A mild and robust direct CH functionalization strategy has been applied to the synthesis of axially chiral biaryls. Such an efficient and stereoselective transformation occurs through an original ...dynamic kinetic resolution pathway enabling the conversion of diastereomeric mixtures of non‐prefunctionalized substrates into atropisomerically pure, highly substituted biaryl scaffolds. The main feature of this transformation is the use of an enantiopure sulfoxide as both chiral auxiliary and traceless directing group. The potential of newly synthesized biaryls as valuable building blocks is further illustrated.
Pd makes it rotate: A CH activation/dynamic kinetic resolution method allows access to axially chiral biaryls. The isomerization step is believed to occur via a palladacyclic intermediate. Chiral induction is achieved using the sulfoxide motif as both “traceless” directing group and chiral source.
An efficient, enantio‐ and diastereoselective, copper‐catalyzed coupling of imines, 1,3‐enynes, and diborons is reported. The process shows broad substrate scope and delivers complex, chiral ...homopropargyl amines; useful building blocks on the way to biologically‐relevant compounds. In particular, functionalized homopropargyl amines bearing up to three contiguous stereocenters can be prepared in a single step.
The enantio‐ and diastereoselective, copper‐catalyzed three‐component coupling of imines, 1,3‐enynes, and diborons delivers complex, chiral homopropargyl amines; useful building blocks on the way to biologically‐ and medicinally‐relevant compounds. In particular, functionalized homopropargyl amines bearing up to three contiguous stereocenters can be prepared in a single step.
Despite the widespread application of hypervalent iodines, the corresponding λ3‐bromanes are less explored. Herein we report a general, safe, and high‐yielding strategy to access cyclic diaryl ...λ3‐bromanes. These unique compounds feature reactivity that is appealing and complementary to that of λ3‐iodanes, generating arynes under mild reaction conditions and in the presence of a weak base. Accordingly, formal meta‐selective transition‐metal‐free C–O and C–N couplings may be achieved. Mechanistic studies unambiguously support the aryne generation mechanism.
Diaryl λ3‐bromanes are rare and unexplored hypervalent compounds. An efficient and mild protocol affords now a large panel of these hypervalent compounds, featuring reactivity complementary to that of the corresponding diaryl λ3‐iodanes. Due to their high reactivity, metal‐free meta‐selective C–O and C–N coupling occurs through in situ aryne generation.
An efficient, enantio‐ and diastereoselective, copper‐catalyzed coupling of imines, 1,3‐enynes, and diborons is reported. The process shows broad substrate scope and delivers complex, chiral ...homopropargyl amines; useful building blocks on the way to biologically‐relevant compounds. In particular, functionalized homopropargyl amines bearing up to three contiguous stereocenters can be prepared in a single step.
Aus Drei mach Eins: Die entio‐ und diastereoselektive Kupfer‐katalysierte Dreikomponenten‐Kupplung von Iminen, 1,3‐Eninen und Diborverbindungen liefert komplexe, chirale Homopropargylamine, nützliche Bausteine für biologisch und medizinisch relevante Verbindungen. Funktionalisierte Homopropargylamine mit bis zu drei benachbarten Stereozentren können in einem einzigen Schritt synthetisiert werden.
Abstract Despite the widespread application of hypervalent iodines, the corresponding λ 3 ‐bromanes are less explored. Herein we report a general, safe, and high‐yielding strategy to access cyclic ...diaryl λ 3 ‐bromanes. These unique compounds feature reactivity that is appealing and complementary to that of λ 3 ‐iodanes, generating arynes under mild reaction conditions and in the presence of a weak base. Accordingly, formal meta ‐selective transition‐metal‐free C–O and C–N couplings may be achieved. Mechanistic studies unambiguously support the aryne generation mechanism.
Complex networks at life's origins Dherbassy, Quentin; Muchowska, Kamila B
Nature chemistry,
06/2022, Letnik:
14, Številka:
6
Journal Article
Recenzirano
Explaining the controlled emergence and growth of molecular complexity at life’s origins is one of prebiotic chemistry’s grand challenges. Now, it has been shown that we can observe how the ...self-organization of a complex carbohydrate network can be modulated by its environment.
Herein we disclose the synthesis of original chiral scaffolds—ortho‐orientated terphenyls presenting two atropisomeric Ar–Ar axes. These unusual structures were built up by using the C−H activation ...approach, and remarkably, both chiral axes were controlled with excellent stereoselectivity in a single transformation. During the reaction, not only does atroposelective functionalization of a biaryl precursor occur to establish one stereogenic axis, but an unprecedented atropo‐stereoselective C−H arylation also takes place to generate the second stereogenic element. These enantiomerically pure ortho‐terphenyls show an original tridimensional structure and thus constitute a unique foundation for building up a library of enantiomerically pure bidentate ligands, such as the new ligands S/N‐Biax and diphosphine BiaxPhos.
Double, without the trouble: Unusual chiral scaffolds—ortho‐orientated terphenyls presenting two atropisomeric Ar –Ar axes—were constructed by a C−H activation approach, in which both stereogenic axes were controlled with excellent stereoselectivity in a single transformation (see scheme). The chiral ortho‐terphenyl products with their original three‐dimensional structure form a unique architecture for novel bidentate ligands.
Axially chiral biaryls are ubiquitous structural motifs of biologically active molecules and privileged ligands for asymmetric catalysis. Their properties are due to their configurationally stable ...axis, and therefore, the control of their absolute configuration is essential. Efficient access to atropo‐enantioenriched biaryl moieties through asymmetric direct C−H activation, by using enantiopure sulfoxide as both the directing group (DG) and chiral auxiliary, is reported. The stereoselective oxidative Heck reactions are performed in high yields and with excellent atropo‐stereoselectivities. The pivotal role of 1,1,1,3,3,3‐hexafluoropropanol (HFIP) solvent, which enables a drastic increase in yield and stereoselectivity of this transformation, is evidenced and investigated. Finally, the synthetic usefulness of the herein disclosed transformation is showcased because the traceless character of the sulfoxide DG allows straightforward conversions of the newly accessed, atropopure sulfoxide‐biaryls into several differently substituted axially chiral scaffolds.
Influential solvent: Efficient access to atropo‐enantioenriched biaryl moieties through asymmetric direct C−H activation, by using enantiopure sulfoxide as both the directing group and chiral auxiliary, is reported (see scheme). The key role of 1,1,1,3,3,3‐hexafluoropropanol (HFIP) solvent is investigated.
A formal synthesis of (+)-steganone by means of atroposelective C–H activation is reported. The herein described strategy is very straightforward as the targeted scaffold is afforded in only 10 ...steps, amongst which five of them are conducted without isolation of the crude products. Accordingly, the final product is isolated in remarkable overall yield of 42,3% and with an enantiomeric excess above 98% without need for any expensive chemicals and catalysts. All catalytic steps may be performed at multi gram scale.
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