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M. A. Garcia-Garibay et al. / Tetrahedron 56 (2000) 6729±6737
1
Differential scanning calorimetry was performed on a Ther-
mal Instruments DSC 2910.
diazopropane 1b. H NMR (360 MHz) d: 1.57 (3H, d,
J7.1 Hz, CH3), 3.99 (1H, q, J7.1 Hz, CH), 7.39 (10H,
m, ArH), 7.60 (4H, m, ArH); 13C NMR (90 MHz) d: 20.9
(CH3), 34.7 (CH), 61.2 (CN2), 122.2, 126.6, 126.8, 126.9,
127.6, 128.7, 128.8, 130.1, 136.2, 140.5, 144.1 (Ar); FTIR
(KBr Pellet) cm21: 3081, 3066, 3029, 2971, 2939, 2874,
2033 (CvN2), 1683, 1604, 1557, 1518, 1487, 1455. 1,2-
Synthesis of diazo compounds
The synthesis of diazo compounds 1a and 1d has been
reported before.17 Compounds 1b and 1c were synthesized
in a similar manner according to the sequence of reactions in
Scheme 5.
1
Bis(40-biphenylyl)diazopropane 1c. H NMR (360 MHz)
d: 1.58 (3H, d, J7.1 Hz, CH3), 4.04 (1H, q, J7.1 Hz,
CH), 6.99 (2H, d, J8.6 Hz, Ar-H), 7.25±7.65 (16H, m,
Ar-H); 13C NMR (90 MHz) d: 20.8 (CH3), 34.4 (CH),
61.5 (CN2), 122.2, 126.6, 127.0, 127.2, 127.3, 127.6,
128.7, 130.2, 136.3, 139.8, 140,5, 140.7, 143.2 (Ar); FTIR
(KBr Pellet) cm21: 2035 cm21 (CN2).
Ketones 6b and 6c. Prepared by conventional Friedel±
Crafts procedures as reported before in the synthesis of 1a
from biphenylacetyl chloride and benzene (6b), or biphenyl-
acetyl chloride and biphenyl (6d). 2-(40-Biphenylyl)-1-
1
phenylethanone 6b. H NMR (360 MHz) d: 4.31 (2H, s),
7.30±7.57 (12H, m, ArH), 8.02±8.04 (2H, m, ArH); 13C
NMR (90 MHz) d: 45.0 (CH2), 127.0, 127.2, 127.4, 128.6,
128.7, 129.9, 133.2, 133.5, 136,5, 139.8, 140.8 (Ar), 197.5
(CvO); FTIR (KBr Pellet) cm21: 3057, 3052, 2909, 1684,
1596, 1579, 1566, 1488, 1409, 1333, 1226, 1210. 1,2-
Solution photolysis
Approximately 1 mg of 1 was dissolved in 1 mL of solvent.
The solution was placed in an NMR tube and Ar gas was
bubbled through the solution for 20 min to deoxygenate the
sample. Photolysis was carried out in an ice bath (08C) with
a 410 nm cutoff ®lter. Samples were irradiated for 30 min
after which the characteristic red color of 1 had disappeared.
Upon completion of photolysis, dimethyl acetylenedicar-
boxylate (DMAD) was added to react with any remaining
1. GC analysis revealed the composition of the product
mixture and the results are shown in Table 2.
1
Bis(40-biphenylyl)ethanone 6c. H NMR (360 MHz) d:
4.31 (2H, s), 7.23±7.48 (8H, m, ArH), 7.59±7.78 (8H, m,
ArH), 8.07±8.19 (2H, m, ArH); 13C NMR (90 MHz) d: 45.5
(CH2), 126.9, 127.2, 128.2, 128.7, 128.9, 129.2, 129.4,
134.6, 135.2, 139.8, 145.8 (Ar), 197.2 (CvO); FTIR (KBr
Pellet) cm21: 3089, 3059, 3037, 3029, 2901, 1681, 1603,
1498, 1486, 1453.
