphyrins, and boron analogs of acridine in neutron-capture therapy 04IZV1795. 

Total syntheses of six carboranyl-containing porphyrins bearing 33-44 wt% B for application in BNCT was described by Vicente et al. (2000). This class of compounds features carbon-carbon linkages between the carboranyl groups and the meso-phenyl substituents. The synthesis of tetra (4-carboranylphenyl) porphyrins and their zinc(ll) complexes also was presented (Vicente et al. 2002b). This type of nido-carboranylporphyrin is a promising sensitizer for both BNCT and the photodynamic therapy of tumors. Four more nido-carboranylporphyrins showed promise as boron carriers for the BNCT (Vicente et al. 2002a). 

Vicente, M. G. H., S. J. Shetty, A. Wickramasinghe, and K. M. Smith. 2000. Syntheses of carbon-carbon hnked carboranylated porphyrins for application in boron neutron capture therapy of cancer. Tetrahedron Lett. 41 7623-7627. 

Amphiphilic carboranyl porphyrin complexes have been synthesized use as potential BNCT agents. The free-base carboranyl porphyrin complexes that have been made are shown in structure (25). These have been accessed vie a multi-step pathway. ... 

A number of carboranyl porphyrins have been obtained on the basis of the natural porphyrin derivatives, such as deuteroporphyrin IX and hematoporphyrin IX, and two of than, VCDP and BOPP (Figure 9.12), have been extensively studied in animals. BOPP was reported to have a tumor-normal brain ratio from 13 1 to 400 1 for different glioma models [117,118]. High boron levels in tumor (>60 pg °B/g tumor) were achieved in these animal studies. However, data obtained from a human Phase I clinical trial showed that under intravenous injection BOPP does not deliver therapeutic concentrations of boron to the tumors of glioblastoma patients, and dose escalation is prevented by the toxicity of this compound. Nevertheless, BOPP has shown some promise as an effective PDT photosensitizer [119-121]. More recently, it was demonstrated that convection-enhanced delivery of BOPP significantly enhances the boron concentration in tumors and produces very favorable tumor-brain and tumor-blood ratios [122]. 

Other carboranylporphyrins and boronated chlorine eg for PDT, in which porphyrin is linked to the carboranyl moiety via the boron or the carbon atoms have also been reported by OTshevskaya et al. In arecent work, boronated amide derivatives starting from 5,10,15,20-tetra(p-aminophenyl) porphyrin and 9-o- and 9-m-carborane carboxylic acid chlorides were prepared. Also, the reaction of 2-formyl-5,10,15,20-tetraphenylporphyrin with the lithium salt of 1,2-c/oso-C2BjoHj2, and... 

---