Transition-Metal-Free Stereospecific Cross-Coupling with Alkenylboronic Acids as Nucleophiles

Abstract

We herein report a transition-metal-free cross-coupling between secondary alkyl halides/mesylates and aryl/alkenylboronic acid, providing expedited access to a series of nonchiral/chiral coupling products in moderate to good yields. Stereospecific SN2-type coupling is developed for the first time with alkenylboronic acids as pure nucleophiles, offering an attractive alternative to the stereospecific transition-metal-catalyzed C(sp(2))-C(sp(3)) cross-coupling.

Copper‐Catalyzed Cross‐Coupling of Benzylic Bromides with Arylboronic Acids: Synthesis of Diarylalkanes and Preliminary Antifungal Evaluation Against Magnaporthe Grisea

“…Thus, rigorous drying of the solvent and reagents was not necessary. Control screening disclosed that no expected product could be detected in the absence of ligand, copper catalyst or base, showing that this is not base‐assisted ipso ‐substitution process and undergoes different mechanism from Prof. Tang's report …”

“…Control screening disclosed that no expected product could be detected in the absence of ligand, copper catalyst or base, showing that this is not base-assisted ipso-substitution process [17] and undergoes different mechanism from Prof. Tang's report. [18] With the optimized conditions in hand, the scope and limitation with respect to boronic acid structures of this Cucatalyzed C(sp 3 )À C(sp 2 ) cross-coupling of benzylic bromide was first investigated (Scheme 2). A wide range of arylboronic acids bearing electron-donating and electron-withdrawing groups, and halides (F, Cl, Br, I) at different positions were well tolerated to afford the 1,1-diarylalkanes motifs in good to high yields (3 a-3 v).…”

Transition‐Metal‐Free Deaminative Vinylation of Alkylamines

“…By contrast, metal-free cross couplings of sp 3 -hybridized carbon electrophiles have drawn interest in an effort due to avoid transition metal residues in the synthesis of biologically active compounds. [8] In light of these reported advances, efforts towards exploring metal-free cross coupling of easily available alkyl sources are still important for organic synthesis because new strategies would provide innovative inspiration for the synthesis of complex natural products and other bioactive molecules. Tang developed the first metal-free cross-coupling between benzyl/allyl halides/ mesylates and alkenylboronic acids via an S N 2-type process in 2016 (Figure 1a).…”

Stereospecific Nucleophilic Substitution with Arylboronic Acids as Nucleophiles in the Presence of a CONH Group

“…[2] Because of their low nucleophilicity,arylboronic acids as nucleophiles are mostly reported for addition to a p system, [3] that is,t he Petasis-borono Mannich reaction [4] (Figure 1a), while there have been afew reports on arylboronic acids for nucleophilic substitution to at etravalent sp 3 carbons. [6] Taking inspiration from the a-hydroxy-group-promoted Petasis-borono Mannich reaction, [4c,d] we envisioned that an S N 2-type process with an arylboronic acid as the nucleophile could be accomplished by introducing afunctionality capable of bridging two reactants. [6] Taking inspiration from the a-hydroxy-group-promoted Petasis-borono Mannich reaction, [4c,d] we envisioned that an S N 2-type process with an arylboronic acid as the nucleophile could be accomplished by introducing afunctionality capable of bridging two reactants.…”