The Journal of Organic Chemistry
Note
3JHH = 8.1 Hz, 1H, CH, Ar), 7.60−7.63 (m, 1H, CH, Ar), 8.11 (br s,
(376 MHz, CDCl3) δ: −74.64 (s, 1F). HRMS: calcd for C9H11FN2O
[M + H]+ 183.0934, found 183.0965.
2
1H, CH, Ar), 8.12−8.16 (m, 1H, CH, Ar); (Z-6f) 1.79 (ddd, JHH
=
=
8.3 Hz, 3JHH = 8.5 Hz, 3JHF = 7.2 Hz, 1H, Hb, CH2), 2.18 (ddd, 2JHH
2-Ethyl-4-fluoro-5,6,7,8-tetrahydroquinazoline 1-Oxide (3b).
1
8.3 Hz, 3JHH = 11.4 Hz, 3JHF3 = 16.7 Hz, 1H, Ha, CH2), 2.93 (ddd, 3JHH
Yield: 0.18 g (46%). Light yellow oil. Rf = 0.3 (CHCl3). H NMR
3
3
(400 MHz, CDCl3) δ: 1.23 (t, JHH = 7.5 Hz, 3H, CH3), 1.68−1.75
= 11.4 Hz, JHH = 8.5 Hz, JHF = 17.2 Hz, 1H, CH), 7.55 (pseudo t,
3JHH = 8.1 Hz, 1H, CH, Ar), 7.58−7.61 (m, 1H, CH, Ar), 8.07 (br s,
(m, 2H, CH2, cy-Hex), 1.81−1.88 (m, 2H, CH2, cy-Hex), 2.61 (br t,
3JHH = 6.2 Hz, 2H, CH2, cy-Hex), 2.85 (br t, 3JHH = 6.4 Hz, 2H, CH2,
1H, CH, Ar), 8.14−8.18 (m, 1H, CH, Ar). 13C NMR (100 MHz,
3
cy-Hex), 2.98 (q, JHH = 7.5 Hz, 2H, CH2, Et). 13C NMR (100 MHz,
CDCl3) δ: (E-6f) 23.1 (JCH = 165 Hz, JCF = 11 Hz, CH2), 32.5 (JCH
=
CDCl3) δ: 9.1 (JCH = 129 Hz, JCH = 5 Hz, CH3), 20.2 (JCH = 130 Hz,
CH2, cy-Hex), 20.7 (JCH=131 Hz, CH2, cy-Hex), 21.0 (JCH=131 Hz,
JCF = 3 Hz, CH2, cy-Hex), 24.9 (JCH = 130 Hz, JCF = 5 Hz, CH2, Et),
25.2 (JCH = 132 Hz, JCF = 3 Hz, CH2, cy-Hex), 115.5 (JCF = 36 Hz, C−
CC), 155.4 (JCF = 248 Hz, CF), 159.0 (JCF = 16 Hz, N−CN),
159.4 (JCF = 7 Hz, C−CN). 19F NMR (376 MHz, CDCl3) δ:
−74.56 (s, 1F). HRMS: calcd for C10H13FN2O [M + H]+ 197.1085,
found 197.1086.
165 Hz, JCF = 11 Hz, CH), 79.3 (JCF 301 Hz, CBrF), 122.4 (JCH = 169
Hz, CH, Ar), 123.2 (JCH = 167 Hz, JCF = 1 Hz, CH, Ar), 129.4 (JCH
=
165 Hz, CH, Ar), 134.5 (JCH = 162 Hz, JCF = 1 Hz, CH, Ar), 135.8
(JCF = 2 Hz, C, Ar), 148.3 (C-NO2, Ar); (Z-6f) 22.3 (JCH = 165 Hz,
JCF = 11 Hz, CH2), 30.0 (JCH = 162, JCF = 12, CH), 84.7 (JCF = 303
Hz, CBrF), 122.5 (JCH = 167 Hz, CH, Ar), 123.4 (JCH = 169 Hz, JCF
=
2 Hz, CH, Ar), 129.4 (JCH = 165 Hz, CH, Ar), 134.9 (JCH = 162 Hz,
JCF = 2 Hz, CH, Ar), 137.7 (C, Ar), 148.3 (C-NO2, Ar). 19F NMR
3
3
2-tert-Butyl-4-fluoro-5,6,7,8-tetrahydroquinazoline 1-Oxide (3c).
