使用简单的β-酮酯作为底物开发了一种合成氰基甲酸酯的新方案。(二乙氨基)三氟化硫 (DAST) 用作双重作用试剂以激活肟部分并提供氟化物。关键中间体,α -oximino- β酮酯中,通过高效的酸辅助肟化制备β酮酯。然后,证明了通过氟化 C C 键断裂对α-肟基-β-酮酯的解构提供了氰甲酸酯。在这种情况下,氟化物添加后 CC 键断裂选择性地发生在酮中而不是酯中。由于简单和温和的反应条件,举例说明了各种功能化的氰基甲酸酯。
transesterification reaction has been developed which affords various types of esters under very mild conditions. The reaction was applied to the stereo- and regioselective synthesis of trisubstituted α,β-unsaturatedcarboxylicacids.
Diastereoselective 1,3-dipolar cycloaddition of nitrilimines to γ-oxygenated α,β-unsaturated enones and esters
作者:Lutz Grubert、Guido Galley、Michael Pätzel
DOI:10.1016/0957-4166(96)00119-x
日期:1996.4
stereochemical outcome of the 1,3-dipolarcycloaddition of nitrilimines to γ-oxygenated α,β-unsaturated enones and esters was investigated. By means of X-ray and NMR analysis the main diastereomers were assigned as the syn-derivatives. Novel enantiomerically pure nitrilimines were included in the investigations but did not influence the stereochemical course of the cycloaddition significantly.
A Facile and Selective Procedure for Transesterification of β-Keto Esters Promoted by Yttria-Zirconia Based Lewis Acid Catalyst
作者:Pradeep Kumar、Rajesh Kumar Pandey
DOI:10.1055/s-2000-6496
日期:2000.2
An yttria-zirconia based strong Lewis acid efficiently catalyses the transesterification of β-keto esters under environmentally safe, heterogeneous reaction conditions with high selectivity and in good to excellent yields.
α-Iodo-α,β-Unsaturated Ketones as Vicinal Dielectrophiles: Their Reactions with Dinucleophiles Provide New Annulation Protocols for the Formation of Carbo- and Heterocyclic Ring Systems
作者:Yu Chen、Michael G. Gardiner、Ping Lan、Martin G. Banwell
DOI:10.1021/acs.joc.2c00383
日期:2022.5.6
α-Iodo-α,β-unsaturated ketones such as compound 1 serve as vicinal dielectrophiles and react with a range of dinucleophiles including pentane-2,4-dione and 1,3-indandione to produce [3 + 2]- and [2 + 1]-adducts such as 5 and 38, respectively. [4 + 2]- and [5 + 2]-cycloadducts have been obtained from compound 1 by related means. Preliminary studies reveal that α-iodinated α,β-unsaturated esters can
Insights for diastereoselectivity in synthesis of 2,3-dihydropyrroles by photochemical ring contraction of 1,4-dihydropyridines
作者:Shijie Wang、Huiqin Wang、Nana Tian、Hong Yan
DOI:10.1016/j.tetlet.2020.152797
日期:2021.2
into the photoreactive substrate 1,4-dihydropyridines, an interesting diastereoselectivity of 2,3-dihydropyrroles in the process of photochemical ring contraction was observed. The diastereoselectivity of (2R,3R) and (2S,3S)-2,3-dihydropyrroles was related to the phenyl group and the chirality of C-4 in 1,4-dihydropyridines and similar to that of 1,4-dihydropyridines. The yields and diastereomeric excess