Direct Access to Fully Substituted 3-Formyl-4-iodofurans through Iodocyclization of α-Alkynyl β-Alkoxy Enones

Formation of Benzimidazoisoquinolinium and Benzimidazoisoindolinum Cyclic Systems by the Reaction of 2-(2-Alkynylphenyl)benzimidazoles with Iodine and Iodine-Iodine Interaction Including Halogen Bonding in Their Crystal Structures

The reaction of 2-(2-alkynylphenyl)benz[d]imidazoles with molecular iodine constructed 5- and 6-membered rings as novel organic salts in high yield. The constituted number of ring systems was influenced by the substituent at the triple bond: 6-membered rings were formed from compounds bearing aryl substituents, whereas 5-membered ones were obtained from compounds with hydrogen or alkyl substituents. The products were obtained with triiodide as a counteranion; however, compounds with iodide were also obtainable under certain conditions. We also revealed that they had an iodine-iodine interaction included in halogen bonding between an iodo moiety of the cation and a triiodide or iodide of the counteranion. The iodine-iodine interaction was formed with greater preference than the electrostatic interaction between the cationic atom and triiodide or iodide.

Halogenoheterocyclization of 2-(allylthio)quinolin-3-carbaldehyde and 2-(propargylthio)quinolin-3-carbaldehyde

The reaction of 2-allyl(propargyl)thioquinolin-3-carbaldehyde with halogens (Br or I) results in formation of 1-halogenomethyl(halogenomethylidene)-4-formyl-1,2-dihydrothiazolo[3,2-

Synthesis of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium and [1,2,4]triazolo[5,1-b][1,3]thiazin-4-ium salts via regioselective electrophilic cyclization of 3-[(2-alken-1-yl)sulfanyl]-4H-1,2,4-triazoles

A convenient procedure for the regioselective preparation of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium 10 and [1,2,4]triazolo[5,1-b][1,3]thiazin-4-ium salts 9 via regioselective electrophilic cyclization of 3-[(2-alken-1-yl)sulfanyl]-4H-1,2,4-triazoles 3 is reported. Direction of electrophilic heterocyclization strongly depends on nature of the alkenyl substitutent.

Synthesis of highly substituted 3-formylfurans by a gold(I)-catalyzed oxidation/1,2-alkynyl migration/cyclization cascade

3-Formylfuran derivatives are core structures of a variety of bioactive natural products. However, procedures for their preparation are still rare and generally inefficient in terms of atom economy: These methods require multiple steps or harsh reaction conditions and show selectivity problems. An efficient gold(I)-catalyzed cascade reaction that leads to 3-formylfurans from easily accessible starting materials is now described. A wide variety of 3-formylfurans were obtained from the corresponding symmetric and unsymmetric 1,4-diyn-3-ols in the presence of an N-oxide in good to excellent yields. Isotope-labeling experiments as well as DFT calculations support a mechanism in which, after an initial oxygen transfer, a 1,2-alkynyl migration is favored over a hydride shift; a cyclization ensues to afford the desired functionalized furan core.

Molecular iodine-mediated reaction of 2-(2-phenylethynyl)-Morita–Baylis–Hillman adducts: an easy route to naphthyl ketones and iodo-substituted isochromenes

The iodine mediated reaction of 2-(2-phenylethynyl)-MBH gives corresponding naphthyl ketones and iodo-substituted isochromenes.