Yield: 0.27 g (62%). Light yellow oil. Rf = 0.4 (CHCl3). 1H NMR (400
MHz, CDCl3) δ: 1.49 (s, 9H, 3CH3), 1.73−1.80 (m, 2H, CH2), 1.84−
(376 MHz, CDCl3) δ: (Z-6f) −126.46 (ddd, JHF = 17.2 Hz, JHF
=
16.7 Hz, 3JHF = 7.2 Hz, 1F); (E-6f) −147.16 (ddd, 3JHF = 17.5 Hz, 3JHF
= 9.2 Hz, 3JHF = 2.6 Hz, 1F). MS (EI, 70 eV) m/z: 261 (0.3), 259 (0.3)
[M]+, 181 (3), 180 (24) [M − Br]+. Anal. Calcd for C9H7BrFNO2: C,
41.57; H, 2.71; N, 5.39. Found: C, 41.44; H, 2.75; N, 5.20.
3
1.92 (m, 2H, CH2), 2.65 (br t, JHH = 6.2 Hz, 2H, CH2), 2.88 (br t,
3JHH = 6.5 Hz, 2H, CH2). 13C NMR (100 MHz, CDCl3) δ: 20.2
(CH2), 20.9 (CH2), 21.2 (JCF = 3 Hz, CH2), 25.3 (JCF = 3 Hz, CH2),
26.1 (3CH3), 38.3 (C, t-Bu), 116.0 (JCF = 37 Hz, C−CC), 154.4
(JCF = 246 Hz, CF), 161.0 (JCF = 7 Hz, C−CN), 162.1 (JCF = 16 Hz,
N−CN). 19F NMR (376 MHz, CDCl3) δ: −74.80 (s, 1F). HRMS:
calcd for C12H17FN2O [M + H]+ 225.1398, found 225.1405.
1-(2-Bromo-2-fluorocyclopropyl)-2-fluorobenzene (6g). Yield:
1.64 g (64%), E/Z = 0.6:1. Colorless liquid. Rf = 0.4 (petroleum
1
2
ether). H NMR (400 MHz, C6D6) δ: (E-6g) 1.16 (ddd, JHH = 8.1
Hz, 3JHH = 11.1 Hz, 3JHF = 8.9 Hz, 1H, Ha, CH2), 1.29 (ddd, 2JHH3 = 8.1
Hz, JHH = 8.3 Hz, JHF = 17.5 Hz, 1H, Hb, CH2), 2.47 (ddd, JHH
=
3
3
4-Fluoro-2-phenyl-5,6,7,8-tetrahydroquinazoline 1-Oxide (3d).
3
3
11.1 Hz, JHH = 8.3 Hz, JHF = 1.8 Hz, 1H, CH), 6.60−6.81 (m, 4H,
1
Yield: 0.10 g (20%). Light yellow oil. Rf = 0.2 (CHCl3). H NMR
2
3
3
CH, Ar); (Z-6g) 1.12 (ddd, JHH = 8.0 Hz, JHH = 8.6 Hz, JHF = 7.1
(400 MHz, CDCl3) δ: 1.79−1.85 (m, 2H, CH2), 1.90−1.98 (m, 2H,
Hz, 1H, Hb, CH2), 1.36 (ddd, JHH = 8.0 Hz, JHH = 11.6 Hz, JHF
=
2
3
3
3
3
CH2), 2.73 (br t, JHH = 6.4 Hz, 2H, CH2), 2.98 (br t, JHH = 6.4 Hz,
2H, CH2), 7.44−7.50 (m, 3H, 3CH, Ph), 8.54−8.59 (m, 2H, 2CH,
Ph). 13C NMR (100 MHz, CDCl3) δ: 20.2 (CH2), 20.9 (CH2), 21.4
(JCF = 3 Hz, CH2), 25.5 (JCF = 3 Hz, CH2), 116.7 (JCF = 36 Hz, C−
CC), 128.0 (2CH, Ph), 130.0 (2CH, Ph), 131.0 (C, Ph), 131.3
(CH, Ph), 151.3 (JCF = 17 Hz, N−CN), 155.1 (JCF = 246 Hz, CF),
161.6 (JCF = 7 Hz, C−CN). 19F NMR (376 MHz, CDCl3) δ:
−73.46 (s, 1F). HRMS: calcd for C14H13FN2O [M + H]+ 245.1085,
found 245.1097.
