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T. Borg et al. / Tetrahedron Letters 54 (2013) 3916–3918
8. All the C3-substituted 1,3-bis(silyl)propenes, except for 2e, were prepared from
the corresponding 1,3-bis(silyl)propenes. Typical experimental procedure for the
preparation of 2b: To a stirred solution of (E)-1,3-bis(trimethylsilyl)propene
Hydrocinnamaldehyde 1e was compatible with the reaction condi-
tions providing 3j in 53% and 19% yields (entries 16 and 17).
In conclusion, a novel method for the stereoselective formation
of tetrasubstituted tetrahydrofurans under mild conditions has
been developed.
(560 mg, 3.0 mmol) in Et2O (10 mL) were added TMEDA (450 lL, 3.0 mmol)
and n-BuLi (1.6 mL, 2.5 M in hexanes) dropwise at ꢁ78 °C and the resultant
mixture was stirred for 1 h before it was allowed to reach ambient temperature
and left overnight. The reaction mixture was cooled to ꢁ78 °C, and MeI (210
lL,
3.3 mmol) was added. After 15 min, the solution was allowed to reach rt and
stirred for an additional 1 h. The reaction was quenched by the addition of H2O
(5 mL). The aqueous phase was extracted (Et2O, 3 ꢂ 10 mL), and the combined
organic phases were washed (H2O, 2 ꢂ 20 mL), dried (MgSO4) and concentrated
under reduced pressure. The residue was purified by flash chromatography
(pentane) to give 2b (580 mg, 2.9 mmol) as a colorless oil in 97% yield. 1H NMR
(500 MHz, CDCl3) d 6.08 (dd, J = 18.7, 7.2 Hz, 1H), 5.40 (dd, J = 18.7, 1.4 Hz, 1H),
1.71–1.67 (m, 1H), 1.06 (d, J = 7.1 Hz, 3H), 0.04 (s, 9H), ꢁ0.04 (s, 9H); 13C NMR
(500 MHz, CDCl3) d 150.0, 124.3, 30.6, 12.7, ꢁ0.9, ꢁ3.6. For the preparation of the
1,3-bis(silyl)propenes see: Knolker, H. J.; Foitzik, N.; Goesmann, H.; Graf, R.;
Jones, P. G.; Wanzl, G. Chem. Eur. J. 1997, 3, 538–551. Compound 2e was prepared
according to: Despons, O.; Franzini, L.; Schlosser, M. Synthesis 1997, 150–152.
9. Typical experimental procedure for the preparation of 3: To a stirred solution of
Acknowledgments
The authors would like to thank the KTH Royal Institute of
Technology, Lund University, and the Estonian Ministry of Educa-
tion (Project no. SF0180073s08) for funding.
References and notes
7. For the use of 1,3-bis(silyl)propenes in organic synthesis, see: Seashore-
Ludlow, B.; Somfai, P. In 1,3-BIS(SILYL)PROPENES e-EROS Encyclopedia of
Reagents for Organic Synthesis; Crich, D., Charette, A. B., Fuchs, P. L., Rovis, T.,
silane 2a (56 mg, 280
sieves (100 mg/mL solvent) in CH2Cl2 (1 mL) at ꢁ78 °C was added a 0.01 M
solution of aldehyde 1a (29 mg, 140 mol) and 1-methylnaphthalene (25 mg,
140 mol) in CH2Cl2 (1 mL) dropwise over 1 h, and the resultant mixture was
lmol), BF3ꢀOEt2 (35 lL, 280 lmol) and 4 Å molecular
l
l
stirred overnight. The reaction was quenched by the addition of NH4Cl (1 mL).
The aqueous phase was extracted (CH2Cl2, 3 ꢂ 5 mL), and the combined organic
phases were washed (H2O, 2 ꢂ 10 mL), dried (MgSO4) and concentrated under
reduced pressure. The residue was purified by flash chromatography
(pentaneꢀCH2Cl2) to give 3a (44 mg, 120
lmol) as a colorless oil in 86% yield.
1H NMR (500 MHz, CDCl3) d 7.34–7.33 (m, 4H), 7.29–7.26 (m, 1H), 4.51 (s, 2H),
3.90 (q, J = 6.5 Hz, 1H), 3.84–3.79 (m, 1H), 3.67–3.63 (m, 1H), 3.57–3.52 (m,
1H), 1.94 (dd, J = 13.4, 6.9 Hz, 2H), 1.27 (d, J = 5.9 Hz, 3H), 1.24–1.21 (m, 1H),
0.89 (dd, J = 8.4, 5.0 Hz, 1H), 0.05 (s, 9H), 0.02 (s, 9H); 13C NMR (500 MHz,
CDCl3) d 138.6, 128.3, 127.7, 127.5, 79.4, 76.8, 73.1, 69.0, 34.9, 33.9, 33.6, 22.3,
12. For a discussion of the mechanism for the formation of 1,3-dienes, see: Ref. 1.
13. See Ref. 4.