A mixture of 316 mg of m-(thiocyanatomethyl)benzaldehyde (10, 1.8 mmol), 396 mg of 5-phenyldipyrromethane (Lee and Lindsey (1994) Tetrahedron, 50: 11427-11440, Littler et al. (1999) J. Org. Chem., 64: 1391-1396) (1.8 mmol) and 1.07 g of NH4Cl (20.0 mmol) in 200 mL of acetonitrile was purged with argon for 30 min. Under stirring at ambient temperature 23 μL of BF3.O(Et)2 (26 mg, 0.18 mmol) was added. Soon the solution turned to yellow and later to dark red. After 6.5 h, 607 mg of DDQ (2.7 mmol) was added. After 1 h the reaction was quenched with 0.5 mL of TEA (365 g, 3.6 mmol). The solvents were removed under reduced pressure. Purification was done by column chromatography over two flash silica gel columns with different solvent mixtures: (column 1) ether/hexanes (3:1) and (column 2) CH2Cl2/hexanes (gradient, start: 1:1). Two fractions of dark purple solids were obtained. I: 12 mg 10,15,20-triphenyl-5-[m-(thiocyanatomethyl)phenyl]porphyrin (17.5 μmol, 2% yield). II: 44 mg of the title compound (58.1 μmol, 7% yield). IR (neat): {tilde over (v)}=2921 (s, CH), 2850 (m, CH), 2154 (m, CN), 1597 (m, arom. C═C), 1471 (s), 1348 (m), 1206 (m), 1181 (w), 1097 (w), 973 (s), 898 (w), 743 (s), 691 (s), 623 (s); 1H NMR (300.5 MHz, CDCl3): δ=−2.811 (s, 2H, NH), 4.57 (s, 4H, CH2), 7.71-7.83 (m, 11H, ArH), 8.17-8.25 (m, 8H, ArH), 8.84 (d, 4H, β-pyrrole, 3J=5.1 Hz), 8.88 (d, 4H, β-pyrrole); LD-MS calcd av mass 756.9, obsd 757.4, 699.2 [M+—SCN], 641.0 [M+−2 SCN]; FAB-MS obsd 756.2172, calcd exact mass 756.2130 (C48H32N6S2); λabs (toluene) 420, 514, 549, 590, 647, 657 nm.
