Four‐Component Borocarbonylation of Vinylarenes Enabled by Cooperative Cu/Pd Catalysis: Access to β‐Boryl Ketones and β‐Boryl Vinyl Esters

Abstract

We report here a general four‐component synthetic procedure for the preparation of β‐boryl ketones and β‐boryl vinyl esters. Joint catalyzed by palladium and copper catalysts, borocarbonylative reaction between vinylarenes, aryl halides/triflates, B2Pin2, and carbon monoxide proceed successfully. A variety of synthetically useful β‐boryl ketones were synthesized in good to high yields by using aryl iodides as the substrates. It is noteworthy that when aryl triflates were applied as the starting materials, β‐boryl vinyl esters were synthesized in a similar manner and with broad functional group tolerance. A rational mechanism for this reaction was also proposed.

Ligand‐Controlled Copper‐Catalyzed Regiodivergent Carbonylative Synthesis of α‐Amino Ketones and α‐Boryl Amides from Imines and Alkyl Iodides

“…Concerning the reaction pathway, based on the experimental results and related literatures, [1–4, 12–14, 18] a possible reaction pathway is proposed (Figure 2). Initially, LCu‐Bpin I , generated from CuCl, B 2 pin 2 and NaO t Bu, inserts into the C=N bond of imine to give α‐boryl amido‐copper complex II .…”

Four‐Component Borocarbonylation of Vinylarenes Enabled by Cooperative Cu/Pd Catalysis: Access to β‐Boryl Ketones and β‐Boryl Vinyl Esters

“…Styrenes substituted in different positions with different substituents reacted efficiently and gave the corresponding products in 58-81 %y ield (5x-5ad); the structure of 5z was confirmed by X-ray crystallography. [13] 2-Vinylnaphthalene, 5-vinylbenzo[d] [1,3]dioxole,and 5-vinylbenzo [b]thiophene were also well applicable in the reaction to afford the desired products (5ae-5ag)i ng ood yield. This protocol was also successfully applied to synthesize the estrone-derived scaffold 5ah in 60 %y ield and 1:1d r. a-o r b-Substituted styrenes are not compatible with the reaction conditions (5ak, 5al), so that the product 5ai can be selectively synthesized.…”

“…Meanwhile, we also tested b-substituted styrenes under the catalytic system; cis-b-methylstyrene afforded product 6ae in 41 % yield and trans-b-methylstyrene gave 6ae in 58 %y ield;t he structure of 6ae was confirmed by X-ray crystallography. [13] (E)-Stilbene delivered 6af in ar elatively low yield of 31 % even with increased catalyst loading. When 1,2-dihydronaphthalene was employed, the desired product 6ag was isolated in 58 %yield with E/Z = 3.5/1.…”

Pd/Cu-Catalyzed amide-enabled selectivity-reversed borocarbonylation of unactivated alkenes

“…Subsequently, we evaluated the inuence of copper precursors. The NHC ligand is proved to be unnecessary as copper iodide can give the target product in 50% yield (Table 1, entries [5][6][7][8]. Various phosphine ligands were studied to examine ligand effects.…”

“…However, due to the inherent reactivity of the palladium species toward alkenes, olefin substrates were usually restricted to styrenes and a large excess of them is typically required (>6 equivalents). 8,9 Therefore, the critical part of the reaction design is to promote the reaction of the acylpalladium intermediate with alkenes faster than the insertion of CuBpin into olefins. One of the ideas is taking advantage of the coordinating group to transform the reaction from intermolecular to intramolecular.…”