Catalytic Olefin-Imine Metathesis: Cobalt-Enabled Amidine Olefination with Enaminones

Abstract

Organic metathesis reactions, the transposition/redistribution of molecular fragments between two chemical entities, allow expedient assembly of diverse molecular skeletons and appendages through the merger of whole-piece building blocks. Olefin-imine variant of this chemical process, in particular, can expand the synthetic toolbox for manipulating carbon-carbon and carbon-nitrogen bonds but has thus far been achieved only on a stoichiometric metal-mediated basis. Herein we report the development of a catalytic olefin-imine metathesis reaction, featuring cobalt-catalyzed amidine olefination with enaminones. Comprehensive investigations offer evidence for a mechanistic sequence of exchange of enaminone amine with amidine imine, cobalt-catalyzed cyclization, and ring fragmentation. The reaction provides rapid access to structurally transformed, primary amine-bearing enaminones that can serve as a versatile synthon for further structural diversification.

Catalytic Olefin–Imine Metathesis: Cobalt-Enabled Amidine Olefination with Enaminones

“…We report herein the development of a thus far elusive catalytic olefin−imine metathesis reaction, and in particular, cobalt catalysis provides a convenient synthetic channel for affecting amidine olefination with enaminone (Scheme 1B). 8 The defining feature of metathesis is exchange of molecular fragments between two chemical entities. The metathesis, typically involving the participation of at least two-carbon-or one-carbon-plus-one-hydrogen-derived covalent bonds, can be divided into three broad categories based on the use of two descriptors for the molecular fragment exchange process: elemental connectivity and bonding modes.…”

“…Our experimental campaign has confirmed the ability to achieve a formal intermolecular reactivity between enaminone and amidine. We report herein the development of a thus far elusive catalytic olefin–imine metathesis reaction, and in particular, cobalt catalysis provides a convenient synthetic channel for affecting amidine olefination with enaminone (Scheme B) . The defining feature of metathesis is exchange of molecular fragments between two chemical entities.…”

Triazenolysis of Alkenes: Aza-version of Ozonolysis

“…[41][42][43] While the previously mentioned methods for converting a C = C bond to new C = C or C = O motifs are wellestablished, there is notable gap in the transformation of ole ns into two C = N units (or corresponding amines). Several studies have focused on ole n-imine metathesis, primarily aimed at creating new C = C bonds; [44][45][46][47][48][49] however, to the best of our knowledge, the conversion of ole ns to imines or amines through carbon-carbon bond cleavage remains practically unexplored. [50][51][52][53][54][55] Undoubtedly, such a transformation would offer signi cant bene ts to the synthetic organic community.…”

A Tandem Regiospecific [3 + 2] Annulation/Ring Cleavage Reaction for the Synthesis of β-Ketoenamides

“…1 H NMR spectral data are in good agreement with the literature data. 15 (Z)-3-Amino-1-(4-phenoxyphenyl)-3-phenylprop-2-en-1-one (3na). Yellow liquid, mp 75−77 °C, yield 37 mg, 59%, R f = 0.42 (PE/ EtOAc 5:1, v/v).…”