= Solution
\b[Product 6 is a remotely oxidized <ketone> of the undecylammonium chain], retaining the ammonium group and its counterion. Number from the ammonium-bearing carbon as C1. Crown-mediated recognition positions the remote C8–C9 region near the Mn–oxo center. A representative major-site product is the C8 <ketone>,
$$
\boxed{\mathrm{[H_3N^+-(CH_2)_7-C(O)-(CH_2)_2-CH_3]BF_4^-}.}
$$
Its adjacent possible regioisomer is the C9 <ketone> $\mathrm{[H_3N^+-(CH_2)_8-C(O)-CH_2-CH_3]BF_4^-}$. The precise single-site assignment is a limitation discussed below.
The <crown ether> binds the primary ammonium end through several N–H···O <hydrogen bonds>. This <host–guest complex> holds a folded portion of the chain close to the manganese oxidant, so the effective local concentration of a remote secondary C–H bond can overcome the intrinsic advantage of a free tertiary C–H bond. Such recognition-driven reversal of substrate preference is experimentally established.<Enzyme-like substrate-selectivity in C–H oxidation enabled by recognition by Giorgio Olivo and others>[Abstract and competitive substrate oxidation experiments]{ref}
The key intermediates are the crown-bound ammonium–Mn=O assembly, a remote carbon radical after H abstraction, and the rebound secondary <alcohol>. A second oxidation removes the remaining hydrogen on the carbinol carbon to give the <ketone>. The overall oxygen-equivalent count is
$$
\mathrm{RCH_2R'+H_2O_2\to RCH(OH)R'+H_2O},
\qquad
\mathrm{RCH(OH)R'+H_2O_2\to RC(O)R'+2H_2O}.
$$
Thus \b[one <ketone> requires two equivalents of peroxide], explaining a maximum near 50% <ketone> yield with one equivalent and near-complete conversion with two.
The primary remote-oxidation study reports preference for \b[C8 and C9], not a universally unique carbon. The schematic <catalyst> drawing and the oxygen budget alone cannot distinguish those positions quantitatively. The “single product” wording is therefore treated as an idealized remote-site assignment; a uniquely verified C8:C9 ratio is not invented.<Supramolecular Recognition Allows Remote, Site-Selective C–H Oxidation of Methylenic Sites in Linear Amines by Giorgio Olivo and others>[Abstract, remote C8–C9 selectivity]{ref}
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