min. Aromatic aldehydes or ketones with electron-donating substituents at the ortho or para position increased the yield of the corresponding dithianes, while electron-withdrawing group decelerated the reaction. Aldehydes were easier to protect than ketones, and aliphatic ketones were also more readily protected than aromatic ketones. The protection was highly selective towards an aldehyde compared to
图形摘要摘要在没有催化剂的情况下,在紫外线照射下用
1,3-丙二硫醇保护
对茴香醛,在 20 分钟内产生 87% 的
1,3-二噻烷。添加六
溴丙酮进一步缩短了反应时间,紫外线照射也加速了二噻烷的形成,仅在 1 分钟内就产生了 95% 的
1,3-二噻烷。在邻位或对位具有给电子取代基的芳香醛或酮增加了相应二噻烷的产率,而吸电子基团则使反应减速。
醛类比
酮类更容易保护,脂肪族酮也比
芳香族酮更容易保护。与酮相比,该保护对醛具有高度选择性。