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WAGGONER ET AL.
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peroxide (0.903 g, 6.2 mmol) in a quartz reaction vessel,
and the resultant solution was deoxygenated using a thin
stream of bubbling argon for 25 min. The solution was
irradiated under ten 300 nm lamps in a Luzchem ORG-
10 photoreactor until the orange color of TEMPO dissi-
pated (7 h). The reaction mixture was filtered through a
short silica plug, and the solvent removed in vacuo.
Radial chromatography of the residue (hexane—10%
EtOAc/hexane gradient) yielded 281 mg (81%) of the
isolated as a colorless oil (301 mg, 86% yield). H NMR
(CDCl3, 400 MHz) δ = 7.23 (dd, J = 6.8, 7.2 Hz, 1H), 7.17
(overlapping s & d, 2H), 7.09 (d, J = 7.2 Hz, 1H), 4.79
(s, 2H), 2.36 (s, 3H), 1.22–1.60 (overlap. mult, 6H), 1.26
(s, 6H), 1.15 (s, 6H) ppm; (d6-DMSO, 400 MHz) δ = 7.19
(dd, J = 7.6, 8.0 Hz, 1H), 7.08 (mult, 3H), 4.67 (s, 2H),
2.26 (s, 3H), 1.22–1.60 (overlap. mult, 6H), 1.17 (s, 6H),
1.04 (s, 6H) ppm. 13C NMR (CDCl3, 100 MHz) δ = 138.3,
137.9, 128.4, 128.2, 128.2, 124.7, 78.9, 60.1, 39.8, 33.2,
21.6, 20.4, 17.2 ppm; (d6-DMSO, 100 MHz) δ = 138.1,
137.9, 128.7, 128.6 (coalesc. 2 peaks), 125.1, 78.9, 59.9,
39.7, 33.3, 21.6, 20.5, 17.2 ppm. FTIR (CDCl3 solution)
1
desired product as a colorless-pale yellow oil. H NMR
(CDCl3, 400 MHz) δ = 7.25–7.39 (mult, 5H), 4.83 (s, 2H),
1.30–1.65 (mult, 6H), 1.26 (s, 6H), 1.15 (s, 6H) ppm; (d6-
DMSO, 400 MHz) δ = 7.26–7.39 (mult, 5H), 4.75 (s, 2H),
1.26–1.62 (mult, 6H), 1.21 (s, 6H), 1.08 (s, 6H) ppm. 13C
NMR (CDCl3, 100 MHz) δ = 138.4, 128.3, 127.6, 127.4,
78.1, 60.1, 39.8, 33.2, 20.4, 17.2 ppm; (d6-DMSO,
100 MHz) δ = 138.3, 128.8, 128.0 (2 coalesc. peaks), 78.6,
60.0, 39.7, 33.3, 20.5, 17.1 ppm. FTIR (CDCl3 solution)
ν = 3089, 3066, 3032, 3006, 2978, 2933, 2873, 1496, 1469,
ν = 3006, 2978, 2933, 2873, 1608, 1483, 1469, 1452 cmꢂ1
HRMS (ESI-TOF) m/z: [M + H]+ = Calcd for
.
C17H27NOH 262.2165; Found: 262.2172.
2.6 | 1-(4-methylbenzyloxy)-
2,2,6,6-tetramethylpiperidine (14)
1452 cmꢂ1 [42]
.
This species was prepared from TEMPO (209 mg,
1.34 mmol) in the same manner as described for 8, with
substitution of p-xylene for toluene as solvent. The
desired product was obtained (235 mg, 67% yield) as a
colorless-pale yellow oil. 1H NMR (CDCl3, 400 MHz)
δ = 7.26 (d, J = 8.0 Hz, 2H), 7.15 (d, J = 8.0 Hz, 2H), 4.78
(s, 2H), 2.35 (s, 3H), 1.30–1.65 (mult, 6H), 1.26 (s, 6H),
1.14 (s, 6H) ppm; (d6-DMSO, 400 MHz) δ = 7.18 (d,
J = 8.0 Hz, 2H), 7.11 (d, J = 8.0 Hz, 2H), 4.65 (s, 2H),
2.25 (s, 3H), 1.20–1.60 (mult, 6H), 1.16 (s, 6H), 1.02 (s,
6H) ppm. 13C NMR (CDCl3, 100 MHz) δ = 137.1, 135.3,
129.0, 127.8, 78.7, 60.1, 39.8, 33.2, 21.3, 20.4, 17.2 ppm.
