The external chiral ligand mediated asymmetric reaction of thiazolyllithium with aldimines was examined. The amino ether (5) gave rise to relatively high selectivity in the reaction of phenylimine, and sparteine (6) provided high selectivity in the reaction of imines bearing an α-methylene group. The reaction was applied to the synthesis of (S)-Doe, a component of antileukemic marine natural product, dolastatin 10.