F. Foubelo et al. / Tetrahedron Letters 48 (2007) 3379–3383
3383
i
OLi
Li
Li
OLi
Li
ii,iii
O
O
O
LiO
18
19
20
OH
E
E
OH
+
O
HO
E
21
22
Scheme 4. Reagents and conditions: (i) Li, DTBB (2.5 mol%), THF, ꢀ78 °C, 30 min, then 0 °C, 2 h; (ii) E+ = H2O, PhCHO, ꢀ78 °C, 30 min; and
(iii) H2O, ꢀ78 to 20 °C.
Chemistry: A Theoretical and Experimental Overview;
to complete the transformation of intermediate 19 into
20, yields become significantly lower and variable
amounts of 1,2,4,5-trimethylbenzene are detected by
GC/MS (Scheme 4).
´
Sapse, A. M., von Rague Schleyer, P., Eds.; J. Wiley &
Sons: New York, 1995; (c) Gray, M.; Tinkel, M.;
Snieckus, V. In Comprehensive Organometallic Chemistry
II; Abel, E. W., Stone, F. G. A., Wilkinson, G., McKillop,
A., Eds.; Pergamon: Oxford, 1995; Vol. 11, pp 1–92; (d)
Clayden, J. Organolithiums: Selectivity for Synthesis;
Pergamon: Oxford, 2002; For a review on metal-promoted
dehalogenation, see: (e) Alonso, F.; Beletskaya, I. P.; Yus,
M. Chem. Rev. 2002, 102, 4009–4091.
In conclusion, we report here that the reductive opening
of different phthalan derivatives 4, 9 and 12 with an
excess of lithium in the presence of a catalytic amount
of DTBB at different temperatures takes place in a
regioselectivity fashion. The regiochemistry of the
process can be explained taking into account the elec-
tron density of either the dianion or the radical anion,
which undergoes the reductive cleavage. The reaction
of the resulting intermediates with electrophiles allows
the preparation of regioselectively functionalised
naphthalene and biphenyl derivatives 7, 11 and 14.
3. For reviews, see (a) Yus, M.; Foubelo, F. Rev. Heteroatom
Chem. 1997, 17, 73–107; (b) Yus, M.; Foubelo, F. Targets
Heterocycl. Syst. 2002, 6, 136–171; (c) Yus, M. Pure Appl.
Chem. 2003, 75, 1453–1475.
4. Almena, J.; Foubelo, F.; Yus, M. Tetrahedron 1995, 51,
3351–3364.
5. Azzena, U.; Demartis, S.; Fiori, M. G.; Melloni, G.;
Pisano, L. Tetrahedron Lett. 1995, 36, 8123–8126.
6. (a) Soler, T.; Bachki, A.; Falvello, L. R.; Foubelo, F.; Yus,
M. Tetrahedron: Asymmetry 1998, 9, 3939–3943; (b) Soler,
T.; Bachki, A.; Falvello, L. R.; Foubelo, F.; Yus, M.
Tetrahedron: Asymmetry 2000, 11, 493–517.
Acknowledgements
7. (a) Falvello, L. R.; Foubelo, F.; Soler, T.; Yus, M.
Tetrahedron: Asymmetry 2000, 11, 2063–2066; (b) Foub-
elo, F.; Soler, T.; Yus, M. Tetrahedron: Asymmetry 2001,
12, 801–810.
8. Yus, M.; Gomis, J. Eur. J. Org. Chem. 2003, 2043–2048.
9. Yus, M.; Gomis, J. Tetrahedron Lett. 2001, 42, 5721–5724.
10. Yus, M.; Gomis, J. Eur. J. Org. Chem. 2002, 1989–1995.
11. Pastor, I. M.; Yus, M. Tetrahedron Lett. 2000, 41, 1589–
1592.
This work was generously supported by the Spanish
´
Ministerio de Educacion y Ciencia (MEC; Grant No.
CTQ2004-01261) and the Generalitat Valenciana (GV;
Grant Nos. GRUPOS05/052 and GRUPOS05/058).
D.G. thanks the University of Alicante for a predoctoral
fellowship. We also thank Medalchemy S.L. and
Chemetall GmbH for a gift of chemicals, especially
lithium.
12. Pastor, I. M.; Yus, M. Tetrahedron 2001, 57, 2371–2378.
13. Azzena, U.; Demartis, S.; Melloni, G. J. Org. Chem. 1996,
61, 4913–4919.
References and notes
14. Dorigo, A. E.; Houk, K. N.; Cohen, T. J. Am. Chem. Soc.
1989, 111, 8976–8978.
1. For reviews on functionalised organolithium compounds,
15. Bestmann, H. J.; Both, W. Chem. Ber. 1974, 107, 2926–
2930.
´
see: (a) Najera, C.; Yus, M. Trends Org. Chem. 1991, 2,
´
155–181; (b) Najera, C.; Yus, M. Org. Prep. Proc. Int.
16. Kirmse, W.; Kund, K. J. Org. Chem. 1990, 55, 2325–2332.
17. Witulski, B.; Stengel, T. Angew. Chem., Int. Ed. 1999, 38,
2426–2430.
´
1995, 27, 383–457; (c) Najera, C.; Yus, M. Recent Res.
Dev. Org. Chem. 1997, 1, 67–96; (d) Yus, M.; Foubelo, F.
´
Rev. Heteroatom Chem. 1997, 17, 73–107; (e) Najera, C.;
18. The same reaction in the absence of the DTBB catalyst
takes place in longer reaction times being also not so clean
than in the presence of the electron transfer agent.
19. In a recent paper on the reductive cleavage of an alkyl
naphthyl thioether, Donohoe, Compton and co-workers
proved that at 20 °C the dissociation of alkyl carbon–
sulfur bond occurs after the substrate accepts a single
electron (radical anion), however, at ꢀ78 °C the radical
anion is stabilised at sufficiently longer timescales to
accept a second electron, leading to the corresponding
dianion which cleaves at the aryl–sulfur bond: Paddon, C.
A.; Bhatti, F. L.; Donohoe, T. J.; Compton, R. G. Chem.
Commun. 2006, 3402–3404.
´
Yus, M. Curr. Org. Chem. 2003, 7, 867–926; (f) Najera, C.;
Sansano, J. M.; Yus, M. Tetrahedron 2003, 59, 9255–9303;
(g) Chinchilla, R.; Najera, C.; Yus, M. Chem. Rev. 2004,
104, 2667–2722; (h) Chinchilla, R.; Najera, C.; Yus, M.
Tetrahedron 2005, 61, 3139–3176; (i) See also the special
´
´
´
issue of Tetrahedron Symposium in Print (Eds.: Najera, C;
Yus, M.) devoted to ‘Functionalised Organolithium
Compounds’, Tetrahedron 2005, 61; (j) Yus, M.; Foubelo,
F. In Handbook of Functionalized Organometallics; Kno-
chel, P., Ed.; Wiley–VCH: Weinheim, 2005; Chapter 2.
2. For monographs, see: (a) Wakefield, B. J. Organolithium
Methods; Academic Press: London, 1988; (b) Lithium