(d6-DMSO, 100 MHz) δ = 137.2, 135.2, 129.4, 128.2, 78.8,
59.9, 39.7, 33.3, 21.3, 20.5, 17.1 ppm. FTIR (CDCl3 solu-
tion) ν = 3051, 3006, 2978, 2933, 2871, 1516, 1471, 1469,
1452 cmꢂ1. HRMS (ESI-TOF) m/z: [M + H]+ = Calcd
for C17H27NOH 262.2165; Found: 262.2146.
2.4 | 1-(2-methylbenzyloxy)-
2,2,6,6-tetramethylpiperidine (10)
This species was prepared from TEMPO (210 mg,
1.34 mmol) in the same manner as described for 8, with
substitution of o-xylene for toluene as solvent, and irradi-
ation for only 4.5 h. The desired product was obtained
(207 mg, 59 % yield) as a white crystalline solid, melting
1
range 44ꢀC–47ꢀC. H NMR (CDCl3, 400 MHz) δ = 7.46
(mult, 1H), 7.12–7.23 (mult, 3H), 4.84 (s, 2H), 2.33
(s, 3H), 1.30–1.65 (overlapping mults, 6H), 1.27 (s, 6H),
1.17 (s, 6H) ppm; (d6-DMSO, 400 MHz) δ = 7.29 (mult,
1 H), 7.14–7.15 (overlapping bands, 3H), 4.71 (s, 2H), 2.25
(s, 3H), 1.22–1.60 (overlap. mult, 6H), 1.17 (s, 6H), 1.03
(s, 6H) ppm. 13C NMR (CDCl3, 100 MHz) δ = 136.8,
135.8, 130.0, 127.9, 127.2, 125.8, 76.9, 60.1, 39.9, 33.2,
20.4, 19.4, 17.3 ppm; (d6-DMSO, 100 MHz) δ = 136.6,
136.3, 130.4, 128.5, 127.9, 126.3, 77.2, 59.9, 39.8, 33.3,
20.5, 19.4, 17.2 ppm. FTIR (CDCl3 solution) ν = 3068,
2.7 | 1-(3,5-dimethylbenzyloxy)-
2,2,6,6-tetramethylpiperidine (16)
3006, 2978, 2933, 2871, 1493, 1469 cmꢂ1
. HRMS
(ESI-TOF) m/z: [M + H]+ = Calcd for C17H27NOH
262.2165; Found: 262.2191 (calc.)
This species was prepared from TEMPO (226 mg,
1.44 mmol) in the same manner as described for 8, with
substitution of mesitylene (1,3,5-trimethylbenzene) for
toluene as solvent, and irradiation for only 4 h. The
desired compound was isolated as a crystalline solid
(351 mg, 88% yield, melting range = 71ꢀC–74ꢀC). 1H
NMR (CDCl3, 400 MHz) δ = 6.97 (s, 2H), 6.92 (s, 1H),
4.74 (s, 2H), 2.32 (s, 6H), 1.30–1.65 (overlapping mults,
6H), 1.26 (s, 6H), 1.15 (s, 6H) ppm; (d6-DMSO, 400 MHz)
δ = 6.88 (coalesc. 2 ꢁ s, 3H), 4.62 (s, 2H), 2.22 (s, 6H),
1.22–1.60 (overlap. mult, 6H), 1.17 (s, 6H), 1.04 (s, 6H)
2.5 | 1-(3-methylbenzyloxy)-
2,2,6,6-tetramethylpiperidine (12)
This species was prepared from TEMPO (210 mg,
1.34 mmol) in the same manner as described for 8, with
substitution of m-xylene for toluene as solvent, and irra-
diation for only 3.5 h. The desired compound was