Tandem Inter [4 + 2]/Intra [3 + 2] Cycloadditions of Nitroalkenes. The Bridged Mode (β-Tether)
作者:Scott E. Denmark、Julie A. Dixon
DOI:10.1021/jo9802168
日期:1998.9.1
A new variation of the tandem inter [4 + 2]/intra [3 + 2] cycloaddition of nitroalkenes has been developed. This method involves the Lewis acid-promoted [4 + 2] cycloaddition of nitro olefins 12 with 1-alkoxy-1,4-dienes 3. The resulting nitronates 13, bearing a C(5) tethered dipolarophile, undergo thermal, intramolecular [3 + 2] cycloaddition to afford stable tricyclic nitroso acetals 14, which can
已开发出硝基烯烃串联[4 + 2] /内部[3 + 2]环加成的新变体。此方法涉及路易斯酸促进硝基烯烃12与1-烷氧基-1,4-二烯3的路易斯酸促进的[4 + 2]环加成反应。所得的含C(5)系双极性亲和剂的硝酸盐13经历热的分子内作用[3] +2]环加成得到稳定的三环亚硝基缩醛14,随后可以将其还原以揭示新的碳环16。因此,在三个步骤中,可以高产率立体选择性地构建高度官能化的氨基环戊烷。