A Micellar Catalysis Strategy for Suzuki–Miyaura Cross-Couplings of 2-Pyridyl MIDA Boronates: No Copper, in Water, Very Mild Conditions
摘要:
Suzuki-Miyaura (SM) cross-couplings of 2-pyridyl MIDA boronates can be successfully carried out in the complete absence of copper by attenuation of the Lewis basicity associated with the pyridyl nitrogen using selected substituents (e.g., fluorine or chlorine) on the ring. This strategy imparts additional synthetic options compared with existing approaches based on the use of Lewis acids or N-oxides. Thus, access to highly valued 2-substituted pyridyl rings via an initial Suzuki-Miyaura coupling can be followed by dehalogenation, SNAr reactions, or a second SM coupling to arrive at 2,6-disubstituted pyridyl arrays, all run in a single pot, enabled by micellar catalysis in water. Accessing targets within drug-like space is demonstrated in a four-step, one-pot sequence. Computational data suggest that the major role being played by electron-withdrawing substituents in promoting these cross-couplings without the need for copper is to slow the rates of protodeboronation of intermediate 2-pyridylboronic acids.
4-HO-TEMPO-Catalyzed Redox Annulation of Cyclopropanols with Oxime Acetates toward Pyridine Derivatives
作者:Jun-Long Zhan、Meng-Wei Wu、Dian Wei、Bang-Yi Wei、Yu Jiang、Wei Yu、Bing Han
DOI:10.1021/acscatal.9b00832
日期:2019.5.3
for the synthesis of pyridines through the annulation of cyclopropanols and oxime acetates has been developed. This protocol features good functional group tolerance and high chemoselectivity and also promises to be efficient for the late-stage functionalization of skeletons of drugs and natural products. Mechanism studies indicate that the reaction involves the in situ generated α,β-unsaturated ketones
presents the first example of the Pd-catalyzed cascade reactions of 5-oxohexanenitrile with arylboronicacids, affording important synthon 2-methylpyridines that can be further translated through C(sp3)-H functionalization to construct pyridine derivatives. Furthermore, this chemistry allows 5-oxo-5-arylpentanenitrile to react with arylboronicacids to provide unsymmetrical 2,6-diarylpyridines. This protocol
One-Pot Double Suzuki−Miyaura Couplings: Rapid Access to Nonsymmetrical Tri(hetero)aryl Derivatives
作者:Floriane Beaumard、Philippe Dauban、Robert H. Dodd
DOI:10.1021/ol900358n
日期:2009.4.16
We describe a one-pot, simultaneous Suzuki−Miyaura cross-coupling of two different aryl boronic acids with symmetrical dibromo aryl and heterocyclic substrates to give as major products the unsymmetrical disubstituted tri(hetero)aryl derivatives. Yields of unsymmetrical dicoupled products were generally in the 52−75% range. This methodology is particularly suited to the generation of chemical libraries
An efficient approach for the synthesis of unsymmetrical and symmetrical multi-substituted pyridines is demonstrated. This process is preceded via iron−catalysed [3+3] annulation of oxime acetates with enaminones. Operational simplicity, use of easily available starting materials and inexpensive catalyst, avoiding the use of additives or ligands are the major advantages of this protocol.