Towards the Total Synthesis of Jerangolids – Synthesis of an Advanced Intermediate for the Pharmacophore Substructure

Here, we present a new strategy for the total synthesis based upon a skipped diyne as central building block. This was transformed so far into an advanced intermediate related to the pharmacophore of the jerangolids. The jerangolids are a class of natural products with a skipped diene substructure isolated from Sorangium cellulosum. Here,...

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The Cyclization of Allenyl‐Substituted Hydroxylamines to 1,2‐Oxazines: An Experimental and Computational Study

To gain a deeper understanding of the formation of the synthetically important 3,6‐dihydro‐2H‐1,2‐oxazines, the 6‐endo‐trig cyclization of allenyl‐substituted hydroxylamines was experimentally investigated in detail employing a model compound. The solvent effect was moderate with respect to the rate, but crucial to suppress side‐product formation. Surprisingly,...

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Intramolecular dehydrogenative coupling approach to 2‐oxindoles using Fe(OAc)2/NaI/Na2S2O8

Oxindole units were common structure features of natural products and drugs. A novel method for synthesizing 2‐oxindoles from 1,3‐dicarbonyl compounds based on ferrous salt and iodide catalyst was described. Using Fe(OAc) 2 /NaI/Na 2 S 2 O 8 , various 2‐alkyl‐3‐phenylamino‐3‐oxopropanoates bearing fluoro, chloro, bromo, alkyl, alkoxy, trifluoromethyl,...

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Amino Acid‐Based Dithiocarbamates as Efficient Intermediates for Diversity‐Oriented Synthesis of Thiazoles

A novel category of di‐ and tri‐substituted thiazoles were synthesized by the condensation of amino acid‐based dithiocarbamates with various reagents such as anhydrides, acyl halides, benzene sulfonyl chloride, trifluoromethanesulfonic anhydride, chloroethyl formate, and diethyl chlorophosphate. Amino acid‐based dithiocarbamates were introduced...

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Tetraaryl Cyclopentadienones: Experimental and Theoretical Insights into Negative Solvatochromism and Electrochemistry

The synthesis of a series of tetraaryl cyclopentadienones comprising different substitution patterns is reported. Their photophysical and electrochemical properties are investigated by UV/Vis spectroscopy and cyclic voltammetry as well as by supporting quantum chemical simulations and reveal a distinct effect of substituents on the redox behavior of...

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Mechanism and Regioselectivity of Intramolecular [2+2] Cycloaddition of Ene–Ketenes: A DFT Study

Intramolecular [2+2] cycloaddition of ene–ketenes gives either fused‐ring (via normal [2+2] cycloaddition) or bridged‐ring (via cross‐[2+2] cycloaddition) cyclobutanones. Herein, DFT calculations have been applied to understand the reaction mechanism. According to the relative stability of the forming internal and external carbocations in the transition...

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Conformationally restricted oxazolidin‐2‐one fused bicyclic iminosugars as potential glycosidase inhibitors

The synthesis of fused bicyclic oxazolidin‐2‐one (OZO) iminosugars was achieved through a tandem Staudinger reduction/retro‐Michael/intramolecular Michael addition from the corresponding OZO azidosugars. Those precursors, based on both aldopentofuranoses and ketofuranohexoses backbones, were obtained following alkylation and oxidation of the related...

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A Morita–Baylis–Hillman Pathway to Wittig Products: One‐Pot Transformation of Nitroalkylideneoxindoles to Oxindolylidene‐Carboxylates

Reaction of nitroalkylideneoxindoles with selected activated carbonyl compounds under Morita–Baylis–Hillman (MBH) conditions (DABCO/CH3CN) led to unexpected formation of Wittig type products. While the first two steps involve MBH pathway (Michael addition and aldol reaction), the subsequent steps in this one‐pot process are presumably intramolecular...

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Palladium‐Catalyzed Olefination of N‐Tosylhydrazones as β‐Diazo Phosphonate Precursors with Arylhalides

An efficient Pd‐catalyzed olefination of N‐tosylhydrazones as β‐diazo phosphonate precursors with aryl halides was described. A series of 2,2‐disubstituted vinylphosphonates and (2,2‐diphenylvinyl)diarylphosphine oxides were easily obtained in moderate to excellent yields. An efficient palladium‐catalyzed olefination of N‐tosylhydrazones as...

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Facile Synthesis of γ‐Ketonitriles in Water via C(sp2)–H Activation of Aromatic Aldehydes over Cu@g‐C3N4 under Visible‐Light

Photocatalytic synthesis of γ‐ketonitriles using various aromatic aldehydes and acrylonitrile is disclosed. The reaction is catalyzed by Cu@g‐C3N4 in water under visible‐light reaction conditions at room‐temperature. A facile C(sp2)–H activation of aldehyde under visible‐light conditions using Cu@g‐C3N4 as photocatalyst and water as solvent...

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