Silica-supported fluoroboric acid (HBF4–SiO2) catalyzed highly productive synthesis of thiomorpholides as activators of l-asparaginase as well as the antioxidant agent

Recent advances in the Willgerodt–Kindler reaction

“…The group of Bandgar developed a solvent-free procedure for the synthesis of thiomorpholides employing solid-supported fluoroboric acid (HBF 4 -SiO 2 ) as a catalyst. 43 More recently, Akamanchi and co-workers have shown that sulfated tungstate can also promote the Willgerodt-Kindler reaction under solvent-free conditions. 44 In addition to high yields and relatively short reaction times, both of these catalysts could be recovered and re-used several times without significant loss of activity.…”

Silica supported Brönsted acids as catalyst in organic transformations: A comprehensive review

“…Bandgar et al [69] catalyzed a highly productive synthesis of thiomorpholides in the presence of a catalytic amount of solid-supported fluoroboric acid (5 mol%). In the earlier reported method, a traditional approach, i.e., the Willgerodt-Kindler reaction was used which has limited applications because of the high reaction temperature, expensive and large amount of catalyst, drastic reaction condition, long reaction period required and low to moderate yield obtained.…”

Glycerol‐K2CO3 Deep Eutectic Solvent as Environmentally Friendly Media with Basic and Dehumidifier Synergistic Effect for Running of Willgerodt‐Kindler Reaction

“…To our best knowledge, the first time in 2007 Yadav reported the green ionic medium as a promoter (or catalyst), [bmim]BF 4 , for the construction of carbon‐sulfur bonds . In following, HBF 4 –SiO 2 and sulfated tungstate are another catalyst for conventional W‐K reaction to attain the well‐known structures of tertiary thioamides. Thiomorpholides as fundamental structures are related to carboxylic acid derivatives, exhibit their great importance in medicinal chemistry.…”