Miyaura Borylations of Aryl Bromides in Water at Room Temperature

Abstract

New technology for palladium-catalyzed cross-couplings between B2pin2 and aryl bromides leading to arylboronates is described. Micellar catalysis serves to enable borylations to take place in water as the only medium at ambient temperatures.

Transitioning organic synthesis from organic solvents to water. What's your E Factor?

“…This situation has been observed previously with Miyaura borylations, 41 where conditions leading to facile C-B bonds derived from aryl chlorides in organic media 42 are not particularly useful under otherwise identical conditions when applied to aryl bromides . 43 In the case of MIDA boronates, as illustrated in Scheme 10, cross-couplings have been performed under micellar (entry 1) as well as traditional conditions on both types of halides. 38 The quality of the coupling to arrive at 7 using a precursor aryl bromide in an organic medium (aqueous dioxane; entries 2, 3), albeit at room temperature, was poor (27%).…”

Design, synthesis and insecticidal activity of novel analogues of flubendiamide containing alkoxyhexafluoroisopropyl groups

“…These intermediates and title compounds were readily synthesized according to the reported methods. 26,[31][32][33] In some case, slight modications of these reaction conditions were necessary in order to obtain satisfying yields (see ESI † for details).…”

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“…70) (Ref. 77) (Ref. 77) appreciate that micellar catalysis, by virtue of synthetic design and manipulation, de facto offers a virtually unlimited array of potential reaction media tailored to best match a given transformation, each to be used catalytically as a nanoreactor.…”

“…However, in water containing 2–3 wt % TPGS-750-M, aryl pinacolatoboranes ( 36 ) could be smoothly prepared usually within three hours at a global concentration of 0.25 M (eq 20). 77 A Pd(0) catalyst, Pd(P t -Bu 3 ) 2 (8, 3 mol %), afforded the highest yields over several alternatives examined (e.g., Pd(OAc) 2 –XPhos, PdCl 2 (dppf), Pd 2 (dba) 3 –2PCy 3 , etc.). Given that palladium is already present in the form of Pd(P t -Bu 3 ) 2 , as well as its known use in Suzuki–Miyaura couplings, 78 introduction of a second aryl bromide into the reaction mixture ultimately leads to biaryl 37 (eq 21).…”