通过串联 8/9-endo-二氢和 8-exo-二氢烷氧基化-形式-[4 + 2]环加成反应，快速实现了中环杂环稠合色烯的立体选择性合成。
Expeditious diastereoselective synthesis of medium ring heterocycle-fused chromenes via tandem 8/9-endo-dig and 8-exo-dig hydroalkoxylation-formal-[4 + 2] cycloaddition.
机构信息
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India.
出版信息
Org Biomol Chem. 2019 Oct 9;17(39):8806-8810. doi: 10.1039/c9ob02030f.
The first examples of highly diastereoselective tandem 8/9-endo-dig and 8-exo-dig hydroalkoxylation-formal-[4 + 2] cycloaddition are described for the synthesis of medium ring heterocycle-fused chromenes. TMS-alkynols preferred the exo-dig mode of hydroalkoxylation over the endo-dig mode leading to spiro-cyclic chromenes. The method could be used for the synthesis of linearly-fused ladder-like polyethers. A thia-heterocycle-fused chromene could be transformed into a complex bridged tricyclic ketal by a tandem carbene-insertion-[2,3]-sigmatropic shift.
本文首次报道了高非对映选择性串联 8/9-endo-和 8-exo-氢烷氧基化-形式-[4 + 2]环加成反应，用于合成中环杂环稠合色烯。TMS-炔醇优先选择 exo-氢烷氧基化模式而不是 endo-氢烷氧基化模式，从而生成螺环色烯。该方法可用于合成线性稠合梯形聚醚。一个硫杂杂环稠合色烯可以通过串联卡宾插入-[2,3]-σ迁移转化为复杂桥连三环缩酮。
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