Haloboration: scope, mechanism and utility

Abstract

<p>Haloboration, the addition of B–X (X = Cl, Br, I) across an unsaturated moiety e.g. C=Y or C≡Y (Y = C, N etc.), is dramatically less utilised than the ubiquitous...</p>

Alkynophilicity of Group 13 MX3 Salts: A Theoretical Study

“…With a gem -dimethyl rather than a gem -diester group in the enyne tether, the 1,2-chloride transfer described above is no longer spontaneous (Scheme ). This process was thus compared with the formation of the cyclobutene intermediate. Again, all MX 3 species appear as good alkynophilic π-Lewis acids in the sense that the transition state III-TS-IV is readily accessible and the formation of IV is exergonic and followed by another low-lying transition state IV-TS-V leading to an even more stable species.…”

Unexpected boratranes: BBr3 mediated synthesis and mechanistic insights

“…Noteworthy, boratranes preparation using BBr3 as reagent is unprecedented. The formation mechanism of the unique structures of 1 and 2 which involves the reactivity of BBr3 towards methoxy groups and alkyne function [20] was investigated. As supplementary experiments, we showed that no reaction occurred starting from the corresponding diphenol analog of compound 4 under the same reaction conditions (10 equiv of BBr3, 0°C, 1h).…”

Regio‐ and Stereoselective 1,2‐Carboboration of Ynamides with Aryldichloroboranes

“…To our delight, commercially available dichlorophenylborane 2 a (3 equiv) gave after treatment of the crude product with pinacol the targeted trisubstituted alkenylpinacol boronate 3 a in good yield (76 % NMR yield; for the structure of 3 a , see Scheme 2). [14] Other common boron reagents, including phenyl boronic acid ( 2 b ), phenyl pinacol boronic ester ( 2 c ), phenyl catechol boronic ester ( 2 d ), and triphenylboroxine ( 2 e ) did not engage in the 1,2‐carboboration, because their boron Lewis acidity is too low for the initial electrophilic borylation step (see the Supporting Information, SI). Solvent screening revealed CHCl 3 to be superior to all other solvents tested.…”