2. Labelling Studies. When the deuterated enediyne below is subjected to Bergman cyclization the only product isolated is the corresponding ortho-di-deuterated product drawn below. Does this result support an intramolecular pathway or a fragmentation-recombination pathway? Briefly explain (note, use necessary drawings to support your answer). only product isolated with 2 deuterium atoms ortho no meta or para di-deuterated products isclated no mono-deuterated products isolated no tri-deuterated products isolated Let's evaluate the results of some non-kinetic experimental studies on the Bergman cyclization to differentiate the five possible mechanistic pathways proposed in the lecture notes for this reaction (some of these are hypothetical, some are actual literature studies). The five proposed mechanisms (three intramolecular cyclizations I1I3 and two dissociative (fragmentation-recombination) mechanisms F1 and F2 ) are summarized below. Intramolecular Mechanistic Pathways I1 SOHH Radical 12 HHHH lonic Fragmentation-Recombination Mechanistic Pathways F1 solH Radical F2 lonic