Reaction of small-size cycloalkane rings with RuO4. Oxidative scission of ethyl 2,2-dimethoxycyclopropane-1-carboxylates and methyl 2,2,6,6-tetramethoxybicyclo[2.2.0] hexane-1-carboxylates.

The reaction of ethyl 2,2-dimethoxycyclopropane-1-carboxylates 1a-d and methyl 2,2,6,6-tetramethoxybicyclo[2.2.0]hexane-1-carboxylates 5a and 5b with RuO4 in CCl4 at room temperature leads in both cases to the oxidative ring opening by regioselective scission of the electron-rich C1-C2 bond for lad, and both C1-C2 and C1-C6 bonds for 5a and 5b. Methyl ethyl oxobutanedioates 2a-d were obtained in the first case while the 3-substituted ethyl methyl 2-oxopentanedioates 6a and 6b in the second one. In the same reaction conditions, cyclopropanes substituted with electron withdrawing groups, namely cyclopropyl methyl ketone (3a) and cyclopropane-1,1-dicarboxylic acid (3b) are unreactive; methyl 2,2-dimethoxycyclobutane-1-carboxylate 4 is unreactive as well.