for a second, single-flask coupling at the allylic phenyl ether
site, once methyl formate and DPEphos has been added to the
mixture. Thus, an unsymmetrical diamine such as 3q could be
realized in excellent overall yield (Scheme 4).
In summary, the first general method for Pd-catalyzed
aminations of allylic ethers has been developed. These
reactions occur in excellent yields, without inert atmosphere
conditions, in water as the only medium,13 and at room
temperature. Further applications from our laboratory will
be described in due course.
Notes and references
Scheme 2 Limits of allylation.
1 (a) Z. Lu and S. Ma, Angew. Chem., Int. Ed., 2008, 47, 258, and
references cited therein; (b) S. A. Weissman and D. Zewge,
Tetrahedron, 2005, 61, 7833; (c) Protective Groups in Organic
Synthesis, ed. T. W. Greene and P. G. M. Wuts, John Wiley and
Sons, New York, 3rd edn, 1999, p. 17; (d) K. Takahashi,
A. Miyake and G. Hata, Bull. Chem. Soc. Jpn., 1972, 45, 230.
2 J. Terao, H. Watabe, H. Watanabe and N. Kambe, Adv. Synth.
Catal., 2004, 346, 1674.
3 (a) G. Mora, O. Piechaczyk, X. F. Le Goff and P. Le Floch,
Organometallics, 2008, 27, 2565; (b) H. Murakami, T. Minami and
F. Ozawa, J. Org. Chem., 2004, 69, 4482; (c) M. Fisher and R. C. D
Brown, Tetrahedron Lett., 2001, 42, 8227; (d) D. E. Bergbreiter,
B. Chen and T. J. Lynch, J. Org. Chem., 1983, 48, 4179;
(e) Y. Inoue, M. Taguchi, M. Toyofuki and H. Hashimoto, Bull.
Chem. Soc. Jpn., 1984, 57, 3021.
4 J. Muzart, Eur. J. Org. Chem., 2007, 3077.
5 T. Nishikata and B. H. Lipshutz, Org. Lett., 2009, 11, 2377
Scheme 3 Chemoselective reaction of 1f.
6 Other leaving groups were not examined, although from related
studies, it is expected to react far more slowly under similar
conditions; see T. Nishikata and B. H. Lipshutz, J. Am. Chem.
Soc., 2009, 131, 12103.
7 (a) Arylboron reagents: M. Tobisu, T. Shimasaki and N. Chatani,
Angew. Chem., Int. Ed., 2008, 47, 4866; (b) Grignard reagents with
aryl ether: J. W. Dankwardt, Angew. Chem., Int. Ed., 2004, 43,
2428; (c) Grignard reagents with vinyl ether: E. Wenkert,
E. L. Michelotti and C. S. Swindell, J. Am. Chem. Soc., 1979,
101, 2246.
8 B. H. Lipshutz and S. Ghorai, Aldrichimica Acta, 2008, 41, 58.
9 T. Dwars, E. Paetzold and G. Oehme, Angew. Chem., Int. Ed.,
2005, 44, 7174.
10 (a) M. Feuerstein, D. Laurenti, H. Doucet and M. Santelli, J. Mol.
Catal. A: Chem., 2002, 182; (b) M. Feuerstein, D. Laurenti,
H. Doucet and M. Santelli, Tetrahedron Lett., 2001, 42, 2313.
11 B. H. Lipshutz and A. R. Abela, Org. Lett., 2008, 10, 5329.
12 B. H. Lipshutz, D. W. Chung and B. Rich, Adv. Synth. Catal.,
2009, 351, 1717.
13 (a) C. I. Herrerıas, X. Yao, Z. Li and C.-J. Li, Chem. Rev., 2007,
´
107, 2546; (b) K. H. Shaughnessy and R. B. DeVasher, Curr. Org.
Chem., 2005, 9, 585; (c) C.-J. Li, Chem. Rev., 2005, 105, 3095.
Scheme 4 One-pot synthesis of diamine 3q from 1f.
While functionalized amino acid 2i was unreactive toward
1a, allyl phenyl ether itself (1c) reacted smoothly to produce 3l
in 85% yield (Scheme 2). In the case of the allylic substrate 1f
having both acetate and ether moieties (Scheme 3), coupling
first occurred chemoselectively (in the absence of methyl
formate) at the acetate in the presence of Xantphos to give
3n. That is, no product (3p) resulting from phenyl ether
displacement was detected, nor was potential product 3o
observed from double substitution. While the resulting amine
3n formed could be isolated (83%), its in situ generation allows
ꢀc
This journal is The Royal Society of Chemistry 2009
6474 | Chem. Commun., 2009, 6472–6474