The shown bicyclic ketone reacts with NaH (2 equivalents) and MeI (2 equivalents) to form major product P. How many broadband proton-decoupled ¹³C NMR peaks does P exhibit?
NaH forms the enolate at the carbonyl-adjacent methylene and methyl iodide alkylates that carbon. Two equivalents replace its two hydrogens, forming a gem-dimethyl centre. Together with the original bridgehead methyl, the product has eleven carbons: eight skeletal carbons and three methyl carbons. A symmetry plane makes corresponding carbons of the two unsubstituted bridges equivalent (two pairs), and the two newly introduced methyl carbons form another equivalent pair. Thus eleven carbons give 11−2−1 = 8 distinct environments. Proton decoupling removes C–H splitting but does not change this chemical-equivalence count.
More Experimental Techniques in Organic Chemistry: Optical rotation (polarimetry). Application of various chromatographic techniques such as thin-layer, column, HPLC and GC. Applications of UV-visible, IR, NMR spectroscopy and Mass spectrometry in the structural determination of organic molecules. questions
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