Continuous-flow generation of diazoesters and their direct use in S–H and P–H insertion reactions: synthesis of α-sulfanyl, α-sulfonyl, and α-phosphono carboxylates

The synthesis of α-sulfanyl, α-sulfonyl, and α-phosphono carboxylates has been achieved using a two-step procedure involving the in-flow generation of diazoesters from sulfonylhydrazones, via Bamford–Stevens elimination, and then subsequent S–H, sulfinate, and P–H carbene insertion reactions. The method for α-sulfonyl ester is particularly noteworthy as it represents a very atom economic (‘green’) way to access the products, and it completely avoids the use of alkyl halides.