Baeyer-Villiger has always been one of my favorite reactions, owing to the double coolness of the use of peracids and an alkyl migration in the mechanism. Malkov et al. have written a very nice JOC paper describing the enantioselective preparation of lactones from prochiral cyclic ketones using the Baeyer-Villiger reaction, complete with a rich history of recent chemistry in the area. They don’t actually use a peracid as oxidant, opting instead for UHP (urea-hydrogen peroxide), but this slight coolness deduction is more than made up for by their use of palladium catalysis. Using chiral P,N-ligands (derived, interestingly, from terpenes), they were able to obtain up to 80% ee of chiral gamma lactones, more or less state-of-the-art for asymmetric B-V reactions. Procedures for making the ligands and even the cyclobutanone starting materials are included right there in the paper! Woohoo!
Aside: here’s to hoping that when some poor grad student googles “state of the art baeyer-villiger,” they end up here.
There’s an odd double-slash mark next to the title of the paper, which links to a dedication to the memory of Otto Exler. I’ve read a lot of papers in my day, and I’ve honestly never seen that before. Call me sentimental, but I thought it was nice. See? Not all scientists are heartless!
For the mechanistically thirsty, this paper discusses intermediates involved in a few variants of the asymmetric B-V reaction.
And last but not least: happy end of the semester everybody!