Regioselectivity in the reactions of methoxydehydrobenzenes with furans. Part 1. Reactions of 3-methoxydehydrobenzene and 3-(methoxycarbonyl)-dehydrobenzene with 2-substituted furans
The isomer ratios for the cycloadducts obtained for the reaction of 3-methoxydehydrobenzene, generated from 2-amino-6-methoxybenzoic acid by aprotic diazotization, or from 2-bromo-3-methoxyphenyl toluene-p-sulphonate by treatment with butyllithium, and for the reaction of 3-(methoxycarbonyl)dehydrobenzene, generated from 2-amino-6-(methoxycarbonyl) benzoic acid by aprotic diazotization, with seven 2-substituted furans are recorded. These results are discussed in terms of an asynchronous, concerted, biradicaloid reaction pathway.