Transition metal-mediated metathesis between P–C and M–C bonds: Beyond a side reaction

Abstract

Phosphine ligands often play an important role in controlling reactivity and selectivity in transition metal catalyzed reactions. However, one common drawback of the phosphine ligands is the undesired occurrence of an interchange between P bound aryl and M bound aryl or alkyl groups in the catalytic cycle. This results in the formation of undesirable coupling products as well as changes in catalyst structure through the replacement of the phosphine ligand. This review discusses approaches to 2 understand this metathesis reaction between P-C and M-C and its productive application in catalytic reactions.

Transforming PPh3into bidentate phosphine ligands at Ru–Zn heterobimetallic complexes

“…Both 4 and 5 displayed only limited stability, slowly degrading over time in solution (5 also slowly degraded in the solidstate) at room temperature. 11 to the best of our knowledge, there are no examples in which they have been observed in concert with one another. The role of ZnMe 2 is central to the observation of the chemistry, as it provides a means to bring about the elimination of both CH 4 and ZnMeCl, allowing access to highly reactive, low-valent ruthenium fragments capable of performing the array of bond activation/formation steps observed.…”

“…Further reaction with ZnMe 2 , followed by C-C coupling, 10 generates the late intermediates IV-VI (step ii) which contain 2,2′-bis(diphenylphosphino)biphenyl (BIPHEP) ligands. A formal P-C/Ru-C metathesis reaction 11 involving BIPHEP and PPh 2 (C 6 H 4 ) ligands in step iii 12 ultimately yields 1. 13 Support for the formation of BIPHEP containing species on the mechanistic pathway was provided by the reaction of ZnMe 2 with an in situ generated sample of [Ru(BIPHEP)(PPh 3 )HCl] (Scheme 3, step iv) which produced NMR signals for IV-VI, as well as the final product 1 (ESI ‡).…”

Palladium‐Catalyzed Decarbonylative Iodination of Aryl Carboxylic Acids Enabled by Ligand‐Assisted Halide Exchange

“…A strategic CÀP reductive elimination with the ligand to form a phosphonium chloride provides an efficient and unusual platform to facilitate chloride/iodide exchange with the alkyl iodide in an outer sphere nucleophilic substitution. [26] Results and Discussion…”

Ring-opening carbonyl–olefin metathesis of norbornenes

“…Inspired in large part by the great success of catalytic olen metathesis, 1 there has been increasing interest in the development of other catalytic metathetical reactions. 2,3 In particular, carbonyl-olen metathesis (COM) has the potential to enable a number of important new catalytic transformations, [4][5][6][7] including the ring-opening carbonyl-olen metathesis (ROCOM) of cyclic olens to generate alkenyl aldehydes ( Fig. 1a).…”