The diterpine Cinncassiol D1, a polyhydroxylated 5-6-5 pentacyclic system, was identified as a synthetic target for evaluation. It demonstrated potent biological activity as both an anti-allergic compound and as a potential novel agent for the treatment of various carcinomas Previous investigation into the synthesis of Cinncassiol D1 has permitted the elucidation of the ABC carbocyclic carbon framework via a Homer-Wadsworth-Emmons olefination and subsequent Diels-Alder reaction. Herein we report investigated methodologies for the preparation of several alkylating agents in an attempt to curtail previously explored syntheses as well as an attempt to prepare the 5-6, AB rings of Cinncassiol D1 via a Type 2 intramolecular Diels-Alder reaction Efforts to prepare an array of bromo enol ether phosphonates via free radical bromination of enol ether phosphonates and SN2 reactions of phosphonate anions with a 1,3 dibromo ketal were explored with limited success. In addition, implications of a thiirane rearrangement in regard to the preparation of a terminally brominated beta-ketophosphonate were explored. A method for the nonselective-bromination and subsequent selective-debromination of a beta-ketophosphonate will be discussed. Reference will be made to routes for O-alkylation of beta-ketophosphonates
