The scale up and process development for synthesis of the MMP inhibitor CH5902 is described.The first objective was to minimize the number of stages, preferably avoiding the isolation of intermediates that are oils or that are potentially unstable to ambient conditions.The route then naturally simplifies to four discrete stages: formation of the thioacetate, Me 4-(acetylsulfanylmethyl)tetrahydropyran-4-carboxylate (stage 1), oxidation and coupling to form the sulfonamide ester, methyl-[4-[4-(4-chlorophenyl)piperazin-1-yl]sulfonylmethyl]tetrahydropyran-4-carboxylate (stage 2), hydrolysis to the corresponding acid, [4-[4-(4-chlorophenyl)piperazin-1-yl]sulfonylmethyl]tetrahydropyran-4-carboxylic acid (stage 3), and conversion to the hydroxamic acid, [4-[4-(4-chlorophenyl)piperazin-1-yl]sulfonylmethyl]tetrahydropyran-4-carboxylic acid N-hydroxy amide (stage 4).In this approach, the original discovery route was streamlined and telescoped into a four-stage sequence, which was demonstrated on a multikilogram scale.A number of issues arising from both process development and process safety concerns are discussed.