(a) A Bu3SnH/AIBN (azobisisobutyronitrile) mediated radical cyclization is shown below. Provide a full chain reaction mechanism. Identify the radical cyclization, and explain why the cyclization is favoured in terms of radical stability. Briefly explain why termination reactions are insignificant in a chain reaction. Draw the likely product (X) formed if Bu3SnH was not used under high dilution conditions. Give a brief reaction mechanism for the formation of X. N N BuzSnH, AIBN (trace), slow addition PhMe, reflux N 'N Br