Site-Selective Functionalization of C(sp³) Vicinal Boronic Esters

Abstract

Selective functionalization of the C−B bond in 1,2bis(boronate) esters has emerged as a powerful tool to prepare 1,2difunctionalized compounds with stereocontrol. Selective Suzuki crosscoupling, oxidation, amination, and homologation reactions serve as platforms to prepare a wide variety of compounds from a common intermediate. The exquisite selectivity offered and their easy preparation from feedstock material using a myriad of catalytic transformations make them attractive building blocks for the preparation of complex molecules. In this Perspective, we summarize the examples of selective C−B bond functionalization of vicinal bis(boronates), attending to the nature of the C−B bond functionalization.

Controllable Regiodivergent Alkynylation of 1,3‐Bis(Boronic) Esters Activated by Distinct Organometallic Reagents

“…The bromo group might originate from LiBr, [15] generated during the preparation of 1 c. Notably, we applied the benzoyl group protection immediately after oxidation to facilitate isolation, considering the low boiling point of the precursor of 23. When the reaction of the cyclopropyl 1,3bis(boronic) ester was carried out under the standard 4). Finally, when the radical scavenger TEMPO was subjected to the reaction using ArLi as the activating reagent, selective alkynylation was completely inhibited.…”

Enantioselective Suzuki cross-coupling of 1,2-diboryl cyclopropanes

“…1a). However, despite the elegant strategies developed to selectively functionalize 1,2-bis-boronates, 11,12 the enantioselective desymmetrization of these species is still an unmet challenge (Fig. 1b).…”

Copper-Catalyzed Umpolung Reactivity of Propargylic Carbonates in the Presence of Diboronates: One Stone Four Birds

“…The protocol avoids relatively tedious synthesis of the related nucleophilic reagents, does not use precious transition metals, and affords three types of homoallylic alcohols and one type of homopropargylic alcohols. Although copper-catalyzed borylative transformations have been well developed, , using propargylic carbonates as the nucleophilic allylation and propargylation reagents has not been disclosed to the best of our knowledge. Moreover, most of the corresponding allylation products bear syn -vicinal stereocenters, which are ubiquitous subunits or key skeletons in numerous natural products or pharmacologically active molecules (Scheme d) …”