Conjugate additions boron nucleophiles

Boron—nitrogen coordination polymers, with ferrocene, 6, 208 Boron nucleophiles, in conjugate additions asymmetric 1,4-additions, 10, 388 mechanisms, 10, 384 to nitroolehns, 10, 388 to a,/3-unsaturated amides, 10, 386 to a,/3-unsaturated esters, 10, 386 to a,/3-unsaturated ketones, 10, 384 Boron-silicon bonds, addition to alkenes, 10, 760 to alkynes, 10, 758 to allenes, 10, 760 to carbenoids, 10, 766 to 1,3-dienes, 10, 762 to isocyanides, 10, 765... 

This commoner type of reaction involves the attack of carbon or heteroatom nucleophiles onto carbonyl compounds, by direct or conjugate addition, and onto imines. Because we have just dealt with boranes we shall start with the reaction of allylic boron compounds with such electrophiles. You might strictly not call this nucleophilic attack. 

The treatment of one equivalent of 5-lithio-2,3-dihydro-1,4-dioxin with 0.5 equivalent of copper(I) cyanide solubilized as its lithium chloride (0.5 equiv.) complex at — 15°C affords the corresponding cyanocuprate. The reactivity of this cuprate was assessed by its conjugate addition to cyclic enones, and by nucleophilic epoxide opening the presence of boron trifluoride etherate led to enhancement... 

Enantioselective synthesis of [3.3.1]-bicyclic ketals can be achieved by palladium(ll)-catalyzed 1,4-conjugate addition of 2-hydroxyphenylboronic to enones (Scheme 33). The reaction involves an in situ transmetalation of the boronic acid, that acts as bis(nucleophile) (13CC3360). Similar structures are obtained via a sequential Michael addition—bicyclization reactions... 

Scheme 2 Copper(I)-catalyzed enantioselective conjugate addition of boron nucleophiles to different a,p-unsaturated acceptors by Yun (upper) and its application to the two-directional desymmetrization of prochiral bis(a,p-unsaturated) acceptors by Oestreich (lower)...

Scheme 4 Chemoselective NHC-copper(I)-calalyzed conjugate addition of boron nucleophiles to esters and aldehydes by Fernandez...

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