Search

A diastereoselective cascade annulation between allenoates and

A novel copper-catalyzed cycloisomerization of unactivated allene-tethered O-propargyl oximes has been developed for the synthesis of hexahydropyrrolo[3,4-b]azepin-5(4H)-ones. This one-pot domino reaction proceeds via a [2,3]-sigmatropic rearrangement, a [3 + 2] cycloaddition, and another [3,3]-sigmatropic rearrangement. The methodology offers a practical and straightforward route for the rapid assembly of both ring components of the fused bicyclic motifs from acyclic precursors by simultaneously forming four new bonds (a C═O, a C═N, and two C-C bonds) in a single step.

The silver(I)-catalyzed reaction of ortho-alkynylbenzaldoximes with propargylic alcohols represents a new strategy for the divergent one-pot synthesis of 2-(isoquinolin-1-yl) prop-2-en-1-ones via tandem 6-endo-cyclization, 1,3-dipolar cycloaddition, and intramolecular dehydrative opening of the 2,3-dihydroisoxazole ring. This synthetic protocol tolerates a wide variety of ortho-alkynylbenzaldoximes and propargylic alcohols and affords the corresponding products in excellent yields.

A novel copper-catalyzed cycloisomerization of unactivated allene-tethered

An efficient approach for the synthesis of pyranoquinolines through the indium-catalyzed activation of alkynes is reported. Intramolecular hydroamidation of alkynes can proceed through alkyne activation by indium(III) and then 6-exo-dig cyclization, leading to a fused pyran ring with high selectivity, high atom economy, and good to excellent yields. The cyclization was accomplished through the oxygen, not the nitrogen, of the amide functional group.