STUDY OF SYNTHETIC ROUTES FOR THE SPIROKETAL FRAGMENT IN CALYCULIN A BASED ON CONFORMATIONAL ANALYSIS

摘要

The conformational analysis of the spiroketal fragment of calyculin A revealed that a series of the Wittig reaction by way of the Swern oxidation was suitable for the addition of the C1-unit for the preparation of the spiroketal fragment. It also clarified that failure in the reaction of cyanide and the tetraol equivalents was attributed to the steric and electrostatic effects of the symmetrical structures.