= Solution
Ba$^{2+}$ competes strongly for the <crown ether> receptors. With the recognition sites occupied, the undecylammonium chain can no longer be effectively preorganized near manganese. \b[The reaction should move back towards oxidation of methylcyclohexane to 1-methylcyclohexan-1-ol], with suppression of the selectively formed remote amino <ketone>.
The single available peroxide equivalent is then sufficient for tertiary C–H hydroxylation, whereas a secondary-chain <ketone> would require two oxidations. Competitive binding constants and metal-induced structural changes would determine the exact conversion and residual selectivity; neither a numerical yield nor complete inhibition of all oxidation follows merely from adding two equivalents of barium salt.
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