Access to Functionalized Imidazolidin‐2‐one Derivatives by Iron‐Catalyzed Oxyamination of Alkenes

Abstract

Functionalized imidazolidin-2-one were prepared by using an iron-catalyzed alkene oxyamination reaction. Hydroxylamine derivatives were used in this atom-economical process, and the addition of an external oxidant was not required. The conditions developed were shown to be efficient for mono-, di-, and trisubstituted double bonds, and a large scope of diamino alcohol precursors were delivered in good yields with good diastereoselectivities. The mechanistic pathway was studied and appears to involve both a fused aziridine and a carbocationic species.

Recent Advances in the Catalytic Synthesis of Imidazolidin-2-ones and Benzimidazolidin-2-ones

“…Very recently, Prestat and Berhal proposed an iron-catalyzed methodology for the construction of an imidazolidin-2-one scaffold [165]. Their approach consists in the anti aminooxygenation of allylbenzoyloxy ureas using iron acetate and phenanthroline as a catalytic system in acetonitrile at 100 degrees (Scheme 48).…”

“…For example, in Pd-catalyzed coupling reactions, the vinyl group enhances the binding of the aziridine substrate, but also in non-metal mediated reactions, the vinyl group is able to favor the reaction, since it is an activating group. In 2000, Alper et al, who had already published the cycloaddition of aziridines and carbodiimides to form imidazolidinimine [165], reported the catalytic preparation of imidazolidin-2-ones by the ring-opening cyclization reaction of 2vinylaziridines with isocyanates in the presence of palladium acetate and PPh3 (Scheme 49) [166].…”

Synthesis of N−H Bearing Imidazolidinones and Dihydroimidazolones Using Aza‐Heck Cyclizations

“…These include Wacker‐type cyclizations, carboaminations, alkene diamination, C−H functionalization, and other methods . However, with the exception of C−H functionalization, all require protection or acidification of the nitrogen centers, and result in N ‐protected or N ‐functionalized imidazolidinones; none of these methods can deliver imidazolidinones with a free N−H . Furthermore, none (including C−H functionalization) can prepare bis‐unprotected imidazolidinones (Figure ).…”

Efficient Amination of Activated and Non‐Activated C(sp3)−H Bonds with a Simple Iron–Phenanthroline Catalyst

“…The transition metal catalyzed insertion of nitrenes into C À H bonds is an attractive method for the amination of C(sp 3 ) À H bonds. [7] We became interested in exploring the use of simple iron salts for such reactions and commenced our study by investigating the ring-closing CÀH amination of the N-benzoyloxyurea 1 a [8,9] to the cyclic urea 2, a reaction which we recently disclosed with a ruthenium complex as catalyst. [10][11][12] Encouragingly, we found that FeBr 2 (5 mol %) in CH 2 Cl 2 at room temperature afforded the imidazolidin-2-one, although only in a low yield of just 8 % ( .…”

“…With optimized reaction conditions in hands, we explored the scope of this new iron catalysis employing a broad variety of N-benzoyloxyurea as depicted in Figure 2 (see Figure S1 of the Supporting Information for a variation of the carboxylate leaving group). We started with the C À H amination of benzylic C(sp 3 )ÀH bonds (Figure 2 a, imidazolidin-2-ones 2-23) and found that the method tolerates well a large variety of N-substituents at the urea, including different alkyl groups (2-6), a trimethylsilylmethyl 7, and propargyl group (8). Even an unprotected N-H group provided the C À H amination product (9) in high yields of 92 %.…”