Nitrogen → HCID 131735722, compound

Participants

Reaction Conditions

Reaction Steps

Neutral alumina (15 g) was heated in a flask at 180° C. under high vacuum for 4 h. After cooling down to room temperature, the flask was filled with N2. Compound 31 (7.2 g, 25.5 mmol), 1,7-octadien-3-one (4.3 g, 30 mmol), and CH2Cl2 (30 mL) were added to the anhydrous alumina at room temperature. The mixture was stirred at room temperature for 16 h. The suspension was filtered through Celite® 545 which was washed with CH2Cl2 (100 mL×3). The solvent was removed under reduced pressure and the residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 32 (9.4 g, 91%). The compound is a mixture of diastereomers at position C-5 in a 3 to 1 ratio. The major diastereomer had: 1H NMR (CDCl3) δ 5.72-5.60 (m, 1H), 4.95-4.86 (m, 2H), 3.64 (s, 3H), 3.35 (t, J=7.1 Hz, 1H), 1.05 (s, 9H), 0.75 (s, 3H); 13C NMR (CDCl3) δ 209.5, 208.0, 173.7, 137.8, 115.0, 79.9, 72.4, 56.2, 52.2, 46.9, 45.5, 42.4, 42.1, 41.7, 38.1, 32.9, 31.3, 30.5, 28.6, 28.4, 25.5, 22.6; IR νmax 1714, 1641, 1435 cm−1. Anal. Calcd for (C24H38O5): C, 70.90; H, 9.42. Found: C, 71.16; H, 9.70.

Provenance & Evidence