The reaction of N-mono an N,N-disubstituted hydroxylamines with palladium catalyst

Rearrangement of the Active Ester Intermediate During HOBt/EDC Amide Coupling

“…[1] The conversion of A into the N-oxide isomer B was reported. [2,3] The N-oxide is favored in polar solvents, while the desired active ester A predominates in less-polar solvents. [4] It appears that the active ester A is the kinetic product, which is reactive towards rearrangement to the corresponding urethane form B.…”

Aza‐Henry Reaction with Nitrones, an Under‐Explored Transformation

“…The oxidation of hydroxylamines by air oxygen is usually metal‐catalyzed, but the formation of a conjugated system might account here for the ease of such a process in the absence of any metal. [21a] Conversely, compound 4 was not susceptible to oxidation when it was kept under argon, either in solution or neat.…”

1,3-Dipolar Cycloaddition Reaction of 3,4-Dihydro-β-carboline 2-Oxide

“…40 When comparing the vicinal coupling constants in the formed isoxazoline rings between the cis and trans cycloadducts, generally it is observed that the coupling constants for cis relationship show higher values than those for trans relationship. The coupling constants between H-1 and H-10b for the cis cycloadducts, 7 (J = 8.9 Hz), 8 (J = 9.9 Hz), 9 (J = 8.9 Hz), 10 (J = 9.4 Hz), and 11 (J = 7.9 Hz) showed higher values than the ones for the trans cycloadducts, 7¢ ¢ (J = 8.2 Hz), 9¢ ¢ (J = 7.2 Hz), 10¢ ¢ (J = 6.2 Hz), and 11¢ ¢ (J = 2.8 Hz).…”

“…The regioselectivity in the 1,3-dipolar cycloaddition reaction of 1 with these dipolarophiles showed a tendency similar to that of other cyclic nitrones such as 3,4-dihydroisoquinoline N-oxide. 38,40,45 The reactions with 1,1-disubstituted dipolarophiles gave regioselectively the adducts, 24-26¢ ¢ (Table 4). Thus, the symmetrical diphenylethene gave the adduct 24.…”