p-Toluenesulfonic acid (PTSA or pTsOH)

Methanol

Triethyl amine

A solution of (1R)-1-((3aS,6S,6aS)-6-methoxy-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-yl)allyl methanesulfonate (250mg, 0.81 mmol) in anhydrous methanol (5 mL) was degassed and kept under an atmosphere of argon or dinitrogenbefore addition of p-TSA (70 mg, 0.40 mmol). The solution was heated to reflux at 90^°C for 70-72 hrs. After the conversion was complete as indicated by TLC (50% ethyl acetate in petroleum ether), the reaction mixture was cooled to room temperature and treated with triethylamine (approx. 2-3 mL). The solvent was evaporated under reduced pressure. Purification by column chromatography (30-60% ethyl acetate in petroleum ether as eluent) gave (2S,3S,4S,5S)-2-(dimethoxymethyl)-5-vinyltetrahydrofuran-3,4-diol (120 mg, 72%).

Methanol used for reaction is freshly dried by using given procedure – (D. Bradley, G. Williams and M. Lawton, J. Org. Chem., 2010, 75, 8351-8354; DOI: 10.1021/jo101589h).

¹H NMR (200 MHz, CDCl₃) δ: 2.27 (d, J = 3.0 Hz, 1H), 3.34 (d, J = 9.7 Hz, 1H), 3.49 (s, 3H), 3.54 (s, 3H), 3.82–3.90 (m, 2H), 4.30 (bs, 1H), 4.42 (d, J = 3.5 Hz, 1H ), 4.46–4.50 (m, 1H), 5.29 –5.35 (m, 1H), 5.36–5.46 (m, 1H), 6.05 (ddd, J = 17.4, 10.6, 6.6 Hz, 1H).

¹³C NMR (50 MHz, CDCl₃)δ: 56.2 (CH₃), 57.7 (CH₃), 77.9 (CH), 78.2 (CH), 82.9 (CH), 85.7 (CH), 105.0 (CH), 118.9 (CH₂), 132.7 (CH) ppm.

R. S. Patil, K. M. Ahire and C. V. Ramana, Tetrahedron Lett., 2012, 53, 6347-6350 DOI: 10.1016/j.tetlet.2012.09.015