Direct access to 2-amino-5-azidomethylfurans through palladium-catalyzed azidative cycloisomerization of homoallenyl amides.

A room temperature, efficient, and palladium-catalyzed azidative cycloisomerization of homoallenyl amides using TMSN3 as the azidation reagent and PhI(O2CCF3)2 as the oxidant is described, producing a variety of 2-amino-5-azidomethylfurans in moderate to excellent yields. The products can be applied to the concise synthesis of 1,2,3-triazoles via a Cu-catalyzed azide-alkyne cycloaddition.

Divergent Synthesis of 2-Aminofurans via Palladium-Catalyzed Acetoxylative, Alkoxylative, and Hydroxylative Cycloisomerization of Homoallenyl Amides.

A fine-tunable transformation, including Pd-catalyzed acetoxylative, alkoxylative, and hydroxylative cycloisomerization of homoallenyl amides, has been realized with hypervalent iodine organic compounds as the oxidants, giving polysubstituted 2-aminofurans in promising yields at room temperature. The selective formation of three different types of products from the same starting materials makes this reaction particularly attractive and useful for organic synthesis.

Copper-Catalyzed Trifluoromethylation of Alkenes with Redox-Neutral Remote Amidation of Aldehydes.

A room-temperature and one-pot synthesis of ε-CF3-substituted amides via the copper-catalyzed trifluoromethylation of alkenes with redox-neutral remote amidation of aldehydes is described. This reaction is featured by an unprecedented 1,5-H atom abstraction from aldehydic C-H bonds by α-CF3-alkyl radicals resulting from the radical trifluoromethylation of alkenes, thus enabling a new possibility of the trifluoromethylation-initiated remote sp(2) C-H functionalization.

Palladium-catalyzed cycloisomerization and aerobic oxidative cycloisomerization of homoallenyl amides: a facile and divergent approach to 2-aminofurans.

A Pd-catalyzed divergent cyclization, including cycloisomerization and aerobic oxidative cycloisomerization of homoallenyl amides, is described. Varieties of functionalized 2-amino-5-alkylfurans and 2-amino-5-formylfurans can be selectively synthesized in good to excellent yields. Preliminary mechanistic studies show that peroxide may be a key intermediate for this Pd-catalyzed radical aerobic oxidative cycloisomerization of homoallenyl amides. The mild reaction conditions, high atom economy, and utilization of air as the oxygen source make this protocol very environmentally benign and practical to the synthetic community.