maculalactone B 在
palladium on activated charcoal 氢气 作用下,
以
乙酸乙酯 为溶剂,
20.0 ℃
、448.16 kPa
条件下,
反应 16.0h,
以75%的产率得到2,3,4-tribenzyl-γ-butyro-2-en-lactone
参考文献:
名称:
天然存在的生物活性丁内酯的合成:黄酮内酯A–C和Nostoclide I
摘要:
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。
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。
Total synthesis of (±) maculalactone A, maculalactone B and maculalactone C and the determination of the absolute configuration of natural (+) maculalactone A by asymmetric synthesis
作者:Geoffrey D Brown、Ho-Fai Wong
DOI:10.1016/j.tet.2004.04.060
日期:2004.6
inexpensive starting materials. Maculalactones B and C were synthesized by a minor modification to this procedure, and the synthetic design also permitted an asymmetric synthesis of maculalactone A to be achieved in around 85% ee. The (+) and (−) enantiomers of maculalactone A were assigned, respectively, to the S and R configurations on the basis of the chiral selectivity expected for catecholborane reduction
Modified Julia Olefination on Anhydrides: Extension and Limitations. Application to the Synthesis of Maculalactone B
作者:Nicolas Dussart、Huu Vinh Trinh、David Gueyrard
DOI:10.1021/acs.orglett.6b02160
日期:2016.10.7
esters from cyclic anhydrides is reported using a modifiedJuliaolefination. The reaction is highly stereoselective. The Smiles rearrangement can be performed in a one-pot process, giving a straightforward access to exo-enol lactones. Furthermore, the reaction was extended to semistabilized sulfones, and this methodology was applied to the synthesis of maculalactone B.