A carbonyl compound P, which gives positive iodoform test, undergoes reaction with MeMgBr…

A carbonyl compound P, which gives positive iodoform test, undergoes reaction with MeMgBr followed by dehydration to give an olefin Q. Ozonolysis of Q leads to a dicarbonyl compound R, which undergoes intramolecular aldol reaction to give predominantly S.

\(\mathrm{P} \xrightarrow[\substack{2 \cdot \mathrm{H}^{+} \cdot \mathrm{H}_{2} \mathrm{O} \\ 3 \cdot \mathrm{H}_{2} \mathrm{SO}_{4}^{2} / \text { heat }}]{1 . \mathrm{MgBr}} \mathrm{Q} \xrightarrow{\mathrm{O}_{3} / \mathrm{Zn}-\mathrm{H}_{2} \mathrm{O}} \mathrm{R} \xrightarrow[\text { heat }]{\mathrm{OH}^{-}} \mathrm{S}\)