反应详情

Triphenylphosphine (11.1 g) was added to a solution of the subtitle product of step ii) (5.0 g) in DCM (200 ml) followed by the portionwise addition of carbon tetrabromide (14.0 g). The reaction was stirred for 4 h before the addition of further triphenylphosphine (2.0 g) and carbon tetrabromide (2.0 g) and stirring maintained for 1 h. The mixture was concentrated to 30 ml volume and diluted in Et2O (300 ml). The solid precipitate was filtered and washed with Et2O (3×) and the filtrate concentrated in vacuo. The residue was purified by column chromatography (10% Et2O/iso-hexane) to afford the subtitle compound as a clear oil. Yield: 5.2 g.

1. temperaturemaintained for 1 h
2. concentrationThe mixture was concentrated to 30 ml volume
3. additiondiluted in Et2O (300 ml)
4. filtrationThe solid precipitate was filtered
5. washwashed with Et2O (3×)
6. concentrationthe filtrate concentrated in vacuo
7. customThe residue was purified by column chromatography (10% Et2O/iso-hexane)