Migratory Insertion of Alkenes into Metal–Oxygen and Metal–Nitrogen Bonds

Abstract

The insertion of an unsaturated ligand into a MC or MH bond proceeds through migratory insertion, a fundamental organometallic reaction. Recent literature documents evidence of the migratory insertion of alkenes into an MO and MN bonds for alkene alkoxylation and alkene amination reactions, respectively. Herein we provide an overview of the literature and a perspective on how these recent experiments relate to classic experiments on CO and CN bond formation with alkene complexes of the late transition metals.

Diverse N‐Heterocyclic Ring Systems via Aza‐Heck Cyclizations of N‐(Pentafluorobenzoyloxy)sulfonamides

“…[24c] In summary,wereport aza-Heck cyclizations initiated by oxidative addition of Pd 0 -catalysts into the N À Ob ond of N-(pentafluorobenzoyloxy)sulfonamides.T hese studies provide direct access to N-heterocyclic ring systems that are not accessible using the Narasaka aza-Heck procedure. [20] The approach exploits stepwise unveiling of the nitrenoid character embedded within N-(pentafluorobenzoyloxy)sulfonamide reagents.S equential nucleophilic-electrophilic C À Nb ond forming strategies of this type,which involve the intermediacy of atunable aza-Pd II intermediate,should enable awide array of N-heteroannulation processes.Byanalogy to the utility of oxime ester derived imino-Pd intermediates (2), [4,5,[8][9][10][11][12][13] we also anticipate that the catalysis platform outlined here,which involves ar are example of oxidative addition of Pd 0 into an N À Ob ond, [7] should find broad applicability in the design of redox neutral C À Nb ond forming methods outside the immediate area of N-heterocyclic chemistry.…”

“…[3] Our focus has been on the development of aza-variants of the Heck reaction, because of the importance of N-containing ring systems in drug discovery. [4][5][6][7] Within this context, the Narasaka process, [4] which involves the Pd-catalyzed cyclization of O-pentafluorobenzoyl ketoxime esters with alkenes,is unique in harnessing key steps that are analogous to the conventional Heck reaction:1)anunusual oxidative addition into the N À Ob ond of 1 to afford cationic imino-Pd intermediate 2; [7,8] 2) C À Nb ond forming alkene migratory insertion; [9] and 3) b-hydride elimination (Scheme 1A). Imino-Pd II intermediates 2 can also be exploited more widely in redox neutral processes,s uch as diverse alkene 1,2-carboaminations, [8] aryl CÀHa minations, [7a] alkene aziridinations, [10] alkene 1,2-iodoaminations, [11] aryne aminofunctionalizations, [12] and C À Cb ond activations.…”

Well‐Defined Four‐Coordinate Iron(II) Complexes For Intramolecular Hydroamination of Primary Aliphatic Alkenylamines

“…[18] The reactivity of 2 b is a rare illustration of the migratory insertion of an alkene into the metal-amido bond of a well-defined and isolated metal amido complex. [19] Encouraged by these initial stoichiometric results, we evaluated the ability of dimer 2 b to catalytically promote the reaction of 3. To our delight, only 5 mol % of 2 b leads to almost complete conversion of 3 into 4, 5, and 6 with a 82 % yield in 4 ( Table 1, entry 2).…”

Recent Developments in Pd0‐Catalyzed Alkene‐Carboheterofunctionalization Reactions

“…However, alkene anti-heteropalladation reactions are well-documented, and have played ar ole in many well-established Pd II -catalyzed alkene-functionalizationr eactions. [1,34] The mechanism of alkeneh eteropalladation is often dependent on the catalyst structure, but it can also be influenced by subtle changes to other reaction parameters, such as substrate structure and solvent polarity.T his dependence is exemplified by studies on Pdcatalyzed Wacker oxidations andW acker-type oxidative cyclizations of alkenes that have been reported by the groups of Henry,S igman, Stahl, ando thers. [34,35] However,i ns ome instances, it can be difficult to control the stereochemical pathway and, under certain conditions, it is possible for both syn-a nd anti-heteropalladation mechanisms to be operative at the same time.…”