Clean synthesis of alpha-bromo ketones and their utilisation in the synthesis of 2-alkoxy-2,3-dihydro-2-aryl-1,4-benzodioxanes, 2-amino-4-aryl-1,3-thiazoles and piperidino-2-amino-1,3-thiazoles using polymer-supported reagents

An array of 2-alkoxy-2,3-dihydro-2-aryl-1,4-benzodioxane derivatives and 2- amino-1,3-thiazoles were prepared in high yield using a straightforward thr ee-step and two- step sequence of polymer-supported reagents, respectively and other polymer-supported sequestering reagents without any chromatograph ic purification step. A key step involves clean and efficient bromination o f acetophenones using polymer-supported pyridinium bromide perbromide (PSPB P) and subsequent cyclisation reaction.