... Tetrahedron. Volume 56, Issue 49, 1 December 2000, Pages 9633–9640. ... mmol) and DMAP (7 mg, 0.06 mmol) in CH 2 Cl 2 (5 mL) gave the crude product which was purified by chromatography (4:1 hexane–EtOAc) to give alkene 5f (72 mg, 78%) as white crystals, mp 56– ...