Sterically Hindered Carbonyl O-Oxides and Dioxiranes
FULL PAPER
(meta-C), 137.52 (para-C), 143.46 (ortho-C, tert-butyl-CH3), 2.31 (s, 3 H, para-CH3), 3.20 (s, 1 H, OH), 3.48/3.50 (d, 1 H, J ϭ
150.92, 170.60 (COO) ppm. MS (EI, 70 eV): m/z (%) ϭ 296 (0.33) 11.0 Hz), 3.91/3.94 (d, J ϭ 11.0 Hz, 1 H), 6.89 (s, 1 H, aromat.),
[Mϩ], 281 (0.5), 256 (0.5), 203 (100), 161 (12), 145 (5), 133 (8), 119 7.27Ϫ7.34 (m, 5 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ ϭ
(6), 105 (5), 91 (5), 84 (8), 65 (5), 55 (8), 41 (5).
15.62 (meta-CH3), 17.98 (ortho-CH3), 21.14 (para-CH3), 25.96
(ϪCH3), 28.41 (ϪCH3), 33.64 (Cquat.), 70.44 (CH2), 98.20 (semiace-
tal-C), 124.36, 125.81, 127.64, 128.04, 132.48 (ipso-C), 134.82 (or-
tho-C, -CH3), 135.13 (meta-C), 136.92 (para-C), 141.94, 144.81
(ipso-C) ppm. IR (KBr): ν˜ ϭ 3394 (vs, OH), 2952 (s), 2868 (m),
1601 (w), 1449 (s, tert-butyl), 1388 (m), 1356 (m), 1309 (w), 1207
(s), 1172 (s), 1075 (m), 1025 (s), 1000 (m), 978 (m), 964 (m), 896
(m), 867 (m), 832 (m), 758 (s), 699 (s), 619 (m) cmϪ1. MS (EI,
70 eV): m/z (%) ϭ 296 (18) [Mϩ], 279 (8), 265 (15), 250 (7), 235
(8), 219 (100), 201 (20), 189 (5), 173 (6), 161 (14), 143 (5), 118 (8),
105 (30), 77 (22), 65 (4), 51 (5), 43 (7), 28 (7).
(6-tert-Butyl-2,3,4-trimethylphenyl) Phenyl Ketone (3b): 0.134 g of
diazomethane 2b in 60 mL of CCl3F was placed in a cuvette cooled
to Ϫ20 °C. The solution was purged with oxygen and irradiated
with a high-pressure mercury arc lamp. The ketone 3b was isolated
from the reaction mixture by preparative HPLC (RP-18; methanol/
water, 85:15) as a colourless solid. 1H NMR (400 MHz, CDCl3):
δ ϭ 1.21 (s, 9 H, tert-butyl-CH3), 1.90 (s, 3 H, ortho-CH3), 2.14 (s,
3 H, meta-CH3), 2.33 (s, 3 H, para-CH3), 7.19 (s, 1 H, aromat.),
7.40Ϫ7.42 (m), 7.43Ϫ7.53 (m) ppm. 13C NMR (100.6 MHz,
CDCl3): δ ϭ 15.17 (meta-CH3), 17.56 (ortho-CH3), 21.16 (para-
CH3), 32.53 (tert-butyl-CH3), 35.94 (tert-butyl-Cquat.), 126.50,
128.58, 132.49 (ortho-C, -CH3), 133.00 (meta-C), 136.00 (ipso-C),
136.49 (para-C), 144.24 (ortho-C, tert-butyl-CH3), 202.39 (CO)
ppm. MS: m/z ϭ 280 [Mϩ], 265, 250, 203, 128, 115, 105, 77, 51.
1,1,4,5,6-Pentamethyl-3-phenylindan: Yellow oil. 1H NMR
(400 MHz, CDCl3): δ ϭ 1.23 (s, 3 H, -CH3), 1.24 (s, 3 H, -CH3),
1.83 (s, 3 H, ortho-CH3), 1.87Ϫ1.92 (dd, 1 H, J ϭ 6.02, J ϭ
8.53 Hz), 2.13 (s, 3 H, meta-CH3), 2.33 (s, 3 H, para-CH3),
2.47Ϫ2.50 (dd, 1 H, J ϭ 9.03, J ϭ 13.06 Hz), 4.42Ϫ4.46 (dd, 1 H,
J ϭ 6.03, J ϭ 12.8 Hz), 6.89 (s, 1 H, aromat.), 7.05Ϫ7.08 (m, 2 H),
7.13- 7.17 (m, 1 H), 7.21Ϫ7.26 (2 H) ppm. 13C NMR (100.6 MHz,
CDCl3): δ ϭ 15.28 (meta-CH3), 16.89 (ortho-CH3), 21.18 (para-
CH3), 30.04 (ϪCH3), 30.35 (ϪCH3), 43.36, 48.81 (ϪCH), 52.55
(ϪCH2), 121.09, 125.59, 127.72, 128.29, 133.35 (meta-C), 133.55
(ortho-C, -CH3), 135.71 (para-C), 140.20 (ipso-C), 147.26 (ipso-C),
150.51 ppm. MS: m/z ϭ 264 [Mϩ], 249, 234, 219, 201, 171, 156,
141, 129, 115, 91, 78, 51.
Synthesis of Carbonyl Oxide 1b in Solution or in an Organic Glass:
A solution of 3 mg of 6b in 6 mL of CFCl3/CF2BrCF2Br (1:1) was
purged with oxygen for 15 min and cooled to 185 K for solution
experiments in the Oxford cryostat or to 78 K to form an organic
glass. The carbonyl oxide 1b was generated by irradiation of the
solution or glass with a high-pressure mercury arc lamp in combi-
nation with cut-off filters (λ Ͼ 515 nm or 495 nm). The formation
and thermal decay of 1b was monitored by UV/Vis spectroscopy.
Synthesis of Dioxirane 2b in Solution: For the small-scale synthesis
of dioxirane 2b a solution of 6b in CFCl3/CF2BrCF2Br (1:1) was
purged with oxygen and irradiated with λ Ͼ 495 nm at Ϫ60 °C.
The reaction was monitored by analytical HPLC (RP-18, meth-
anol). For the preparative-scale synthesis of 2b a specially designed
photoreactor with a 150-W Hg/Cd medium-pressure arc lamp
(Heraeus-Nobelight TQ 150 Z3) was used (Figure 4). The filtering
solution with 50% transmission at 435 nm contained 43.88 g of
CuCl2 ϫ 2 H2O, 600 mL of water and 115 mL of concentrated
aqueous HCl. The flask was filled with 300 mL of CFCl3 and
purged with O2 for 10 min. The photolysis was performed at Ϫ78
°C under O2 purging. To prevent the reaction of carbonyl oxide 1b
with excess of the diazo compound 6b to give ketone 3b, a solution
of 100Ϫ150 mg of 6b in 20 mL CCl3F was added in small portions
during the photolysis. The reaction was monitored by analytical
HPLC (RP-18, methanol). After the consumption of 6b, the solvent
was evaporated in vacuo at low temperature (Ϫ50 to Ϫ20 °C).
Acknowledgments
This work was financially supported by the Deutsche Forschungs-
gemeinschaft and the Fonds der Chemischen Industrie.
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