| Title: | Asymmetric Synthesis of Spiroketals with Aminothiourea Catalysts |
| Author(s): | Yoneda N; Fukata Y; Asano K; Matsubara S; |
| Address: | "Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510 (Japan). Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510 (Japan). asano.keisuke.5w@kyoto-u.ac.jp. Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510 (Japan). matsubara.seijiro.2e@kyoto-u.ac.jp" |
| ISSN/ISBN: | 1521-3773 (Electronic) 1433-7851 (Linking) |
| Abstract: | "Chiral spiroketal skeletons are found as core structures in a range of bioactive compounds. These natural compounds and their analogues have attracted much attention in the field of drug discovery. However, methods for their enantioselective construction are limited, and easily available optically active spiroketals are rare. We demonstrate a novel catalytic asymmetric synthesis of spiroketal compounds that proceeds through an intramolecular hemiacetalization/oxy-Michael addition cascade mediated by a bifunctional aminothiourea catalyst. This results in spiroketal structures through the relay formation of contiguous oxacycles, in which multipoint recognition by the catalyst through hydrogen bonding imparts high enantioselectivity. This method offers facile access to spiroketal frameworks bearing an alkyl group at the 2-position, which are prevalent in insect pheromones. Optically active (2S,5S)-chalcogran, a pheromone of the six-spined spruce bark beetle, and an azide derivative could be readily synthesized from the bicyclic reaction product" |
| Keywords: | aminothiourea cascade reactions natural products organocatalysis spiroketals; |
| Notes: | "PubMed-not-MEDLINEYoneda, Naoki Fukata, Yukihiro Asano, Keisuke Matsubara, Seijiro eng Research Support, Non-U.S. Gov't Germany 2015/10/30 Angew Chem Int Ed Engl. 2015 Dec 14; 54(51):15497-500. doi: 10.1002/anie.201508405. Epub 2015 Oct 29" |
