Solid-phase combinatorial synthesis of benzothiazole and 2,3-dihydro-[1,5]-benzothiazepine derivatives

Bis-(2-nitro-4-carboxyphenyl) disulfide was loaded on Wang resin and Rink amide resin. The nitro group was reduced to its amine with concomitant cleavage of the disulfide bond using SnCl2·2H2O to afford 2. Condensation of an aldehyde and nucleophilic attack on an α,β-unsaturated ketone, followed by TFA cleavage from the resin, gave benzothiazole 3 and 2,3-dihydro-[1,5]-benzothiazepine 4, respectively.