Journal ArticleDOI
Synthesis of 2-Substituted Benzofurans and Indoles Using Functionalized Titanium Benzylidene Reagents on Solid Phase
Calum Macleod,Gordon J. McKiernan,Emma J. Guthrie,Louis J. Farrugia,Dieter Hamprecht,Jackie Macritchie,Richard C. Hartley +6 more
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Titanium(IV) benzylidenes bearing a masked oxygen or nitrogen nucleophile in the ortho position were generated from thioacetals, using low-valent titanocene complex, Cp2Ti[P(OEt)3]2.Abstract:
Titanium(IV) benzylidenes bearing a masked oxygen or nitrogen nucleophile in the ortho position were generated from thioacetals, using low-valent titanocene complex, Cp2Ti[P(OEt)3]2. Methylene acetal, alkyl ether, silyl ether, fluoro, tertiary amino, and N-alkyl, N-benzyl, N-prenyl, and N-silyl tert-butyl carbamate groups were tolerated in the titanium alkylidene reagents (Schrock carbenes). Aryl−chlorine bonds were stable to the titanium benzylidene functionality, but there was poor chemoselectivity for the reduction of the thioacetal in the presence of an aryl chloride. The titanium benzylidenes converted Merrifield and Wang resin-bound esters into enol ethers. The oxygen nucleophile was masked as a TMS ether, and when the resin-bound enol ethers bearing this ortho substituent were treated with 1% TFA in dichloromethane, benzofurans were released from resin in high yields. The chameleon catch strategy ensured excellent purity. In a similar way, N-alkylated and N-silylated tert-butyl carbamates were used...read more
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Solid-phase synthesis of biologically active benzoannelated nitrogen heterocycles: an update.
Carmen Gil,Stefan Bräse +1 more
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A Practical and Chemoselective Reduction of Nitroarenes to Anilines Using Activated Iron
TL;DR: In this paper, the reduction of nitroarenes to anilines using activated iron generated by Fe/HCl or Zn/FeSO 4 was described, and a variety of functional groups such as alkyne, ketone, enone, nitrile, lactone, and aromatic halide were well tolerated under these conditions.
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Phosphane-Free Green Protocol for Selective Nitro Reduction with an Iron-Based Catalyst
TL;DR: In the present study, dinitro compounds have been regioselectively reduced to the corresponding amines with high yield and the conversion and selectivity was greater than 99% as determined by GC-MS analysis.
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Copper‐Catalyzed N‐Arylation/Hydroamin(d)ation Domino Synthesis of Indoles and its Application to the Preparation of a Chek1/KDR Kinase Inhibitor Pharmacophore
TL;DR: The broad scope of this domino N-arylation/hydroamin(d)ation process is highlighted by the synthesis of highly functionalized indoles, as well as of a Chek1/KDR inhibitor pharmacophore.
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Trans Influence on the Rate of Reductive Elimination. Reductive Elimination of Amines from Isomeric Arylpalladium Amides with Unsymmetrical Coordination Spheres
TL;DR: Variation of the aryl group at the amido nitrogen showed systematically that complexes with more electron-donating groups at nitrogen undergo faster reductive elimination than those with less electron- Donating Groups at nitrogen.
References
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Olefin homologation with titanium methylene compounds
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p-alkoxybenzyl alcohol resin and p-alkoxybenzyloxycarbonylhydrazide resin for solid phase synthesis of protected peptide fragments.
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The Preparation of Merrifield‐Resins Through Total Esterification With Cesium Salts
TL;DR: The reaction of chloromethylated polystyrene-co-1%-divinylbenzene resin with the cesium salts of N-protected amino acids proceeds fast and without side reactions to give Nprotected amino acyl resin esters free of quaternary ammonium sites or reactive chloride as discussed by the authors.