Our recent investigations have found chlorocarbene (RCCl; R = Cl, Ph) additions to dibenzocyclooctyne (DIBO, 1) to proceed over a barrier of 11-12 kcal/mol, which contrasts greatly with the barrierless reaction of RCCl with parent cyclooctyne. Direct dynamics trajectories reveal the addition of CCl2 to proceed from a shared transition state to either vinylcarbene 2 (4%) or directly to cyclopropene 3 (96%). Our experimental findings reveal the addition of two equivalents of PhCCl to DIBO to give three isomeric products which we believe to be dienes 4-Ph. Subsequent calculations show the addition of the second equivalent of RCCl to 2 and to 3 to proceed with little or no barrier and the products of these additions depend on the conformations of 2 and 3. The stationary-point potential energy surface (PES) and direct dynamics trajectories initiated from different points on the PES show the second equivalent of RCCl to add to 2 to give dienes 4 and add to 3 to produce a possible new cyclopropene product, 5. We report our progress on the experimental characterization of the 2 RCCl + DIBO products, experimental efforts towards the synthesis of diazirine 6 as a precursor to vinylcarbene 2, and our recent calculations on these systems.

Reactivity and dynamics of chlorocarbene additions to dibenzocyclooctyne

253rd National Meeting (2017)

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