Oxidative cyclisation of chalcones with thallium(III)nitrate: Synthesis of (Z)-2-phenylmethylene-7-nitro-3(2H)-benzofuranones

Oxidation of 2-hydroxy-3-nitrochalcones with thallium(III) nitrate gives (Z)-2-phenylmethylene-7-nitrobenzofuran-3(2H)-one derivatives, rather than the more usual 1,2-diaryl-3,3-dimethoxypropan-1-ones or the corresponding isoflavones.

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Oxydative Cyclisierung von Chalconen mit Thallium(III)nitrat: Synthese von (Z)-2-Phenylmethylen-7-nitro-3(2H)-benzofuranonen (Kurze Mitteilung)

Zusammenfassung Die Oxidation von 2-Hydroxy-3-nitrochalconen mit Thallium(III)nitrat ergab (Z)-2-Phenylmethylen-7-nitro-3(2H)-benzofuranon-Derivate und nicht die üblichen 1,2-Diaryl-3,3-dimethoxypropan-1-one bzw. die entsprechenden Isoflavone.

     

General synthesis of n-membered cyclic sulfamides

A general method for the synthesis of n-membered cyclic sulfamides (cyclosulfamides) is described. An application to the synthesis of constrained peptidal cyclic sulfamide is illustrated.     

Synthesis of a shape-persistent macrocycle with intraannular carboxylic acid groups

The synthesis of a shape-persistent macrocycle based on the phenylene-ethynylene backbone by the intermolecular oxidative Glaser-coupling of appropriate bisacetylenes is described. The ring contains two intraannular methyl carboxylates that were hydrolyzed to give the free diacid. In order to achieve sufficient solubility it was necessary to attach additional intraannular branched alkyl groups to the ring.     

Access to 4-substituted 3,4-dihydroquinolin-2(1H)-ones by an unusual radical cyclisation of a secondary amide

A novel route to 3,4-dihydroquinolin-2(1H)-ones involving two radical addition steps is reported, starting from readily accessible xanthates and N-aryl-3-butenamides.     

Cyclisation of Allenylidene Ligands to Indenyl Groups on Ruthenium Clusters

Thermolysis of Ru₃ cluster complexes containing diarylallenylidene and dppm ligands results in phenyl migration from dppm to the allenylidene with concomitant H migration and C–C bond formation reactions to give several complexes each containing a cluster-bound indenyl group. In initially-formed complexes 3 or 6, the diarylindenyl group is attached to the cluster by two localized C=C double bonds of one aryl group and a benzylic interaction of the remaining C=C double bond combined with one carbon of the five-membered ring. Thermal rearrangement of these complexes with concomitant loss of CO gives 4 or 7, respectively, in which the indenyl group is more symmetrically bonded to the cluster by two C=C double bonds from the six-membered ring and an ⁵-interaction from the five-membered ring, both of the indenyl ligand. The X-ray crystal structure determination of Ru₃( ₃-PPhCH₂PPh₂)( ₃-C₉H₅Ph₂)(CO)₅ (4) is reported. A related reaction was found between Ru₃(-H)(-CCCPh₂)(-OH)(CO)₉ and Co₂(CO)₈, which afforded CoRu₃( ₃-C₉H₆Ph) (-CO)₄(CO)₅ (8), also structurally characterized, in which the indenyl group caps the Ru₃ face of a CoRu₃ tetrahedron; unusually, there are four CO groups bridging the three Co–Ru bonds.     

Solvolysis reactions at the 13th carbon of 1-aryl organoiron complexes

Acid-catalysed solvolysis procedures exchange protecting groups on benzyl alcohol derivatives in the synthesis of η⁵ 1-arylcyclohexadienyliron building blocks for alkaloid synthesis. The reaction proceeds via a carbocation intermediate which can also be intercepted by intramolecular electrophilic addition to the tricarbonyl(η⁴-diene)iron(0) moiety to provide a novel and high-yielding cyclisation reaction forming a 5aα-cyanomethyl-5a,8a-dihydrofluorene tricarbonyliron complex in 96% yield.     

单质碘促进的有机反应研究进展

单质碘作为有机化学中结构最为简单的反应试剂之一,其促进的有机转化在最近几年越来越受到人们的关注.总结了单质碘的氧化性,酸性和亲电性3类基本化学性质,并针对3类性质所涉及的相关反应性报道进行了介绍.除此之外,还总结了近5年来单质碘作为催化剂在杂环合成,偶联反应,及C—H官能团转化等方面的应用.     

Stereoselective synthesis of polyketide precursors containing an anti-1,3-diol system via a Prins cyclisation and reductive cleavage sequence

A new approach for the stereoselective synthesis of polyketide precursors containing anti-1,3-diol units flanked by a variety of alkyl branches and functional groups through a Prins cyclisation and reductive cleavage sequence is described.     

Convenient Synthesis of N-Heterocycle-Fused Tetrahydro-1,4-diazepinones

A general approach towards the synthesis of tetrahydro-4H-pyrazolo[1,5-a][1,4]diazepin-4-one, tetrahydro[1,4]diazepino[1,2-a]indol-1-one and tetrahydro-1H-benzo[4,5]imidazo[1,2-a][1,4]diazepin-1-one derivatives was introduced. A regioselective strategy was developed for synthesizing ethyl 1-(oxiran-2-ylmethyl)-1H-pyrazole-5-carboxylates from easily accessible 3(5)-aryl- or methyl-1H-pyrazole-5(3)-carboxylates. Obtained intermediates were further treated with amines resulting in oxirane ring-opening and direct cyclisation—yielding target pyrazolo[1,5-a][1,4]diazepin-4-ones. A straightforward two-step synthetic approach was applied to expand the current study and successfully functionalize ethyl 1H-indole- and ethyl 1H-benzo[d]imidazole-2-carboxylates. The structures of fused heterocyclic compounds were confirmed by ¹H, ¹³C, and ¹⁵N-NMR spectroscopy and HRMS investigation.