Gold(I)-Catalyzed Heteroannulation of Salicylic Amides with Alkynes: Synthesis of 1,3-Benzoxazin-4-one Derivatives

Gold(I)-catalyzed heteroannulation affords the efficient and straightforward construction of heterocyclic compounds. Herein, we developed a gold(I)-catalyzed heteroannulation of salicylic amides with alkynes producing a broad range of 1,3-benzoxazin-4-ones. The utility of this protocol was highlighted by synthesizing variously substituted benzoxazinones containing quaternary carbon centers, showing a high functional group tolerance and excellent atom economy of the thus introduced reaction course.

Trifluoroacetic Acid-Mediated Denitrogenative ortho-Hydroxylation of 1,2,3-Benzotriazin-4(3H)-ones: A Metal-Free Approach

An efficient trifluoroacetic acid-mediated denitrogenative hydroxylation of 1,2,3-benzotriazin-4(3H)-ones is described. This metal-free approach is compatible with a wide range of 1,2,3-benzotriazin-4(3H)-ones, affording ortho-hydroxylated benzamides in good to high yields with a short reaction time. The reaction is believed to proceed via a benzene diazonium intermediate. The synthetic utility of the reaction was successfully demonstrated by the preparation of an antimicrobial drug, Riparin C, and benzoxazine-2,4(3H)-diones in good yields.

Construction of bridged cyclic N,O-ketal spirooxindoles through a Michael addition/N,O-ketalization sequence

The first highly diastereoselective TfOH-catalyzed Michael addition/N,O-ketalization sequence of 3-aminooxindoles and ortho-hydroxychalcones was achieved to afford a wide range of bridged cyclic N,O-ketal spirooxindoles in 41–97% yields.

Copper-catalyzed one-pot reactions of acetyl chloride, o-halobenzoic acids and Wittig reagents toward 3-methyl isocoumarin synthesis

The synthesis of 3-methtyl isocoumarins is achieved via the copper-catalyzed one-pot reactions of Wittig reagents, acetyl chloride and o-iodobenzoic acids via tandem construction of CC, C–O and C–C bonds.