I don’t want you to think that I have been reading only Diels-Alder literature of late, but I found the recent JACS paper from Michael Doyle’s lab to be quite remarkable. The authors report a mild conversion of diene-tethered diazo compounds to the corresponding [4+2] cycloaddition products. Prior to the Doyle work, diazo compounds were not known to partake in cycloadditions of this kind. When I read stuff like this, I inevitably ask myself: how many times such a reaction happened (unbeknownst to the experimentalist) in the past? You have to agree that people must have studied metal-catalyzed intramolecular cyclopropanation processes in which a diene was evaluated as the carbenoid acceptor. But then maybe no one bothered to evaluate dienes in that capacity. Otherwise, how can one possibly imagine that a room temperature pathway to the Diels-Alder adducts shown below has remained veiled for so long? There is some gold-based catalysis described in this paper as well, but it is the room temperature transformation in chloroform that is surprising.
Was the title of this post an ode to Bond girls of yore? Always enjoy reading your thoughts…
Ha! Indeed, Warren. Good to hear from you.