Reference and Notes
-
Strong anionic nucleophiles, such
as lithium amides and alkoxides, were used in SNAr reaction
of nonactivated haloarenes:
-
1a
Huisgen R.
Sauer J.
Chem. Ber.
1958,
91:
1453
-
1b
Wittig G.
Schmidt HJ.
Renner H.
Chem.
Ber.
1962,
95:
2377
-
1c
Rodriguez JR.
Agejas J.
Bueno
AB.
Tetrahedron Lett.
2006,
47:
5661
- 2
Otsuka M.
Endo K.
Shibata T.
Chem.
Commun.
2010,
46:
336
-
There had been limited examples
of catalytic SNAr reaction with oxygen nucleophiles using
modified cyclopentadienyl rhodium complexes:
-
3a
Houghton RP.
Voyle M.
Price R.
J.
Chem. Soc., Perkin Trans. 1
1984,
925
-
3b
Goryunov LI.
Litvak VV.
Shteingarts VD.
Zh. Org. Khim.
1987,
23:
1230
-
4a
Semmelhack MF.
Chlenov A.
Transition Metal Arene π-Complexes
in Organic Synthesis and Catalysis
Kündig EP.
Springer-Verlag;
Berlin / Germany:
2004.
p.43
-
4b
Semmelhack MF. In
Comprehensive Organometallic Chemistry
II
Vol. 12:
Abel EW.
Stone FGA.
Wilkinson G.
Pergamon;
New York:
1995.
p.979
-
For recent examples of the SNAr
reactions of nonactivated fluoroarene with amines using a stoichiometric
amount of transition metals, see:
-
5a
Braun W.
Calmuschi-Cula B.
Englert U.
Höfener K.
Alberico E.
Salzer A.
Eur. J. Org. Chem.
2008,
12:
2065
-
5b
Kamikawa K.
Kinoshita S.
Furusyo M.
Takemoto S.
Matsuzaka H.
Uemura M.
J. Org. Chem.
2007,
72:
3394
-
5c
Baldoli C.
Maiorana S.
Licandro E.
Casiraghi L.
Zinzalla G.
Seneci P.
Magistris ED.
Paio A.
Marchioro C.
J.
Comb. Chem.
2003,
5:
809
- 6
Takaya J.
Hartwig JF.
J. Am. Chem. Soc.
2005,
127:
5756
-
Molecular sieves were suggested
to operate as solid base:
-
8a
Okachi T.
Fujimoto K.
Onaka M.
Org.
Lett.
2002,
4:
1667
-
8b
Ono F.
Ohta Y.
Hasegawa M.
Kanemasa S.
Tetrahedron Lett.
2009,
50:
2111
-
[Ru(p-cymene)(OTf)(dppben)]OTf [DPPBen:
1,2-bis(diphenylphosphino)benzene] was synthesized and characterized
by X-ray single crystal structural analysis:
-
12a
Oe Y.
Ohta T.
Ito Y.
Sci.
Eng. Rev. Doshisha Univ.
2009,
50:
30
-
12b
Oe Y.
Ohta T.
Ito Y.
Tetrahedron
Lett.
2010,
51:
2806
7 Dichloro(p-cymene)ruthenium(II)
dimer was also a good precursor and product 3 was
obtained in the comparable yield (49%).
9 When 1-allyl-4-fluorobenzene was submitted
under the previous conditions (ref. 2), the yield of the styrene derivative
was low (21%). Moreover, a hydrogenated by-product also
formed, because silane was used as an additive.
10 Excess amounts of fluoroarenes would
be needed for efficient arene exchange: when 1-dimethylamino-4-fluorobenzene
(3 equiv) was used, the yield significantly decreased to 30%.
11 When the reaction was examined at
the higher reaction temperature (160 ˚C), the yield decreased
to 25%.
13 The detected isotopic patterns of A, B and C ([M - TfOH]+) by
ESI-MS matched with the theoretical isotope patterns.
14
Typical Procedure (Entry
15 in Table 1): Under an atmosphere of argon, MS4A (40 mg) was dried
up in a Schlenk tube. To this container, the mixture of [Ru(benzene)Cl2]2 (5.0
mg, 0.010 mmol) and AgOTf (10.8 mg, 0.042 mmol) in acetone was transferred
with a syringe filter. After acetone was excluded, a 1,4-dioxane
solution (0.10 mL) of P(p-FC6H4)3 (15.2
mg, 0.048 mmol), p-fluorotoluene (220 µL,
2.0 mmol) and morpholine (35 µL, 0.40 mmol) was added.
The reaction mixture was stirred under reflux for 24 h, then MS4A
was filtered off. After the filtrate was evaporated, the crude products
were purified by thin-layer chromatography (hexane-AcOEt = 10:1)
to give analytically pure 3 (80%).