40
BARBARINI ET AL.
EXPERIMENTAL
Melting points were determined on a MQAPF-301 apparatus without correction.
Boiling points were read by distillation under reduced pressure. IR spectra were
1
recorded on a Perkin–Elmer 1430 or FTIR 1600, H NMR spectra were taken on
Varian Gemini-300 or Bruker AC 300/P spectrometers in CDCl3-TMS.
Aryl N,N-dimethylcarbamates (1b–8b): A General Procedure
A solution of appropriately substituted 5-N,N-dimethylaminophenol 1a–8a (32.5
mmol) in DMF (20 ml) was added dropwise at 0–5ЊC to a slurry of sodium hydride
(36 mmol) stirred under nitrogen in DMF (10 ml). When hydrogen evolution ceased,
N,N-dimethylcarbamyl chloride (41.5 mmol) in DMF (10 ml) was dropped in at
10ЊC. The resulting solution was heated slowly to 110ЊC (ca. 45 min) and maintained
in these conditions for an additional 2 h. The mixture was cooled and then poured
into 1% aqueous potassium hydroxide (100 ml) and extracted with a benzene-
diethyl ether (4 : 1 v/v) mixture (4 ϫ 50 ml). The organic extract was washed with
water (3 ϫ 25 ml), dried (Na2SO4), filtered, condensed, and distilled under low
pressure to yield 1b–7b. Compound 6b required further purification by column
chromatography. The nitroderivative 8b precipitated straight after addition of an
aqueous potassium hydroxide solution. It was collected and rinsed with water.
Yields and some properties of the parent (1b) and of the new compounds (2b–8b)
are given below. NMR data are listed in the Table 1.
3-NЈ,NЈ-dimethylaminophenyl N,N-dimethylcarbamate (1b). Oil, b.p. 175–176ЊC/
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9 mmHg [lit. (9) 195ЊC/20 mmHg]; yield 67%; IR (film), 1720 cmϪ .
CO
2-Methyl-5-NЈ,NЈ-dimethylaminophenyl N,N-dimethylcarbamate (2b). Oil, b.p.
1
140ЊC/1 mmHg; yield 77%; IR (film), 1720 cmϪ .
CO
2-Methoxy-5-NЈ,NЈ-dimethylaminophenyl N,N-dimethylcarbamate (3b). Oil, b.p.
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158–160ЊC/0.75 mmHg; yield 73%; IR (film), 1720 cmϪ .
CO
2-Chloro-5-NЈ,NЈ-dimethylaminophenyl N,N-dimethylcarbamate (4b). Oil, b.p.
1
178ЊC/2 mmHg; yield 83%; IR (film), 1732 cmϪ .
CO
2-Bromo-5-NЈ,NЈ-dimethylaminophenyl N,N-dimethylcarbamate (5b). Oil; b.p.
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161ЊC/1.2 mmHg; yield 65%; IR (film), 1725 cmϪ .
CO
2-Iodo-5-NЈ,NЈ-dimethylaminophenyl N,N-dimethylcarbamate (6b). Oil, yield
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77%; IR (film), 1725 cmϪ .
CO
2-Acetyl-5-NЈ,NЈ-dimethylaminophenyl N,N-dimethylcarbamate (7b). Solid, m.p.
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86–88ЊC; yield 74%: IR (in KBr), 1719 cmϪ .
CO
2-Nitro-5-NЈ,NЈ-dimethylaminophenyl N,N-dimethylcarbamate (8b). Solid, m.p.
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122–123ЊC; yield 58%; IR (in KBr), 1720 cmϪ .
CO
NЈ-(3-NЉ,NЉ-Dimethylaminophenyl)-N,N-dimethylurea (9b)
To a cold (2ЊC) stirred solution of N,N-dimethyl-1,3-phenylenediamine (5.2
mmol) in benzene (10 ml), a solution of N,N-dimethylcarbamyl chloride (6.4 mmol)
in benzene (5 ml) was added all at once. Ten minutes later the temperature was
raised up to 25ЊC and the solution was stirred for 2 h. The resulting mixture was
washed with 5% aqueous potassium hydroxide (3 ϫ 10 ml) and water (3 ϫ 10 ml),