Electrocyclic Ring-Opening/π-Allyl Cation Cyclization Reaction Sequences Involving <i>g</i><i>em</i>-Dihalocyclopropanes as Substrates: Application to Syntheses of (±)-, (+)-, and (−)-γ-Lycorane
作者:Martin G. Banwell、Joanne E. Harvey、David C. R. Hockless、Angela W. Wu
DOI:10.1021/jo991791u
日期:2000.7.1
to give the saturated analogue (+/-)-24, which undergoes Bischler-Napieralski cyclization on reaction with phosphorus oxychloride. The resulting lactam (+/-)-25 is then reduced with lithium aluminum hydride to give (+/-)-gamma-lycorane [(+/-)-1]. By using (-)-menthyl-derived carbamates 27 and 28, this chemistry has been extended to the synthesis of the (+)- and (-)-modifications of the title compound
容易制备的宝石-二溴环丙烷(+/-)-13和(+/-)-19各自参与银(I)促进的电环开环/π-烯丙基阳离子环化序列以提供六氢吲哚(+/- )-20,其与芳基硼酸3参与Suzuki交叉偶联反应,得到四环化合物(+/-)-21。最后一种化合物的催化加氢反应以完全立体选择性的方式进行,得到饱和的类似物(+/-)-24,该类似物在与三氯氧化磷反应后经历Bischler-Napieralski环化反应。然后将所形成的内酰胺(+/-)-25用氢化锂铝还原,得到(+/-)-γ-二十二烷[[+/-]-1]。通过使用(-)-薄荷基氨基甲酸酯27和28,该化学反应已扩展到标题化合物的(+)-和(-)-修饰的合成。