Silica Phosphoric Acid (SPA) as a Highly Active, Reusable, Heterogeneous Catalyst for the Synthesis of 2-Amino/Anilino-5-ARYL-1,3,4-Thiadiazine Bromide Derivatives

Abstract

Silica phosphoric acid has been found to be an efficient catalyst for the synthesis of 2-amino/anilino-5-aryl-1,3,4-thiadiazine bromide derivatives from the reaction of thiosemicarbazide and α-bromoketones in acetonitrile at room temperature. The catalyst can be reused for four times without any significant loss of catalytic activity. The experimental procedure is simple, and the products are obtained in high yield.

Keywords:

• Heterogeneous catalyst
• phenacyl bromide
• silica phosphoric acid (SPA)
• 1,3,4-thiadiazine
• thiosemicarbazide

Notes

^a Isolated yield.

^a Reaction was performed with thiosemicarbazide (1.2 mmol), phenacyl bromide (1 mmol)in acetonitrile.

^b Isolated yield.

^a Reaction was performed with thiosemicarbazide (1.2 mmol), phenacyl bromide (1 mmol) in acetonitrile, and 0.2 g catalyst.

^b Isolated yield.