A convenient one-pot method for the synthesis of N-Boc protected S-alkylcysteines, useful intermediates for the solution-phase synthesis of glutathione-conjugates and modified peptides is presented, together with the reactivity of epoxides, halohydrins and α-halo carbonyl derivatives towards the sulfur nucleophile of the substrate. The reactions with α-halo esters lead to thiomorpholinocarboxylic acids which are interesting potential inhibitors of transport systems.