SYNTHETIC MODIFICATIONS OF BIOLOGICALLY INTERESTING NATURAL-PRODUCTS

The role of synthesis in a research program primarily devoted to the i solation, structure elucidation, and development of biologically activ e natural products is often to aid in the structure elucidation, provi de homologues for examination of structure-activity relationships, and to prepare analogues with modified activity. Examples of each activit y are presented from work on the maytansinoids and steganins. Another consequence of some of the natural products studies have been short sy ntheses of ancepsenolide and natural products containing a 1,3,3-trime thyl-7-oxabicycl[2.2.1]heptane nucleus. 1. Introduction 2, Semi-Synthe tic Modifications of Natural Products 3. Syntheses of ''Small'' Natura l Products 4. Conclusion