A general metal-free route to 1,4-disubstituted and 1,4,5-trisubstituted 1,2,3-triazoles was developed. α-Haloacroleins reacted with organic azides in a DMSO/H2O mixture solvent at room temperature to produce 1,4-disubstituted triazoles (up to 99%) with exclusive regioselectivities. This protocol is convenient and scalable with a broad substrate scope including aliphatic and aromatic azides. The resulting
开发了一种通向1,4-二取代和1,4,5-三取代的1,2,3-三唑的无金属路线。在室温下,α-卤代丙烯醛与有机叠氮化物在DMSO / H 2 O混合溶剂中反应,生成具有区域选择性的1,4-二取代三唑(最高99%)。该协议方便且可扩展,具有广泛的底物范围,包括脂肪族和芳香族叠氮化物。所得三唑在C4位上显示醛基,并证明了其合成用途。还鉴定了一种含有非对映体质子的1,2,3-三唑化合物。
Catalytic Enantioselective [2+2] Cycloaddition of α‐Halo Acroleins: Construction of Cyclobutanes Containing Two Tetrasubstituted Stereocenters
A catalytic enantioselective formal [2+2] cycloaddition between α‐halo acroleins and electronically diverse arylalkenes is described. In the presence of (S)‐oxazaborolidinium cation as the catalyst, densely functionalized cyclobutanes containing two vicinal tetrasubstituted stereocenters were produced in high yields and high diastereoselectivities with excellent enantioselectivities. Mechanistic studies
differentiation of the asymmetric reaction space is possible by the remote control of the pentafluorophenyl group. Furthermore, we have conducted theoretical studies to clarify the roles of both intra- and intermolecular hydrogen bonds in the C1-symmetric chiral environment of chiral bis-phosphoric acid catalysts. The developed strategy, C1-symmetric catalyst design through hydrogenbonding, is potentially applicable
Chiral oxazaborolidinium ion-catalyzed asymmetric cyclopropanation of α- or α,β-substituted acroleins with α-alkyl-α-diazoesters has been developed. With this methodology, chiral functionalized cyclopropanes containing a quaternary stereogenic center were obtained with high to excellent enantioselectivities (up to >99% ee). The synthetic utility of optically enriched functionalized cyclopropane was
Catalytic Enantioselective Synthesis of 2,5-Dihydrooxepines
作者:Su Yong Shim、Soo Min Cho、Anipireddy Venkateswarlu、Do Hyun Ryu
DOI:10.1002/anie.201700890
日期:2017.7.17
addition initiated cyclopropanation/retro-Claisen rearrangement tandem reaction was developed for the enantioselectivesynthesis of highly functionalized 2,5-dihydrooxepines. In the presence of a chiral oxazaborolidinium ion (COBI) catalyst, the reaction proceeds to give good yields and high enantioselectivity.