[Show abstract][Hide abstract] ABSTRACT: Hail boration! 2-Dimethylaminopyridine-ligated dihaloborocations [X2 B(2-DMAP)](+) with a strained four-membered boracycle were used for the haloboration of terminal and dialkyl internal alkynes. Esterification then provided vinyl boronate esters as useful precursors to tetrasubstituted alkenes. Following mechanistic studies, the scope of the haloboration was expanded simply by variation of the amine. Pin=2,3-dimethyl-2,3-butanedioxy.
Angewandte Chemie International Edition 06/2013; · 11.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: One-electron oxidation of the tetragonal Cu(II) complex [Bu(4)N][LCuOH] at -80 °C generated the reactive intermediate LCuOH, which was shown to be a Cu(III) complex on the basis of spectroscopy and theory (L = N,N'-bis(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamide). The complex LCuOH reacts with dihydroanthracene to yield anthracene and the Cu(II) complex LCu(OH(2)). Kinetic studies showed that the reaction occurs via H-atom abstraction via a second-order rate law at high rates (cf. k = 1.1(1) M(-1) s(-1) at -80 °C, ΔH(‡) = 5.4(2) kcal mol(-1), ΔS(‡) = -30(2) eu) and with very large kinetic isotope effects (cf. k(H)/k(D) = 44 at -70 °C). The findings suggest that a Cu(III)-OH moiety is a viable reactant in oxidation catalysis.
Journal of the American Chemical Society 11/2011; 133(44):17602-5. · 10.68 Impact Factor
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