Abstract
A copper-catalyzed N-N bond-forming reaction was performed
by a dehydrogenative homocoupling of N -alkylanilines, affording N ,N ′-dialkyl-N ,N ′-diphenylhydrazines
in 72-88% yields. This new strategy has the advantages
of direct synthesis from N -alkylanilines,
using air as the oxidant, convenient manipulations, mild reaction
conditions and moderate to good yields. A possible mechanism by
coordination and reductive elimination has been proposed.
Key words
homocoupling - oxidative dehydrogenation - copper catalyst - direct synthesis - hydrazine
References and Notes
For recent reviews on oxidative
cross-dehydrogenative-coupling, see:
<A NAME="RW18910ST-1A">1a </A>
Li C.-J.
Acc.
Chem. Res.
2009,
42:
335
<A NAME="RW18910ST-1B">1b </A>
Scheuermann CJ.
Chem. Asian J.
2010,
5:
436
<A NAME="RW18910ST-1C">1c </A>
Zhang M.
Adv.
Synth. Catal.
2009,
351:
2243
For representative papers on oxidative
dehydrogenative homocouplings for the formation of C-C
bonds, see:
<A NAME="RW18910ST-2A">2a </A>
Truong T.
Alvarado J.
Tran LD.
Daugulis O.
Org. Lett.
2010,
12:
1200
<A NAME="RW18910ST-2B">2b </A>
Chen Q.-A.
Dong X.
Chen
M.-W.
Wang D.-S.
Zhou Y.-G.
Li Y.-X.
Org. Lett.
2010,
12:
1928
<A NAME="RW18910ST-2C">2c </A>
Egami H.
Katsuki T.
J. Am. Chem. Soc.
2009,
131:
6082
<A NAME="RW18910ST-2D">2d </A>
Hull KL.
Lanni EL.
Sanford MS.
J. Am. Chem. Soc.
2006,
128:
14047
<A NAME="RW18910ST-2E">2e </A>
Matsushita M.
Kamata K.
Yamaguchi K.
Mizuno N.
J. Am. Chem. Soc.
2005,
127:
6632
<A NAME="RW18910ST-2F">2f </A>
Masui K.
Ikegami H.
Mori A.
J.
Am. Chem. Soc.
2004,
126:
5074
<A NAME="RW18910ST-2G">2g </A>
Takahashi M.
Masui K.
Sekiguchi H.
Kobayashi N.
Mori A.
Funahashi M.
Tamaoki N.
J.
Am. Chem. Soc.
2006,
128:
10930
<A NAME="RW18910ST-2H">2h </A>
Kamata K.
Yamaguchi S.
Kotani M.
Yamaguchi K.
Mizuno N.
Angew.
Chem. Int. Ed.
2008,
47:
2407
<A NAME="RW18910ST-2I">2i </A>
Oi S.
Sato H.
Sugawara S.
Inoue Y.
Org. Lett.
2008,
10:
1823
<A NAME="RW18910ST-2J">2j </A>
Oishi T.
Katayama T.
Yamaguchi K.
Mizuno N.
Chem. Eur. J.
2009,
15:
7539
For representative papers on the
synthesis of disulfides by dehydrogenative homocoupling reactions,
see:
<A NAME="RW18910ST-3A">3a </A>
Arterburn JB.
Perry MC.
Nelson SL.
Dible BR.
Holguin MS.
J. Am. Chem. Soc.
1997,
119:
9309
<A NAME="RW18910ST-3B">3b </A>
Singh D.
Galetto FZ.
Soares LC.
Rodrigues OED.
Braga AL.
Eur. J. Org. Chem.
2010,
14:
2661
<A NAME="RW18910ST-3C">3c </A>
Banfield SC.
Omori AT.
Leisch H.
Hudlicky T.
J.
Org. Chem.
2007,
72:
4989
<A NAME="RW18910ST-3D">3d </A>
Choi J.
Yoon NM.
J. Org. Chem.
1995,
60:
3266
<A NAME="RW18910ST-3E">3e </A>
Ramesha AR.
Chamedarsekran S.
J.
Org. Chem.
1994,
59:
1354
<A NAME="RW18910ST-4A">4a </A>
Rosenberg L.
Davis CW.
Yao J.-Z.
J. Am. Chem. Soc.
2001,
123:
5120
<A NAME="RW18910ST-4B">4b </A>
Braunstein P.
Morise X.
Chem. Rev.
2000,
100:
3541
<A NAME="RW18910ST-5A">5a </A>
Kajimoto T.
Takahashi H.
Tsuji J.
Bull. Chem. Soc. Jpn.
1982,
55:
3673
<A NAME="RW18910ST-5B">5b </A> For an excellent report
on copper-catalyzed dehydrogenative coupling of anilines leading
to azo compounds, see:
Zhang C.
Jiao N.
Angew. Chem. Int. Ed.
2010,
49:
6174
<A NAME="RW18910ST-6A">6a </A>
Hydrazine
and Its Derivatives, In Kirk-Othmer Encyclopedia
of Chemical Technology
Vol. 13, 4th ed.:
Wiley;
New
York:
1995.
<A NAME="RW18910ST-6B">6b </A>
Encyclopedia
of Reagents for Organic Synthesis
Paquette LA.
Wiley;
Chichester:
1995.
<A NAME="RW18910ST-6C">6c </A>
Ragnarsson U.
Chem.
Soc. Rev.
2001,
30:
205
<A NAME="RW18910ST-7A">7a </A>
Han H.
Janda KD.
J.
