2024-03-28T21:22:03Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/387522022-11-17T02:08:08Zhdl_2115_20044hdl_2115_124Asymmetric approach to the pentacyclic skeleton of Aspidosperma alkaloids via enantioselective intramolecular 1,3-dipolar cycloaddition of carbonyl ylides catalyzed by chiral dirhodium(II) carboxylatesNambu, HisanoriHikime, MayukaKrishnamurthi, JanagiramanKamiya, MegumiShimada, NaoyukiHashimoto, ShunichiCarbonyl ylides1,3-Dipolar cycloadditionsChiral dirhodium(II) carboxylatesVindorosine499This paper describes asymmetric tandem carbonyl ylide formation-intramolecular 1,3-dipolar cycloaddition reaction of diazo imides containing a tethered indole catalyzed by chiral dirhodium(II) carboxylates as an approach to the pentacyclic skeleton of Aspidosperma alkaloids. The cycloaddition of carbonyl ylides derived from indolyl-substituted 2-diazo-5-imido-3-ketoesters under the influence of dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate], Rh2(S-TCPTTL)4, provides cycloadducts in moderate yields and enantioselectivities of up to 66% ee as well as with perfect endo diastereoselectivity. This is the first example of asymmetric induction in an intramolecular cycloaddition of a carbonyl ylide across an indolyl π-bond.Elsevier Ltd.Journal Articleapplication/pdfhttp://hdl.handle.net/2115/38752https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/38752/1/50-26_p3675-3678.pdf0040-4039Tetrahedron Letters5026367536782009-07-01enginfo:doi/10.1016/j.tetlet.2009.03.142author