Ketones 7b and 7c. Prepared by conventional alkylation
procedures as reported before using NaH and MeI. 2-(40-
Biphenylyl)-1-phenylpropanone 7b. H NMR (360 MHz)
Microscale solid state photolysis
1
Samples of 20 mg of 1 were ground into ®ne powders and
mixed with 5 mg of ground crystals of triphenyl methanol
which served as a standard to determine extent of conver-
sion. Powdered samples were placed between two micro-
scope slides in a polyethylene bag immersed in an ice bath
(08C). Photolyses were performed with a 410 nm cutoff
®lter. Approximately 1 mg of the irradiated sample was
removed for analysis every 15±60 min. The removed
portions were dissolved in diethyl ether, DMAD was
added, and the resulting solutions analyzed by GC (Table
3). Microscale photolysis were also carried out with
amorphous solid samples. Samples were prepared by
melting 5 mg of crystalline 1 followed by fast cooling
under liquid N2. The glassy material thus obtained was sand-
wiched between two microscope slides, irradiated for about
3 h in an ice bath (08C) with the 410 nm ®lter, and analyzed.
d: 1.55 (3H, d, J6.8 Hz, CH3), 4.71 (1H, q, J6.8 Hz,
CH), 7.20±7.45 (8H, m, ArH), 7.55±7.60 (4H, m, ArH),
8.01±8.04 (2H, m, ArH); 13C NMR (90 MHz) d: 19.5
(CH3), 47.9 (CH), 126.9, 127.1, 127.2, 127.7, 128.1,128.9,
129.0, 129.3, 135.1, 139.8, 141.5, 145.4 (Ar), 199.8 (CvO);
FTIR (KBr Pellet) cm21: 3084, 3067, 3027, 2982, 2975,
2932, 2673, 1605, 1497, 1453. 1,2-Bis(40-biphenylyl)pro-
panone 7c. 1H NMR (360 MHz) d: 1.63 (3H, d, J6.8 Hz,
CH3), 4.80 (1H, q, J6.8 Hz, CH), 7.30±7.62 (14H, m,
ArH), 7.64 (2H, d, J8.3, ArH), 8.10 (2H, d, J8.3,
ArH); 13C NMR (90 MHz) d: 19.6 (CH3), 47.6 (CH),
127.0, 127.2, 127.3, 127.3, 127.8, 128.3, 128.8, 129,
129.5, 135.2, 139.9, 140.6, 140.7, 145.5 (Ar), 199.9 (CO).
Hydrazones 8b and 8c. Prepared by re¯uxing ketones 7b
and 7c with a 10 M excess of anhydrous hydrazine in
ethanol as reported before. 2-(40-Biphenylyl)-1-phenylpro-
panone hydrazone 8b. 1H NMR (360 MHz) d: 1.51 (3H, d,
J7.1 Hz, CH3), 3.92 (1H, q, J7.1 Hz, CH), 5.10 (2H, s,
NH2), 6.96±7.00 (2H, m, ArH), 7.17±7.54 (12H, m, ArH);
13C NMR (90 MHz) d: 19.0 (CH3), 47.5 (CH2), 126.4,
126.9, 127.4, 127.5, 127.9, 128.2, 128.8, 132,9, 140.2,
141.10, 143.1 (Ar), 154.3 (CvN); FTIR (KBr Pellet)
cm21: 3372 (N±H), 3268 (N±H), 3025, 2974, 2928, 2884,
1599, 1484, 1452. 1,2-Bis(40-biphenylyl)propanone hydra-
Medium scale solid state photolysis
Samples of 50±100 mg of 1a±1d were ground into a ®ne
powder. This powder was placed on a watch glass and
covered with a 410 nm ®lter. At varying time intervals
(60 min) irradiation was stopped and the sample removed
for DSC (5 mg), solid state FT-IR (1 mg) and GC (1 mg)
analysis.
1
zone 8c. H NMR (360 MHz) d: 1.55 (3H, d, J7.1 Hz,
CH3), 3.98 (1H, q, J7.1 Hz, CH), 5.1 (br, 24), 7.03 (d,
2H, J8.2 Hz, Ar-H), 7.25±7.60 (16H, m, Ar-H).
Acknowledgements
Diazo Compounds 1b and 1c. Diazo compounds were
prepared from the appropriate hydrazone by yellow HgO
oxidation as reported before. 2-(40-Biphenylyl)-1-phenyl-
Financial support by the National Science Foundation
through grants CHE-9619344 and CHE-9624950) is grate-
fully acknowledged.