Abstract
A simple one-pot palladium-catalyzed reaction for the conversion of aryl halides to aryl amines using urea as an ammonia equivalent is reported. Arylation of urea in the presence of Pd2 dba3 , t -Bu3 P·HBF4 and t -BuOK in dioxane gives di- and triarylamines in 65-95% yields.
Key words
palladium - arylations - amines - ammonia equivalents - urea
References and Notes
1a Hartwig JF.
Synlett
1997,
329
1b Hartwig JF.
Angew. Chem. Int. Ed.
1998,
37:
2046
1c Wolfe JP.
Wagaw S.
Marcoux J.-F.
Buchwald SL.
Acc. Chem. Res.
1998,
31:
805
1d Yang B.
Buchwald SL.
J. Organomet. Chem.
1999,
576:
125
1e Belfield AJ.
Brown GR.
Foubister AJ.
Tetrahedron
1999,
55:
11399
1f Hartwig JF.
Pure Appl. Chem.
1999,
71:
1417
1g Muci AR.
Buchwald SL.
Top. Curr. Chem.
2002,
219:
131
1h Prim D.
Campagne J.
Joseph D.
Andrioletti B.
Tetrahedron
2002,
58:
2041
1i Hartwig JF. In Handbook of Organopalladium Chemistry for Organic Synthesis
Vol. 2:
Negishi E.
Wiley-Interscience;
New York:
2002.
p.1051
2 Huang X.
Buchwald SL.
Org. Lett.
2001,
3:
3417
3a Artamkina GA.
Sergeev AG.
Beletskaya IP.
Tetrahedron Lett.
2001,
42:
4381
3b Artamkina GA.
Sergeev AG.
Beletskaya IP.
Zh. Org. Khim.
2002,
38:
563
4a Sergeev AG.
Artamkina GA.
Beletskaya IP.
Tetrahedron Lett.
2003,
44:
4719
4b Sergeev AG.
Artamkina GA.
Beletskaya IP.
Zh. Org. Khim.
2003,
39:
1814
5a Wolfe JP.
Buchwald SL.
Angew. Chem. Int. Ed.
1999,
38:
2413
5b Wolfe JP.
Tomori H.
Sadighi JP.
Yin J.
Buchwald SL.
J. Org. Chem.
2000,
65:
1158
6a Hartwig JF.
Kawatsura M.
Hauck SI.
Shaughnessy KH.
Alcazar-Roman LM.
J. Org. Chem.
1999,
64:
5575
6b Stauffer SR.
Hartwig JF.
J. Am. Chem. Soc.
2003,
125:
6977
6c Stambuli JP.
Kuwano R.
Hartwig JF.
Angew. Chem. Int. Ed.
2002,
41:
4746
6d Strieter ER.
Blackmond DG.
Buchwald SL.
J. Am. Chem. Soc.
2003,
125:
13978
7
Representative Procedure for Tri(
m
-tolyl)amine.
m -Bromotoluene (282 mg, 1.65 mmol), urea (31 mg, 0.51 mmol), Pd2 dba3 ·CHCl3 (31.5 mg, 0.03 mmol), t -Bu3 P·HBF4 (25.2 mg, 0.087 mmol), t -BuOK (325 mg, 2.9 mmol), and anhydrous dioxane (6 mL) purged with argon were placed into an argon-filled reactor. The reaction was carried out with stirring at 100 °C under positive argon pressure. After the aryl halide was completely consumed (according to GC), the reaction mixture was cooled to r.t., diluted with EtOAc (30 mL), filtered through the short plug of Celite® and evaporated on silica gel. The residue was chromatographed on silica gel (Merck 60, 40-63 µm), eluting with light PE, then EtOAc-light PE mixture 1:40 and 1:20 at the end to give 122 mg (85%) of the product as a white solid. Mp 66 °C (ref. 2: 64-65 °C). 1 H NMR (400 MHz, acetone-d
6 ): δ = 7.14 (t, 3 H, 7.7 Hz), 6.77-6.87 (m, 9 H), 2.23 (s, 9 H). MS (EI, 70 eV): m/z (%) = 287 (100) [M+ ], 271 (2) [M - CH3 - H+ ], 257 (4) [M+ - 2 CH3 ], 180 (5) [C13 H10 N+ ].
8 Netherton MR.
Fu GC.
Org. Lett.
2001,
3:
4295
9 Harris MC.
Buchwald SL.
J. Org. Chem.
2000,
65:
5327
10 Sachinvala N.
Winsor DL.
Maskos K.
Hamed GO.
Vigo TL.
Bertoniere NR.
J. Org. Chem.
2000,
65:
9234
