A study is proposed of the Lewis acid catalyzed reactions of various alkenes and cyclopropanes with methoxy-1,4-benzoquinones to selectively yield dihydrobenzofurans A-C and chromans D-F, respectively. The generality, limitations and synthetic utility of the reactions will be explored and the reactions should provide a direct, efficient and versatile method for the regioselective synthesis of highly substituted dihydrobenzofurans and chromans. The regioselectivity of the reactions will be controlled by the nature of the Lewis acid via selective coordination with one of the carbonyl oxygens of the quinone. Investigation of novel high pressure promoted 5+2 cycloadditions of hydroxy-1, 4-quinones with alkenes and alkynes to produce G and H, respectively, is also planned. The synthetic method will be applied to the synthesis of biologically important dihydrobenzofurans and chromans (Vitamin E analogs). Synthetic targets include kadsurenone, an effective platelet-activating factor receptor antagonist with potential therapeutic value, and the potent antimicrobial pterocarpan, 3-phenylchroman, 2-phenylchroman and 2- phenylbenzofuran phytoalexins and analogs prepared in this study will be evaluated and, if these studies are encouraging, a systematic evaluation of the structure-activity relationship profiles of these novel antimicrobial agents may be warranted.