16.6 Hz, 1H, Ha, CH2), 2.47 (ddd, 3JHH = 8.6 Hz, 3JHH = 11.6 Hz, 3JHF
= 17.6 Hz, 1H, CH), 6.48−6.54 (m, 1H, CH, Ar), 6.60−6.81 (m, 3H,
CH, Ar). 13C NMR (100 MHz, CDCl3) δ: (E-6g) 22.0 (JCF = 11 Hz,
JCF = 1 Hz, CH2), 27.1 (JCF = 11 Hz, JCF = 4 Hz, CH), 79.9 (JCF = 301
Hz, JCF = 1 Hz, CBrF), 115.4 (JCF = 22 Hz, CH, Ar), 121.0 (JCF = 15
Hz, JCF = 3 Hz, C, Ar), 124.0 (JCF = 4 Hz, CH, Ar), 129.0 (JCF = 3 Hz,
JCF = 2 Hz, CH, Ar), 129.1 (JCF = 9 Hz, CH, Ar), 162.3 (JCF = 247 Hz,
CF, Ar); (Z-6g) 21.4 (JCF = 11 Hz, JCF = 1 Hz, CH2), 25.2 (JCF = 12
Hz, JCF = 3 Hz, CH), 85.1 (JCF = 302 Hz, JCF = 2 Hz, CBrF), 115.3
(JCF = 22 Hz, CH, Ar), 123.1 (JCF = 15 Hz, JCF = 1 Hz, C, Ar), 123.9
(JCF = 4 Hz, CH, Ar), 129.1 (JCF = 4 Hz, JCF = 4 Hz, CH, Ar), 129.2
(JCF = 8 Hz, CH, Ar), 162.2 (JCF = 248 Hz, CF, Ar). 19F NMR (376
MHz, CDCl3) δ: (Z-6g) −116.21 to −116.31 (m, 1F, Ar), −127.04
(ddd, 3JHF = 7.1 Hz, 3JHF = 16.6 Hz, 3JHF = 17.6 Hz, 1F, cy-Pr); (E-6g)
6-Butyl-4-fluoro-2-methylpyrimidine 1-Oxide (7a). Yield: 0.16 g
(44% for the mixture of 7a and 8a isomers in 3:1 ratio). Light yellow
oil. Rf = 0.3 (CHCl3). 1H NMR (400 MHz, CDCl3) δ: 0.95−1.05 (m,
3H, CH3, Bu), 1.41−1.50 (m, 2H, CH2, Bu), 1.63−1.72 (m, 2H, CH2,
Bu), 2.69 (s, 3H, CH3), 2.91 (t, 3JHH = 7.8 Hz, 2H, CH2, Bu), 6.82 (d,
JHF = 3.8 Hz, 1H, CH). 13C NMR (100 MHz, CDCl3) δ: 13.7 (CH3,
Bu), 20.0 (CH3), 22.3 (CH2), 27.3 (CH2), 30.6 (JCF = 2 Hz, CH2),
104.2 (JCF = 39 Hz, CH), 156.8 (JCF = 250 Hz, CF), 159.1 (JCF = 17
Hz, N−CN), 163.8 (JCF = 8 Hz, C−CN). 19F NMR (376 MHz,
CDCl3) δ: −68.98 (br s, 1F). HRMS: calcd for C9H13FN2O [M + H]+
185.1085, found 185.1092. 5-Butyl-4-fluoro-2-methylpyrimidine 1-
Oxide (8a). 1H NMR (400 MHz, CDCl3) δ: 0.95−1.05 (m, 3H, CH3,
−116.44 to −116.53 (m, 1F, Ar), −145.57 (ddd, 3JHF = 8.9 Hz, 3JHF
=
17.5 Hz, 3JHF = 1.8 Hz, 1F, cy-Pr). MS (EI, 70 eV) m/z: 234 (0.6), 232
(0.6) [M]+, 154 (7), 153 (73) [M − Br]+. Anal. Calcd for C9H7BrF2:
C, 46.38; H, 3.03. Found: C, 46.01; H, 2.96.
