Regioselective O-alkylation of 2-pyridones by TfOH-catalyzed carbenoid insertion

Abstract

We have developed a novel TfOH-catalyzed regioselective O-alkylation of 2-pyridones with diazo compounds in high regioselectivity. This protocol is characterized by mild reaction conditions, metal-free, and simplicity.

2‐Hydroxypyridines as N‐ and O‐Nucleophiles in Organic Synthesis

“…Very recently, chemoselective O ‐alkylation of 2‐hydroxypyridines 1 and diazoacetates 135 was also achieved by using triflic acid as catalyst, affording desired products 136 with up to 99 % yield (Scheme 39). [81] This transformation featured mild reaction conditions, broad substrate scope and excellent functional group compatibility. Upon conducting a thorough investigation into the mechanism, a plausible reaction pathway was proposed.…”

Synthesis of 2,4-Disubstituted Oxazoles and Thiazoles via Brønsted Acid-Catalyzed Cyclization of α-diazoketones with Amides

“…In comparison, although the cheaper copper catalyst has been used, attempts to realize a similar transformation of α-fluoroalkyl-α-diazoketones have been beset by both harsh reaction conditions and limited scope. In view of these limitations, developing efficient synthetic methods of oxazoles and thiazoles is still high in demand and rewarding . Over the past decade, the reaction under the catalysis of Brønsted acids has been developed rapidly.…”

Thermal/photochemical micro-flow probe system for direct C–H bond functionalization of biologically active molecules

“…[9][10][11][12][13][14][15][16][17][18][19][20] Transition-metal-catalyzed carbenoid insertion into N-H bonds has proven to be a straightforward method in this respect, with the advantages of mild reaction conditions, good functional group tolerance, and readily available reactants. 21,22 Recently, Tp Br3 Ag-catalyzed and 1,2-diaminocyclohexane (DACH)-ligand-assisted N-H insertion reactions have been successfully applied for the synthesis of several amines using aqueous ammonia solution. 18 However, strong Lewis bases lead to strong coordination with the expensive metal carbenoid.…”