다음, 반응 혼합물로 용매를 증류제거한 다음, 컬럼 크로마토그래피로 정제하여 화합물 4 (6.08 g)을 얻는다.
Then, the solvent is removed from the reaction mixture by distillation and the resultant is purified with a column chromatography to obtain Compound 4 (6.08 g).