Birch reduction regiochemistry

As a further illustration of the regiochemistry associated with the Birch reduction of anisole derivatives, 11 p-acetoxy-O-methylestrone [274] offers an interesting case. 

Regiochemistry. Birch reduction of monosubstituted benzenes could furnish either of two possible 1,4-cyclohexadienes, A or B below. 

An activating group could be put at the nucleophilic site (27) but that leaves no proton, so the double bond must be moved (28). The anion (28) is starting to look like a Birch reduction product (Chapter 36) and the conversion of the ketone into an enol ether (29) completes the design. Reagent (29) would be derived from a salicylate (30) and the regiochemistry of the reduction is correct (Chapter 36). 

---