We are utilizing complementary experimental and computational approaches to explore the mechanism of chlorocarbene (RCCl; R = Cl, Ph) additions to dibenzocyclooctyne (DIBO, 1). Our experiments show the addition of two equivalents of PhCCl to DIBO to give three products. Ongoing characterization of these products reveal them to not be predicted dienes 4-Ph, but perhaps unexpected product 5-Ph or 6-Ph, formed from loss of HCl. DFT calculations show the addition of the second equivalent of RCCl to vinylcarbene 2 and to cyclopropene 3 to proceed with little or no barrier, with product formation conformationally dependent on 2 and 3. Preliminary direct dynamics trajectories of CCl2 + 2-Cl show evidence of the formation of dienes 4-Cl, whereas CCl2 + 3-Cl appears to produce 5-Cl. Given the challenge of elucidating the mechanism of this system, we are alternatively entering the reaction path midway. We are synthesizing the diazirine precursors to vinylcarbenes 2-Ph and its open-chain analogue 2’-Ph. Calculations show 2’-Ph to preferentially form cyclopropene 3’-Ph or cyclopentene 7’-Ph, which also appears to form enantiospecifically. We report our progress on the experimental characterization of the 2 RCCl + DIBO products, experimental efforts towards the synthesis of the diazirine precursors of vinylcarbenes 2-Ph and 2’-Ph, and our recent calculations on these systems.

Untangling the mechanism of chlorocarbene additions to dibenzocyclooctyne

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.