Synthesis and transformation of organoboronates and stannanes by pincer-complex catalysts

Abstract

Palladium pincer-complexes readily catalyze the formation of allylstannanes, allenylstannanes/silanes and allylboronates from easily available allylic and propargylic substrates and dimetallic reagents. The catalytic activity and selectivity of the pincer-complexes can efficiently be fine-tuned by changing the heteroatoms in the side arms. Pincer-complexes with nitrogen, sulfur and selenium atoms in the side arms are very efficient for creating C-Sn, C-Si and C-B bonds, while phosphorus based complexes can be employed for catalytic cleavage of C-Sn and C-B bonds. Most of the catalytic metallation (stannylation and borylation) processes can easily be combined with other reactions, and thus one-pot procedures can be designed for the synthesis of homoallylic alcohols, homoallylic amines and alpha-amino acids from simple precursors.

Cyclometalation Using d-Block Transition Metals: Fundamental Aspects and Recent Trends

“…Apart from the genuine interest in the mechanism and scope of this fundamental bond activation process, cyclometalation is a highly attractive and versatile synthetic method for creating organometallic entities, with wide application potential. Metallacycles have been successfully applied in traditional domains encompassing organic transformations and catalysis, [42][43][44][45][46][47][48] especially the catalytic activation of C-H bonds in unreactive alkanes, [49][50][51] and the stabilization of reactive intermediates. 52,53 In addition, they have been employed in various other domains of materials science, for example as active units in sensors, 54,55 in anticancer agents and for other bioorganometallic applications, [56][57][58][59] as photophysical devices in organometallic light-emitting diodes, [60][61][62] for light harvesting and energy transfer such as in photovoltaic cells, 63 as gelators 64 and birefringents in liquid crystalline materials, 65,66 and as molecular 67,68 or crystalline switches.…”

Mononuclear versus dinuclear palladacycles derived from 1,3-bis(N,N-dimethylaminomethyl)benzene: Structures and catalytic activity

“…In other words, that same reaction catalyzed by 1 is about 1855 times slower than that of 2 per palladium atom. This discovery provides direct evidence that the pincer system is not as proficient at promoting the methanolysis of fenitrothion, although pincer complexes are good catalysts in the carbon-carbon coupling reactions [8][9][10].…”

“…As a consequence of the structural rigidity, pincer complexes have shown better stability and special selectivity in some catalysis due to the fact that three of the four coordination sites are occupied on the metal center. On the other hand, this rigidity may reduce the catalytic activity for some other reactions where two free coordination sites are needed during the catalytic process [8][9][10].…”

Transition‐Metal‐Catalyzed Synthesis of Chiral Allylboronates†

“…In recent decades, transition‐metal catalyzed borylation reactions have been extensively studied, aiming at lower catalyst loading, better functional group tolerance and stereoselectivity, and milder reaction conditions. [ 2‐12 ] The most common methods include: 1) borylation of organic halides; [ 13‐18 ] 2) direct C—H borylation; [ 19‐23 ] 3) boryl addition to unsaturated organic compounds, such as alkenes, alkynes, allenes, [ 24‐35 ] aldehydes, ketones, [ 36 ] and α , β ‐unsaturated compounds. [ 37‐40 ] In fact, noncatalytic methodologies are an important complement and should not be ignored.…”