Application of Green Solvents: PEG and scCO₂ in the Mono- or Biphasic Catalytic Systems for the Repetitive Batch Coupling of Vinylsilanes with Vinyl Boronates toward 1-Boryl-1-silylethenes

Abstract

A new method for the repetitive batch silylative coupling (trans-silylation) of vinylsilanes with vinyl boronates in the presence of Ru(CO)Cl(H)(PCy 3 ) 2 immobilized in poly-(ethylene glycols) (PEGs) has been developed. Three PEGs (PEG600, PEG2000, and MPEG2000) with different molecular weights and end groups (MW = 600−2000) were tested as solvents and immobilization media, while an aliphatic solvent (n-hexane or n-heptane) or supercritical CO 2 was used for product extraction. By applying 2 mol % of the Ru−H catalyst, it was possible to carry out up to 15 complete runs, with the predominant formation of 1-boryl-1-silylethenes. This immobilization strategy permitted for catalyst reuse and obtaining higher TON values (approximately 660−734) compared to the reaction in conventional solvents (∼50). Detailed kinetic studies of the most effective catalytic system were performed to determine catalyst activity and stability. Moreover, the reactions were carried out in an MPEG2000/scCO 2 biphasic system, positively influencing the process sustainability.

Organocatalytic hydroboration of carbonyl compounds promoted by choline-based ionic liquids

“…High efficiency and chemoselectivity towards the carboxyl group in the presence of the ester group was observed for substrate 8n. In the next stage of our study, bearing in mind green chemistry principles and our previous research on catalyst recycling in the synthesis of organoboron compounds, [31][32][33][60][61][62] we tested the possibility of recycling the catalyst, carrying out our reaction in a repetitive batch mode. Hydroboration of acetophenone (1a) was performed under standard conditions (1 h, rt, 2 mol% of IL1, neat).…”

Directed cis-hydrosilylation of borylalkynes to borylsilylalkenes

“…Methods for the synthesis of borylsilylalkenes include hydro-, 8 mono-, 9 di-, 10 and carboboration 11 of silylalkynes, silaboration of alkynes, 12 silylative coupling of vinylboranes with vinylsilanes, 13 hydrosilylation of borylalkynes, 8 e ,14 and others. 15 The detailed literature screening of the protocols for the synthesis of the analog isomers of borylsilylalkenes described in this work is presented in ESI† (Table S6, page 7 and Scheme S1, page 9).…”