UPDATES
Lossen Rearrangements under Heck Reaction Conditions
1-Butyl-3-(para-toluyl)urea (18b) (R=p-toluyl): White
crystals; yield: 330 mg (49%); Rf =0.4 (methanol/chloro-
form, 2%); mp 120–1218C (reported: mp 1198C);[35]
1H NMR (300 MHz, CDCl3): d=7.93 (bs, 1H), 7.16 (d, 2H,
J=8.60 Hz), 6.99 (d, 2H, J=8.0 Hz), 6.01 (bs, 1H), 3.19–
3.08 (m, 2H), 2.24 (s, 3H), 1.55–1.31 (m, 2H), 1.33–1.15 (m,
2H), 0.85 (t, 3H, J=7.2 Hz); 13C NMR (75 MHz, CDCl3):
d=157.10, 136.83, 131.94, 129.34, 120.04, 39.81, 32.33, 20.70,
20.08, 13.80; ESI-MS: m/z=207.14 (M+ +1).
(1-Butyl-3-cyclohexylurea) (18c) (R=cyclohexyl): White
crystals; yield: 394 mg (94%); recrystallized from ethyl ace-
tate/n-hexane; Rf =0.3 (methanol/chloroform, 5%); mp 100–
1028C (reported: mp 105);[36] 1H NMR (300 MHz, CDCl3):
d=5.76 (bs, 1H), 3.35 (bs, 1H), 3.20–2.96 (m, 2H), 1.83–
0.72 (m, 18H); 13C NMR (75 MHz, CDCl3): d=158.82,
48.39, 39.70, 33.82, 32.50, 25.56, 24.91, 19.98, 13.63; ESI-MS:
m/z=199.3 (M+ +1).
(1-Butyl-3-pentylurea (18d) (R=pentyl): Off white solid;
yield: 222 mg (52%); Rf =0.5 (methanol/chloroform, 3%);
mp: 30–328C (reported: 32–318C);[37] 1H NMR (300 MHz,
CDCl3): d=5.83 (bs, 1H), 3.39 (bs, 1H), 3.28–2.96 (m, 1H),
1.86–0.74 (m, 18H); 13C NMR (75 MHz, CDCl3): d=158.84,
48.44, 39.75, 33.84, 32.52, 29.65, 25.59, 24.94, 20.01, 13.66;
ESI-MS: m/z=187.2 (M+ +1), 173 (M+ÀCH3).
Physical Properties and Spectroscopic Data of the
Symmetrical Ureas (10c–f)
1,3-Cyclohexylurea (10c) (R=cyclohexyl): After cooling the
sealed tube, white needles that had settled were filtered and
washed with acetonitrile then n-hexane to afford the prod-
uct; yield: 101 mg (67%); mp 229–2308C (reported: mp
229–2318C);[30] 1H NMR (300 MHz, DMSO, 908C): d=5.42
(br, 2H), 3.38–3.36 (m, 2H), 1.77–1.72 (m, 4H), 1.65–1.61
(m, 4H), 1.53–1.43 (m, 2H), 1.31–1.23 (m, 10H); 13C NMR
(75 MHz, DMSO, 908C,): d=156.66, 47.45, 32.94, 25.04,
24.02. ESI-MS: m/z=225 (M+ +1).
1,3-Dipentylurea (10d) [R=CH3ACTHNUTRGNEUNG(CH2)4]: White needles;
recrystallized from n-hexane; yield: 93 mg (62%), mp 808C
(reported: mp 888C);[31] 1H NMR (300 MHz, CDCl3): d=
5.04 (bs, 2H), 3.16–3.10 (m, 4H), 1.52–1.34 (m, 4H), 1.33–
1.27 (m, 8H), 0.93–0.87 (t, J=6.61 Hz, 6H); 13C NMR
(75 MHz, CDCl3): d=159.22, 40.33, 30.06, 29.11, 22.40,
13.93; ESI-MS: m/z=201 (M+ +1), 187 (M+ÀCH3).
1,3-Diundecylurea (10e) [R=CH3 ACHTNUGTRNE(UNG CH2)10]: White crystal-
line solid; recrystallized from acetone, yield: 74 mg (49%),
mp 130–1328C (reported: mp 131–1328C);[32] 1H NMR
(300 MHz, CDCl3): d=3.58 (s, 2H), 2.26 (t, J=7.47 Hz,
4H), 1.60–1.51 (m, 4H), 1.29–1.19 (m, 32H), 0.83–0.76 (t,
J=6.61 Hz, 6H); 13C NMR (75 MHz, CDCl3): d=180.37,
51.33, 34.09, 31.88, 29.57, 29.41, 29.30, 29.22, 29.04, 24.65,
22.63, 13.99; ESI-MS: m/z=271.3 (M+ÀC7H15), 243.2
(M+ÀC9H19), 200.2 (M+ÀC11H23NH).
