The invention relates to the synthesis and complete stereochemical assignments of cytotoxic compounds such as compound 28-a and its stereoisomers:The invention further provides processes for making the compounds, their synthetic intermediates, and for methods of using the compounds and their pharmaceutical compositions for the treatment of neoplastic diseases. The abstract test case representation is based on a test case representation model that includes application states, external interaction sequences and input data. The second method provides an increased coupling coefficient for a pulse type transformer with a magnetic core that utilizes a non-uniform cross-sectional area along the magnetic path where the cross-sectional area is increased within the primary and secondary windings.