Sc(OTf)₃-catalyzed [3 + 2]-cycloaddition of nitrones with ynones

Abstract

An efficient approach to access functionalized (2,3-dihydroisoxazol-4-yl) ketones has been developed by reacting nitrones 4 with ynones 7 or terminal ynones 10 in a one-pot fashion.

A Convenient Synthesis of Novel Isoxazolidine and Isoxazole Isoquinolinones Fused Hybrids

“…For the first batch of 1,3-dipoles, we chose to proceed with N -benzyl nitrones of various commercially available aldehydes, consisting mostly of benzaldehydes. A modified procedure of a typical one reported in the literature [ 21 ] was followed, and, in total, 14 nitrones [ 22 , 23 , 24 , 25 , 26 , 27 ] were synthesised ( Scheme 3 A). In a similar manner, a variety of aldehydes were transformed to the corresponding oximes ( Scheme 3 B), following a known general protocol [ 28 ].…”

How a Chromium Tricarbonyl Complex Catalyzes the [3 + 2] Cycloaddition Reaction of N-Substituted Phenylnitrones with Styrene: A Molecular Electron Density Theory Analysis

“…According to the authors, the chiral one-point binding ruthenium LA catalyst was the main factor in obtaining the sole product with good regio-and diastereoselectivity. He et al 20 have developed an efficient method to synthesize substituted (2,3-dihydroisoxazol-4-yl) ketones via the Sc-(OTf) 3 -catalyzed 32CA reaction of N-benzylphenylnitrone with ynones. They claimed that the Sc(OTf) 3 catalyst allowed the reaction to achieve a good yield.…”

Synthesis of indene-fused spiro-dibenz(ox)azepines via Rh(iii)-catalyzed cascade regioselective C–H activation/annulation

“…Therefore, we hypothesized that by inducing structural modifications on the dibenzo[ b , f ][1,4]oxazepines at the C11-position and leveraging the imine functional group we could mimic the C–H activation/spiroannulation cascade reaction with ynones, suitable and relatively less explored coupling partners (Scheme 1d), which might provide a robust route to the synthesis of dihydrodibenzo[ b , f ][1,4]oxazepane containing spirocycles. Although, alkynes and other unsaturated coupling partners are the frequent go-to partners in C–H annulation reactions, 3,4 ynones remain as common electrophilic coupling partners in non-metallic reactions 5 and have thus far remained underutilized in C–H activation reactions. 6 Ynones as a potential coupling partner could directly give access to tetra-substituted spirocyclic indenes on coupling with appropriate substrates.…”