PinB-Bpin

Alkanes regiospecifically reacted at the terminal carbon with pinB-Bpin at 150 °C. In the presence of Cp Rh(r 4-C6Me6) (4.0-6.0 mol%), one equivalent of pinB-Bpin afforded almost two equivalents of 1-borylalkanes, thus indicating participation of pinBH in the catalytic cycle. Indeed, pinBH in ra-octane gave pinacol -octylboronate in 65% yield (Scheme 41).132... 

Scheme 14.12 Ni-catalysed coupling reaction of tertiary alkyl halides with pinB-Bpin.

The combination of NiBr2 diglyme and 7 (R = r Pr) catalyses the crosscoupling of unactivated primary, secondary and tertiary alkyl halides with diboron reagent, pinB-Bpin, affording alkylboronates in good yields (Scheme 14.12). Compared with related nickel-catalysed carbon-carbon bond-forming reactions, this reaction exhibits an inverse reactivity order of all l halides. Thus, tertiary all l halides are more reaetive than seeondaty or primary all l halides in this C-B bond formation. ... 

A copper complex of the NHC ligand (409) has been developed as a catalyst for the Michael addition of pinB-Bpin (pin = pinacol) to a, -unsaturated esters. The adducts were obtained with <89% ee The Rh(III) complex (410) catalysed the same reaction fe with <97% ee ... 

Generation of the catalytically active Cp Rh(H)2 species from the precataiyst Cp RhCeMe6 by oxidative addition of either pinB-Bpin or H-Bpin (pin = pinacoiate, see above) foiiowed by a-bond metathesis of the Rh-B and R-H bonds... 

The catalytic alkane borylation whose mechanistic scheme is detailed in section 2.6 also works according to the same mechanism with benzene in the sense that it can be borylated by pinB-Bpin to form the phenylboronate ester in 82% yield using only 0.25 mol% of the same catalyst, [Cp Rh(T]" -C6Me6)]. This efficient reaction is extremely useful in view of the Suzuki coupling leading to aryl functionalization using such boron derivatives (see Chap. 19.3.8) ... 

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