H. A. Wegner and R. Reuter
the solvent, a dark-green oil was obtained, which was purified by column
chromatography on silica gel (hexane/EtOAc 5:1) to yield 19 as a green
oil, which crystallized in the freezer to form a brown solid (1.61 g, 60%).
1H NMR (400 MHz, CDCl3): d=8.04 (s; 1H), 7.87 (s; 1H), 7.74 (s; 1H),
4.78 (s, CH2; 2H), 4.74 (s, CH2; 2H), 3.44 ppm (s, CH3; 3H); 13C NMR
(101 MHz, CDCl3): d=165.4, 142.6, 136.7, 124.2, 121.6, 120.7, 96.6 (CH2),
67.9 (CH2), 56.1 ppm (CH3); MS (EI, 70 EV): m/z (%): 259 (12) [M]+, 45
(100); elemental analysis calcd (%) for C9H10BrNO3: C 41.56, H 3.88, N
5.39; found: C 41.65, H 4.07, N 5.41.
to cool down and the organic layer was separated and washed with water
and brine (50 mL). After drying over MgSO4 and removal of the solvent
under reduced pressure, the residue was purified by column chromatog-
raphy on silica gel (CH2Cl2/MeOH 100:3) to yield a red oil, still contain-
ing impurities, which did not influence the next step (1.61 g, quant.).
1H NMR (400 MHz, CDCl3): d=8.24 (s; 2H), 8.12 (s; 2H), 7.98 (s; 2H),
7.94 (s; 2H), 7.84 (s; 2H), 7.72 (s; 2H), 7.08 (s; 2H), 6.95 (s; 2H), 6.73
(s; 2H), 4.82 (s, 4H, CH2), 4.80 (s, CH2; 4H), 4.79 (s, CH2; 4H), 4.76 (s,
CH2; 4H), 4.74 (s, CH2; 4H), 4.60 (s, CH2; 4H), 3.81 (s, NH2; 4H), 3.48
(s, CH3; 6H), 3.46 (s, CH3; 6H), 3.44 ppm (s, CH3; 6H); 13C NMR
(101 MHz, CDCl3): d=153.7, 153.5, 147.5, 142.9, 142.0, 140.3, 140.2,
140.0, 132.5, 129.42, 129.35, 122.0, 121.8, 121.4, 121.1, 117.5, 114.3, 113.7,
96.4 (CH2), 96.3 (CH2), 96.1 (CH2), 69.5 (CH2), 69.2 (4C, CH2), 56.0
(CH3), 55.9 (CH3) 55.8 ppm (CH3); MS (FAB): m/z (%): 989 (9)
[M+H]+, 45 (100).
Boronic ester 20: A three-necked flask was charged with 1-bromo-3-
[(methoxymethoxy)methyl]-5-aminobenzene (18; 3.00 g, 12.2 mmol,
1.00 equiv), [PdACHTUNGTRENNUNG(dppf)Cl2]·CH2Cl2 (797 mg, 0.98 mmol, 8 mol%), bis(pi-
nacolato)diboron (3.41 g, 13.4 mmol, 1.1 equiv), and potassium acetate
(4.18 g, 36.6 mmol, 3.00 equiv). The flask was flushed with argon for
5 min and dry DMF (90 mL) was added with a syringe. After degassing
the mixture with an argon stream for 20 min, the reaction mixture was
stirred at 1008C for 1 h. After the reaction mixture had cooled, it was di-
luted with diethyl ether (150 mL) and washed with brine (50 mL) and
water (50 mL). After drying over MgSO4, removal of the solvent, and
flash column chromatography on a short column of silica gel (hexane/
MOM-CTB 24: A suspension of PbACTHNUTRGNE(UNG OAc)4 (4.86 g, 11 mmol, 6.90 equiv)
in THF (250 mL) was added dropwise to a solution of bisazodiamine 23
(1.57 g, 1.59 mmol, 1.00 equiv) in THF (150 mL) and triethylamine
