1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

6 Experimental Section
6.2.6.3 5 2 - (Bromomethyl)- 5 4 , 10 4 , 20- Tri- t - Butyl - 5 6 - Methyl - 15 4 - Nitro -5,10,15,20-
Br
180
Tetraphenylporphyrin, 88
N
NH HN
N
88
C 58 H 56 BrN 5 O 2
M = 935.00 g·mol -1
NO 2
In a 2 L round bottom flask, methoxymethyl dipyrromethane
39a (3.36 g, 10.0 mmol), nitro dipyrromethane 85 (2.67 g,
10.0 mmol) and 4-t-butyl benzaldehyde (3.24 g, 3.35 mL,
20.0 mmol) are dissolved in 1 L of CHCl3. After addition of
TFA (1.55 mL, 20 mmol), the reaction mixture is stirred at rt
for 60 min. Then, TEA (2.8 mL, 20 mmol) is added followed
by addition of DDQ (4.54 g, 20 mmol) to the claret solution
and stirring is continued for 2 h. After evaporation of the
solvent, the residue is filtered through a silica plug (CH2Cl2 as
eluent) and pre-cleaned by FC (silica, CH2Cl2 : hexanes = 3 : 2) to give a binary mixture of
porphyrins 86 and 87 (Scheme 53, p. 113). This material is then taken up in 150 mL of CH2Cl2
and HBr (5.4 M in glacial AcOH, 30 mL) is added whereupon the solution turns dark green.
The flask is closed by a one-hole stopper with exhaust duct and the reaction mixture is
stirred at rt for 12 h. After that, the green solution is transferred into a separatory funnel
and repeatedly washed with water until the color changes to purple-red. Then, the solution
is neutralized by shaking with a saturated aqueous solution of NaHCO3, washed with water,
dried over MgSO4 and evaporated to dryness to give the mixture of porphyrins 87 and 88
(Scheme 53, p. 113) which is separated by FC (silica, CH2Cl2 : hexanes = 3 : 2) to furnish 1.39 g
(1.49 mmol) of pure 88 as purple powder, equiv. to 14.9 % yield based on 85.
1 H NMR (400 MHz, rt, CDCl3): δ [ppm] = -2.65 (s, 2 H, NH), 1.61 (s, 18 H, t-BuH), 1.63 (s, 9 H,
t-BuH), 1.89 (s, 3 H, CH3), 4.15 (s, 2 H, CH2), 7.59 (d, 4 J = 1.5 Hz, 1 H, Ar’H), 7.77 (m, 4+1 H,
ArH+Ar’H), 8.14 (d, 3 J = 7.6 Hz, 2 H, ArH), 8.18 (d, 3 J = 7.6 Hz, 2 H, ArH), 8.39 (d, 3 J = 6.1 Hz,
2 H, ArH), 8.62 (d, 3 J = 8.8 Hz, 2 H, ArH), 8.69 (d, 3 J = 4.6 Hz, 2 H, β-H), 8.73 (d, 3 J = 4.9 Hz, 2 H,
β-H), 8.90 (d, 3 J = 4.6 Hz, 2 H, β-H), 8.96 (d, 3 J = 4.6 Hz, 2 H, β-H).
13 C NMR (100.5 MHz, rt, CDCl3): δ [ppm] = 21.8, 31.5, 31.6, 33.1, 34.9 (two peaks), 116.2,
116.8, 120.8, 123.8 (two peaks), 124.7, 126.7, 130.2 (br), 130.8 (br), 132.0 (br), 134.5, 134.6,
135.2, 138.2, 138.6, 138.8, 140.0, 147.8, 149.5, 150.8, 152.2.
MS (FAB+, NBA): m/z (%) = 935 (100) [M] +· , 854 (15) [M-Br] +· .