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Table 1
2. House, H. O. In Modern Synthetic Reactions; Benjamin: Menlo Park, 1972; pp
359–387.
3. Rubottom, G. M. In Oxidation in Organic Chemistry; Trahanovsky, W. H., Ed.;
Academic: London, 1982. Chapter 1.
4. Sheldon, R. A.; Kochi, J. K. Org. React. 1972, 19, 279–421.
5. Pinhey, J. T. Aust. J. Chem. 1991, 44, 1353–1382.
6. Pinhey, J. T.. In Comprehensive Organometallic Chemistry II; McKillop, A., Ed.;
Pergamon: Oxford, 1995; Vol. 11,. Ch 11.
7. Elliott, G. I.; Konopelski, J. P. Tetrahedron 2001, 57, 5683–5705.
8. Buston, J. E. H.; Claridge, T. D. W.; Heyes, S. J.; Leech, M. A.; Moloney, M. G.;
Prout, K.; Stevenson, M. Dalton Trans. 2005, 3195–3203.
9. Cottrell, I. F.; Cowley, A. R.; Croft, L. J.; Hymns, L.; Moloney, M. G.; Nettleton, E.
J.; Smithies, H. K.; Thompson, A. L. Tetrahedron 2009, 65, 2537–2550.
10. Cottrell, I. F.; Moloney, M. G.; Smithies, H. K. Tetrahedron Lett. 2009, 50, 1097–
1099.
11. Moloney, M. G.; Nettleton, E.; Smithies, K. Tetrahedron Lett. 2002, 43, 907–909.
12. Moloney, M. G.; Paul, D. R.; Prottey, S. C.; Thompson, R. M.; Wright, E. J.
Organomet. Chem. 1997, 534, 195–205.
13. Buston, J. E. H.; Howell, H. J.; Moloney, M. G.; Poster, V. Main Group Metal Chem.
1998, 21, 51–54.
14. Moloney, M. G.; Paul, D. R.; Thompson, R. M.; Wright, E. J. Organomet. Chem.
1998, 560, 77–88.
15. Bailey, J. H.; Cherry, D.; Dyer, J.; Moloney, M. G.; Bamford, M. J.; Keeling, S.;
Lamont, R. B. J. Chem. Soc., Perkin Trans. 1 2000, 2783.
16. Dyer, J.; Keeling, S.; King, A.; Moloney, M. G. J. Chem. Soc., Perkin Trans. 1 2000,
2793.
17. Oae, S.; Uchida, Y. Acc. Chem. Res. 1991, 24, 202–208.
18. Abramovitch, R. A.; Barton, D. H. R.; Finet, J.-P. Tetrahedron 1988, 44, 3039–
3071.
19. Barton, D. H. R. In Heteroatom Chemistry; Block, E., Ed.; VCH: New York, 1990.
Ch 5.
20. Barton, D. H. R.; Parekh, S. I. Pure Appl. Chem. 1993, 65, 603–608.
21. Buston, J. E. H.; Coop, A.; Keady, R.; Moloney, M. G.; Thompson, R. M. J. Chem.
Res. (M) 1994, 1101–1116.
Yields of arylation products 5 and 6 formed according to Schemes 2 and 3 using a lead
tetracarboxylate and ligands 2a–f
Ligand
Pb(O2CR0)4 R0
=
Yield 5 (%)
Yield 6 (%)
2a
2b
2c
2d
2e
2f
2a
2b
2c
2d
2e
2f
2a
2b
2c
2d
2e
2f
2a
2b
2c
2d
2e
2f
CH3
CH3
CH3
CH3
CH3
CH3
18
22
27
8
25
27
34
12
26
17
28
37
38
22
30
27
27
33
34
21
28
22
31
35
32
25
32
24
21
15
22
35
30
24
24
23
23
29
27
25
24
17
27
30
26
22
27
21
p-MeC6H4
p-MeC6H4
p-MeC6H4
p-MeC6H4
p-MeC6H4
p-MeC6H4
m-MeOC6H4
m-MeOC6H4
m-MeOC6H4
m-MeOC6H4
m-MeOC6H4
m-MeOC6H4
2-Thienyl
2-Thienyl
2-Thienyl
2-Thienyl
2-Thienyl
2-Thienyl
22. Gilroy, J. B.; Ferguson, M. J.; McDonald, R.; Hicks, R. G. Inorg. Chim. Acta 2008,
361, 3388–3393.
23. Gilroy, J. B.; Patrick, B. O.; McDonald, R.; Hicks, R. G. Inorg. Chem. 2008, 47,
1287–1294.
