Alpha wins the relay race: A direct transformation of ortho‐alkynylated aromatic vinyl ethers to 1‐iodonaphthalenes and other iodo‐heterocycles under mild Lewis acidic conditions in presence of iodide as an external nucleophilic source has been described. The first example of an iodoannulation strategy using a nucleophilic source of iodine, coupled with good to excellent yields, exclusive alpha regioselectivity and a broad substrate scope makes this work an attractive avenue towards the construction of aromatic iodides. DFT calculations suggest that these substituents stabilize the dihydropyranyl cations, thus leading to a more uniform reorganization of the electronic density in the ring, and do not have a direct effect on the formally positively charged carbon atom.Ī direct transformation of ortho‐alkynylated aromatic vinyl ethers to 1‐iodonaphthalenes and other iodo‐heterocycles under mild Lewis acidic conditions in the presence of iodide as an external nucleophile is reported. The trimethylsilyl group as a substituent at the alkyne and electron-withdrawing groups (CH2Cl and CH2CN) located at the alpha-position to the carbinol center are shown to be effective. The formal 2-oxonia-sigmatropic rearrangement may be disfavored by destabilizing the resultant allenyl oxocarbenium ion or by stabilizing an intermediate dihydropyranyl cation.

This rearrangement was shown to occur slowly under typical alkyne Prins cyclization conditions when the allenyl oxocarbenium ion that results from the rearrangement is similar to or higher in energy than the starting alkynyl oxocarbenium ion. The relative stability of the intermediates involved in the alkyne Prins cyclization and the competitive 2-oxonia-sigmatropic rearrangement was studied. Based on the results, we constructed not only a plausible catalytic cycle of SnCl4♵H2O but also the mechanism of catalyst decomposition. As for the unexpected heteroatom-containing products, oxygen and chlorine atoms were originated from the coordinated water and chloride ligands of the catalyst. This conversion was thought to be promoted by Brønsted acid activity of the catalyst, which resulted from a Lewis acid-base interaction between the stannic (Sn(IV)) center and the coordinated water ligands. From α-pinene, dimeric products (hydrocarbons and alcohols/ethers) were mostly formed and their yield showed a steady increase of up to 61 wt% based on the reaction mixture along with the reaction temperature. Almost 100% of the conversion was shown after 1 h of reaction above 90 ☌. Overall, the content of α-pinene in a reaction mixture decreased precipitously with an increasing reaction temperature. In this regard, the conversion of α-pinene in turpentine over stannic chloride molten salt hydrates (SnCl4♵H2O) as a catalyst was investigated, and the reaction products were analyzed with gas chromatography/flame ionization detector/mass spectrometer (GC/FID/MS).

The synthesis of dimeric products from monoterpene hydrocarbons has been studied for the development of renewable high-density fuel.

Trisha oestreich goldenratio makeup