Deconstructive Oxygenation of Unstrained Cycloalkanamines

Abstract

A deconstructive oxygenation of unstrained primary cycloalkanamines has been developed for the first time using an auto‐oxidative aromatization promoted C(sp3)−C(sp3) bond cleavage strategy. This metal‐free method involves the substitution reaction of cycloalkanamines with hydrazonyl chlorides and subsequent auto‐oxidative annulation to in situ generate pre‐aromatics, followed by N‐radical‐promoted ring‐opening and further oxygenation by 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and m‐cholorperoxybenzoic acid (mCPBA). Consequently, a series of 1,2,4‐triazole‐containing acyclic carbonyl compounds were efficiently produced. This protocol features a one‐pot operation, mild reaction conditions, high regioselectivity and ring‐opening efficiency, broad substrate scope, and is compatible with alkaloids, osamines, and peptides, as well as steroids.

Site-Specific Oxidation of (sp3)C–C(sp3)/H Bonds by NaNO2/HCl

“…Recently, a few elegant strategies for selective cleavage of specific (sp 3 )­C–C­(sp 3 ) bonds in amines, alcohols, and aryl alkanes have been achieved (Scheme a–c). Nevertheless, most of these systems suffer from excess chemical oxidants, limited substrate scope, or hash conditions.…”

Synthesis of 3H-1,2,4-Triazol-3-ones via NiCl2-Promoted Cascade Annulation of Hydrazonoyl Chlorides and Sodium Cyanate

“…Encouraged by the excellent viability of the cyanate anion in transition-metal-catalyzed cross-coupling reactions and our continuous interest in the efficient synthesis of structurally diverse N -heterocycles, we herein report a general and atom-economical approach for the preparation of biologically valuable 1,2,4-triazol-3-ones from the nickel-mediated cascade annulation of hydrazonoyl chlorides and sodium cyanate (Scheme e). Hydrazonoyl chlorides have frequently been applied as a versatile building block to build diverse heterocycles . The first nickel-catalyzed coupling reaction with metal cyanates was developed by Tkatchenko in 1986, but the reaction efficiency was generally lower .…”

Synthesis of Functionalized Aliphatic Acid Esters via the Generation of Alkyl Radicals from Silylperoxyacetals

“…In this catalytic system, TEMPO can also act as a reducing reagent for the transition‐metal catalyst. We also thought that the weak N−O bond of the resulting TEMPO adduct could be selectively cleaved giving access to various oxygen functionalities (hydroxy, formyl, or carboxyl groups) depending on the reaction conditions used [10b,f] …”