l-amino acids provided 18 active antitumor cis-2-carbonylmethyl-4,5- di(l-aminoacyloxymethyl)-1,3-dithiolane analogs (5a–r). Five compounds (5b,c,e,k,p) exhibited remarkable antitumor activity in in vivo assays. The in vivo antitumor potency of 5e,k,p at 44.64 μmol/kg was similar to that of cytarabine at 89.28 μmol/kg. Several different assay systems, including UV–vis of CT DNA with or without the representative