A catalytic version of hypervalent aryl-λ³-iodane-induced Hofmann rearrangement of primary carboxamides: iodobenzene as an organocatalyst and m-chloroperbenzoic acid as a terminal oxidant

Abstract

The first catalytic version of hypervalent aryl-λ(3)-iodane-induced Hofmann rearrangement of primary carboxamides, which probably involves in situ generation of a tetracoordinated bis(aqua)(hydroxy)phenyl-λ(3)-iodane complex as an active oxidant from a catalytic amount of iodobenzene by the reaction with m-chloroperbenzoic acid in the presence of HBF(4) in dichloromethane-water under mild conditions, was developed.

Hofmann Rearrangement of Carboxamides Mediated by N-Bromo­acetamide

“…Several organohypervalent iodine species have been used extensively, including [bis(trifluoroacetoxy)iodo]benzene (PIFA), 11 (tosylimino)phenyl-λ 3 -iodane (PhINTs), 12 (diacetoxyiodo)benzene (PIDA) 13,14 and others. [15][16][17] Cyclic imides are also useful substrates. 18 A number of aromatic five-membered cyclic ureas were prepared by intramolecular Hofmann rearrangement, [19][20][21][22][23][24] while five-and six-membered ureas resulted from protected asparagine and glutamine respectively.…”

Lewis Acid Enabled Copper-Catalyzed Asymmetric Synthesis of Chiral β-Substituted Amides

“…Deprotection 19 of 2e afforded chiral β-ethyl amide 4 , which in turn can be used for the synthesis of the chiral γ-ethyl chiral amine 5 via reduction of the carbonyl moiety or to β-ethyl chiral amine 6 through Hoffman rearrangement. 20 We have also applied our ACA methodology for the methylation of trifluoromethylated enamide 1y, leading to β-methyl-substituted amide product 3j with 99% ee ( Figure 1 d). When subjected to deprotection and Hoffman rearrangement, this product could lead to a direct precursor of the drug candidate ZENECA ZD 3523.…”

Recent Advances in Intramolecular Metal‐Free Oxidative C–H Bond Aminations Using Hypervalent Iodine(III) Reagents

“…Owing to their electrophilic nature, leaving group capabilities hypervalent iodine(III) reagents recently have been employed in various oxidative rearrangement reactions . Hofmann rearrangement stands as an important transformation of amides to amines and their derivatives , . In this context several groups disclosed rearrangement reactions particularly C to N migrations induced by hypervalent iodine(III) reagents and applications to useful heterocycles …”