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The efficiently effected intramolecular oxidative radical cyclization of primary alkyl iodides to aromatic nuclei using dicumyl peroxide is described. The procedure was also used to provide quick access to derivatives of the pharmacologically important 5,6,8,9,10, 11-hexahydroindolo[2,1-alpha]isoquinolines.

Excellent yields of protected homoallylic amines are obtained using iodine to catalyze the three-component condensation of aldehydes, benzylcarbamate and allyltrimethylsilane. It is demonstrated that iodine has a very strong catalyst activity, and the procedure is a one-pot, rapid and a high yielding process.

A versatile and efficient protocol for the synthesis of highly substituted benzopyrrolizidines (tetrahydro-3H-pyrrolo[2,1-a]isoindol-3-ones) is reported. The strategy consisted of an Ugi four-component reaction/elimination methodology to afford dehydroalanines containing trans-cinnamic acid derivatives and different substituted 2-bromobenzylamines, followed by a palladium-catalyzed 5-exo-trig/5-exo-trig cascade carbocyclization process. Gratifyingly, benzopyrrolizidines were obtained in moderate to good yields (42-77%) with a Z geometry due to the structural requirements for syn-β-hydride elimination. The prepared heterocyclic scaffolds are decorated with several substituents and incorporate a benzopyrrolizidine-fused system, along with an embedded cinnamic acid derivative, two privileged medicinal chemistry scaffolds. Additionally, since some of the compounds are derived from the well-known antioxidants ferulic and sinapinic acids, they were tested for their in vitro antioxidant capacity. The data suggested that compounds having a p-hydroxyl group showed moderate 2,2-diphenyl-1-picrylhydrazyl-radical-scavenging activity and were effective antioxidants in preventing lipoperoxidation in a thiobarbituric acid reactive substances assay. [ABSTRACT FROM AUTHOR]

A practical two-step synthesis of 2,3-dihydropyrroles from Ugi 4-CR/propargyl adducts is presented. The protocol includes a base-mediated formation of an allenamide functional group and an in situ metal-free formal 5-endocycloisomerization that occurs in a highly regioselective manner at the allenamide C-γ. [ABSTRACT FROM AUTHOR]

[reaction: see text] A new nonchain 5-endo radical cyclization starting with xanthates was exploited in a short synthesis of (+/-)-alpha-lycorane and the erythrina ring system.