Recently we published an example of the synthetic utility of the gem-dialkoxy effect for the efficient preparation of strained four-membered rings by radical cyclizati~ n.~ As shown below, under similar conditions cyclization of the ethyl 6-bromo-2-hexenoates la-c gave either the acyclic 2a-c or cyclic 3a-c products. The dihydrido substrate la gave only the acyclic product 2a. gemdimethyl substitution, eg, lb, increased the amount of cyclic ...
