Phosphate → (2R,3R)-3-[t-Butyldimethylsilyloxy)-2-methylhexanal

Temperatur

-42 °C

This is a representative procedure for the rearrangement of epoxy alcohols with trialkylsilyl trifluoromethanesulfonates. Epoxy alcohol 15 (74.3 mg, 0.4647 mmol) was dissolved in 4.0 ml of CH2Cl2, treated with 100 mg of 4 Å powdered molecular sieves, DIPEA (129 μl, 0.7419 mmol, 1.3 eq) and cooled to -42° C. TBSOTf (157.2 μl, 0.6849 mmol, 1.3 eq) was then added drop wise and stirred for 80 min at which time the solution was poured onto 20 ml of Et2O and shaken with 5 ml of pH 5.5 phosphate buffer. The layers were separated and the aqueous phase extracted with Et2O (2×5 ml ). The combined organic phases were washed with H2O (3×2 ml), 5% NaHCO3 (2×2 ml), brine (1×2 ml), dried over MgSO4 and the solvent evaporated to yield 132.0 mg of aldehyde 16 (slight contamination of silanol, 95%+yield). 1H NMR (CDCl3, 360. 134 MHz) δ:9.67 (1H, d, J=2.35 Hz), 3.89 (1H, q, J=5.40 Hz), 2.44 (1H, qdd, J=7.02, 5.40, 2.35 Hz), 1.5-1.3 (4H, m), 1.02 (3H, d, J=7.02 Hz), 0.86 (3H, t, J=7.31 Hz), 0.82 (9H, s), 0.01 (3H, s,), and -0.01 (3H, s). 13C NMR (CDCl1 90.55 MHz) δ:205.0, 73.2, 51.1, 37.0, 25.6, 18.01, 17.99, 14.2, 10.3, -4.3 , and -4.8. IR (thin film): 2959 (s), 2934 (s), 2859 (s), 1727 (s), 1472 (s), 1464 (s), 1362 (m), 1256 (s), 1125 (s), 1090 (s), 1074 (s), 1038 (s), 1007 (m), 889 (w), 837 (s), and 775 (s) cm-1. High resolution MS (m/z): 187.1161, calcd for C9H19O2Si 187.1154 (M-C4H9). [α]D =-18.4° (c=1.43, CH2Cl2). 1H NMR integration of δ 3.89 and the contaminating diastereomer at δ 3.89 and the contaminating diastereomer at δ 4.05 indicated a 20:1 ratio.

1. additiontreated with 100 mg of 4 Å
2. customThe layers were separated
3. extractionthe aqueous phase extracted with Et2O (2×5 ml )
4. washThe combined organic phases were washed with H2O (3×2 ml), 5% NaHCO3 (2×2 ml), brine (1×2 ml)
5. dry with materialdried over MgSO4
6. customthe solvent evaporated

ORD-Eintrag

ord-2b4b558bcc844b5a87c62bab6fae111c

Quelldatensatz

uspto-grants-1995_06

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US05426206