Aerobic oxidative C-H phosphorylation of quinoxalines under catalyst-free conditions.

We herein report a direct and efficient protocol for phosphorylation of quinoxalines, which employs aerobic oxygen as the green oxidant under catalyst-free conditions. This methodology represents one of the most environmentally friendly and easily handled protocols, providing a series of phosphorylated quinoxalines in good to excellent yields. Control experiments clearly indicated that the reaction followed a dearomatization-rearomatization strategy.

Selective Alkynylallylation of the C-C σ Bond of Cyclopropenes.

A Pd-catalyzed regio- and stereoselective alkynylallylation of a specific C-C σ bond in cyclopropenes, using allyl propiolates as both allylation and alkynylation reagents, has been achieved for the first time. By merging selective C(sp )-C(sp ) bond scission with conjunctive cross-couplings, this decarboxylative reorganization reaction features fascinating atom and step economy and provides an efficient approach to highly functionalized dienynes from readily available substrates. Without further optimization, gram-scale products can be easily obtained by such a simple, neutral, and low-cost catalytic system with high TONs.

Expeditious Synthesis of Isoquinolone Derivatives by Rhodium(I)-Catalyzed Annulation Reaction through C-C Bond Cleavage.

A Rh(I)-catalyzed intermolecular cyclization between isocyanates and benzocyclobutenols leading to isoquinolin-1(2 H)-ones through selective cleavage of a C-C bond has been realized. Exploiting the same strategy, we developed a Rh(I)-catalyzed three-component reaction of benzocyclobutenols, isonitriles, and sulfonyl azides to access isoquinolin-1(2 H)-imines. These procedures provide unique and expeditious access to isoquinolone derivatives which are otherwise difficult to prepare in satisfactory yields with excellent functional-group tolerance under mild reaction conditions.