General Procedure for Reaction of gem-Dihalogenocyclo-
propanes with NOBF4. NOBF4 (0.28 g, 2.4 mmol) was added to the
solution of gem-dihalogenocyclopropane (2.0 mmol) in 2 mL of the
corresponding nitrile. The reaction mixture was stirred for 5 h at 80 °C
for alkyl-substituted cyclopropanes 1a−c and 6a,b or for 24−72 h at rt
for aryl-substituted cyclopropanes 6d−g. It was then was treated with
an equal amount of water. The organic phase was separated and the
water phase extracted with chloroform (3 × 2 mL). The combined
organic layers were washed with water (3 × 2 mL) and dried over
MgSO4. The solvent was evaporated in vacuo; the residue was purified
by preparative column chromatography on silica gel (for isoxazoles) or
aluminum oxide (for pyrimidine N-oxides), using chloroform as the
eluent.
3
Bu), 1.48−1.62 (m, 4H, 2CH2, Bu), 2.54 (t, JHH = 7.8 Hz, 2H, CH2,
Bu), 2.63 (s, 3H, CH3), 8.32 (d, JHF = 7.8 Hz, 1H, CH). 13C NMR
(100 MHz, CDCl3) δ: 13.8 (CH3, Bu), 19.0 (CH3), 22.6 (CH2), 26.8
(CH2), 30.2 (CH2), 121.5 (JCF = 35 Hz, C−CN), 148.3 (JCF = 6 Hz,
CH), 156.5 (JCF = 17 Hz, N−CN), 156.7 (JCF = 251 Hz, CF). 19F
4
NMR (376 MHz, CDCl3) δ: −72.49 (d, JHF = 7.8 Hz, 1F).
4-Fluoro-6-hexyl-2-methylpyrimidine 1-Oxide (7b). Yield: 0.24 g
(57%). Light yellow oil. Rf = 0.3 (CHCl3). 1H NMR (400 MHz,
CDCl3) δ: 0.82−0.91 (m, 5H, CH2 + CH3), 1.45−1.54 (m, 4H, CH2),
3
1.65−1.75 (m, 2H, 2CH2), 2.70 (s, 3H, CH3), 2.91 (t, JHH = 7.8 Hz,
2H, CH2), 6.82 (3JHF = 4.1 Hz, 1H, CH). 13C NMR (100 MHz,
CDCl3) δ: 14.0 (CH3, Bu), 20.0 (CH3), 22.4 (CH2), 28.9 (CH2), 30.9
(JCF = 3 Hz, CH2), 31.4 (CH2), 31.6 (CH2), 104.1 (JCF = 39 Hz, CH),
157.1 (JCF = 250 Hz, CF), 159.2 (JCF = 17 Hz, N−CN), 164.0 (JCF
4-Fluoro-2-methyl-5,6,7,8-tetrahydroquinazoline 1-Oxide (3a).
1
Yield: 0.17 g (47%). Light yellow oil. Rf = 0.3 (CHCl3). H NMR
(400 MHz, CDCl3) δ: 1.76−1.84 (m, 2H, CH2), 1.88−1.97 (m, 2H,
CH2), 2.68 (s, 3H, CH3), 2.70 (br t, 3JHH = 6.4 Hz, 2H, CH2), 2.94 (br
t, 3JHH = 6.5 Hz, 2H, CH2). 13C NMR (100 MHz, CDCl3) δ: 19.5 (JCH
= 131 Hz, CH3), 20.2 (JCH =131 Hz, CH2), 20.7 (JCH = 131 Hz, CH2),
21.1 (JCH = 131 Hz, JCF = 2 Hz, CH2), 25.2 (JCH = 131 Hz, JCF = 3 Hz,
CH2), 116.0 (JCF = 36 Hz, C−CC), 155.2 (JCF = 248 Hz, CF), 155.4
(JCF = 17 Hz, N−CN), 159.6 (JCF = 7 Hz, C−CN). 19F NMR
= 8 Hz, C−CN). 19F NMR (376 MHz, CDCl3) δ: −69.68 (d, 3JHF
=
4.1 Hz, 1F). HRMS: calcd for C11H17FN2O [M + H]+ 213.1397, found
213.1398. 4-Fluoro-5-hexyl-2-methylpyrimidine 1-Oxide (8b).41 1H
NMR (400 MHz, CDCl3) δ: 0.75−0.90 (m, 5H, CH2 + CH3), 1.47−
1.60 (m, 4H, CH2), 1.60−1.71 (m, 2H, 2CH2), 2.65 (s, 3H, CH3),
2.71 (t, 3JHH = 7.5 Hz, 2H, CH2), 8.37 (d, 2JCH = 8.0 Hz, 1H, CHpyr).
E
dx.doi.org/10.1021/jo301880m | J. Org. Chem. XXXX, XXX, XXX−XXX