Preparation of N-[(Phenylcarbamoyl)oxy]benzamide
(17)
1,3-Di(pyridin-4-yl)urea (10f) (R=4-pyridyl]: Colourless
needles; recrystallized from acetone; yield: 96 mg (64%);
Rf =0.4 (methanol/chloroform, 5%); mp: 202–2038C (re-
ported: mp 2008C);[33] 1H NMR (300 MHz, DMSO): d=8.22
(bs, 2H), 8.09 (d, J=6.94 Hz, 4H), 6.85 (d, J=6.97 Hz, 4H);
13C NMR (75 MHz, DMSO): d=159.51, 149.99, 139.80,
108.59; ESI-MS: m/z=215 (M+ +1).
A solution of 8a (1.4 g, 10 mmol) and phenyl isocyanate
(1.2 g, 10 mmol) in dichloromethane (1 mL) and THF
(1 mL) was heated on a water-bath for 1 h. After cooling
and adding n-hexane, crude product was obtained.[21] Re-
crystallization from ethyl acetate afforded 17 as short white
needles; yield: 1.7 g (65%); Rf =0.7 (methanol/chloroform,
5%); mp 1808C (reported: mp 181–1828C);[39] 1H NMR
(300 MHz, DMSO): d=12.42 (s, 1H), 10.41 (s, 1H), 7.91 (d,
2H, J=7.51 Hz), 7.58–7.53 (m, 5H), 7.34 (t, 2H, J=
7.79 Hz), 7.08 (t, 2H, J=7.49 Hz); 13C NMR (75 MHz,
DMSO): d=165.09, 152.36, 138.23, 132.22, 131.13, 128.97,
128.61, 127.36, 123.19, 118.41.
General Procedures for the Reaction of Aromatic
and Aliphatic Hydroxamic Acids with n-Butylamine
TEA (0.06 g, 0.09 mL, 0.645 mmol) was added to a solution
of the hydroxamic acid (5 mmol), and n-butylamine
(25 mmol) in acetonitrile (15 mL), the mixture was then
heated with stirring in a capped sealed glass tube at 908C
for 24 h. After cooling, the solvent was removed under re-
duced pressure; the residue was dissolved in chloroform
(30 mL) and washed with water (3ꢁ15 mL) and brine. The
organic layer was dried with anhydrous sodium sulfate, fil-
tered and evaporated under reduced pressure to give a resi-
due that was further purified by flash chromatography.
Preparation of N-(Benzoyloxy)benzamide (16):[22]
A solution of 8a (500 mg, 3.65 mmol, 1 equiv.) and potassi-
um tert-butoxide (409 mg, 3.65 mmol, 1 equiv.) was stirred at
room temperature in diethyl ether (30 mL) for 30 min. Ben-
zoyl chloride (513 mg, 3.65 mmol, 1 equiv.) was added drop-
wise and the reaction mixture stirred at room temperature
for 16 h, diluted with ethyl acetate and washed with water
and NaHCO3. The collected organic phases were dried with
anhydrous MgSO4 and evaporated under reduced pressure
to afford the desired product as a white solid; yield: 759 mg
(86%); mp 157–1588C (reported: mp 154–1578C);[40]
1H NMR (300 MHz, DMSO): d=12.67 (bs, 1H), 8.16–8.09
(m, 2H), 7.92–7.89 (m, 2H), 7.79–7.71 (t, J=7.5 Hz, 1H),
7.64–7.53 (m, 5H); 13C NMR (75 MHz, DMSO,): d=164.87,
164.37, 134.35, 132.34, 130.95, 129.48, 129.13, 128.68, 127.40,
126.88; ESI-MS: m/z=242 (M+ +1).
Physical Properties and Spectroscopic Data of the
Unsymmetrical Ureas (18a–d)
1-Butyl-3-phenylurea (18a) (R=phenyl): White crystal;
yield: 830 mg (85%); Rf =0.6 (methanol/chloroform, 5%);
mp 128–1308C (reported: mp 131–1338C);[34] 1H NMR
(300 MHz, DMSO): d=8.41 (bs, 1H), 7.39 (d, J=7.99 Hz,
2H), 7.20 (t, J=7.73 Hz, 2H), 6.87 (t, J=7.34 Hz, 1H), 6.14
(bs, 1H), 3.08 (d, J=6.22 Hz, 2H), 1.41–1.29 (m, 4H), 0.89
(t, J=7.16 Hz, 3H); 13C NMR (75 MHz, DMSO): d=155.28,
140.48, 128.48, 120.87, 117.60, 79.06, 31.86, 19.49, 13.57; ESI-
MS: m/z=193 (M+ +1).
Preparation of Methyl Phenyl Carbamate (19a)[23]
A 100-mL, round-bottomed flask equipped with a magnetic
stir bar was charged with anhydrous methanol (40 mL).
Adv. Synth. Catal. 2014, 356, 3456 – 3464
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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