Diels−Alder Reaction−Aromatization Approach toward Functionalized Ring C Allocolchicinoids. Enantioselective Total Synthesis of (−)-7<i>S</i>-Allocolchicine
作者:Andrei V. Vorogushin、Alexander V. Predeus、William D. Wulff、Hans-Jürgen Hansen
DOI:10.1021/jo034420t
日期:2003.7.1
reported for the synthesis of ring C functionalized allocolchicinoids, which is based on a Diels-Alder reaction-aromatization sequence. This route is complementary to the previously disclosed benzannulation approach involving Fischer carbene complexes and alkynes. Dienes 12 and 14 incorporate the natural substitution pattern on ring A and undergo Diels-Alder reactions with various dienophiles. Subsequent
异古龙碱类化合物是重要的抗有丝分裂化合物(-)-秋水仙碱1的类似物。已报道了一种基于Diels-Alder反应-芳香化序列合成C环官能化的allocchichicinoids的策略。该途径是先前公开的涉及Fischer卡宾配合物和炔烃的苯环化方法的补充。二烯12和14在环A上掺入天然取代图案,并与各种亲二烯体进行Diels-Alder反应。随后的芳构化提供了一组不同功能的环C allocchichicinoids 15-19、23和25,具有较高的区域选择性和中等至良好的产率。分子内Diels-Alder反应-芳香化序列可通过逆向区域化学引入C环取代基来接近二十碳五烯类化合物。在三种NMR溶剂中研究了15和19的阻转异构体的平衡。二烯12和14与DMAD的反应导致相应的环加合物,但是随后的芳构化是复杂的。区域选择性Diels-Alder反应-芳香化序列被用作(-)-allocolchicine