Direct synthesis of methyl 2-diazo-4-aryl-3-butenoates and their application to the enantioselective synthesis of 4-aryl-4-(1-naphthyl)-2-butenoates
摘要:
An improved one-flask synthesis of various methyl 2-diazo-4-aryl and 4-heteroaryl-3-butenoates, precursors to donor/ acceptor Substituted carbenoids, is described. Their Rh-2(S-DOSP)(4) catalyzed reaction with 1-acetoxy-3,4-diliydronaphthalene, via a combined C-H activation/Cope rearrangement pathway followed by elimination of acetic acid affords a highly enantioselective (98-99% ee) entry to methyl 4-aryl- and 4-heteroaryl-4-(1-naphthyl)-2-butenoates. (c) 2006 Elsevier Ltd. All rights reserved.
Operationally Simple and Highly (<i>E</i>)-Styrenyl-Selective Heck Reactions of Electronically Nonbiased Olefins
作者:Erik W. Werner、Matthew S. Sigman
DOI:10.1021/ja203164p
日期:2011.6.29
Simple, mild, and efficient conditions are reported for a Pd(0)-catalyzed Heck reaction that delivers high yields and selectivity for (E)-styrenyl products using electronically nonbiased olefin substrates bearing a range of useful functionality. Preliminary mechanistic studies demonstrate that the σ-donating DMA solvent is crucial for high selectivity. Further studies suggest that the catalyst distinguishes
<i>p</i>
-Cymene as Solvent for Olefin Metathesis: Matching Efficiency and Sustainability
作者:Artur V. Granato、Alexandra G. Santos、Eduardo N. dos Santos
DOI:10.1002/cssc.201700116
日期:2017.4.22
The underexploited biorenewable p‐cymene is employed as a solvent for the metathesis of various substrates. p‐Cymene is a nontoxic compound that can be obtained in large amounts as a side product of the cellulose and citrus industry. For the cross‐metathesis of estragole with methylacrylate, this solvent prevents the consecutive double‐bond isomerization of the product and affords the best yield of
aliphatic alcohols (also as solvent) allow to produce useful α,β-unsaturatedesters in good to excellent yields at 70 °C. Efficient regioselectivity could be controlled in the presence of N-ligands while the P-ligands had no influence on the conversion of substrates and the chemo/regioselectivity of target products. By involving N-ligand 4,7-dimethyl-1,10-phenanthroline in the catalytic system, α,β-unsaturated