A multicomponent approach for the preparation of homoallylic alcohols

Abstract

The generation of transient boronic acid species followed by their subsequent trapping with aldehydes as electrophiles to yield homoallylic alcohols, in a multicomponent and metal-free fashion.

Unveiling the role of boroxines in metal-free carbon–carbon homologations using diazo compounds and boronic acids

“…Coupling between boronic acids and diazo compounds has attracted considerable interest in the synthetic community as boronic acids are readily available, usually stable and more atom efficient reagents when compared to their ester analogues. 16 , 24 – 26 Additionally, the homologation using TMS-diazomethane (TMSCHN 2 ) and organoboron compounds is useful to install a trimethylsilyl and boron functionality in a metal-free fashion. 27 – 32 These doubly functionalised carbon substrates are of interest, as they may be used to generate sequential or orthogonal functionalization at the same carbon atom.…”

“… 28 , 29 To date, the homologation with TMSCHN 2 has only been performed in combination with boronic acids to access the TMS-free homologation products. 26 , 33 While several proposed mechanisms have been reported, the role of a boronic acid anhydride (boroxine) intermediate in these reactions remains unclear. 16 , 26 , 33 …”

“… 26 , 33 While several proposed mechanisms have been reported, the role of a boronic acid anhydride (boroxine) intermediate in these reactions remains unclear. 16 , 26 , 33 …”

Engineering chemistry: integrating batch and flow reactions on a single, automated reactor platform

“…This idea has been partially explored by some, [7][8][9][10] however in the vast majority of reported cases there has not been a true and free integration between the two schools of thought. Although operating a flow process which culminates in dropwise addition of the product stream into a stirred round bottom flask can be useful, it does not constitute full amalgamation.…”

Transition-Metal-Free Reactions Between Boronic Acids and N-Sulfonylhydrazones or Diazo Compounds: Reductive Coupling Processes and Beyond

“…The reaction works well with a variety of aryl boronic acids yielding the corresponding benzyl pinacol boronates with yields varying from moderate to good. Selected examples and the reaction conditions are represented in Scheme 35. free synthesis of homoallylic alcohols 32. This transformation consists in the reaction of E-alkenylboronic acids 107 with TMSCHN2, forming in situ the homologated allylboronic acid intermediates 109.…”