Cyanophosphates (CPs) can be easily prepared from either ketones or aldehydes, and their reaction with NaN3–Et3N·HCl results in the formation of azidotetrazoles. Under microwave irradiation, successive fragmentation of the azidotetrazoles generates alkylidene carbenes that undergo [1,2]-rearrangement and are transformed into homologous alkynes. Treatment of ketone-derived CPs with TMSN3 and Bu2SnO
The Direct Conversion of α-Hydroxyketones to Alkynes
作者:Francesca Ghiringhelli、Lukas Nattmann、Sabine Bognar、Manuel van Gemmeren
DOI:10.1021/acs.joc.8b02941
日期:2019.1.18
Alkynes are highly important functional groups in organic chemistry, both as part of target structures and as versatile synthetic intermediates. In this study, a protocol for the directconversion of α-hydroxyketones to alkynes is reported. In combination with the variety of synthetic methods that generate the required starting materials by forming the central C–C bond, it enables a highly versatile
A Modular Synthesis of Functionalized Pyridines through Lewis-Acid-Mediated and Microwave-Assisted Cycloadditions between Azapyrylium Intermediates and Alkynes
conditions to furnish the expected pyridine derivatives 3k and 3l in respectable yields. The 3-bromo-substituted pyridines 11 were further functionalized through palladium-catalyzed couplings such as Suzuki or Sonogashira reactions, which led smoothly to tri- or tetrasubstituted pyridine derivatives such as 19–21 and 23. Reductive debromination of 11e afforded the pyridine 17 in excellent yield, whereas
Epimerization of <i>trans</i>‐Cycloalkenes with the X−C=C−SeR*‐Unit – The Steric Demand of X=H, F, Cl, Br, I, Me, Et and CF<sub>3</sub>
作者:Helmut Poleschner、Matthias Heydenreich、Andreas J. Achazi
DOI:10.1002/ejoc.202300838
日期:2023.11.14
The ring inversion of trans-cycloalkenes, ring sizes 9–20, investigated with temperature variable 13C NMR spectroscopy, is a highly sensitive method to characterize the steric demand of substituents: H≪F≪Cl
环尺寸为9-20 的反式环烯烃的环反转,通过温度可变13 C NMR 光谱进行研究,是一种表征取代基空间需求的高度灵敏的方法:H≪F≪Cl