8930
M. O. Senge et al. / Tetrahedron 56 (2000) 8927±8932
alumina (Alfa, 60 mesh) (Brockmann Grade III, i.e. deacti-
vated with 7% water) were used for column chromato-
graphy. Analytical thin-layer chromatography (TLC) was
carried out using Merck silica gel 60 plates. 1H NMR
spectra were recorded at a frequency of 250 MHz (Bruker,
AC 250) or 500 MHz (Bruker, AMX 500) while 13C NMR
spectra were recorded with a Bruker AM 270 instrument.
All chemical shifts are given in ppm, referenced on the d
scale down®eld from the TMS signal as internal standard.
Electronic absorption spectra were recorded on a Specord
S10 (Carl Zeiss) spectrophotometer using dichloromethane
as solvent. Mass spectra were recorded using a Varian MAT
711 mass spectrometer using the EI technique with a direct
insertion probe and excitation energy of 80 eV.
[M122£C4H9); HRMS [C40H40N4]: calcd 576.3253, found
576.3282.
5,15-Di(tert-butyl)-5,15-dihydro-10,20-di(p-tolyl)por-
phyrin (5). Yield: 4 mg red-brown crystals from CH2Cl2/
MeOH; mp 250±2558C; UV/Vis (CH2Cl2): lmax (rel.
int.)451 nm (1); 1H NMR (250 MHz, CDCl3, TMS):
d1.12 (s, 18H, C(CH3)3), 2.40 (s, 6H, CH3±C6H6), 3.84
(s, 2H, Cm±H), 5.88±6.15, 6.42±6.74 (each d, J4.1 Hz,
4H, Hb), 7.19±7.23 (m, 4H, Hphenyl), 7.34±7.37 (m, 4H,
Hphenyl), 11.2 (s, 2H, NH); HRMS [C42H44N4]: calcd
604.3566, found 604.3545.
5,10-Di(tert-butyl)-5,10,-dihydro-15,20-di(p-tolyl)por-
phyrin (6). Yield: 3 mg red-purple crystals from CH2Cl2/
MeOH; mp 245±2508C; UV/Vis (CH2Cl2): lmax (rel.
int.)431 nm (1); 1H NMR (500 MHz, CDCl3, TMS):
d0.89 (s, 18H, C(CH3)3), 2.42 (s, 6H, CH3±C6H6), 3.8
(s, 2H, Cm±H), 5.8 (d, J2.5 Hz, 2H, Hb-pyrrole), 6.14 (d,
J2.3 Hz, 2H, Hb), 6.4 (d, J4.4 Hz, 2H, Hb), 6.71 (d,
J4.4 Hz, 2H, Hb), 7.22 (d, J8.1 Hz, 4H, Hm-phenyl), 7.32
(d, J6.9 Hz, 4H, Ho-phenyl), 11.2 (s, 1H, NH), 13.47 (s, 1H,
NH); 13C NMR (CDCl3): d22.65 (CH3±C6H6), 28.24
(C(CH3)3), 37.04 (C(CH3)3), 51.97, 138.53 (Cm), 105.08,
136.94, 151.83, 177.3 (Ca), 120.75, 127.08, 130.29,
134.61 (Cb), 128.26 (Cm-phenyl), 131.34 (Co-phenyl), 134.71
(Cp-phenyl), 138.67 (Cp-phenyl); HRMS [C42H44N4]: calcd
604.3566, found 604.3598.
Condensation reactions
Individual reactions were performed on a mmol scale and
4 equiv. of pyrrole were reacted with 3 equiv. of pivalyl-
aldehyde and 1 equiv. of arylaldehyde under Lindsey-con-
ditions8 using tri¯uoroacetic acid as acid catalyst. Oxidation
was performed with either DDQ (for the benzaldehyde reac-
tion) or silver(I) oxide (for the tolylaldehyde reaction).
Chromatography was laborious and involved ®rst ®ltration
of the crude reaction mixture through a short plug of
alumina. After concentration of the ®ltrate, the residue
was taken up in a minimum volume of methylene chloride
and applied to the top of a silica gel column. For separation
of the individual compounds the column was developed
using a gradient method. Elution started ®rst with neat
n-hexane and then gradually the content of methylene
chloride was increased until a ratio of 1:1 (v/v) was
obtained. Compounds eluted in the following order: yellow
porphomethenes with neat hexane, followed by porphodi-
methenes (10:1). Increase of the methylene chloride content
to 1:1 eluted then the asymmetric substituted porphyrins or
silver porphyrins followed by the symmetric (silver)
porphyrins. The individual fractions were rechromato-
graphed on silica gel under the same conditions and recrys-
tallized. The individual yields of the isolated products were
about 1%. Compounds 74 and 1019 gave analytical data
identical to literature values.
