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D-A环丙烷在Lewis酸的活化作用下,形成l,3-两性离子中间体,可以发生[3+n]形式环加成反应构建多元碳(杂)环、并环结构,已成为有机反应中一类重要的合成砌块.利用Cu(Ⅱ)/BOX为催化剂,首次实现了吲哚与四取代D-A环丙烷的[3+2]环化反应,抑制了最常见的傅一克反应副产物,以最高91％的产率和＞20/1的非对映选择性,简单高效、原子经济性地构建了吲哚并五元碳环结构骨架,在五元环上可以一次性引入三个季碳中心.对含有不同取代基的吲哚、色胺、色醇及各类四取代D-A环丙烷都能取得很好的结果,为一些天然产物核心骨架的构建提供了新的方法.“,”D-A cyclopropanes have emerged as versatile synthons for construction of carbocycles and heterocycles via a [3 +2] annulation reactions,and have been used in the total synthesis of natural products.Recently,it has been witnessed tremendous progress within the area of transformation of 2-monosubstituted-cyclopropane-l,l-diesters.However,cyclopropane-1,l-diesters with full substitution at the donor site have not been well explored.C2,C3-fused indolines are widely existed in a plenty of natural products and biologically active compounds,and have been the synthetic targets for decades.Among the various approaches to access these important structural motifs,the cyclopentannulation of indoles with Donor-Acceptor (D-A) cyclopropanes,represents a concise,economical and effective method.Previously,we have developed a highly diastereo-and enantioselective BOX/Cu(Ⅱ) catalyzed C2,C3-cyclopentannulation of indoles with 2-monosubstituted-cyclopropane-l,l-diesters,a facile access to a series of enantioenriched cyclopenta-fused indoline products.As our further studies,Lewis acid catalyzed [3+2] annulation of indoles with 1,1,2,2-tetrasubstituted D-A cyclopropanes was reported in this paper.This annulation method of C3-substituted indoles with quaternary donor site D-A cyclopropanes yielded C2,C3-fused indolines,bearing three quaternary stereocentres on the newly built cyclopentane ring without the formation of the common Friedel-Crafts byproducts.The ester groups on cyclopropane,ligand,and protection group of indole have great influence on both yield and dr selectivity.Thus,the reaction between indole (1b,-NMe) and cyclopropane 2 (CO2R2=CO2CH2CF3) can give the highest yield and the best dr in the presence of 10 mol％ BOX/Cu(SbF6)2 in DCM,which is prepared in situ.Under the optimal conditions,the [3+2] annulation reacts smoothly with a wide range of substituted indole derivatives and D-A cyclopropanes,giving the desired products in up to 91％ yield with up to ＞20/1 diastereoselectivity.The relative configuration of the products is determined by X-ray crystallographic analysis of the major diastereoisomer of3b.The general experimental procedure for the [3+2] annulations is shown below:A mixture of CuBr2 (0.02 mmol),AgSbF6 (0.04 mmol),and bisoxazoline (L,0.024 mmol) in DCM (1 mL) was stirred at room temperature for 3 h under the atmosphere of nitrogen.Then,the mixture was cooled to 0 ℃ for 20 min and the cyclopropane 1 (0.2 mmol) and the indole derivative 2 (0.4 mmol) in 1 mL DCM were added to the mixture of catalyst via a syringe.After the reaction was complete (monitored by TLC),the reaction was filtered through a glass funnel with thin layer (20 mm) of silica gel (100～200 mesh) and eluted with DCM (approx 100 mL).The filtrate was concentrated under reduced pressure.After the determination of the diatereoselectivity by 1H NMR,the residue was purified by flash chromatography to afford the product 3.