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Highly substituted 1H-isochromenes, isobenzofurans and pyranopyridines are prepared by allowing o-(1-alkynyl)arenecarboxaldehydes and ketones to react with I2, ICl, NIS, Br2, NBS, p-O2NC6H4SCl or PhSeBr and different alcohols or carbon-based nucleophiles at room temperature. Naphthyl ketones and iodides can be prepared by the reaction of 2-(1-alkynyl)arenecarboxaldehydes with I2 and simple olefins or alkynes.

The heterocyclic ring formation by means of PdI2-catalyzed oxidative cyclization-alkoxycarbonylation reactions to aliphatic acetylenic ketones is investigated. It is found that cyclopentenone, dihydropyridinone and tetrahydropyridinedione derivatives, formed when the reaction is carried out at higher temperature and for a long time, can also be selectively obtained through an acid treatment of tetrahydrofuran and oxazoline derivatives.

The synthesis of 4H- 3,1-benzoxazines, quinazolin-2-ones, and quinoline-4-ones is described by using a palladium-catalytic system. These nitrogen heterocycles are used as intermediaries for the further preparation of dyestuffs and of pharmaceutical products, as they exhibit a wide range of biological activity.

o-Biaryl carbaldeydes and ketones are obtained through the one-pot reaction of o-aryl iodides with o-bromobenzyl alcohols under the catalytic action of Pd and norbornene, in the presence of a base. The same reaction can also give dibenzopyrans by Pd and norbornene catalysis with a different termination, leading to C–O ring closure. In both cases the process first leads to a five-membered palladacycle, which controls C–C coupling, then to a seven-membered oxapalladacycle, which gives aldehydes and ketones or dibenzopyrans. [ABSTRACT FROM AUTHOR]