In 2019,European Journal of Organic Chemistry included an article by Van Beek, Wim E.; Smets, Robert J.; Kushwaha, Khushbu; Herrebout, Wouter A.; Abbaspour Tehrani, Kourosch. COA of Formula: C5H6BNO2. The article was titled 《Synthesis of 3,3-Dichloropiperidines and Further Functionalization via Pd-Catalyzed Cross-Coupling Reactions of the Dichloromethylene Moiety》. The information in the text is summarized as follows:
A new synthetic methodol. for the functionalization of the dichloromethylene moiety in 3,3-dichloropiperidines via Pd-catalyzed cross-coupling reactions is reported. A range of 3,3-dichloropiperidines was synthesized via a hydride induced cyclization of α,α,δ-trichloroaldimines or an indium(III) triflate catalyzed alkynylation/cyclization procedure of α,α,δ-trichloroaldimines. Subsequently, a dehydrochlorination followed by a cross-coupling with the thus formed vinylic chloride was envisioned. The non-alkynylated 3,3-dichloropiperidines could be regioselectively eliminated and by careful choice of solvent and base both of the two regioisomeric vinyl chlorides could be exclusively formed. Palladium-catalyzed Suzuki cross-coupling of the thus formed 5-chloro-1,2,3,6-tetrahydropyridines led to C3-substituted 1,2,3,6-tetrahydropyridines, which could be easily reduced to 3-substituted piperidines, generating therapeutic agent (±)-Preclamol for example. The 2-alkynyl-3,3-dichloropiperidines were regioselectively eliminated giving the cyclic enamine, which was subsequently cross-coupled in one-pot. The presence of the alkynyl function, in this case, clearly directs elimination towards enamine structures. Hydrogenation of the resulting, unstable 2-alkynyl-3-substituted-1,2,3,4-tetrahydropyridines, yields stable 2,3-disubstituted piperidines. In addition to this study using 2-Pyridinylboronic acid, there are many other studies that have used 2-Pyridinylboronic acid(cas: 197958-29-5COA of Formula: C5H6BNO2) was used in this study.
2-Pyridinylboronic acid(cas: 197958-29-5) belongs to pyridine. Pyridine is very deactivated towards electrophilic substitution with respect to benzene. For this reason classical formylation, using methods such as the Gattermann or Vilsmeier reactions, are not generally successful. COA of Formula: C5H6BNO2