Organolithium-Induced Synthesis of Unsaturated Diols from Epoxides of Dihydrofurans and Dihydropyrans; 4-(Trimethylsilyl)-3-methylenebutane-1,2-diolSyntheticPage 196 (2002)
Submitted 25th Mar 2002, published 26th Mar 2002
A contribution from the Hodgson Group, Oxford
3,4-Epoxytetrahydrofuran (Tetrahedron, 1993, 49, 6263-6276)
(Trimethylsilyl)methyllithium (1.0 M in pentane, Aldrich)
Tetrahydrofuran (distilled from sodium benzophenone)
A solution of 3,4-epoxytetrahydrofuran (80 mg, 930 mmol) in THF (5 mL) cooled to –78 °C is treated dropwise with TMSCH2Li (2.3 mL, 2.3 mmol, 2.5 eq.). After stirring at –78 °C for 1 h and then at 25 °C for 1 h, phosphate buffer (pH 7, 5 mL) was added. The mixture was extracted with EtOAc (2 x 10 mL), the combined organic layers dried (MgSO4), filtered and concentrated under reduced pressure. Purification of the residue by column chromatography (SiO2, 3 : 1 Et2O : 40 - 60 °C petrol) gave the product as a colourless oil (0.12 g, 73%).
For optimal yields both the epoxide (distillation, boiling point: 65 °C / 45 mmHg) and THF need to rigorously dried prior to use, all glassware should be flame dried and needles and syringes should be purged with argon. Analogous procedures have been successfully conducted on up to a 5 mmol scale with no reduction in yield.
Rf 0.25 (3 : 1 Et2O : 40 - 60 °C petrol).
1H NMR (400 MHz, CDCl3) 4.83 (s, 1 H, C=CH2), 4.59 (s, 1 H, C=CH2), 3.91 - 3.86 (m, 1 H, C(2)-H), 3.57 - 3.50 (m, 1 H, C(1)-H), 3.34 - 3.20 (m, 3 H, C(1)-H and 2 x OH), 1.46 (d, 1 H, J = 14.0 Hz, C(4)-H), 1.21 (d, 1 H, J = 14.0 Hz, C(4)-H), –0.12 (s, 9 H, TMS).
13C NMR (100 MHz, CDCl3) 146.0 (C(3)), 108.2 (C=CH2), 75.6 (C(2)), 65.5 (C(1)), 23.3 (C(4)), –1.5 (TMS).
D. M. Hodgson, M. A. H. Stent and F. X. Wilson, Org. Lett., 2001, 3401 – 3403.
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