A simple and effective Lewis acid assisted synthesis of indole-3-sulfonyl carbamates and sulfonamides using Burgess reagent

Indole-3-sulfonyl carbamate served as a key intermediate for the synthesis of a HPK1 inhibitor, bearing a primary sulfonamide group. A simple and efficient synthesis of this key indole-3-sufonyl carbamate was developed using the readily available Burgess reagent and Lewis acids. A systematic evaluation of a variety of Lewis acids with Burgess reagent to optimize the synthetic yield of indole-3-sulfonyl carbamate is reported in this paper.