Nickel‐Catalyzed Reductive C−Ge Coupling of Aryl/Alkenyl Electrophiles with Chlorogermanes

Abstract

Cross-electrophile coupling has emerged as a promising tool for molecular synthesis; however, current studies have focused mainly on forging CÀC bonds. We report a crosselectrophile CÀGe coupling reaction and thereby demonstrate the possibility of constructing organogermanes from carbon electrophiles and chlorogermanes. The reaction proceeds under mild conditions and offers access to both aryl and alkenyl germanes. Electron-rich, electron-poor, and ortho-/ meta-/para-substituted (hetero)aryl electrophiles, as well as cyclic and acyclic alkenyl electrophiles, were coupled. Gramscale reaction, incorporation of the -GeR 3 moiety into complex biologically active molecules, and derivatization of formed organogermanes are demonstrated.

Nickel-Catalyzed Reductive Csp3–Ge Coupling of Alkyl Bromides with Chlorogermanes

“…However, the use of tridentate nitrogen ligands L5 and L6 gave no target product; the reactions typically afforded the dimer of alkyl-Br (entries 7 and 8). These results are opposite to those observed for the reductive Csp 2 –Ge coupling . No desired product was observed in the absence of a nickel catalyst or a reductant; alkyl-Br remained intact (entry 9).…”

“…Very recently, we and others have extended this chemistry to reductive C–Si couplings . In 2021, we reported the first reductive Csp 2 –Ge coupling reaction and demonstrated the power of cross-electrophile coupling in the preparation of aryl and vinylgermanes (Scheme b) . Herein we report the first reductive Csp 3 –Ge coupling of alkyl bromides with chlorogermanes (Scheme c).…”

Modular Generation of (Iodinated) Polyarenes Using Triethylgermane as Orthogonal Masking Group

“…The amination protocol also tolerated other potentially reactive functional handles such as ArÀ Cl (13,(16)(17) and ArÀ SiMe 3 (13). These examples illustrate that starting from a bifunctional arene bearing both a CÀ Br and a CÀ Ge functionality (which can be readily accessed from a commercial bromo arene via CÀ H germylation), [23] it is possible to sequentially arylate/alkylate within a few minutes, followed by halogenation as unmasking event…”

“…In line with previous results, [8] aryl bromides were selectively coupled in the presence of aryl chlorides and aryl fluorosulfates, such as 22. Also ortho-substituents were well tolerated (22,23). Heteroaromatic germanes such as the thiophene moiety in 21 were also successfully iodinated, allowing access to iodinated poly(hetero)arenes in an extremely efficient manner.…”

Modular Generation of (Iodinated) Polyarenes Using Triethylgermane as Orthogonal Masking Group

“…CÀ Br, CÀ Cl, CÀ OTf, CÀ B(OR) 2 , CÀ SiR 3 ) under Pdnanoparticle, [18] Au-catalysis [19] or with electrophilic halogenation [20] (Figure 1, bottom). [21] The non-toxic, [22] and easily installed GeEt 3 functionality [23] offers high stability to a range of reaction conditions including air, moisture, as well as acidic and basic media. [18] Since the [Ge]-transmetalation is associated with an unsurmountable activation barrier as well as lack of driving force on [L n Pd II (Ar)] intermediates, [18] the [GeEt 3 ] unit is unreactive in homogeneous L n Pd 0 /L n Pd II cross-couplings.…”