Electrochemical-Induced Ring Transformation of Cyclic α-(ortho-Iodophenyl)-β-oxoesters.

Cyclic α-(ortho-iodophenyl)-β-oxoesters were converted in a ring-expanding transformation to furnish benzannulated cycloalkanone carboxylic esters. The reaction sequence started by electrochemical reduction of the iodoarene moiety. In a mechanistic rationale, the resulting carbanionic species was adding to the carbonyl group under formation of a strained, tricyclic benzocyclobutene intermediate, which underwent carbon-carbon bond cleavage and rearrangement of the carbon skeleton by retro-aldol reaction.

From Five to Seven: Ring Expansion of Monoazadiene Titanium Complexes by Insertion of Aldehydes, Ketones and Nitriles.

The ring enlargement reactions at ambient temperatures of non C-terminus substituted monoazabutadiene (η -RN=CHCH=CH ) titanium complexes 2 are investigated. The insertion of aldehydes/ketones (five examples) and nitriles (four examples) into the Ti-C bonds result in expansion of the five-membered rings to uncommon seven-membered titanacycles 3 and 4 in good yields. These new compounds are fully characterized by NMR spectroscopy and single-crystal X-ray diffraction.

A three-component reaction for rapid access to underexplored 1,3-thiazine-2-thiones.

Driven by the shortage of known effective possibilities for the synthesis of 4-hydroxy-3,4-dihydro-2H-1,3-thiazine-2-thiones on the one hand and the promising potential of these structures as novel drug candidates on the other hand, synthetic access to 4-hydroxy-3,4-dihydro-2H-1,3-thiazine-2-thiones was developed. The desired products could be synthesized effectively and facilely starting from β-chlorovinyl aldehydes with the aid of a new MCR (multicomponent reaction). Furthermore, the 4-hydroxy-3,4-dihydro-2H-1,3-thiazine-2-thiones are shown to be appropriate substrates in the preparation of diverse annulated polycyclic systems.