Mechanistic analysis of an asymmetric palladium-catalyzed conjugate addition of arylboronic acids to β-substituted cyclic enones

Abstract

Mechanistic insight into a Pd-catalyzed conjugate addition reaction was gained using desorption electrospray ionization coupled to mass spectrometry.

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

“…That means that the catalytically relevant species is monomeric Pd-PyOx. This was further supported by a mass spectrometric study [52]. The catalytic cycle was also suggested in accordance with DFT calculations and mechanistic studies (Scheme 13) [48,49].…”

Elusive Reaction Intermediates in Solution Explored by ESI‐MS: Reverse Periscope for Mechanistic Investigations

“…[4] Although beyond the scope of this Minireview,w ec ite af ew examples.A na symmetric palladiumcatalyzed conjugate addition reaction of arylboronic acids to enone substrates has been investigated mechanistically by DESI-MS,t hus leading to the identification of intermediates along the catalytic cycle and allowing differentiation the substrate reactivity. [62] In polymer growth studies,D ESI-MS was used for real-time monitoring of the homogeneously catalyzed polymerization of ethylene. [63] Ther eaction progress was monitored, and the catalytic reactive species were identified by tandem MS.…”

CH Bond Arylation of Diamondoids Catalyzed by Palladium(II) Acetate

“…“Elimination” of acetic acid from C2 1g (CH activation step) produces the palladacycle C3 1g . The mechanism of the palladacycle formation (assistance of acetate in the insertion of Pd into the CH bond) on similar systems was recently proposed computationally32e, 38a–c and by MS studies 43. Acidolysis of the palladacycle C3 to C2 is the slowest step in the reaction cycle.…”

“…The mechanism of the palladacycle formation (assistance of acetate in the insertion of Pd into the C À H bond) on similar systems was recently proposed computationally [32e, 38a-c] and by MS studies. [43] Acidolysis of the palladacycle C3 to C2 is the slowest step in the reaction cycle. Complex C3 reacts with aryl iodide 2 to complex C4 (not detected/proposed on similar systems) and upon reductive elimination produces compound C5, which exchanges an iodide anion for the acetate and can be detected in MS. Transmetalation with silver acetate produces product C b and regenerates the Pd(OAc) 2 .…”