Modified aza-claisen rearrangement: Generation and isomerization of allyl enammonium salts
作者:John C Gilbert、K.P.A Senaratne
DOI:10.1016/s0040-4039(01)80240-9
日期:1984.1
Base-promoted reaction of ketones and diethyl (diazomethyl)phosphonate in the presence of allylic amines affords allylic enamines in good yields. These enamines undergo [3,3]-sigmatropic rearrangement upon alkylation and heating at 80°C to iminium salts which can be hydrolysed to aldehydes. The procedure allows generation of quaternary carbon centers under mild reaction conditions.
Memory of Chirality in the Asymmetric Synthesis of Piperidines with Vicinal Stereocenters by Intramolecular S
<scp>n</scp>
2′ Reaction
作者:Seungbae Park、Seokwoo Lee、Jae Hyun Kim、Won Jun Choi、Sanghee Kim
DOI:10.1002/asia.202100669
日期:2021.10.18
By using memory of chirality and the Thorpe-Ingold effect, we developed an efficient method of intramolecular Sn2′ cyclization of α-amino ester enolates, providing asymmetric multisubstituted piperidine derivatives. DFT calculations provided a mechanistic rationale for increasing the degree of chirality preservation of gem-disubstituted substrates.
通过使用手性记忆和 Thorpe-Ingold 效应,我们开发了一种有效的 α-氨基酯烯醇化物分子内 S n 2' 环化方法,提供不对称多取代哌啶衍生物。DFT 计算为增加宝石二取代底物的手性保留程度提供了机械原理。
Palladium-Catalyzed Trans-Selective Synthesis of Spirocyclic Cyclobutanes Using α,α-Dialkylcrotyl- and Allylhydrazones
作者:Isaiah K. Eckart-Frank、Sidney M. Wilkerson-Hill
DOI:10.1021/jacs.3c05699
日期:2023.8.23
vinylcyclobutanes in a diastereoselective fashion. We show 24 examples of a 1,1-insertion/4-exo-trig tandem process to produce these motifs. Additionally, spirocyclic alkylidene cyclobutanes can be obtained by using α,α-disubstituted allylated hydrazones (11 examples). In this study, we show that the aryl migrating group has a dramatic impact on the course of the reaction. Specifically, allylic C–H insertion