TfOH catalyzed One-Pot Schmidt–Ritter reaction for the synthesis of amides through N-acylimides

Harnessing Protonated 2,2'-Bipyridinium Salts as Powerful Brønsted Acid Catalysts in Organic Reactions

It is the first time that the readily available protonated 2,2'-bipyridinium salts are used as Brønsted acid catalysts to accelerate a series of organic transformations that included the hydration of aromatic alkynes, etherification of alcohols, cyclotrimerization of aliphatic aldehydes, Ritter reaction, Mannich reaction, Biginelli reaction, preparation of substituted alkenes from alcohols, synthesis of spirooxindole, bisindolylmethane, and noncyclized tetraketone with good to excellent yields. These results strongly suggest that there exists enormous potentiality in the development of the protonated 2,2'-bipyridinium catalytic system.

Tf2O- and Cu(OTf)2-Assisted Acylamination Reaction of Unactivated Alcohols with Nitriles: A One-Pot P(IV) Activation, Stereoretention in Cycloalkanols and Deprotection Approach

Described herein is a simple, novel, one-pot acylamination reaction of unactivated alcohols. This reaction employs the combination of PCl₃ and triflic anhydride (Tf₂O) or copper triflate Cu(OTf)₂, which serves as a source of P(IV)-activated complex for nitriles to react under the Ritter-type mechanism. The synthetic utility of Tf₂O-promoted reactions was demonstrated by its effectiveness to generate different acylaminated products. By employing Cu(OTf)₂, this method represents a rare example of α-selective acylamination reaction. With chiral cycloalkanols, using the Cu(OTf)₂-promoted procedure, acylaminated products are formed with complete retention of configuration. The synthetic utility of the copper-assisted reaction in acetonitrile was readily demonstrated as a mild deprotection strategy.

Recent advances of Ritter reaction and its synthetic applications

This review provides a comprehensive survey of Ritter reactions from 2014 to 2020.

Highly efficient one-pot tandem Friedlander annulation and chemo-selective Csp3–H functionalization under calcium catalysis

Highly efficient and regioselective Friedlander synthesis of 2-methyl-3-acyl quinolines and their chemoselective C_sp3–H functionalization is described for the first time using Ca(OTf)₂ as the sustainable catalyst under solvent free conditions with atom and step economy.