(2.21 mL, 15.9 mmol, 10.0 equiv) over 20 min. After stirring for an addi-
tional 3 h, ethylenediaminetetraacetate (EDTA; 4.65 g, 15.9 mmol,
10.0 equiv) and water/CH2Cl2 (1:1, 200 mL) was added. After the mixture
had been stirred for 20 min, the organic layer was separated and the
aqueous layer was extracted with CH2Cl2 (4ꢃ50 mL). The combined or-
ganic layers were dried over MgSO4 and the solvent was removed under
reduced pressure. The residue was purified by column chromatography
on neutral alox (hexane/toluene/EtOAc 1:1:2) to yield an orange-red
solid (1.26 g, 80%). M.p. 162–1658C; 1H NMR (400 MHz, CDCl3): d=
8.64 (s; 6H), 8.01 (s; 6H), 7.98 (s; 6H), 4.83 (s, CH2; 12H), 4.82 (s, CH2;
12H), 3.49 ppm (s, CH3; 18H); 13C NMR (101 MHz, CDCl3): d=153.6,
140.4, 140.3, 128.2, 121.8, 121.7, 96.4 (CH2), 69.3 (CH2), 56.0 ppm (CH3);
MS (FAB): m/z (%): 985 (7) [M+H]+, 45 (100); elemental analysis calcd
(%) for C54H60N6O12: C 52.95, H 4.94, N 6.86; found: C 52.98, H 5.03, N
6.83.
1
EtOAc 1:1), 20 was obtained as a pale-brown oil (2.95 g, 83%). H NMR
(400 MHz, CDCl3): d=7.18 (s; 1H), 7.07 (s; 1H), 6.82 (s; 1H), 4.69 (s,
CH2; 2H) 4.52 (s, CH2; 2H), 3.66 (bs, NH2; 2H), 3.41 (s, CH3; 3H),
1.33 ppm (s, CH3; 12H); 13C NMR (101 MHz, CDCl3): d=146.1, 138.4,
124.4, 120.6, 117.4.6, 95.7 (CH2), 83.7 [C
ACHTUNGNERT(UNNG CH3)2] 69.1 (CH2), 55.3 (CH3),
24.9 ppm [C
ACHTUNGTRENNUNG
mental analysis calcd (%) for C15H24BNO4: C 61.45, H 8.25, N 4.78;
found: C 61.03, H 8.66, N 4.58.
5,5’-Bis[(methoxymethoxy)methyl]biphenyl-3,3’-diamine (21):
A three-
necked flask was charged with boronic ester 20 (1.34 g, 4.55 mmol,
1.10 equiv), 1-bromo-3-[(methoxymethoxy)methyl]-5-aminobenzene (18;
1.02 g, 4.14 mmol, 1.00 equiv), and [PdACHTNUTRGEN(UNG PPh3)4] (145 mg, 0.12 mmol,
3 mol%) and flushed with argon. THF (200 mL) and aqueous K2CO3
(2m, 50 mL) were added to the reaction mixture, which was degassed
with an argon stream for 20 min and stirred at 808C overnight. The reac-
tion was allowed to cool, and the organic layer was separated and
washed with water and brine (100 mL). After drying over MgSO4 and re-
moval of the solvent under reduced pressure, the residue was purified by
column chromatography on silica gel (EtOAc/hexane 3:1!5:1) to yield
21 as a yellow oil, which still contained residual EtOAc even after exten-
sive drying under high vacuum (1.15 g, 83%). 1H NMR (400 MHz,
CDCl3): d=6.94 (s; 2H), 6.80 (s; 2H), 6.67 (s; 2H), 4.72 (s, CH2; 4H)
4.55 (s, CH2; 4H), 3.74 (bs, NH2; 4H) 3.42 ppm (s, CH3; 6H); 13C NMR
(101 MHz, CDCl3): d=147.2, 143.0, 139.8, 117.6, 113.9, 113.7, 96.0 (CH2),
69.5 (CH2), 55.8 ppm (CH3); MS (EI, 70EV): m/z (%): 332 (44) [M]+,
272 (100).
