IIT-JEE 2009 · Paper 1, Chemistry question 17

Paragraph for Question Nos. 16 to 18

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.

$$\mathbf P\ \xrightarrow[\text{2. }\ce{H+, H2O}\ \ \text{3. }\ce{H2SO4},\ \Delta]{\text{1. MeMgBr}}\ \mathbf Q\ \xrightarrow[\text{2. Zn, }\ce{H2O}]{\text{1. }\ce{O3}}\ \mathbf R\ \xrightarrow[\text{2. }\Delta]{\text{1. }\ce{OH-}}\ \mathbf S$$