3,4-dihydro-2H-pyran → 5-Bromo-2-propyl-4-(((2-tetrahydropyranyl)oxy)methyl)oxazole

Participants

Reaction Steps

To a solution of 1.96 g (8.91 mmol) of the compound from step 29b in 55 mL of methylene chloride at room temperature were sequentially added 7 mL of 3,4-dihydro-2H-pyran (76.7 mmol) and 1 g (3.98 mmol) of PPTS. The reaction was stirred at room temperature for 20 min, 30 mL of satd. NaHCO3 was added, and the mixture was stirred for 5 min. The organic layer was separated, and the aqueous layer was extracted with 2×50 mL of methylene chloride. The organics were combined, dried over MgSO4 and concentrated. The residue was purified by flash chromatography on silica gel, eluting with 10-30% ethyl acetate in hexane, to afford, after removal of the solvent and drying, 2.70 g (100% yield) of the title product as a colorless oil. NMR (CDCl3) δ:4.75 (t, J=3 Hz, 1H), 4.57 and 4.33 (ABq, J=12 Hz, 2H), 3.93 (m, 1H), 3.56 (m, 1H), 2.72 (t, J=8 Hz, 2H), 190-1.48 (m, 8H), 1.00 (t, J=8 Hz, 3H).

Provenance & Evidence