Efficient preparation of dolastatin and auristatin analogs through a common intermediate

Methods for making a dolastatin, auristatin or related compounds comprising the steps of providing a universal dolastatin core of Formula (I) reacting the C-terminal carboxylic acid group with an amine (A) to form an amide bond and reacting the N-terminal amine with a carboxylic acid (CA) to form an amide bond, wherein the steps can be performed in either order. Also provided are an isolated salt of the universal dolastatin core for use in preparation of dolastatins, auristatins and related compounds. Also provided are a number of intermediates and process steps which are useful for the preparation of high purity dolastatin core and high purity dolastatin and auristatin compounds.