The First Crystalline Calcium Porphyrin and Tetrakis(tert-butylphenyl)porphyrinato Calcium(II): Its Synthesis, Structure, and Binding Properties Towards Alkali and Alkaline Earth Metal Salts

✍ Scribed by Lucia Bonomo; Marie-Line Lehaire; Euro Solari; Rosario Scopelliti; Carlo Floriani

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 112 KB
• Volume: 113
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/1521-3757(20010216)113:4<793::aid-ange7930>3.0.co;2-t

✦ Synopsis

The study of alkaline earth metals and particularly of calcium in porphyrin systems is of great importance because of their relationship to the role of magnesium and iron porphyrin derivatives in naturally occurring systems. This notwithstanding, information available on the synthesis, structure, and spectroscopic properties of calcium porphyrin is practically nonexistent, [1] with only UV/Vis data being available. [1a] The field of alkali metal porphyrin and porphyrin analogues has burgeoned in recent years, [2] with a significant example being that of calcium porphyrinogen chemistry. [3] The isolation and characterization of alkaline earth metal porphyrin systems have failed so far because of the use of protic conditions in their synthesis. [1] Therefore, we turned our Zr(OiPr) 4 (109 mg, 0.28 mmol) in CH 2 Cl 2 (5 mL) with 4 molecular sieves at À 20 8C (salt/ice bath), followed by tert-butyl hydroperoxide (3.8 m solution in toluene, 0.085 mL, 0.32 mmol). The reaction mixture was stirred at À 20 8C for 0.5 h before addition of diallylic alcohol 12 (30 mg, 0.094 mmol) in CH 2 Cl 2 (5 mL) which was also cooled to À 20 8C. The reaction mixture was then stirred for a further 0.5 h before transfer to a freezer at À 20 8C for 3 days. H 2 O (2.5 mL) and saturated aqueous Na 2 SO 3 (2.5 mL) were added to the reaction mixture. The resulting biphasic system was stirred vigorously for 0.5 h at ambient temperature and the aqueous layer extracted with CH 2 Cl 2 (3 Â 10 mL). The combined organic phases were dried (MgSO 4 ), filtered through Celite, and concentrated under vacuum. Flash column chromatography (elution with EtOAc:petroleum ether (1:3)) gave epoxy alcohol ()-13 as a colorless oil (14 mg, 44 %). (see Supporting Information for analytical data,).