Communication
ChemComm
Table 2 (continued)
Fundamentals to Applications, ed. R. Luisi and V. Capriati, Wiley-VCH
Verlag & Co, Weinheim, Germany, 2014.
2 F. Mongin and A. Harrison-Marchand, Chem. Soc. Rev., 2013,
c
d
Entry Substrate
Conditions
Product
113, 7563.
3
(a) R. E. Mulvey, F. Mongin, M. Uchiyama and Y. Kondo, Angew.
Chem., Int. Ed., 2007, 46, 3802; (b) B. Haag, M. Mosrin, H. Ila,
V. Malakhov and P. Knochel, Angew. Chem., Int. Ed., 2011, 50, 9794.
A. J. Martinez, D. R. Armstrong, B. Conway, B. J. Fleming, J. Klett,
A. R. Kennedy, R. E. Mulvey, S. D. Robertson and C. T. O’Hara, Chem.
Sci., 2014, 5, 771.
1
4
20 1C, 1.5 h, 0.33 equiv.
4
a
c
b
0
.5 mmol of substrate was used. 1.5 mmol of substrate were used.
Time, temperature and amount of base 2 for the metalation reactions.
Yields refer to isolated yields of analytically pure products (495%
d
5 C. Unkelbach, D. F. O’Shea and C. Strohmann, Angew. Chem., Int.
Ed., 2014, 53, 553.
6 W. Clegg, B. Conway, P. Garcia-Alvarez, A. R. Kennedy, R. E. Mulvey,
L. Russo, J. Sasmannshausen and T. Tuttle, Chem. – Eur. J., 2009,
purity determined by NMR or GC-analysis), unless otherwise stated.
e
1
Yield was determined by H-NMR analysis using an internal standard
ferrocene).
(
1
5, 10702.
7
H. Haward, O. Bayh, C. Hoarau, F. Tr ´e court, G. Qu ´e guiner and
2
led to regioselective deprotonation at the 2-position. The corre-
F. Marsais, Tetrahedron, 2008, 64, 3236.
8 M. Hatano, T. Matsumura and T. Ishihara, Org. Lett., 2005, 7, 573.
S. E. Baillie, W. Clegg, P. Garcia-Alvarez, E. Hevia, A. R. Kennedy,
J. Klett and L. Russo, Chem. Commun., 2011, 47, 388.
0
0
sponding iodinated (6m–o) and carboxylated (6m , 6n ) hetero-
cycles were produced in equally high yields (81–95%, Table 2,
9
entries 12–14). With unsubstituted thiophene (4o) 8% of twofold 10 W. Clegg, B. Conway, A. R. Kennedy, J. Klett, R. E. Mulvey and
0
L. Russo, Eur. J. Inorg. Chem., 2011, 721.
1 See ESI† for details.
metallation leading to 2,5-diiodothiophene (6o ) was observed.
1
1
In summary, we have uncovered the structures of a new
family of homoalkyl potassium magnesiates. Revealing an
important donor effect, addition of polydentate N-Lewis bases to
the highly aggregated magnesiate 1, not only induces formation of
smaller aggregates but also changes the mixed-metal formulation,
to higher-order magnesiates 2 and 3. A new straightforward
methodology, using 2 as a metallating reagent, to promote
2 These values are similar to those previously reported for the
structure of [MeK] where K also forms long distance interactions
with the Me groups of other units (mean Kꢀ ꢀ ꢀMe, 3.441 Å) which are
significantly elongated when compared to the K–Me distances
towards the carboanion (2.447 Å), see E. Weiss, T. Lambertsen,
B. Schubert and J. K. Cockcroft, J. Organomet. Chem., 1988, 358, 1.
3 Compounds 2 and 3 can also be rationally synthesized by reaction of
1
the relevant N-donor, KR and MgR
2
in a 2 : 2 : 1 ratio (isolated
crystalline yields 78 and 45% for 2 and 3 respectively).
regioselective Mg–H exchange of a wide range of aromatic and 14 Similar linear arrangements have been described as classical ‘‘Weiss
motifs’’ in related Li and Na magnesiate structures, see: E. Weiss,
Angew. Chem., Int. Ed. Engl., 1993, 32, 1501.
5 C. Lichtenberg, T. P. Spaniol, I. Peckermann, T. P. Hanusa and
J. Okuda, J. Am. Chem. Soc., 2013, 135, 811.
6 For DoM reactions see: (a) V. Snieckus, Chem. Rev., 1990, 90, 879;
heteroaromatic substrates under mild reaction conditions has
been disclosed. Our studies suggest the involvement of CIP
1
intermediates, with the presence of K being the key to facilitate
these novel magnesiation reactions.
We thank the EPSRC, the Carnegie Trust for the Universities
of Scotland the Royal Society and the ERC for their generous
sponsorship of this research and Professor R. E. Mulvey for
insightful discussions.
1
(
b) A. Wagner, J. R. Desmurs, V. Pe and C. Mioskowski, Angew.
Chem., Int. Ed., 2002, 41, 340; (c) S. Wunderlich, T. Bresser, C. Dunst,
G. Monzon and P. Knochel, Synthesis, 2010, 2670.
7 For an insightful discussion on the ortho-lithiation of anisole see
ref. 16a.
8 S. E. Baillie, W. Clegg, P. Garcia-Alvarez, E. Hevia, A. R. Kennedy,
J. Klett and L. Russo, Organometallics, 2012, 31, 5131.
1
1
Notes and references
19 For regioselective metalation of 4f in 2-position and 4h in 6-position
overriding the directing effect see: (a) S. M. Manolikakes, N. M. Barl,
C. S ¨a mann and P. Knochel, Z. Naturforsch., 2013, 68b, 411; (b) M. Jaric,
B. A. Haag, A. Unsinn, K. Karaghiosoff and P. Knochel, Angew. Chem.,
Int. Ed., 2010, 49, 5451.
1
(a) M. Schlosser, in Organometallics in Synthesis. A Manual, ed.
M. Schlosser, Wiley, Chichester, 2nd edn, 2002, p. 1; (b) E. Carl
and D. Stalke, in Lithium Compounds in Organic Synthesis: From
1
2862 | Chem. Commun., 2014, 50, 12859--12862
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