New Directions in Ketene Chemistry: The Land of Opportunity

Abstract

Selected recent developments in ketene chemistry are described. They include examples of stereoselective reactions, ketenes and polymers, ketenes and carbenes, ketenes in synthesis, ketenes from photochemical processes, and bis‐β‐lactam formation.

Synthesis of Amido Esters and Amido Phosphonates through Carbonylation of Diazo Compounds Followed by Nucleophilic Addition Reaction

“…[21,22] Ketenes are known to participate in cycloadditions as well as nucleophilic and electrophilic addition reactions, which result in the formation of -lactones, -lactams, and many other synthetic and biologically important molecules. [21,26] The synthesis of ketenes by the carbonylation of carbenes using carbon monoxide offers several advantages when other known methods suffer from low yields and harsh reaction conditions. The subsequent reaction with an amine afforded the expected amido esters and phosphonates.…”

Catalytic Generation of C1 Ammonium Enolates from Halides and CO for Asymmetric Cascade Reactions

“…As early as 1982, Wynberg and co‐workers reported the seminal work of chiral β‐lactones synthesis through a cinchona alkaloid catalyzed aldol lactonization strategy, leading to a rapid development of this type of organocatalysis ,. Since most of the ketenes are unstable and ready to undergo dimerization and other side reactions, their synthesis and the following reactions have to be performed at low temperature . To avoid the use of unstable ketenes, searching for alternative routes to C1‐ammonium enolates has become an active research field.…”

A Novel Method for the Synthesis of Newfangled Asymmetric Schiff Bases from α‐amino Acids under Ultrasonic Conditions and in Aqueous Medium

“…[5][6][7][8][9][10][11] Especially, imipenem and alprazolam show antibacterial and anxiolytic effects, respectively. Because of their structural characteristics, Schiff bases are frequently used in addition reactions, [12][13][14][15][16] Staudinger reactions, [17][18][19][20][21] hetero-Diels-Alder reactions [22][23][24][25][26][27][28] and in several ligand complexes. In addition, they are widely used in the electronic, cosmetic, and polymer industries.…”

“…6 In addition, they are widely used in the electronic, cosmetic, and polymer industries. Because of their structural characteristics, Schiff bases are frequently used in addition reactions, [12][13][14][15][16] Staudinger reactions, [17][18][19][20][21] hetero-Diels-Alder reactions [22][23][24][25][26][27][28] and in several ligand complexes. [29][30][31][32][33][34][35] In particular, the enantiomeric synthesis of Schiff bases has gained considerable significance in recent years.…”