Am. Chem. Soc.
1996,
118:
2539
<A NAME="RW18910ST-7B">7b </A>
Zhang R.
Durkin JP.
Windsor WT.
Bioorg. Med. Chem. Lett.
2002,
12:
1005
<A NAME="RW18910ST-7C">7c </A>
Lee T.-W.
Cherney MM.
Huitema C.
Liu J.
James KE.
Powers JC.
Eltis LD.
James MNG.
J.
Mol. Biol.
2005,
353:
1137
For representative papers for the
synthesis of hydrazines from the compounds containing N-N
or N=N bonds, see:
<A NAME="RW18910ST-8A">8a </A>
Bredihhin A.
Groth UM.
Maeorg U.
Org.
Lett.
2007,
9:
1097
<A NAME="RW18910ST-8B">8b </A>
Kisseljova K.
Tsubrik O.
Org. Lett.
2006,
8:
43
<A NAME="RW18910ST-8C">8c </A>
Bredihhin A.
Maeorg U.
Org. Lett.
2007,
9:
4975
<A NAME="RW18910ST-8D">8d </A>
Maeorg U.
Grehn L.
Ragnarsson U.
Angew.
Chem. Int. Ed.
1996,
35:
2626
<A NAME="RW18910ST-8E">8e </A>
Rosamilia AE.
Aricò F.
Tundo P.
J. Org. Chem.
2008,
73:
1559
<A NAME="RW18910ST-8F">8f </A>
Tsubrik O.
Maeorg U.
Org. Lett.
2001,
3:
2297
<A NAME="RW18910ST-8G">8g </A>
Alberti A.
Canè F.
Dembech P.
Lazzari D.
Ricci A.
Seconi G.
J. Org. Chem.
1996,
61:
1677
<A NAME="RW18910ST-8H">8h </A>
Brosse N.
Pinto M.-F.
Bodiguel J.
Jamart-Gregoire B.
J. Org. Chem.
2001,
66:
2869
<A NAME="RW18910ST-8I">8i </A>
Grehn L.
Lohn H.
Ragnarsson U.
Chem. Commun.
1997,
15:
1381
<A NAME="RW18910ST-8J">8j </A>
Brosse N.
Pinto M.-F.
Jamart-Gregoire B.
J.
Org. Chem.
2000,
65:
4370
<A NAME="RW18910ST-8K">8k </A>
Maeorg U.
Ragnarsson U.
Tetrahedron Lett.
1998,
39:
681
<A NAME="RW18910ST-8L">8l </A>
Maeorg U.
Pehk T.
Ragnarsson U.
Acta
Chem. Scand.
1999,
53:
1127
<A NAME="RW18910ST-8M">8m </A>
Bredihhin A.
Maeorg U.
Tetrahedron
2008,
64:
6788
<A NAME="RW18910ST-8N">8n </A>
Tsubrik O.
Maeorg U.
Sillard R.
Ragnarsson U.
Tetrahedron
2004,
60:
8363
<A NAME="RW18910ST-9">9 </A>
Vidal J.
Hannachi J.-C.
Hourdin G.
Mulatier J.-C.
Collet A.
Tetrahedron
Lett.
1998,
39:
8845
<A NAME="RW18910ST-10">10 </A>
Huddleston PR.
Coutts GC.
Comprehensive
Organic Functional Group Transformations
Vol. 2:
Katritzky AR.
Meth-Cohn O.
Rees CW.
Pergamon/Elsevier;
Oxford:
1995.
p.371-383
<A NAME="RW18910ST-11">11 </A>
Furst A.
Moore RE.
J. Am. Chem. Soc.
1957,
79:
5492
<A NAME="RW18910ST-12">12 </A> Similarly, inorganic metal oxide
MnO2 promoted an oxygen-mediated oxidation:
Joyce LL.
Batey RA.
Org. Lett.
2009,
11:
2792
<A NAME="RW18910ST-13A">13a </A>
Steinhoff BA.
King AE.
Stahl SS.
J.
Org. Chem.
2006,
71:
1861
<A NAME="RW18910ST-13B">13b </A>
Schultz MJ.
Hamilton SS.
Jensen DR.
Sigman MS.
J.
Org. Chem.
2005,
70:
3343
<A NAME="RW18910ST-14">14 </A>
General Experimental
Procedure : To a solution of
N -alkylaniline 1 (0.107 g, 1.0 mmol) in DMF (2 mL) were added
CuBr (0.029 g, 0.2 mmol), TMEDA (0.232 g, 2.0 mmol), CuO (0.016
g, 0.2 mmol), K2 CO3 (0.276 g, 2.0 equiv) and
4 Å MS (0.1 g) successively, and the reaction mixture was
stirred at 70 ˚C or 95 ˚C for 12-24 h
in air. After the reaction was completed, the mixture was filtered,
and the residue was washed with EtOAc (3 × 5 mL). Then,
the combined filtrates were concentrated in vacuum, and the residue
was purified by column chromatography (silica gel, PE-EtOAc
as eluent) to afford the desired hydrazine 2 .
<A NAME="RW18910ST-15A">15a </A>
Lewis EA.
Tolman WB.
Chem. Rev.
2004,
104:
1047
<A NAME="RW18910ST-15B">15b </A>
Mirica LM.
Ottenwaelder X.
Stack TDP.
Chem. Rev.
2004,
104:
1013
<A NAME="RW18910ST-15C">15c </A>
Collman JP.
Zhong M.
Zhang C.
Costanzo S.
J. Org. Chem.
2001,
66:
7892