Acknowledgements
We thank the Swiss National Science foundation (SNSF) for financial
support. H.A.W. is indebted to the Fonds der Chemischen Industrie for a
Liebig fellowship.
[1] a) Molecular Switches (Ed.: B. L. Feringa), Wiley-VCH, Weinheim,
[2] a) H. Rau in Photochemistry and Photophysics, Vol. 2 (Ed.: J. F.
Rabek), CRC Press, Boca Raton, 1990, pp. 119; b) for specific appli-
cations of azobenzene switches, see references [3–11].
[3] a) V. Balzani, M. Venturi, A. Credi, Molecular Devices and Ma-
chines - A Journey into the Nanoworld, 1st ed., Wiley-VCH, Wein-
Vçgtle, Supramolecular Chemistry: An Introduction, Wiley, Chiches-
ter, 1993; c) H. An, J. S. Bradshaw, R. M. Izatt, Z. Yan, Chem. Rev.
[5] a) H. W. Losensky, H. Spelthann, A. Ehlen, F. Vçgtle, J. Bargon,
27, 1189; b) F. Vçgtle, W. M. Mꢂller, U. Mꢂller, M. Bauer, K. Rissa-
1993, 32, 1295.
Bisazodibromide 22: A solution of 5,5’-bis[(methoxymethoxy)methyl]bi-
phenyl-3,3’-diamine (21; 967 mg, 2.91 mmol, 1.00 equiv) and 1-bromo-3-
[(methoxymethoxy)methyl]-5-nitrosobenzene (19; 1.59 g, 6.11 mmol,
2.10 equiv) in acetic acid (70 mL) was stirred for 19 h at room tempera-
ture. The solvent was removed under reduced pressure and the black res-
idue was purified by flash column chromatography on silica gel (hexane/
EtOAc 3:1!3:2) to yield 22 as a red oil, which crystallized upon standing
at room temperature (1.54 g, 65%). M.p. 868C; 1H NMR (400 MHz,
CDCl3): d=8.19 (s; 2H), 8.03 (s; 2H), 7.96 (s; 2H), 7.92 (s; 2H), 7.84 (s;
2H), 7.65 (s; 2H), 4.81 (s, CH2; 4H), 4.79 (s, CH2; 4H), 4.77 (s, CH2;
4H), 4.69 (s, CH2; 4H), 3.48 (s, CH3; 6H) 3.45 ppm (s, CH3; 6H);
13C NMR (101 MHz, CDCl3): d=153.8, 153.4, 141.8, 141.7, 140.5, 133.1,
129.7, 124.5, 123.6, 122.3, 122.0, 121.6, 96.41 (CH2), 96.39 (CH2), 69.1
(CH2), 68.4 (CH2), 56.0 ppm (CH3); MS (FAB): m/z (%): 817 (18) [M+
H]+, 45 (100); elemental analysis calcd (%) for C36H40Br2N4O8: C 52.95,
H 4.94, N 6.86; found: C 52.98, H 5.03, N 6.83.
Bisazodiamine 23: A three-necked flask was charged with boronic ester
20 (1.19 g, 4.07 mmol, 2.20 equiv), bisazodibromide 22 (1.51 g, 1.85 mmol,
1.00 equiv), and [PdACHTUNGTRENNUNG(PPh3)4] (130 mg, 0.11 mmol, 6 mol%) and flushed
Peters, A. Kuhn, S. Heiles, R. Goddard, M. Bꢂhl, C. M. Thiele, S.
with argon. THF (90 mL) and aqueous K2CO3 (2m, 23 mL) was added to
the reaction mixture, which was degassed with an argon stream for
20 min and stirred at 808C overnight. The reaction mixture was allowed
2994
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Chem. Eur. J. 2011, 17, 2987 – 2995