Showing posts with label Maimone. Show all posts
Showing posts with label Maimone. Show all posts

Saturday, August 15, 2015

Hyperspeed Hyperforin

Kudos to the Maimone group (UC-Berkeley), who have published in JACS ASAP what seems to be the speediest synthesis of a hyperforin on record - just ten steps!

Perhaps this lends more credence to the Eastgate's "current complexity" index, which measures synthetic simplification over time thanks to improved methods. But who would have guessed that in just five short years this synthesis would telescope from 50 steps down to just 10? Strychnine, albeit a very different challenge, took nearly 60 years to simplify from 30 steps down to Vanderwal's highly-convergent six.

For Chemists: Steps of interest include a highly-oxidized [4+2] diketene cycloaddition, a iodoacetate-promoted ring expansion, and a highly modular synthesis widely amenable to analogue production.

For Everyone Else: Why should I care that this ungainly-looking molecule was made faster than before? First, hyperforin and related secondary metabolites (natural products produced by living organisms) isolated from famous folk remedy St. John's wort suggest new avenues for the treatment of of malaria and certain forms of depression. Second, if chemists can make variations on this molecule in roughly one-fifth the time, we can expect a venturesome start-up somewhere to begin fleshing out the SAR (what chemical modifications product what activities?) in record time.

Friday, March 28, 2014

Friday Fun: Sweet Cardamom (Peroxide)

Rice pudding. Ginger snaps. And...malaria?

That's what'll be going through my head next time I cook with cardamom, thanks to Tom Maimone and coworkers (UC-Berkeley) and their under-the-wire JACS ASAP from yesterday afternoon. The title and abstract scratch all the Baran lab alumni itches: 1) biosynthetically inspired, 2) novel mechanisms, 3) scalable, 4) just four steps! And hey, we're making stable endoperoxides, which all the cool kids are into nowadays.


Not their actual abstract graphic...
As Maimone points out, the latent symmetry of the final product offers a really neat assembly strategy. The group McMurrys together two units of (-)-myrtenal, then hits it with singlet oxygen, initially forming a 6-membered endoperoxide they fragment / rearrange with base. A gentle oxidation (DMP) sets them up for the wild step: stitching together a 7-membered endoperoxide using Mn(III)*, a radical source, a silane reducing agent, and even more oxygen. Simple phosphine reduction knocks down the last hydroperoxide into an alcohol, and the whole target (7 stereocenters!) falls out as a single stereoisomer.

Pretty sweet.

P.S. - Since the group's made over half a gram in just this first push, I'd assume an efficacy paper against live Plasmodium parasite hot on the heels of this one...

*We're apparently already calling this the "Shenvi catalyst"...wasn't this only two months ago?