Synthesis of naturally occurring bioactive butyrolactones: maculalactones A–C and nostoclide I
作者:Anirban Kar、Sanjib Gogoi、Narshinha P. Argade
DOI:10.1016/j.tet.2005.03.065
日期:2005.5
Starting from citraconic anhydride (13), a simple multistep (9–10 steps) synthesis of naturally occurring butyrolactones maculalactone A (3), maculalactone B (1), maculalactone C (2) and nostoclide I (4) have been described with good overall yields via dibenzylmaleic anhydride (20) and benzylisopropylmaleic anhydride (27). The two anhydrides 20 and 27 were prepared by SN2′ coupling reactions of appropriate
从柠康酸酐(13)开始,已描述了天然丁酸内酯简单的多步合成(9-10个步骤)甲壳酸内酯A(3),甲壳酸内酯B(1),甲壳内酯C(2)和诺司特灵I(4)。通过二苄基马来酸酐(20)和苄基异丙基马来酸酐(27)的总收率。通过适当的Grignard试剂与溴代富马酸二甲酯(14的S N 2'偶联反应)制备两种酸酐20和27),LiOH诱导的酯水解为酸,碳-碳双键溴化,原位脱水,然后脱氢溴化,并用合适的格氏试剂在二取代酸酐19和26中对溴原子进行化学选择性烯丙基取代。这些酸酐20和27的NaBH 4还原分别提供了所需的内酯21和29。内酯21在Knoevenagel与苯甲醛缩合,得到了马来酸内酯B(1),异构化后得到了马来酸内酯C(2)。1的选择性催化加氢得到了黄酮内酯A(3)。内酯29到诺司肽I(4)的转化是已知的。