Construction 7-membered ring via Ni–Al bimetal-enabled C–H cyclization for synthesis of tricyclic imidazoles

Construction of Five-Membered Heterocyclic Compounds via Radical Cyclization

Stereoselective synthesis of three-membered ring compounds via ylide routes

Three types of small ring compounds (epoxides, aziridines and cyclopropanes) can be synthesized stereoselectively via ylide route. Among them, the stereochemistry of vinyloxiranes, vinylaziridines, cyclopropylesters, amides and ketones can be tuned by the choice of reaction conditions and ylides with varying heteroatoms and ligands. Optically active epoxides and acetylenylaziridines can be prep...

Construction of a six-membered fused N-heterocyclic ring via a new 3-component reaction: synthesis of (pyrazolo)pyrimidines/pyridines.

A conceptually new three-component reaction was developed to construct a six-membered fused N-heterocyclic ring affording (pyrazolo)pyrimidines/pyridines as potential inhibitors of PDE4. The reaction is catalyzed by triflic acid in acetic acid in the presence of aerial oxygen.

Stereoselective synthesis of 5-7 membered cyclic ethers by deiodonative ring-enlargement using hypervalent iodine reagents.

Stereoselective synthesis of 5-7 membered cyclic ethers was achieved by deiodonative ring-enlargement of cyclic ethers having an iodoalkyl substituent. The reaction took place readily under mild conditions using hypervalent iodine compounds and an acetoxy or a trifluoroacetoxy group was introduced into the rings depending on the hypervalent iodine reagent employed. The use of hexafluoroisopropa...

New cyclization mechanism for squalene: a ring-expansion step for the five-membered C-ring intermediate in hopene biosynthesis.

Three triterpenes having the 6/6/5-fused tri- and 6/6/6/5-fused tetracyclic skeletons were isolated from an incubation mixture of the mutated F601A enzyme, these products being in accordance with a Markovnikov closure. Successful trapping of the tricyclic cationic intermediate by using the squalene analog having a highly nucleophilic hydroxyl group leads us to propose that the ring expansion pr...