Synthesis of Secondary Amines via N-(Benzoyloxy)amines and Organoboranes

Abstract

A variety of primary amines (R-NH(2)) were converted to their corresponding N-(benzoyloxy)amines (i.e., R-NHOCOPh) under biphasic conditions in excellent yields (63-90%). The intermediate N-(benzoyloxy)amines were converted to their N-ethylamine derivatives upon reaction with triethylborane in THF in good yield (54-89%). These experiments demonstrated the similar chemistry of N-chloro- and N-(benzoyloxy)amines with organoboranes.

Scope and Mechanism of Intramolecular Aziridination of Cyclopent-3-enyl-methylamines to 1-Azatricyclo[2.2.1.02,6]heptanes with Lead Tetraacetate

“…We decided to test the possibility of an N -acetoxy intermediate by independent synthesis of the hydroxylamino ester 35 from the parent cyclopentenylmethylamine 6 as shown in Scheme 5 36. However, the reaction of 35 with Pb(OAc) 4 under the usual conditions with monitoring by 1 H NMR spectroscopy proceeded slowly with the development of numerous peaks, of which none were the characteristic signals of aziridine 26 .…”

Amide‐Forming Ligation of Acyltrifluoroborates and Hydroxylamines in Water

“…In the first pathway, amide formation proceeds via acyldifluoroborane 9 (Scheme 3, path A) followed by 1,2-migration, a pathway, which parallels the known reactivity of organoboranes and O-benzoyl hydroxylamines to give amines. [15] Such reactions, however, generally require a fluorophile to break the strong BÀF bond. In the other two pathways, the hydroxylamine would attack the electrophilic carbonyl group of the acyltrifluoroborate to form hemiaminal 10, which would proceed to the amide by concerted elimination (path B) or via nitrilium 12 generated from iminium 11 (path C).…”

Electrophilic Amination: The Case of Nitrenoids

“…described preparation of substituted N ‐benzoyloxyamines 37 directly from amines and benzoyl peroxide and their reaction with equimolar amount of triethylborane to furnish secondary amines (Table 14). 63 Most primary amine‐ derived N ‐benzoyloxyamines undergo reaction at ambient temperature (Table 14, entries 1 and 2), while bulkier substituents require heating under reflux in THF (Table 14, entries 3–6).…”