Recent Advances in the Stereoselective Additions of Allylic Boronates to Carbonyl Compounds

Abstract

The addition of allylboronates to carbonyl compounds remains an invaluable transformation in synthetic organic chemistry for the stereoselective synthesis of a wide variety of substituted homoallylic alcohols. The use of allylboronates is an exceptionally attractive tool, in part due to the stability of organoboron nucleophiles and the inherently high and predictable stereoselectivity consistently observed. Herein, key advances regarding the thermal and catalyzed allylboration of aldehydes and ketones from the past decade are summarized, with a focus on aspects concerning the scope, mechanism, and stereoselectivity. Notably, novel modes of activation are described for both enantioenriched α‐substituted allylboronates and catalytic enantioselective additions of achiral boronates using chiral protic acids and organocatalysts. A number of innovative metal‐catalyzed enantioselective borylation approaches to allylboronates and their subsequent use as substrates, including bimetallic double allylation reagents, are also highlighted. The current innovative progress and limitations in the field of carbonyl allylboration are discussed.

Boron-Catalyzed, Diastereo- and Enantioselective Allylation of Ketones with Allenes

“…and the pseudoaxial versus pseudoequatorial positioning of the ketone substituents in the Zimmerman–Traxler-type transition-state structure. In line with stoichiometric reports , the ( E )-allylic borane gave an anti -homoallylic borinic ester. Reaction with HBpin regenerated the catalyst and gave the product as a Bpin-protected alcohol, alkoxy boronic ester 6 .…”

Amine adducts of triallylborane as highly reactive allylborating agents for Cu(i)-catalyzed allylation of chiral sulfinylimines

“…Allylboranes and allylboration reactions are extremely important synthetic tools for extending the carbon skeleton of molecular systems on the allylic fragment ready for different transformations, particularly ring closing metathesis. [1][2][3][4][5][6][7][8][9][10][11] The products of allylation of CvO and CvN bonds-homoallylic alcohols and amines-are used as versatile synthetic intermediates in pharmaceutical chemistry, and in the synthesis of natural products, heterocyclic compounds and biologically active molecules for medicinal chemistry [12][13][14][15][16][17][18][19][20][21][22][23][24][25] (Fig. 1).…”