Table 2
Yields of arylation products 5 and 6 formed according to Schemes 2 and 3 using a lead
tetracarboxylate and ligands 3a, 3b and 4
24. Nineham, A. W. Chem. Rev. 1955, 55, 355–483.
Ligand
Pb(O2CR0)4 R0=
Yield 5 (%)
Yield 6 (%)
25. Crystallographic data for the structures of 2d and 2e have been deposited with
the Cambridge Crystallographic Data Centre, CCDC 730375 and 730376. Copies
of these data can be obtained free of charge from The Cambridge
26. Gilroy, J. B.; Ferguson, M. J.; McDonald, R.; Patrick, B. O.; Hicks, R. G. Chem.
Commun. 2007, 126–128.
27. Allred, G. D.; Liebeskind, L. S. J. Am. Chem. Soc. 1996, 118, 2748–2749.
28. Savarin, C.; Liebeskind, L. S. Org. Lett. 2001, 3, 2149–2152.
29. Buston, J. E. H.; Claridge, T. D. W.; Moloney, M. G. J. Chem. Soc., Perkin Trans. 2
1995, 639–641.
3a
3b
4
3a
3b
4
3a
3b
4
p-MeC6H4
p-MeC6H4
p-MeC6H4
m-MeOC6H4
m-MeOC6H4
m-MeOC6H4
2-Thienyl
21
20
30
17
27
35
27
22
33
27
25
40
21
24
43
30
20
37
2-Thienyl
2-Thienyl
30. Claridge, T. D. W.; Nettleton, E. J.; Moloney, M. G. Magn. Reson. Chem. 1997, 35,
159–167.
31. Buston, J. E. H.; Claridge, T. D. W.; Compton, R. G.; Moloney, M. G. Mag. Res.
Chem. 1998, 36, 140–144.
32. Volkova, K. A.; Albanov, A. I. Russ. J. Org. Chem. 2006, 42, 1730–1731.
33. Ogata, S.; Mochizuki, A.; Kakimoto, M.; Imai, Y. Bull. Chem. Soc. Jpn. 1986, 59,
2171–2177.
34. Morgan, J.; Pinhey, J. T. J. Chem. Soc., Perkin Trans. 1 1990, 715–720.
35. The lead(IV) complex (1.0 equiv), phenylboronic acid (1.1 equiv) and HgCl2
(1.0 equiv) were dissolved in DMSO (10–25 mL) and stirred at 40 °C for 2 h.
Ethyl 2-oxocyclopentane carboxylate (1.0 equiv) in pyridine (3.0 equiv) was
added to the above reaction mixture dropwise, which was then stirred at 40 °C
for 2 h and then at 80 °C for 10 h. The product was extracted from DMSO by
washing with water and CH2Cl2. The combined organic fractions were then
concentrated in vacuo. Purification by column chromatography (eluting with
95:5 pentane/ether) gave ethyl 2-oxo-1-phenylcyclopentanecarboxylate5 as a
colourless oil.
under previously reported conditions,5,6 and unlike other amine
ligands,37 the formazan and imine systems did not appear to give
a ligand acceleration effect.
We conclude from this work that although arylation reactions
do proceed with lead(IV) salts in the presence of formazan and
imine ligands, there is no observable rate acceleration effect and
yields are not improved when compared to reactions conducted
in the absence of nitrogen-containing ligands; however, it is clear
that electronic factors may be important in the processes, and opti-
misation of the reaction may be possible.
36. The lead(IV) complex (1.0 equiv), phenylboronic acid (1.1 equiv) and HgCl2
(1.0 equiv) were dissolved in DMSO (10–25 mL) and stirred at 40 °C for 2 h.
Methyl Meldrum’s acid (1.0 equiv) in pyridine (3.0 equiv) was added to the
above reaction mixture dropwise, which was then stirred at 40 °C for 2 h and
then at room temperature for 10 h. The product was extracted from DMSO by
washing with water and CH2Cl2. The combined organic fractions were
concentrated in vacuo. Purification by column chromatography [eluting with
CH2Cl2–petroleum ether (80:20)] gave 2,2,5-trimethyl-5-phenyl-1,3-dioxane-
4,6-dione.5
Acknowledgement
A.I. gratefully acknowledges the award of a Pakistani Govern-
ment HEC IRSIP Scholarship.
References and notes
37. Buston, J. E. H.; Moloney, M. G.; Parry, A. V. L.; Wood, P. M. Tetrahedron Lett.
2002, 43, 3407–3409.
1. Wiberg, K. B.. In Oxidation in Organic Chemistry; Academic Press: New York,
1965; Vol. A.