基于光氧化反应的1-苯甲酰基-3,4-二氢异喹啉类生物碱Nelumstemine和Longifolonine的首次全合成

First Total Syntheses of 1-Benzoyl-3,4-dihydroisoquinoline Alkaloids Nelumstemine and Longifolonine Based on the Photo-oxidation

研究了1-苯甲酰基-3,4-二氢异喹啉生物碱的一条新的合成路线.以3,4-二甲氧基苯甲醛为起始原料,通过6步反应,以50%的总收率首次全合成得到生物碱Nelumstemine;另外,以香兰醛为起始原料,通过9步反应,以35%的总收率首次全合成得到生物碱Longifolonine.上述全合成的关键步骤为,可见光照射下1-苄基-3,4-二氢异喹啉在室温下被空气氧化为1-苯甲酰基-3,4-二氢异喹啉的反应,并对此温和的光化学反应进行了详细研究.

A novel synthetic route for the total syntheses of 1-benzoyl-3,4-dihydroisoquinoline alkaloids was developed.Nelumstemine was synthesized for the first time via 6 steps in 50%overall yield starting from 3,4-dimethoxybenzaldehyde,and longifolonine was also synthesized for the first time via 9 steps in 35%overall yield starting from vanillin.The key step of these total syntheses is photo-oxidation of 1-benzyl-3,4-dihydroisoquinolines to 1-benzoyl-3,4-dihydroisoquinolines by air under visible-light irradiation at room temperature.The unique mild photo-oxidation of 1-benzyl-3,4-dihydro-isoquinolines has been studied in detail.