This proposal describes an efficient approach to the synthesis of the antitumor antibiotics actinobolin and bactobolin. Bactobolin in particular, is a promising antitumor agent. Our route for the synthesis of actinobolin is based on an analysis of the likely biogenetic pathway. An acyclic pentaketide precursor will be cyclized to a cyclohexanone carboxylate using either a mercury mediated or an epoxide mediate approach. The Delta-lactone will be formed by halolactonization, a procedure which will allow the introduction of the amino group. In the optimal case only nine steps will be needed to synthesize actinobolin. The syntheses of actinobolin and bactobolin have been designed to allow the synthesis of analogs. These analogs will be useful in developing structure-activity relationships and may also prove to be more useful pharmacological agents. These syntheses are efficient and stereoselective. This proposal should lead to the development of new synthetic methods and a better understanding of the chemistry of actinobolin and bactobolin. In the course of model studies, it has been found that bromolactonization of Gamma,Delta-unsaturated acids gives predominantly the Delta-lactone while iolodactonization gives predominantly the Gamma-lactone. The scope of this reaction will be explored with a variety of substrates to determine the extent of these differences in regio- and stereoselectivity. In the course of elaborating the scope of bromolactonization as a route to Delta-lactones, a variety of naturally occurring dideoxy sugars will be synthesized.
