E. Pereira et al. / Tetrahedron Letters 46 (2005) 2691–2693
2693
Inoue, Y.; Fujita, E. J. Am. Chem. Soc. 1986, 108, 4673;
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Dai, W-M.; Ochiai, M.; Tsukagoshi, S.; Fujita, E. J. Org.
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THF/MeOH and the crude product was treated with
TFA in CH2Cl2 in the presence of Et3SiH as a tert-butyl
cation scavenger. After stirring 24 h at rt, the reaction
was quenched with NaHCO3 and vigorously stirred with
satd aq NaHCO3 for 16 h. After purification of the
crude product by column chromatography on neutral
alumina, (+)-isoretronecanol (1) was isolated in 43%
overall yield from 7 and (4S)-4-isopropyl-1,3-thiazol-
idine-2-thione was recovered in 66% yield. The identity
of our synthetic sample with (+)-isoretronecanol was
10. (a) Nagao, Y.; Dai, W.-M.; Ochiai, M. Tetrahedron Lett.
1988, 29, 6133; (b) Nagao, Y.; Dai, W.-M.; Ochiai, M.;
Shiro, M. Tetrahedron 1990, 46, 6361.
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loids; CRC, 1991.
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established by comparison of its 1H and 13C NMR spec-
20
D
tra and specific optical rotation (½aꢁ ¼ þ71:0) (c 1.29,
EtOH) with those reported in the literature.19a,g
In summary, the feasibility of the coupling reaction be-
tween the titanium(IV) enolate from of N-4-chloro-
butyryl 1,3-thiazolidine-2-thiones (3) and the exocyclic
N-acyliminium ion derived from N-Boc-2-methoxy pyr-
rolidine (4) has been demonstrated. Despite the lower
diastereoselection when compared to the reaction of
the titanium(IV) enolate of the corresponding N-acyl-
1,3-oxazolidin-2-one, the use of 1,3-thiazolidine-2-thi-
ones proved to be beneficial in the recovery of the chi-
ral auxiliary and the total synthesis of (+)-
isoretronecanol (1) was completed in four steps and
36% overall yield.
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Acknowledgements
The authors would like to thank FAPESP (Fundac¸a˜o de
Amparo a Pesquisa no Estado de Sa˜o Paulo) for finan-
cial support and fellowships (M.A.B and E.P.), CNPq
´
(Conselho Nacional de Desenvolvimento Cientıfico e
Tecnologico) for fellowships (R.A.P. and C.F.A.) and
´
18. (a) Hart, N. K.; Johns, S. R.; Lamberton, J. A. Aust. J.
Chem. 1968, 21, 1393; (b) Lindstro¨m, B.; Luning, B. Acta
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Chem. Scand. 1971, 25, 895; (c) Branda¨nge, S.; Luning, B.;
FAEP-Unicamp for fellowship (C.F.A.).
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Moberg, C.; Sjo¨strand, E. Acta Chem. Scand. 1972, 26,
2558; (d) Mohnraj, S.; Subramanian, P. S.; Herz, W.
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