5-(tert-Butyl)-5,10,15-triphenylporphyrin (8). Yield:
3 mg purple crystals from CH2Cl2/MeOH; mp .3008C;
UV/Vis (CH2Cl2): lmax (rel. int.)421 nm (1), 523
1
(0.035), 563 (0.018), 600 (0.009), 656 (0.004); H NMR
(250 MHz, CDCl3, TMS): d21.79 (br. s, 2H NH), 2.38
(s, 9H, C(CH3)3), 7.69±7.75 (m, 9H, Hphenyl), 8.08±8.12 (m,
6H, Hphenyl), 8.52±8.54 (d, J4.3 Hz, 2H, Hb-pyrrole), 8.59±
8.61 (d, J4.3 Hz, 2H, Hb-pyrrole), 8.87±8.89 (d, J4.3 Hz,
2H, Hb-pyrrole), 9.52±9.54 (d, J4.3 Hz, 2H, Hb-pyrrole);
HRMS [C42H34N4]: calcd 594.2783, found 594.2765.
{5-(tert-Butyl)-5,10,15-tri(p-tolyl)porphyrinato}silver(II)
(9). Yield: 6 mg purple crystals from CH2Cl2/MeOH; mp
.3008C; UV/Vis (CH2Cl2): lmax (rel. int.)429 nm (1),
549 (0.082), 591 (0.031); MS (80 eV); m/z (%): 743 (75)
[M1], 697 (95) [M12C3H10] 636 (100) [M12Ag]; HRMS
[C45H38N4Ag]: calcd 741.2147, found 741.2108.
5,10,15-Tri(tert-butyl)-5,10,15,22-tetrahydro-20-phenyl-
porphyrin (2). Yield: 5 mg yellow crystals from CH2Cl2/
MeOH.; mp 220±2308C.; UV/Vis (CH2Cl2): lmax (rel.
int.)425 nm (1); 1H NMR (250 MHz, CDCl3, TMS):
d0.65±0.72 (m, 9H, C(CH3)3), 0.90±1.05 (m, 18H,
C(CH3)3), 3.65 (s, 1H, Cm±H), 4.01 (s, 2H, Cm±H), 5.80±
5.85 (m, 2H, Hb-pyrrole), 6.13±6.15 (m, 4H, Hb-pyrrole), 6.23±
6.27 (m, 2H, Hb-pyrrole), 7.35±7.51 (m, 5H, Hphenyl), 9.23 (br,
s, 2H, NH); HRMS [C38H46N4]: calcd 558.3722, found
558.3734.
(5,10,15,20-Tetratolylporphyrinato)silver(II) (11). Yield:
10 mg purple crystals from CH2Cl2/MeOH; mp .3008C;
UV/Vis (CH2Cl2): lmax (log e)427 nm (5.24), 542
(4.38); MS (80 eV); m/z(%): 777 (100) [M1], 670 (10)
[M12Ag]; HRMS [C48H36N4Ag]: calcd 775.1991, found
775.1942.
{5,10,15,20-Tetrakis(1-ethylpropyl)porphyrinato}silver-
(II) (13). To a solution of the free base 12 (0.25 mmol) in
50 ml dichloromethane 3 equiv. of Ag2O are given and the
mixture treated with 3 drops of tri¯uoroacetic acid. Stirring
for 20 min is followed by ®ltration of the mixture through
silica gel, evaporation of the solvation and recrystallization.
Yield: 110 mg (0.1578 mmol, 63%) red crystals from
CH2Cl2/MeOH; mp .3008C; UV/Vis (CH2Cl2): lmax
(log e)424 nm (5.07), 479 (4.21), 544 (4.24); MS
5,15-Di(tert-butyl)-5,15-dihydro-10,20-diphenylporphyrin
(4). Yield: 4 mg orange-red crystals from CH2Cl2/MeOH;
mp 250±2608C; UV/Vis (CH2Cl2): lmax (rel. int.)471 nm
(1) 686 (0.015); 1H NMR (250 MHz, CDCl3, TMS): d1.09
(s, 18H, C(CH3)3), 3.91 (s 2H, Cm±H), 5.75±5.96, 6.23±
6.51 (each d, J4.1 Hz, 4H, Hb), 7.10±7.15 (m, 6H, Hphenyl),
7.24±7.28 (m, 4H, Hphenyl), 11.0 (s, 2H, NH); MS (80 eV);
m/z (%): 576 (3) [M1], 518 (1) [M12C4H9), 463 (100)