Molecular Chirality Research Center, Synthetic Organic Chemistry, Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522 (Japan).
Department of Chemistry, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan).
Angew Chem Int Ed Engl. 2015 Oct 19;54(43):12767-71. doi: 10.1002/anie.201505748. Epub 2015 Sep 14.
A newly developed aminoiminophenoxy copper carboxylate (L7-Cu-OAc)-catalyzed asymmetric iodocyclization of N-Tosyl alkenamides gave O-cyclized products in good yields with high enantioselectivity. From the O-cyclized products, a skeletal transformation was succeeded in the synthesis of biologically important chiral 8-oxa-6-azabicyclo[3.2.1]octanes. DFT calculations suggested that the acetoxy anion of the [L7-Cu-OAc] acts as a base to generate the anion of N-Tosyl alkenamide substrates. The exchanged acetic acid reconstructs a new hydrogen-bonding network between the catalyst and the substrates to accomplish the highly efficient asymmetric O-iodocyclization of N-Tosyl alkenamides.
一种新开发的氨基酸氧代铜羧酸酯（L7-Cu-OAc）催化的 N-对甲苯磺酰烯酰胺不对称碘化环化反应，以高产率和高对映选择性得到了 O-环化产物。从 O-环化产物中，成功地进行了骨架转化，合成了具有生物重要性的手性 8-氧代-6-氮杂双环[3.2.1]辛烷。DFT 计算表明，[L7-Cu-OAc]中的乙酰氧基阴离子充当碱，生成 N-对甲苯磺酰烯酰胺底物的阴离子。交换的乙酸在催化剂和底物之间重建了一个新的氢键网络，从而实现了 N-对甲苯磺酰烯酰胺的高效不对称 O-碘化环化。
