We are applying experimental and computational strategies to elucidate the mechanism of phenylchlorocarbene (PhCCl) addition to dibenzocyclooctyne (DIBO, 1b). Our experiments have shown the addition of two equivalents of PhCCl to DIBO to give three products. Our characterization of these products reveals at least one of them not to be dienes 4b-A-Ph or 4b-C-Ph, but perhaps unexpected products 4b-B-Ph or 4b-B-Ph’, formed from loss of HCl. DFT calculations show the addition of the second equivalent of PhCCl (also, CCl2) to vinylcarbene 2b-Ph and to cyclopropene 3b-Ph to proceed with little or no barrier. Our other approach to deciphering the reaction path involves the syntheses of diazirines 6b-Ph and open chain analogue 6a-Ph, which will allow access to vinylcarbenes 2b-Ph and 2a-Ph, respectively. Calculations show 2a-Ph to preferentially form cyclopropene 3a-Ph or cyclopentene 7a-Ph. Experimentally, we report the characterization of the three products resulting from 2 RCCl + DIBO products thus far. We also describe our progress on the syntheses of diazirines 6-Ph, and our recent calculations on these systems.

Continuing puzzle of the mechanism of phenylchlorocarbene addition to dibenzocyclooctyne

2019 Spring National Meeting

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